HUMB1000 VIP Notes PDF

Human Structure and Function Course Notes Lecture 1- What is Life? 1. Define the levels of organisation in the body. 2. Define the characteristics of living things. 3. Use appropriate anatomical terminology to describe orientation and location of body parts and anatomical relati...

Human Structure and Function Course Notes Lecture 1- What is Life? 1. Define the levels of organisation in the body. 2. Define the characteristics of living things. 3. Use appropriate anatomical terminology to describe orientation and location of body parts and anatomical relations. 4. Describe the major trunk cavities and their divisions. 5. Identify the major organs in each abdominal quadrant/region. 6. Describe the location and function of serous membranes. What is Anatomy? Scientific discipline that investigates the structure of body parts and how they relate to each others- systems/organs/tissues/what organs are made of/shapes of organs and locations. Levels of Anatomy: Gross anatomy: structure examined without microscope. 1. Systemic: body is studied system by system. 2. Regional: body is studied area by area or region by region (identify relationship between various structure of the area. E.g. arm- muscles, nerves and blood vessels in the arm. Surface (type of gross): study of the external form of the body and its relation to deeper structure. E.g. sternum and the ribs overlaying the heart. Microscopic: structures examined with the aid of a microscope. → Cytology: Study of cells and their content- urine sample, papsmear. → Histology: study of tissues and cells that make up the tissues- e.g. diagnosis or melanoma (cut sample of mole to lab where it is viewed at high mag). Developmental: structural changes that occur in the body throughout the lifespan. What is Physiology? Study of the function of living things. Levels of Physiology: Molecular- examines activities of molecules in a cell e.g. proteins/protein channels on cell membrane/ receptors on cell membrane. Cellular- how cells interact and communicate with one another. Systemic- examines physiology of cells and tissues of organs of the body systems. Neurophysiology- study the physiology of the nervous system. Renal- study of the kidneys and urinary system.  Cardiovascular- study of the heart, blood circulation and the blood vessels. Examples of Anatomical and Physiological Studies: Measuring the electrical conductivity of the heart- P Viewing cells under a microscope- A Using a vitalograph (measures capacity of lungs- how much air it can hold, and how much air can be breathed out) to test respiratory function - P Observing the interior and exterior structures of the brain- A Measuring blood pressure after a running race- P Dissecting a heart- A Organisation of the Human Body: 1. Atomic level à Molecular levels = atoms interact to form molecules. 2. Molecular à Cellular = molecules (DNA, RNA) combine to form organelles (organs found in the cell e.g. nucleus). *cell basic structure of the human body. 3. Cellular à Tissue = numerous cells that join together to form a tissue. Tissues are groups of similar cells that work together to perform a similar function. 4. Tissues à Organ= (can be more than one type) form organs. 5. Organ à System = one or more organs make up a system. Characteristics of Living Things: Organisation: relationships among the parts of an organism and how those parts interact to perform specific functions. (E.g. tissues of urinary bladder). Metabolism: chemical reactions taking place within an organism. Responsiveness: organisms’ ability to sense chances in its environment and adjust to those changes (e.g. homeostasis). Growth: increase in size or number of cells (e.g. hair growth). Development: changes an organism undergoes through time (changes undergo through puberty). Reproduction: formation of new cells or organisms. Homeostasis: Existence and maintenance of a relatively constant environment within the body. Includes body temperature, blood pressure, pH, glucose, carbon dioxide, and oxygen. Homeostatic mechanisms maintain the body near an ideal normal point called the set point (e.g. body temperature 37 degrees). Homeostasis is still maintained when small fluctuations occur above or below the set point = normal range. Minor changes: little disturbance that the body can recover from.  Major: more important, body unable to return to normal level and requires intervention and help. Anatomical Position: Used to describe a person who is - Standing erect - Face directed forwards - Hands by side, palms of the hands are facing forward. Why? Because it gives a point of reference to describe the different parts of the body. Body Positions: Supine: person is lying face up. Prone: person is lying face down. Directional Terms: Superior/ Cephalic/ Cranial: towards the head. E.g. the head is superior to the neck. Inferior/ Caudal: towards the tail. E.g. the pelvis is inferior to the stomach. Anterior/ Ventral: towards the front. E.g. the nose is anterior to the ears. Posterior/ Dorsal: towards the back. E.g. the ankles are posterior to the lips. Proximal (limbs): nearest. E.g. the elbow is proximal to the wrist Distal (limbs) : distant/further away from the point of attachment. E.g. the fingers are distal to the wrist. Medial: towards the mid-line of the body. E.g. the nose is medial to the eyes. Lateral: away from the mid-line of the body. E.g. the ears are lateral to the lips. Superficial: close to the surface of… e.g. the epidermis is superficial to the dermis. Deep: towards the interior of… e.g. the bone is deep to the adipose tissue. Body Planes: Saggital plane/median: runs vertically down the body separating the body into left and rights portions. Frontal plane/coronal: runs vertically from left to right, divide the body into anterior and posterior parts. Transverse plane/ horizontal: runs parallel to the ground and divide the body into superior and inferior portions. Oblique: diagonal direction. Body Cavities:  Thoracic Cavity: - Lungs - Mediastinum: collective word to include oesophagus, thymus, blood vessels and the heart. - Diaphragm- sits below cavity- aids in breathing. Abdominal Cavity: - Stomach, intestines, spleen, liver, pancreas, kidneys. Pelvic Cavity: - Bladder, parts of large intestine, reproductive organs. - Abdominal and pelvic cavity are called abdominopelvic cavity. Subdivisions of the Abdomen: Hypo = below. Chondros= cartilage, ribs contain cartilage. Hypochondriac= below the ribs. Lumbar= lumbar regions of the vertebrae. Umbilical= umbilical cord attached near the belly button. Illiac= illium bone of pelvis, is located near there. Serous Membranes: Serosa Serous membranes are membranes that line the cavity in the trunk of the body and cover the organs within these cavities. 2 layers: 1. Parietal- layer lines the trunk cavity.  2. Visceral- layer lines the organs- sits against the organs of your body. Serous fluid produced by the membranes fills the cavity between the two layers and acts as a lubricant between the organ and body wall. WHY WE NEED THEM? We need them as they are a point of attachment to the body, and hold organs to the wall. Additionally they also produce fluid between the two layers, which acts as a lubricant between the organ and body wall. This is especially important for organs that move, to prevent friction. 3 Serous Membranes: Pericardium- serous membrane lining the heart. Pleura- serous membrane lining the lungs and thoracic heart. Peritoneum- abdominopelvic cavity. Pericardium: Peri- outer most. Cardium = cardia = heart. Outermost membrane surrounding the heart. Parietal pericardium- towards the surface. Visceral pericardium- towards the internal. Between two layers is the serous fluid. Pleura: Parietal and visceral layers. Between two layers is the serous fluid. Peritoneum: Parietal (wall of the body) and visceral layers (attached directly to organs). Between two layers is the serous fluid. Retro peritoneum- retro= behind/backwards- sits behind the peritoneum. Lecture 2- How do Cells do What They Do? 1. List the major cell organelles and briefly describe their functions. 2. Distinguish between the cytoplasm, cytosol, and cytoskeleton. 3. Describe the structure of the cell (plasma) membrane. 4. Define the four different types of primary tissues. 5. Define the main characteristics of epithelial tissue. 6. Describe the different cell shapes of epithelia.  7. Define simple, stratified, pseudostratified and transitional epithelia and give an example where each is found including an understanding of why (functionally) it is found in this location. Histology- study of tissues: Preparation of Tissue: 1. Tissue removed from the body- biopsy (alive- e.g. mole), autopsy (person has passed away). 2. Fixation of tissue- placing tissue in chemicals (fixatives, e.g. formalin) to stop metabolic and chemical reactions from occurring the cell. 3. Embedding of tissue- must be embedded, infiltrated with wax and sets so it becomes hard, allows us to later cut the tissue into thin pieces. 4. Slicing of the tissue and mounting on slide- microtome (cuts thin slices of tissue). Thin section is then placed on a slide (the wax used to embed it is dissolved) and then the tissue is stained. 5. Staining Haematoxylin and Eosin: What allows us to visualise tissues Type of stain (H&E). Nuclei are stained purple (from H) whereas the other cells structures, including cytoplasm are stained pink (E). What to Consider When Looking at Histological Images: 1. The plane tissue has been cut in. 2. Magnification of image. Primary Tissues: All organs in the body contain all four primary tissues types: 1. Epithelial à covers 2. Connective tissue à support 3. Muscle tissue à movement 4. Nervous tissue à control Tissue classification based on cells function and extracellular function. Amount of each tissue type varies. Epithelial Tissue 1: Epithelium Characteristics: 1. Covers and protects- surface inside or outside the body. Usually form boundaries between different environments (internal and external). → Covering and lining epithelium  → Glandular epithelium – makes up glands. E.g. sweat glands. 2. Distinct cell surfaces → Free surface- top surface, not attached to anything. → Lateral surface- surface on side. → Basal surface/membrane/lamina- attached to underlying connective tissue (thin supporting sheet, made and secreted by epithelial tissue sitting on top of it). Connective structure of epithelial tissue to underlying connective tissue. Supports/guides cell migration when tissue is damaged. 3. Avascular (doesn’t have blood supply), but innervated (nerve supply). Receives blood from underlying connective tissue. 4. Ability to regenerate. Epithelial Tissue Classification: Classified by number of cells and cell layers/ cell shape. Simple Squamous: One layer of cells. Cell long and flat. Nuclei flat. Little cytoplasm. Functions: 1. Diffusion, filtration and some secretion. Diffusion as its flat, substances can easily diffuse through the flat surface. Location: 1. Air sacs of lungs (diffusion of gases), kidney glomeruli (filtration of substances), serous membranes of pleura, pericardium and peritoneum. Simple Cuboidal: One layer of cells. Cubed shaped. Nuclei rounded. Some of these cells have microvilli or cilia. Functions: 1. Absorption (cube- ease to absorb especially if microvilli) secretion (cube cells have glandular substances in them which allow them to secrete substances) and movement (function of the cilia). Location: 1. Kidney tubules, terminal bronchioles (cilia- role of movement of dust and debris outside of the lungs). Simple Columnar:  One layer of cells. Cells are tall or column shaped. Nuclei oval and located towards base of the cell. Some cilia. Functions: 1. Absorption, secretion and movement. Location: 1. Intestines, stomach (secreted from columnar cell various substances e.g. HCL), fallopian tubes (cilia moves the ovulated egg from ovary to the uterus) and lungs (cilia- move debris/dust out of the lungs). Transitional: Resembles stratified squamous (many layers of squamous cells), and can change shape from cuboidal/squamous depending on it’s state (transitions from one state to the other). Functions: 1. Accommodates changes in fluid volume of the organs. Location: 1. Urinary bladder (cells in bladder need to accommodate changes in urine volume- bladder empty= epithelial cells more up right, full= flattens out), ureter, and upper part of urethra. Stratified Squamous: More than one layer of cells. Thin flat cells- little cytoplasm, flatter nuclei. Usually has protective role in body. Basal cells are cuboidal or columnar and become flatter as you move to the surface. Keratinized- keratin protein which makes tissues durable and long lasting- makes outside of tissue tough. Non-keratinized. Function: 1. Protects against abrasion/loss of water. Location: 1. Keratinized- Sole of feet, palm of hands, skin. 2. Non-Keratinized- Mouth, oesophagus, anus and vagina (friction). Stratified Cuboidal: Rare tissue. Functions: 1. Absorb, secrete and protect. Location: 1. Ducts of sweat glands, salivary glands and developing ovum. Stratified Columnar: Rare tissue. Functions: 1. Secretion and protection. Locations: 1. Mammary glands, larynx and part of male urethra. Pesudostratified Columnar: Single layer of column shaped cells with differing heights, where some cells may no extend all the way to the surface. Nuclei are all over the place and ciliated. Function: - Secretions (tall-shape able to hold contents that needs to be secreted) and movement (cilia carry out function). Location: - Pharynx, trachea, male’s sperm carrying ducts. Cells That Don’t Exist: 1. Simple transitional. 2. Stratified transitional. 3. Pesudostratified squamous/ cuboidal/ transitional Questions: 1. What are the four primary tissue types? Epithelial, connective, muscle and nervous. 2. What are the general characteristics and functions of epithelia? To cover and protect, distinct cell surfaces, avascular but innervated, ability to regenerate. 3. Where are epithelial tissues found? Many locations e.g. lungs, kidneys, bladder, ureters, skin. 4. What are the types of cell surface modifications found in epithelia and what functions do these have? Cilia (help substances move along surface of cell, microvilli (absorption). Lecture 3- Are We What We Eat? 1. List the regions of the digestive system and describe the function of each area. 2. State what contribution the liver, gallbladder and pancreas make to digestion. 3. Explain the difference between digestion and absorption 4. Describe carbohydrates, fats and proteins.  5. Distinguish between vitamins and minerals and state why they are needed. 6. Describe the function of enzymes within the body. Enzymes: A protein catalyst that increases the rate at which a chemical reaction proceeds, without the enzyme being permanently changes. Highly specific- active site on an enzyme can only bind to a specific reactant. Many different enzymes needed in the body for different chemical reactions. Often named by adding ‘ase’ as a suffix to their reactant. E.g. Lipase, enzyme that breaks down lipids. Anatomy of the Digestive System: Digestive tract/alimentary tract. Accessory organs- primarily glands, secrete fluids into tract. Oral cavity with salivary galnds. Pharynx Larynx Oesophagus Stomach Small intestine (duodenum, ileum, jejunum) with liver, gallbladder and pancreas as accessory organs. Large intestine including cecum, colon, rectal and anal canal. Anus Functions of the Digestive System: Ingestion: introduction of food into the stomach (mouth). Mastication: chewing. Chemical digestion requires large surface area so breaking down large particles mechanically facilitates chemical digestion. Secretion: lubricate, liquefy, digest (e.g. mucus secreted along the entire tract, lubricates good, coats and protects lining). Digestion: mechanical and chemical digestion (breaking of bonds, into individual amino acids) of food into nutrients. Absorption: movement of nutrients out of digestive tract into the blood into cells. Elimination: waste products removed from the body; feces, defaction. Histology of the Digestive Tract: One large tube from mouth to anus plus accessory organs. 1. Mucosa: innermost layer, epithelial tissue, secrets mucus, no blood supply. 2. Submucosa: connective tissue later, contains blood vessels (mucus can be rich in the blood vessels, and constantly sends nutrients to the epithelial layer), nerves.  3. Muscularis/Muscle Layers: 2 layers of smooth (involuntary, allow for movement of food (peristalsis)), circular layer, longitudal layer, oblique layer in stomach allowing food to be churned, that will turn bolus into chyme (thick liquid). 4. Serosa/Adventitia: outermost layer, connective tissue, stability. Peritoneum: The walls and organs of the abdominal cabity are lined with serous membranes. - Visceral peritoneum: covers organs. - Parietal peritoneum: covers interior surfaces of body wall. Mesenteries: Peritoneum (epithelial tissue), connects organs together. Routes by which vessels and nerve pass from body wall to organs. - Greater Omentum: connects stomach the transverse to the colon. - Lesser Omentum: connects stomach to liver and diaphragm. Oral Cavity: Process of digestion starts here. Mastication/chewing of food first occurs here. Food broken down into bolus. Palate forms roof of the mouth. - Hard Palate: hard bone, anterior (front). - Soft Palate: soft muscle, important in swallowing. Tongue: - Two sets (childhood, secondary (32)). Teeth: - Types: → 12x molars. → 8x pre molars → 4x canines- grinding. → 8x incisors- cutting food. Saliva Oral Cavity- Salivary Glands: Produce and secret saliva into the oral cavity. Saliva- protects oral cavity, moistens, lubricates and digests food. Amylase- enzyme found in saliva that breaks down carbohydrates (long complex chains of sugars) into smaller sugars. Lysozyme- antibacterial enzyme- protective function- immune defence. Pharynx and Oesophagus: Pharynx (throat)- connects oral cavity to the oesophagus.  Uvula (soft palate) prevents food/drink from entering into the nasopharynx. Oesophagus- tube that connects pharynx to stomach. 25cm long, lies posteriorly to the trachea. Epiglottis (flap of connective tissue) prevents food/drink from entering the trachea, encourages food to go into oesophagus. First 1/3 of oesophagus is skeletal muscle- voluntary control- allows us to cough up food and prevent ourselves from choking. Bottom 2/3 of oesophagus is smooth muscle- involuntary control- peristalsis. Swallowing: 1. Voluntary Phase: Tongue pushes bolus to back of oral cavity towards pharynx, posteriorly towards throat. 2. Pharyngeal Phase: Soft palate closes off nasopharynx (up into nose). Bolus touches receptors on oropharynx there is a reflex that moves bolus of food down the pharynx and into the oesophagus. As it moves down epiglottis closes over trachea and stop food from entering windpipe. 3. Oesophageal phase: Bolus is moved from oesophagus towards the stomach by peristalsis. Peristalsis: Process by which food moves through the gut. Waves of smooth muscle relaxations and contractions. Stomach: Located in abdomen. Holding point for food. Food comes from the Oesophagus and the stomach mixes it with secretions until it turns into chyme. Produces mucus, HCL, digestive enzymes (pepsin). Food comes into stomach via gastooesophageal opening à stomach à third layer of muscle in stomach allows stomach to move around in a circular style. Contains a thick mucus later that lubricates and protects epithelial cells on stomach wall from pH 2-3. Pyloric: opening to duodenum. Parts: 1. Cardiac 2. Fundus 3. Body 4. Pyloric- antrum and canal – exit passageway of chyme into small intestine. Layers: - Visceral peritoneum or serosa- outside covering of all organs in cavity. - Muscle layers- enable churning of food through stomach:  → Outer longitudal. → Middle circular. → Inner oblique. - Submucosa - Muscosa - Rugae: folds in stomach wall that allow stomach to stretch after eating. Movements of the Stomach: 3 muscualar layers enable churning of food. Make chyme. Combination of mixing waves (80%- churning) and peristaltic waves (20%). Both oesophageal and pyloric sphincters are closed. Stomach empties every 4hrs (6-8 after a fatty meal). Small intestine: Very long, approx. 6m, small diameter. Large surface area for efficient absorption of nutrients. Lots of folds in the wall to increase surface area, and increase efficiency of absorption. 3 things that increase SA: 1. Plicae Circulares- circular folds in the wall of the SI. 2. Villi- folds in mucosa that contain capillaries and lacteals. 3. Microvilli- small folds on epithelial cell surface. - Lacteals- lipids- lymphatic system- go to cells when needed. - Carbs/proteins- capillaries- blood. Divisions: 1. Duodenum: - First 25cm beyond the pyloric sphincter. - Chyme mixes with various digestive enzymes. - Liver/gallbladder: Bile made in liver, goes to gallbladder to be concentration, enters through common bile duct into the duodenum. - Role of bile is to emulsify fats in the chyme. - Pancreas: enzymes enter the duodenum via pancreatic duct. o Lipase- lipids. o Pancreatic amylase- carbs o Trypsin- proteins. 2. Jejunum- 2.5m 3. Ileum- 3.5 Liver, Gall Bladder and Pancreas: Liver: - Makes bile. - Stores glucose (as glycogen) and lipids for energy.  - Detoxification. Gallbladder: - Store bile. - Concentrate it there. - Release it during fatty meals. Pancreas: - Produces digestive enzymes. - Produces insulin and glucagon for blood sugar homeostasis. Large Intestine: Absorption of water. Extends from ileocecal junction to anus. Consists of cecum, colon (ascending, transverse, descending, sigmoid), rectum, and anal canal. Bacteria/microbes synthesise vitamin B and K. 18-24hr-transit time: chyme à faeces. 90% of chyme reabsorbed. 10% leaves the body through defecation reflex. The Digestive Process: Digestion- mouth, stomach, SI: - Breakdown of food molecules for absorption into circulation. - Mechanical: breaks large food particles to small. - Chemical: breaking of covalent bonds by digestive enzymes. Absorption: nutrients from the SI, water from the LI. - Molecules are moved out of digestive tract and into circulation for distribution throughout the body. Nutrients: Chemicals are taken in to the body to produce energy, providing building blocks to build other molecules. 6 classes: carbs, proteins, lipids, vitamins, minerals and water. Carbs, proteins and lipids are major organics nutrients (organic= contains carbon). Need large amounts of carbs, proteins, lipids and water. Only need small amounts of vitamins and minerals- taken in to body without being digested. Essential nutrients- is chemicals that must be taken in to the body because we can’t make them ourselves. - Includes some amino acids/fatty acids/ carbs, water, most vitamins and mineral. Classes of Nutrients: 1. Carbs- mono (one sugar)/di (two sugars)/polysaccharides (more than two)- plants, vegetables. 2. Lipids- triglycerides- oils, dairy, animal fats, eggs. 3. Proteins- chains of amino acids- meat, fish, poultry. 4. Vitamins- organic molecules (vit A,B,E)- animal and plant products. 5. Minerals- inorganic nutrients (calcium, iron)- animal and plant products. 6. Water. Recommended Amounts: Carbs- 45-65% of daily intake of kilocalories. Lipids- 10-25% or less of total daily kilocalories. Proteins- 10-35% of total kilocalories per day. Carbohydrates: Most come from plants (besides lactose from milk). Contain carbon (C), hydrogen (H) and oxygen (O) = CHO 2H and 1O for every C (the 2H;1O ratio is the same as for water). Carbo= carbon; hydrate = water/hydrated. Large molecules are made up of small building blocks. - Monosaccharides. Monosaccharides/ Disaccharides: Monosaccharides: - Glucose (blood sugar) - Fructose (fruit sugar) - Galactose (milk sugar). Disaccharides: - Sucrose (table sugar) = glucose + fructose. - Lactose (milk) = glucose + galactose. - Maltose = glucose + glucose. Polysaccharides: Long chains – 3000+ monosaccharides. Glycogen: - Animal polysaccharide - Glucose molecules- stores when too much. - Stored in humans in liver & muscle, until required by body. Starch and Cellulose: - Plant polysaccharides. - Humans break down starch = energy. - Humans can’t break down cellulose = dietary fibre. Carbohydrate Absorption: Polysaccharide chain e.g. glycogen introduced into the body. They begin to be digested by saliva in oral cavity (salivary amylase) and pancreatic amylase in duodenum. Disaccharide e.g. sucrose- digested by sucrose into intestine. Down to monosaccharide e.g. glucose- digested out of the SI into the blood via villi/microvilli in intestine. Going through the body it travels to the liver (hepatic portal vein), where it will decide if body requires it or whether it needs to be stored as glycogen in the liver. Carbohydrates: Uses in the Body: Glucose à ATP. Excess glucose à stored as glycogen in muscle and liver cells. Excess beyond this stage converted to fat and stored in body as adipose tissue. Sugars also become part of DNA, RNA (sugar backbone- sugar comes from carbs that come into the body), ATP, glycoproteins, glycolipids (cell membranes). Proteins: Contain carbon (C), hydrogen (H) oxygen (O), nitrogen (N) and sometime sulphur (S). Amino acids are the basic building blocks. Each amino acid has an amine group (NH2), a carboxyl group (COOH), a hydrogen and side group. Side group is what is different between amino acids. Amino acids link together to form peptides (2 amino acids), polypeptides (more than 2) and proteins. Amino acids are not stored in the body. Essential amino acids, can’t be produced by body so need to be obtained from diet. Non-essential AA which are required by body, cannot be made by body – synthesised by essential AA. Complete protein source- food that contains enough of all 9 essential AA. E.g. meat, dairy. Incomplete protein source- don’t contain all 9 essential AA. E.g. grains, legumes. Functions of Proteins: 1. Globular proteins= haemoglobin. 2. Structural- muscle proteins or CT. 3. Cell membrane transport. 4. Enzymes.  5. Hormone. 6. Antibodies. Protein Absorption: Protein (long chain of AA). Digested firstly by pepsin in the stomach. Proteins are turned into polypeptides, which are further digested by trypsin in the duodenum. Peptides and individual AA are what are absorbed into the blood, by villi/microvilli to be absorbed by different parts of the body. Lipids: Composed of mostly carbon, hydrogen, oxygen, sometimes nitrogen and phosphorus. Lower ratio of O to C than carbs, relatively insoluble in water. Lipids/fats are broken down to release energy when digested. Triglycerides make up 95% of fats in body. - Glycerol + 3 fatty acids. Triglycerides: Glycerol + 3 fatty acids. Fatty acids: - Different lengths. - Saturation: how many H atoms on each chain - Saturated: for all C molecules, they’ve all got H attached to them. E.g. animal fats like beef, pork, milk, cheese, butter. - Unsaturated: double bond between C’s and less hydrogen atoms. Tend to be liquid at room temperature, relaxed structure. - Trans Fats: unsaturated fats that are artificially altered to be more saturated (more H hanging off them) (CVS risk). E.g. fast food. Lipid Absorption: Lipid digestion begins in duodenum. Bile from gall bladder goes into duodenum emulsifies lipids, to increase surface area of the lipid globules. Lipase from the pancreas causes further breakdown. Short chain fatty acids (monoglycerides) are absorbed into the lymphatic system via lacteals à heart à blood stream à distributed around body or stored in adipose tissue/liver until needed. Uses: 1. Triglycerides: used to produce ATP. 2. Cholesterol: found in liver and egg yolks, or manufactured by body. Component of plasma membranes, modified to form bile salts.  3. Phospholipids: major components of plasma membrane, myelin sheath (sheath that covers neurons, increases the rate of transmission of nerve impulses), part of bile. 4. Eicosanoids: derived from fatty acids. Involved in inflammation, blood clotting, tissue repair, and smooth muscle contraction. Water Absorption: Approx. 9L of water enters digestive tract every day. 99% of water entering the intestine is absorbed. Water can move across the intestinal wall in either direction if required. Ions: sodium, potassium, calcium, magnesium, phosphate are actively transported across either side of intestinal wall in the water. Vitamins: Organic molecules in very small quantities in food. Essential for normal metabolism and can’t be produced by the body. No one food provides all necessary vitamins. Some vitamins produced by intestinal bacterial e.g. vit K. Vitamins can be fat soluble (A, D, E, K) or water soluble (B and C vitamins). Too Much: - Vit C- stomach inflammation, diarrhoea. - Vit A- toxic during pregnancy. - Vit D- alter calcium metabolism. Vitamin Deficiencies: - Vit D- rickets. - Vit C- scurvy - Vit B2- beriberi Minerals: Inorganic nutrients. - Major minerals > 100mg/day- e.g. Ca, Na, K. - Trace mineral < 100mg/day- e.g. zinc, copper. Components of co-enzymes, some vitamins, haemoglobin, organic molecules. Functions: 1. Membrane potential and action potentials. 2. Add mechanical strength to bones and teeth. Available from both plant and animal based products. Mineral Deficiencies: - Iron- anaemia. - Potassium- muscle weakness, abnormal heart function. - Iodine- goitre (thyroid). Lecture 4- Why do we Breathe? 1. Describe the basic anatomy of the respiratory tract beginning at the nasal cavity and ending at the alveoli. 2. Describe the structure of the lungs. 3. Explain the role of the thoracic wall and pleura in respiration. 4. Explain how contraction of the respiratory muscles causes a change in the thoracic volume during quiet and active breathing. 5. Describe the changes in the alveolar pressure and how they relate to the movement of air into and out of the lungs. 6. Describe how surfactant and pleural pressure prevent lung collapse. 7. Define alveolar ventilation, pulmonary volumes and capacities. Functions of the Respiratory System: Respiration: breathing in oxygen into the lungs, and exhaling carbon dioxide out of the body. 1. Ventilation/ Pulmonary Ventilation: movement of air in and out of the lungs. Movement of air when you inspire and expire. 2. External Respiration/ Gas Exchange: movement of oxygen, which has been breathed in from the lungs to the blood. And the movement of waste CO2 from the blood to the lungs. 3. Transport of Respiratory Gases: movement of gases around the body into the blood. 4. Internal Respiration: gas exchange between the blood and tissues. Diffusion of oxygen from blood to tissues: Regulation of blood pH. Voice Production: as air moves from lungs past vocal cord folds in throat this process allows your voice to be projected. The vibration of the vocal folds caused by air creates a voice. Smell (olfaction sense): When air contains smell molecules they move through nasal cavity, olfactory receptors in NC pick up smell molecules and transmit messages to the brain. Protection: protects against foreign particles, removes from RS by mucous/ hair. Divisions of the Respiratory System: Structural Classification: - Upper Respiratory Tract: external nose, nasal cavity, pharynx, and larynx. - Lower Respiratory Tract: trachea, bronchi, lungs and structure within. Functional Classification: - Conducting Zone: respiratory passages where air travels from your nose à terminal bronchi in the lungs. Cleansing, humidifying and warming the air, so it can be similar and clean to the air already in your lungs. - Respiratory Zone: located in lungs, exchange of air between the lungs and the blood. Respiratory bronchioles, alveolar ducts, alveoli. Conducting Zone: Nose: - External nose (bone and cartilage, stratified squamous epithelium). - Nasal cavity: → Extends from nostrils à choana. → Vestibule- entry to NC- lined with stratified squamous epithelium, sweat and sebaceous glands as well as hair follicles. → Hard Palate- floor of nasal cavity, separates oral cavity from NC. → Soft Palate- continuation of hard palate, made of muscular tissue, posterior extension of soft palate is uvula (u-shaped hanging structure at the end of your mouth). → Septum- separates nasal cavity into left and right parts. Anterior part- cartilage tissue, posterior- bone. → Concha: v Bony ridges- superior, middle and inferior concha. v Meatus- groove/passage ways that lie inferior to ^. v Role of these is to increase SA in NC- allows air moving through nose to catch onto surface of NC (mucous/hair) catching unwanted debris that we’ve just breathed in. v Both of these creates a more turbulent airflow in NC to allow things to come in contact with the mucous lining of the cavity. v Epithelium of concha is pseudostratified ciliated columnar epithelium. Mucous glands scattered in between epithelium, which produce secretions of nose (snot), mucous catches debris moving in through nose, cilia on cells move mucous down to throat à where it is swallowed and digested. → Functions: 1. Passageway for air- air moves from outside to inside into lungs via NC. 2. Cleans the air- hair that lines vestibule and NC trap dust breathed in. Mucous secreted from epithelium catches unwanted debris/dust in air. Cilia move mucous down to throat where it is swallowed. 3. Humidifies and warms the air- warmed to body temperature by warmed blood in NC, humidified by moisture of the mucous epithelium, and excess tears that drain into NC. 4. Olfaction. 5. Sound of voice- NC resonating chamber for speech. Pharynx: - Opening of the DS and RS both begin. - Runs from choana à larynx. - Three regions: → Nasopharynx: v Posterior to the NC.  v Where soft palate ends. v Lined with pseudostratified ciliated columnar epithelium. v Houses openings of Eustachian tubes from each ear- links NP to middle ear- tubes allow for air pressure in middle ear to equalise with atmospheric pressure, also drain the middle ear of any mucous that is built up (want to drain because it can harbour bacteria which can lead to bacteria if not drained. v On the posterior surface of the NP is the pharyngeal tonsils (lymphoid tissue- first lines of defence, makes body aware of foreign material so a defence can be mounted. → Oropharynx: v Sits behind oral cavity (posterior). v Stratified squamous epithelium- several layers of flattened cells- protection to prevent friction of food going through that area. v Palatine tonsils (side tonsils). v Lingual tonsils (sit rat the back of the tongue). → Laryngopharynx: v Lies posterior to the epiglottis. v Stratified squamous epithelium- friction purposes= protective role. Larynx: - Voice box. - Passageway for air. - Made up of 9 pieces of cartilage- connected by various muscles and ligaments. → 6 of these are paired (two of each, sit on both side). v Arytenoid v Corniculate v Cuneiform. → 3 unpaired: v Thyroid- Adam’s apple- thyroid gland sits underneath next cartilage, which is cricoid. v Cricoid v Epiglottis- spoon shaped- when you swallow food the larynx moves back and the E moves over to carry larynx. - Functions: → Maintains an open passage for air movement- facilitated by thyroid and cricoid cartilages. → Directs food into oesophagus away from respiratory tract- facilitated by epiglottis. → Sound production via vocal cords- when you expire, movement of air past folds causes them to vibrate which produces sound.  → Trap debris from entering lungs- facilitated by pseudostratified cilium columnar epithelium which lines larynx below vocal folds. Removes unwanted particles by the action of the cilia. Trachea: - Descends from larynx and sits anterior to the oesophagus. - Made up of 15-20 ‘C’ shaped hyaline cartilage- provides support for the trachea to maintain an open passageway for the air to move through. - Side of the trachea adjacent to the oesophagus doesn’t have cartilage, but instead smooth muscle and connective tissue- allowing for flexibility of trachea as food moves down the oesophagus, the oesophagus expands anteriorly into the trachea, and the trachea diameter can narrow to allow for this expansion. - Dense connective tissue and smooth muscles in between cartilage rings. - Tracheal lumen (inner most surface) lined with pseduostratified ciliated columnar epithelium with goblet cells scattered in between. Tracheobronchial Tree: - Trachea starts off with mostly cartilage tissue a bit of smooth muscle tissue, between the cartilage rings. As you move down into lungs this changes, the amount of cartilage decreases, and the amount of smooth muscle increase. - Respiratory passages from the trachea, to the terminal bronchioles in the lung. - First structure: carina- large piece of cartilage in trachea- point where trachea bifurcates into two bronchi. Sensitive area- any foreign material making contact with can result in a violent coughing fit. - Carina à two branches (primary bronchi). - L and R primary bronchus à secondary bronchus in lungs. - Right lung- 3 lobes vs left lung- 2 lobes. Each lobe is served by one lobar bronchus.  - Lobar bronchi à tertiary or segmental (each lobe of lung can be further divided into segments- 9 in R, 8 in L) bronchus. - Tertiary or segmental bronchi à bronchioles (smaller than mm in diameter, smallest part of bronchiole is a terminal bronchiole (end of conducting zone). Respiratory Zone: Place where gas exchange takes place- movement of air from lungs to blood. Terminal bronchioleà respiratory bronchioles (have alveoli sitting on the end of them) à alveolar ducts à 2 or 3 alveolar sacs (clusters of alveoli- air filled chambers where gas exchange takes place)à elastic fibres on alveoli allow them to expand and recoil during breathing. Alveoli contribute to providing the large surface area for gas exchange to take place. Respiratory Membrane: - Additional to elastic fibres are veins and small capillaries. - Surface that makes contact between the alveoli and blood capillaries is the site of gas exchange. On outside (blood flowing on alveoli), within alveoli is the gas. - Characteristics of RM or site of gas exchange- Alveolus Side: → Made up of an alveolus side- simple squamous epithelium- one layer, flat cell, allows for quick diffusion of gases in and across the respiratory membrane. → Type 1 Pneumocyte:  v Gas exchange takes place through simple diffusion across membrane. Oxygen from alveolus side is exchanged into the blood, CO2 is diffused the other way. → Type 2 Pneumocyte: v Cuboidal cells- role to secrete surfactant to reduce surface tension. High surface tension can build up in lungs, from the alveoli fluid that lines the alveoli, doesn’t allow gases to penetrate the respiratory membrane. → Macrophage: when foreign material bypasses protective features of upper RS, these destroy unwanted matter. E.g. dust, debris, bacteria. → Basement Membrane: epithelium cells sit on this. - Characteristics of RM or site of gas exchange- Capillary Side: → Basement membrane → Capillary endothelium- epithelium on inner side- simple squamous cells (one cell, flat to allow for rapid diffusion of gases). → Red blood cells (erythrocyte)- presence of these indicates capillary side. Lungs: - Cone shaped with a base and apex. - Left lung has 2 lobes (superior/inferior) + cardiac notch (space where heart sits. - Right lungs have 3 lobes (superior/middle/inferior). - Lobes separated by fissures- indentations. - Hilum on medial surface of each lung- entry point for blood vessels and nervous supply, lymphatic vessels and bronchi. - Lobes à bronchopulmonary segments (9 in R, 8 in L), separated by connective tissue septa, each segment receives own artery and vein.  Pleura: - Serous membrane lining thoracic cavity. - Outer parietal pleura- thoracic wall. - Inner parietal pleura- connects directly to lungs. - In between parietal and visceral (inside) pleura is a pleural cavityà pleural fluid to reduce friction between lungs and thoracic cavity during the process of breathing. Factors Affecting Gas Exchange Through RM: Thickness of RM: - Thicker the membrane reduces the rate of movement of gas. - 0.5-1um – promotes normal rate of gas exchange. Surface Area: - Lower SA reduces the volume of gas exchange taking place. - SA changes: fluid build-up in alveoli, emphysema (alveoli SA decreases rapidly as the walls of the alveoli are broken down), presence of tumour (which covers surface). Diffusion Coefficient: - How easily a gas can diffuse in and out of a liquid or tissue. - A relative number- different coefficients depending on environment. - E.g. Oxygen coefficient of 4 in lungs vs CO2 coefficient of 20, means CO2 can moves through respiratory system 5x more than oxygen. Partial Pressure: - Pressure exerted by each gas in a mixture of gases.  - When Pp is greater on one side of the RM, the gas moves from higher to a lower Pp. - Promotes gas movement across the RM. Gas Transport: Oxygen: - Transported in red blood cells, attached to a protein called haemoglobin molecules (98%). - Remained dissolved in blood plasma (2%). Carbon Dioxide: - Bicarbonate ion dissolved in plasma (70%). - Plasma (7%). - Bound to haemoglobin (23%). Breath in air à alveoli à moves across RM à blood. - Pp causes movement of O across RM into blood. - Once oxygen is in the blood it moves to the heart à heart pumps to rest of the body into the tissues due to Pp. - In tissue oxygen is used, CO2 produced as a waste product à moves from tissues to blood à down concentration gradient à transported back to blood à heart à pumps to lungs à across RM due to Pp à alveoli à lungs to the outside of the body. Pulmonary Ventilation: Process of moving air into and out of the lungs. Structures involved: - Ribs- attach to sternum by cartilage, (12 pairs), protects organs within cavity. - Sternum  - Lungs underneath ribs. - Underneath lungs is diaphragm. - Intercostal muscles- between ribs. Inspiration: Lungs: volume increases as it fills with air. Diaphragm: flattens down. Rib cage: elevated, rise up. Sternum: elevated. Intercostal muscles: contract, so rib cage and sternum can move up and out. Expiration: Lungs: volume decreases as air leaves. Diaphragm: relaxes, moves superiorly. Rib cage: depresses. Sternum: depresses. Intercostal muscles: relax. Airflow in and out of Alveoli: Boyle’s Law: volume is inversely proportional to pressure- opposite. - Inspire- volume increases, pressure of gases decreases. - Expire- volume decreases, pressure of gases increases. Barometric Air Pressure: atmospheric air pressure outside of body. Intra-alveolar Pressure: pressure inside alveoli. End of Expiration: Barometric AP = Intra-alveolar – because there is no movement air. During Inspiration: Diaphragm moves down and flattens, rib cage elevates, IC muscles contract à actions cause volume of lungs to increase. Boyle’s law- lung volume increases; pressure decreases à causes air to move from high pressure to low pressure, into the lungs. End of Inspiration: Alveoli at capacity- stop expanding. Barometric= intra-alveolar. During Expiration: Actions cause lung volume to decrease à pressure in alveoli increases, becoming greater than pressure outside. Air moves from high to low pressure, moving out. Changing Alveolar Volume: Pleura- visceral/parietal, between pleura is cavity. Pressure built up within the cavity is known as intrapleural pressure. Forces Which Promote Lung Recoil: - Movement of air out of lungs. - Alveoli covered in fine elastic fibres- return to natural state. - Fluid which coats alveoli: v Surfactant- reduces surface tension. Forces Which Promotes Lungs Expansion: - Intrapleural pressure - Adhesion of visceral pleura to parietal is absent- Intrapleural would increase above intraalveolar pressure which would make lungs collapse. - Factor for expansion is ensuring Intrapleural < intraalveolar. Pulmonary/ Lung Volumes: Volume of air involved in the different stages of breathing- when you inspire and expire. Tidal Volume: - The amounts of air inspired or expired with each breathe. At rest is ~ 500mls breathed in and out. Inspiratory Reserve Volume: - The amount of air that can be inspired forcefully after inspiration of the tidal volume. Inspiring even further (3L). Expiratory Reserve Volume: - The amount of air that can be forcefully expired after expiration of the tidal volume. Reserve for further expiration (1.1L). Residual Volume: - The volume of air still remaining in the respiratory passages and lungs after the most forceful expiration (1.2L). Pulmonary Capacities: Sum of two or more pulmonary volumes. Inspiratory capacity- amount of air a person can inspire maximally after normal expiration (tidal volume + inspiratory reserve volume). Functional residual capacity- the amount of air remaining in the lungs at the end of a normal expiration (expiratory reserve volume+ residual volume).  Vital capacity- maximum volume of air that can be expelled from the respiratory tract after a maximum inspiration (inspiratory reserve volume+ tidal volume+ expiratory reserve volume). Total lung capacity- inspiratory reserve volume + expiratory reserve volume + tidal volume + residual volume. Definitions: Respiratory Rate: number of breaths taken per minute. 12. Minute Ventilation: total amount of air moved into and out of the respiratory system each minute (tidal volume x respiratory rate). Anatomic Dead Space: space formed by nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles (regions where gas exchange is not taking place). Volume = 150 mls. Alveolar Ventilation: volume of air available for gas exchange per minute. Measuring Lung Function: Why? Diagnose disease (asthma). How? - Using a spirometer (measurements compared to what’s considered in normal range to determine how well lungs are working- STATIC LUNG FUNCTION). - Dynamic. What? - Measuring lung volumes and capacities. Dynamic Lung Function: Lung volume measurement in relation to time. Vitalograph Parameters measured: - Forced vital capacity- maximal volume of air that can be forcefully expired as fast as possible after a deep breath in. - Forced expiratory volume in 1 second- volume of air expired in the first second when performing a FVC. - Forced expiratory volume 1%- FEV1second, expressed as a % of FVC. FEV1sec divided by FCV x 100. - Point of knowing 3 parameters- indicator of what type of lung disease someone has. v Obstructive lung disease: rate of getting air out of lungs is slower. FEV1sec as an indicator of an obstructed airway. 1. FVC: obstructive = normal. 2. FEV1sec: obstructive a lot less than normal. 3. FEV1%= obstructive a lot less than normal.  v Asthma: airways narrowed as muscles around airway are tightened. v Restrictive lung disease: problems fully expanding lungs, not all air can come out, lung volume less. FVC is an indicator of a restricted airway. E.g. emphysema. 4. FVC: restrictive a lot less than normal. 5. FEV1sec: restrictive slightly lower than normal. 6. FEV1%: restrictive = normal. Exercise and Ventilation: Ventilation increases abruptly when you start exercising: - Movement of limbs triggers respiratory centres in brain, controls respiration. If you continue to exercise, ventilation increases gradually 4-6 mins, over time respiratory centre can adapt to continued exercise/training. Exercise adaptions: - Increase in vital capacity. - Decrease in residual volume. - At maximal exercise, tidal volume and minute ventilation increases. Lecture 5- How do we Fuel Our Bodies? 1. List and explain the ways that ions and molecules can pass through the plasma membrane. 2. Explain the process of osmosis and concentration gradients in controlling the movement of water across the membrane. 3. Describe ATP and ADP in terms of the release or input of energy in chemical reactions. 4. Describe the main stages of glycolysis and name its products. 5. Describe the main stages of the citric acid cycle and name its products. 6. Briefly explain oxidative phosphorylation and how ATP is produced in the process. Plasma Membrane: Fluid mosaic model- always in a state of flux and change- can respond to environment around it. Boundary of cell that encloses and supports cells content. Separates intracellular and extracellular environment. Controls what comes in and out of the cell. Base structure is a phospholipid bilayer, with phosphate groups on the outside (hydrophilic= water loving), and the lipid tails on the inside (hydrophobic- don’t like water). Proteins present in membrane.  Membrane channel- protein channel that allows things to move from one side to another easily. Integral vs peripheral proteins- inserted into membrane / sit on the edge. Cytoskeleton- interior, scaffold, provides shape, helps organelles organise themselves. Attaches cells to other cells- cell to cell adhesion, and other matrix (cell matric environment). Selectively permeable- controls what moves in and out at a given time. - Allows intra and extracellular environments to be different. - E.g. Difference in charge across membrane- membrane potential. Lipid bilayer- phospholipids and cholesterol. Proteins- many involved in transporting molecules across the cell membrane. E.g. channel/ carrier proteins, ATP pumps. Transport Proteins- Channel Proteins: Form a tiny channel through the plasma membrane. Molecules of certain size, shape and charge can pass through. Non-gated ion channels always open- free flow for a particular molecule in and out whenever. Gated ion channels- opened or closed by certain stimuli- protein receives messages, which depend on its action- e.g. sodium/potassium pumps. Transport Proteins- Carrier Proteins: Transporters Integral proteins move ions from one side of membrane to the other: - Specific binding sites. - Once it binds causes conformational change. - Proteins changes shape to transport ions or molecules. - Resumes original shape after transport. - Uniporters (transport only one molecule), symporters (two molecules in same direction across the membrane), antiporters (two molecules in opposite directions across the membrane). ATP- Powered Transport: Requires energy in the form of ATP. Transports substances against their concentration gradient, so the cell can accumulate substances (bring in more molecules to increase concentration). E.g. sodium potassium pump. Diffusion and Osmosis- First Principles: All molecules are in a state of random motion (kinetic energy).  Solute: dissolved substance in a solution. E.g. glucose, sucrose, ion-molecule with charge (sodium, potassium, chloride). Solvent: liquid that holds solutes. E.g water. Solution: mixture of solute and solvent. Diffusion: Molecules move from an area of high concentration to an area of lower concentration. Continues until molecules have evenly distributed themselves throughout the solution. Diffusion Through Cell Membrane: 1. Certain specific non-lipid soluble molecules or ions diffuse through the membrane channels. 2. Other non-lipid soluble molecules, for which membrane channels are not present can’t enter the cell. 3. Lipid soluble diffuse directly through the plasma membrane. Facilitated Diffusion: Move large, water-soluble molecules or electrically charge molecules across the plasma membrane. Specific transport mechanism, specific recognition. Amino acids and glucose in, manufactured proteins out. Passive. Osmosis: Diffusion of water across a selectively permeable membrane. A selectively membrane lets water pass through, but not the solutes that are dissolved in the water. Water moves from an area of low solute concentration to high solute concentration à down it’s concentration gradient. Effect of the Concentration of the Solution: Concentration of solute determines how much water moves across. The more concentrated solution, the more the solution will pull water towards it. A dilute or weak solution = weak pull on water and vv. Osmolarity: Pull on water = osmotic pressure/ osmolarity. Osmolarity measured in osmoles/L or mOsmoles/L.  The Osmolarity of a solution is directly related to concentration of solution. Weak solution will have a low Osmolarity value and vv. Osmolarity and Body Cells: Osmolarity of intracellular fluid of a normal cell is approx.. 290mOsmol/L. Body fluids can be divided into intra/extra cellular. Isotonic Solution: When a cell is placed in a solution that has the same osmolarity = isotonic. Water will move between intracellular and extracellular fluid at equal rates. Hypertonic Solution: Higher osmolarity outside of the cell than inside = hypertonic. Exerts a stronger pull on water. Water is pulled out of the cell. The cell loses water and shrinks. Hypotonic Solution: Higher osmolarity inside of the cell than outside = hypotonic Exerts a stronger pull on water. Water is pulled into the cell. The cell takes in water- swells and bursts (cell lyses). Osmosis and Body Cells: A patient needs to be infused with a solution via intravenous drip, to treat dehydration. - Isotonic- slightly dehydrated- encourages movement. - Hypotonic- very dehydrated- fluid back into cells. E.g. 5% dextrose in water. Edema, where excess fluid is accumulating in cells and tissue. Giving a hypertonic solution will encourage fluid to move out of cells and tissue into vascular system to be removed by the kidneys. Metabolism: Total of all chemical processes that occur in the body. Includes: - Catabolism: energy-releasing process, where large molecules are broken down into smaller ones. - Anabolism: energy-requiring process, small molecules are joined to form larger molecules. Anabolism: Two or more reactants chemically combine to form a new and larger product: - Chemical bonds made, energy stored in the bonds. - Responsible for growth, maintenance and repair. - Produce chemicals characteristic of life: carbohydrates, proteins, lipids and nuclei acids. Catabolism: A large reactant is broken down to form smaller products. - Chemical bonds broken, energy released. - Energy in carbs, lipids, and proteins is used to produce energy which drives anabolic reactions. E.g. active cell membrane transport, muscle contraction and protein synthesis. Energy: Capacity to do work. Potential energy- stored in chemical bonds, isn’t working. Kinetic energy- energy doing work, and moving matter. Conservation of energy: - Total energy of the universe is constant, can’t be created or destroyed. - But energy can be converted from one type to another. Focus on chemical energy (and heat energy). Chemical Energy and ATP: Energy is stored in chemical bonds. Breaking chemical bonds releases energy. This energy can then do WORK. There is a large amount of energy stored in the chemical bonds of nutrients. When nutrients are broken down, energy is released. This energy is used to combine ADP with an inorganic phosphate group (P) to make ATP. ATP stores the energy releases from breaking the chemical bonds. ADP + P + Energy à ATP. Some energy released from breaking a bond is not captured and stored as ATP but is lost through heat, which is used to maintain body temperature. ATP and Potential Energy: ATP is the cells preferred way to store energy. The small amount of energy stored in ATP is easier for the cell to access than the larger amount stored in nutrient molecules.  When the cell needs energy it breaks down ATP to ADP. This energy can be used by the cell to make new proteins, repair a damaged cell membrane, and drive active transport across a membrane. Cellular Respiration: Breaks bonds in food to produce energy, which is stored as ATP. Three main stages: 1. Glycolysis- cytoplasm 2. Citric acid cycle- mitochondrial matrix. 3. Electron transport chain/ oxidative phosphorylation- inner mitochondrial membrane. Glycolysis: Cytoplasm. Breaks down 1 glucose (6 carbon molecules) into 2 pyruvate molecules (3 carbon). Uses 2xATP in the early stages. Produces 4x ATP by the end = net production of 2x ATP. Produces 2 NADH molecules – these are used in 3rd step to produce more ATP. Is anaerobic- does not require oxygen. If oxygen is available pyruvate moves into the 2nd stage- the citric acid cycle. If not, pyruvate gets converted to lactic acid (stored until oxygen available). By the end 1 glucose à 2 pyruvate + 2 ATP + 2 NADH. Citric Acid Cycle: Matrix of mitochondria. Acetyl coenzyme A formation. Before the citric acid cycle begins: - Pyruvate (3 carbon) à acetyl CoA (2C), producing 1x NADH and 1 Co2. - Each glucose we started produces 2 pyruvates. - For each glucose molecule we have 2x acetyl CoA + 2x NADH + 2x Co2 Acetyl CoA enters the citric acid cycle and is transferred to a 4C molecule sto make a 6C molecules (citrate). The citrate then goes through a series of chemical reactions and loses 2C groups as 2 Co2 to end up back as a 4C molecules ready to go through another cycle. Every turn of the cycle produces 1xATP, 3x NADH, 1FADH2 and 4 Co2. The cycle turns twice for every glucose that enters glycolysis. 1 glucose à 2 pyruvate à 2 Acetyl CoA à 2xATP, 6x NADH, 2x FADH2 and 4x Co2. NADH and FADH2: Electron carrier molecules. These moelcules collect the electrons that are produced when chemical reactions occur during glycolysis and the citric acid cycle. They transport these electrons to the electron transport chain, donate the electron to the membrane carriers, and oxidative phosphorylation occurs to generate ATP. Oxidative Phosphorylation: Most of the energy produced by cellular respiration is by this. NADH and FADH2 produced by glycolysis and the citric acid cyle pass through the ETC in the inner membrane of the mitochondria. The ETC is a series of electron donors and receptors. NADH and FADH2 donate their electrons to their first acceptor of the chain, releasing H+ in the process. Acceptor molecule 1 then passes the electrons on to the next molecules in the chain and so on. Oxygen is the final electron acceptor and water is produced. The movement of electron from molecule to molecule in the membrane releases energy, this energy is used to generate a proton (H+ ion) gradient across the membrane. The protons then flow back across the membrane through a special channel. This flow of H+ is used by ATP synthesise to produce ATP. OP produces 32-34 ATP, per glucose. Amino Acids and Lipids: Fatty acids: - Undergo beta oxidation to form acetyl CoA. - Acetyl CoA can enter the citric acid cycle to generate ATP, NADH and FADH2. Amino acids:  - Can be converted into intermediate compounds of CHO digestion e.g. keto acid, pyruvate and acetyl CoA. Lecture 6- How do we get Things Around our Body? 1. Describe the major anatomical structures of the heart including chambers, valves, inflow and outflow. 2. Describe the position of the heart within the mediastinum including its coverings. 3. Differentiate between systemic and pulmonary circulation. 4. Define the effects of exercise on cardiac output. 5. Describe the transport of carbon dioxide and oxygen in the blood. The Cardiovascular System: Transports fluids, nutrients, waste products, gases and hormones throughout the body. Exchange materials between blood, cells and extracellular fluid. Plays a role in the immune response, blood pressure and the regulation of body temperature. Consists of the heart (pump), tubing system (blood vessels), capillary beds surrounding the tissues and cells (exchange of substances occurs here) and the blood (transport medium). The Heart- Functions: Contract to generate a pressure that pushes and moves blood through the heart, blood vessels and all around the body. Routing blood through two circulations: pulmonary and system. Ensures one-way blood flow. Regulates the amount of blood that tissues receive- can change in order to match the needs of the tissue. E.g. at rest heart is capable of reducing vs during exercise able to increase the amount of blood pumps and the pressure and rate at which blood comes out of the heart. 2 Pumps in 1: Right side of heart- blue on diagram- receives blood from the body, and pumps through the pulmonary circulation to the lungs where it picks up oxygen. Left side- red- receives oxygenated blood from the lungs à pumps through the systemic circulation à delivering oxygenated blood and nutrients etc to the cells of the body. Location: Side of a closed fist- male’s are larger than female’s. Shape: - Base: superior end of the heart- flattened part. - Apex: inferior end- blunt, rounded end of cone. Located in the thoracic cavity in mediastinum. Heart surrounded by two lungs. Apex sits towards left side of the body- obliquely in mediastinum. Pericardium: Double layered closed sac, which surrounds heart. Fibrous Pericardium: tough fibrous connective layer; prevents distention (stops it from overflowing); acts as an anchor to the mediastinum. Serous Pericardium: thin, transparent, inner later, simple squamous epithelium. - Parietal Pericardium: lines the fibrous outer layer- lining the outside of the fibrous pericardium. - Visceral Pericardium: covers hearts surface- covers the heart itself. - Area in between these two is the pericardial cavity between them is pericardial fluid, which acts as a lubricant. The Heart Wall: Three layers of tissue: - Epicardium (visceral epicardium): serous membrane; smooth outer surface of the heart. - Myocardium: thick middle layer; composed of cardiac muscle cells- contractility, and as muscles contracts this is what allows the heart to beat and carry blood around the body. - Endocardium: smooth (allows blood to flow freely through the chambers) inner surface of heart chambers. Simple squamous epithelium. Pectinate muscles: muscular ridges in auricles and right atrial wall. Trabecular carnae: muscular ridges and  columns on inside of walls of the ventricles. Chambers: Right Atrium: three major openings to receive deoxygenated blood returning from the body. Left Atrium: four openings that receive oxygenated blood from pulmonary veins (from lungs- 2 veins from each side- drain into here). Atrioventricular Canals: openings between atria and respective ventricles. Right Ventricle: opens to pulmonary trunkà lungs Left Ventricle: opens to aorta à body- very muscular wall because the LV must contract with a great force and generate a large amount of pressure to pump the blood around the body. Interventricular Septum: between the two ventricles. Great Vessels: Superior/inferior vena cava- draining into RA. Right/left pulmonary veins- draining into LA. Pulmonary trunk- exiting RV. Aorta- exiting LV. Valves: Control the direction and amount of blood flow. Maintain one-way blood flow through the heart. Semilunar valves- control flow out of the heart. Pulmonary SL valve= flow of blood out of the RV. Aortic SL valve= flow of blood out of the LV. Atrioventricular valves- separate atriums from ventricles. Right AV valve = tricuspid valve- 3 cusps. Left AV valve= bicuspid- 2 cusps. AV Valves: - Each valve has cusps that are attached to cone-shaped by papillary muscles by tendons (chordae tendineae). - Each ventricle contains papillary muscles, which attach to ventricles by these strings, as the wall of ventricle contracts, PM contract, pulls on the strings, closes the valves and prevents it from opening. - Right has 3, left has 2. Semilunar Valves: - Each cusp is shaped like a cup. - When cusps are filled, valve is closed – stop backflow. - When cusps are empty, valve is open- blood exits the heart. Tubing System Overview: Arteries: - Elastic, muscular arterioles. - Take blood away from the heart. - Contain blood under pressure- due to heart pumping, and pushing blood out of the heart. Capillaries: - Site of exchange with tissues (out of blood space à interstitial fluid)- occurs in capillary beds. - Smallest blood vessel. Veins: - Large, medium, small venules. - Take blood to the heart. - Thinner walls than arteries contain less elastic tissue/ less smooth muscle. - Valves to prevent backflow. Form a continuous passageway for blood to flow from the heart to the tissues of the body and back to the heart. Arteries and Veins: Tunica intima: most inner layer, endothelium (epithelium), delicate connective tissue layer, small layer of elastic tissue. Tunica media: smooth muscle cells arranged circularly around the blood vessel. - Vasoconstriction: smooth muscles contact, decrease blood flow. - Vasodilation: smooth muscles relax, increase blood flow. Tunica externa (adventitia): connective tissue layer (looser), joins with loose connective tissue of other tissues/organs/blood vessels. Capillaries: Extensive networks for exchange- capillary beds- increase SA to allow for greater rate of exchange. Thin layer of endothelial cells (simple squamous), basement membrane and a delicate later of connective tissue to help maintain shape. Substances move through capillaries by diffusion- small lipid soluble substances or gases Substances unable to move by diffusion go through fenestrations (gaps in capillary wall, between endothelial cells). Blood- Functions: Transport: gases, nutrients, waste products, processed molecules, hormones enzymes. Regulation of pH and osmosis (normal pH 7.4). Maintenance of body temperature. Protection against foreign substances- immunity. Clot formation- wound/repair. Blood Composition: Connective tissue. Liquid matrix- plasma (55%). Formed elements (45%). Plasma- liquid portion- majority of this is water, dissolved proteins (albumins, globulins, fibrinogen- transport). Cellular portion- majority red blood cells, white blood cells (neutrophils, lymphocytes, monocytes, eosinophil, basophils) and platelets. Red Blood Cells: So many within the blood as they carry oxygen. No nucleus & biconcave shame- shaped like this to increase SA and oxygen carrying capacity. Oxygen from lungs to body cells: 98.5% attached to haemoglobin in RBC and 1.5% dissolved in the blood plasma. Pulmonary Circulation: Gas exchange in the lungs. Deoxygenated blood from lungs à enter right atrium à right ventricle à exits heart through pulmonary trunk à pulmonary trunk divides into left and right pulmonary arteries à carry blood away from heart to the lungs à in the alveoli within the lungs gas exchange occurs à partial pressure of gases causes oxygen to flow into blood and CO2, into the alveoli. Freshly oxygenated blood travels in left of right pulmonary veins (depending on which lung) and enters left atrium. Systemic Circulation: Capillary exchange in the body/cells. Oxygenated blood enters LA à left ventricle à LV contracts (largest amount of contracting- transporting blood around the body) and pushes blood out of the heart through the aorta à aorta branches into ascending aorta, aortic arch, descending aorta à blood is delivered to all cells and tissues in the body for gas/nutrients/fluid exchange.  Once exchange occurs- exits capillary bedà drains into veins à enters heart through inferior/superior vena cava. NOTE: blood supply to itself- blood out of the aorta- first branch of the artery is the coronoary artery supplies blood (nutrients and oxygen to the blood itself) à removing waste from the heart is does so by the coronary sinus which drains blood back into RA. Cycle and Control: As the muscles of the heart contact- this generates a blood pressure which is responsible for moving blood through the heart and pushing blood out of the heart and aound the body. Blood moves from areas of high- low pressure. Cardiac Cycle: repetitive contraction (systole) and relaxation (diastole) of heart chambers- moves blood through the heart and body. Amount of blood flow around the boyd is proportional to the needs and metabolic needs of the tissues. E.g. brain, kidneys, liver, exercising skeletal muscle- very high. Can change: cardiac output= heart rate (no. times heart beats per minute) x stroke volume (amount of blood being ejected with each beat). Nervous and hormonal system can have some effect over the heart: - Maintains blood pressure and thus blood flow. Can re-route blood flow. - Nervous e.g. increase BP with exercise. Re-route blood flow away from the skin and viscera towards the brain and cardiac muscle in response to blood loss/injury. - Hormonal e.g. epinephrine (adrenaline) from adrenal gland- increases HR and SV- vasoconstriction in response to stress or exercise. Conducting System: How does the heart contract? Involuntary nervous control. Self contractible- can generate own action potentials. Action Potentials: rapid change in membrane potential (charge across membrane). Acts as an electrical/ impulse- sends message for the cardiac muscles to contract. Auto-rhythmicity- constant, automatic generation of AP’s, repetitive contractions of the heart. Two clusters of specialised cardiac muscles cells- which can conduct the APs. Sinoatrial node- pacemaker- can generate own APs that spread across atria à AV node. Atrioventricular node- ventricle contractions- spread of these form atria-à ventricles allows contraction of both. Capillary Exchange: Cells are bathed in interstitial fluid (extracellular fluid). Transport (diffusion) in and out of cells- requires a pressure gradient. Needs constant turnover/freshening. Comes via capillary beds and CVS. Capillary Exchange: the movement of substances into and out of capillaries. How cells receive what they need to survive and eliminate waste products. Most important means of exchange is diffusion. Lipid soluble- diffuse through plasma membrane of endothelial cells (oxygen, CO2, hormones, fatty acids). Water soluble- diffuse through intracellular spaces or through fenestrations of capillaries (e.g. glucose, amino acids). Large spaces between endothelial cells- proteins and whole cells can pass e.g. liver or spleen. Very small spaces between cells- e.g. blood brain barrier. Effects on Exchange: - Capillary permeability. - Blood pressure - Osmotic pressure- measure of solute concentration in a fluid. All affect the movement of fluid from capillaries. Exchange Cycle: Gases move due to partial pressures/ concentrations- always move from high to low concentration. At tissue level: oxygenated blood travels to tissues in system circulation à partial pressure of oxygen in blood is higher, so move from the blood to the tissues, and vice versa with carbon dioxide. Lymphatic System: Fluid moves out of capillaries into interstitial space and most returns to capillaries. The fluid, which remains in tissue, is picked up by the lymphatic system then eventually returned to the venous circulation, above superior vena cava à back into blood circulation à and into the heart – 1/10 remains. Edema: swelling caused by excess fluid accumulation in body tissues (interstitial space). Causes: problems with capillaries, heart failure, kidney producing to much fluid, standing/walking too much in hot weather, pregnancy. If capillaries become ‘leaky’ blood proteins can leak into the interstitial fluid. This increases the osmotic pressure outside the capillary. More fluid moves from the capillaries into the interstitial fluid. Lecture 7- How do we get rid of Toxic Wastes? 1. List the organs of the urinary system. 2. Describe the main functions of the kidneys. 3. Describe the location and external anatomy of the kidneys. 4. Describe the structure of the nephron. 5. Describe the three processes necessary for urine formation. 6. Describe the role of various regions of the nephron in terms of reabsorption and secretion. 7. Explain the basic mechanisms by which substances are able to move across the membranes of the nephron. 8. Describe the specific movement of glucose across the cell membranes of the nephron. 9. Briefly state what wastes are secreted in sweat. Anatomy of the Renal System: 2x kidneys- filters the blood and forms urine. 2x tubes ureters- carry urine from the kidneys à bladder. Urinary bladder- organ involved in storing urine. Urethra- exit passageway of the urine from the bladder to the outside of the body. Kidney Location: Abdominopelvic cavity. The kidneys lie behind the parietal peritoneum on the posterior abdominal wall on either side of the vertebral canal. Right kidney smaller than the left- due to the position of the liver. Above kidney on left hand side is the spleen. Extend from the last thoracic vertebrae (T12) à 3rd lumbar vertebrae- only partially protected by the rib cage. Renal arteries and veins supply the kidney. Renal Capsule: kidneys are surrounded by a fibrous connective tissue= Adipose Tissue: surround renal capsule, provide cushioning, protection, and maintain heat. Renal Fascia: thin loose connective tissue, anchors kidneys to posterior abdominal wall. External Anatomy: Hilum: small area where the nerves and blood supply enter/exit from the kidney. Most medial area of the kidney. Ureter: transporting urine made in the kidney to the urinary bladder. Renal Artery: delivers blood from heart à kidneys. Renal Veins: blood from the kidney à heart. Internal Anatomy: Hilum opens into renal sinus- cavity filled with fat and loose connective tissue. Two Main Regions: - Outer Cortex: consists of renal columns, which are part of the cortical tissues that extend into the renal pyramids. - Medulla: area that is closest to and surrounding the renal sinus. Renal Pyramids: cone-shaped, base is boundary between cortext and medulla. - Tips of these pyramids, papilla, forms the junction between the two regions of the kidney. - Apex of pyramid is renal papilla, and they point towards renal sinus, down in a medial direction. Minor Calyces: funnel shaped chambers into which papillae extend- they merge to form major calyces. 8-20 Major Calyces: converge to form the renal pelvis. 2-3. Pelvis: enlarged chamber formed by the major calyces. *ALL MERGE MEDIALLY. The Nephron: Functional unit of the kidney- filter blood and to produce urine. Parts: - Renal Corpuscle: → Cortex → Further divided into glomerulus (network of capillaries, through which blood is travelling into the nephron) and the Bowmans capsule (which surrounds the outside of glomerulus- first part of nephron that will collect filtrates, and start sending it through the nephron. - Proximal Tubule → Cortex - Loop of Henle - Distal Tubule → Cortex → Drains into collecting ducts. - Collecting Ducts → Extend from the papillae into the minor calyces. Oxygenated blood coming from the heart will enter into the nephronà filteredà urine is produced. Urine continues from the nephron à papillary ducts à minor calyces à major calycesà renal pelvis à ureter. Types of Nephrons: 1.3 million nephrons in each kidney.  Juxtamedullary Nephrons: the renal corpuscle located near the medulla. Long loops of Henle, which extend deep in medullary. Cortical Nephrons: renal corpuscle located nearer to the periphery of the cortex. Loops of Henle do not extend deep into medullary. Renal Corpuscle: Bowmans Capsule: - Enlarged end of the nephron, double walled chamber. - Filters the blood/fluid, which enters PCT. - Parietal Layer: outer layer- simple squamous epithelium becomes cuboidal in PCT. - Visceral Layer: inner layer of cells called podocytes, which wrap around capillaries of glomerulus, to facilitate filtration of the blood. Glomerulus: network/ball of capillaries- all blood is coming into here at high pressure, blood is filtered here. Blood enters the glomerulus through the afferent arteriole (much larger- higher blood pressure, encourages filtration), and exits through the efferent arteriole (when substances are too big to pass over filtration membrane). Filtration Membrane: Fenestrae: window-like opening in the endothelial cells of the glomerular capillaries. Filtration Slits: gaps between podocytes- allow small things to move out of blood vessel into BC. Basement Membrane: sandwiched between endothelial cells of capillaries and the podocytes. Fenestrations à in between podocytes = filtration. First stage of the formation of urine – is when liquid passes over the filtration membrane into BC, and it becomes filtrate. Renal Tubules: PCT: filtrate drains from the BC into here. Loop of Henle: each loop has a descending and ascending limb. DCT: shorter than PCT. Collecting Ducts: Extend through medulla towards renal papilla à ureter. Histology of the Nephron: PCT: simple cuboidal epithelium with many microvilli. Active reabsorption of Na+2 , K+, Cl-.  Loop of Henle: thick parts- simple cuboidal, thin parts- simple squamous epithelium for osmosis and diffusion. DCT: simple cuboidal, and very few microvilli. Numerous mitochondria. Collecting Ducts: Simple cuboidal epithelium. Major Renal Veins and Arteries: Abdominal Aorta: heart à kidney. R/L Renal Artery: branch off aorta and take blood into the hilum of the kidney à afferent arterioles à renal corpuscles. R/L Renal Veins à blood flows from the kidneys, and merge to make inferior vena cava. Inferior Vena Cava: return deoxygenated blood to the right atrium. Peritubular Capillaries: efferent arteriole as it exits gives rise to a network of capillaries, these all surround the tubules, where reabsorption and secretion of nutrients is occurring. Merge to become renal vein. Urine Movement: Pressure forces urine through nephron. Smooth muscles in ureters. Peristalsis moves urine from the renal pelvis in the kidneys through the ureters to the urinary bladder. Ureter enters the ladder through trigone- pressure in bladder compresses ureter and prevents backflow. Ureters: Bring urine from pelvis to bladder. Inner part touching the urine- is transitional epithelium- allows for stretch. Epithelium surrounded by mucosa Smooth muscle And outer connective tissue/fatty tissue = adventitia. Bladder: Hollow, muscular organ (smooth muscle). Allows for temporary storage of urine. Lies in pelvic cavity, sits behind Symphysis pubis. Volumes can increase/decrease depending on urine volume. Trigone: interior of the urinary bladder. Triangular area between the entry of the two ureters and the exit of the urethra. Wall of bladder – lined with transitional epithelium. Lamina propria/Submucosa = mucosa layer.  Majority of the wall is made up of smooth muscle, detrusor muscle- contraction that allows urine to be expelled when you need to use the bathroom. Urethra: Transports urine from bladder to the outside of the body. Elastic connective tissue/ smooth muscle= acts as a sphincter to prevent constant flow of urine outside of the body. Lined with transitional epithelium (top), stratified columnar epithelium (external opening). External Urinary Sphincter: skeletal muscle surrounds urethra, as it extends through pelvic floor. Accts as a valve that controls the flow of urine. Males- extends from the inferior part of the bladder through to the tip of the penis. Females- shorter; opens into the vestibule anterior to the vaginal opening. Functions of the Renal System: Excretion: get rid of waste products. Urine production occurs in the kidneys via filtration of the blood and reabsorption of nutrients. Metabolic wastes and toxic molecules are excreted in urine. Regulate blood volume and blood pressure- control extracellular volume by producing large amount of dilute or small amounts of concentrated urine. Urine Production: Kidneys: regulate fluid composition. Sorts chemicals in the blood for removal or for return into the blood. Nephrons: the structural component of the kidneys that sort the blood. Urine Production: 1. Filtration: movement of material across the filtration membrane into the Bowmans capsule. End result is filtrate. 2. Tubular Reabsorption: reabsorption of good solutes (e.g. water) back into interstitial fluid, and into the Peritubular capillaries à heart à used by cells to function. 3. Tubular Secretion: secretion of bad, unwanted, toxic solutes back into the nephron filtrate so that they can be excreted quickly in the urine. 1. Filtration: Substances in the blood are sorted based on their size and charge. Renal corpuscle is the site of blood filtration. Filtrate: Substances filtered into the BC- Seperation of water and small molecules, ions, away from large molecules/proteins and red blood cells. Renal Fraction: part of total cardiac output that passes through the kidneys. Varies from 12-30% in a healthy adult. ~20%.  Glomerular Filtration Rate: Amount of filtrate produced each minute- 125ml/minute. Make ~180 L per day. Average Urine Production: 1-2L per day. Most of filtrate 99% must be reabsorbed. Removes toxins quickly from blood. Filtration Membrane: - Have many characteristics, which allow the blood to be filtered quickly. - Fenestrae, filtration slits, basement membrane. - Prevents large molecules, blood cells and proteins from entering the lumen of the BCs. First stage of the formation of urine- is when things move out of blood vessel, through fenestrae, through podocytes filtration slits and into the BC, large things are too big to pass through the filtration membrane and remain in the blood. Filtrate Includes: - Water, glucose, fructose, amino acids, urea, sodium, potassium, and calcium- very little protein normally found in filtrate and urine. Filtration is driven by blood pressure. Filtration Pressure: pressure gradient responsible for filtration; forces fluid from glomerular capillary across membrane into lumen of BC. Juxtaglomerular Apparatus: Between the afferent and efferent arterioles is the DCT folding back on itself- the juxtaglomerular apparatus is located here. Smooth muscle cells from the wall of the afferent arteriole, and also some specialised tubule cells from the DCT- macula densa. These cells secrete the enzyme called renin, plays a vital role in the formation of filtrate and in the regulation of blood pressure. When secreted travels through blood stream- acts on other organs and proteins to reduce urine volume. If we are loosing less water out of the body through urine, renin acts to increase the amount of fluid in the body and increase blood pressure. 2. Tubular Reabsorption: Return of good substances that are in the filtrate back into the blood. E.g. amino acids, water, sugar, ions. Occurs as filtrate flows through the PCT and LofH through the lumens of the renal tubules. Substances are reabsorbed into interstitial fluid and into circulation via peritubular capillariesà renal veins à general circulation. Substances Reabsorbed:  - Active/passive. - Water - Amino acids - Glucose - Fructose - Various ions. Majority occurs in the PCT: - As filtrate moves along PCT 65% moves out of the PCT and into the interstitial fluid, which reduces the amount of filtrate down to 35%. - An apical surface- surface that allows substances to move out of the filtrate and get into the cell of the nephron- simple cuboidal cell lining the nephron. - Basal surface- cross out the tubule back into the interstitial fluid- picked up by the blood and move around the body. - E.g. Glucose: → On basal surface is a high amount of sodium/potassium pumps- constantly working to move sodium out of the cell, which gives us a low concentration inside of the cell. As the filtrate flows through the PCT, sodium would like to move from high concentration to low concentration, so it moves across the apical surface of the cell. As it moves across here, glucose comes into cell with sodium via symport. Now we have glucose in the cell, it builds up in high concentration within the cell, and now glucose would like to move from highà low concentration. Does so by moving across basal membrane via facilitated diffusion and into interstitial fluid, where it is picked up by peritubular capillaries à back into the body and used by the cells of the body to make ATP for e.g. Loop of Henle: - Thin part- simple squamous epithelium. - Water and ions. - Upon leaving, the filtrate has reduced to 20%. - Ions- moves out through diffusion, active transport, and symport- depending on thickness, permeability, osmotic gradients/concentration at different parts of the LofH (thin/thick parts). DCT/Collecting Ducts: - Most reabsorption occurs under the control of the hormone, anti diuretic hormone. - Diuretic- causes body to produce more urine. - ADH- makes tubule wall more permeable to water- water moves of filtrate back into body- small concentrated urine. 3. Tubular Secretion: The movement of non-filtered substances, toxic by-products of metabolism, drugs or molecules not normally produced by the body, into the nephron from excretion. Occurs mainly in DCT  Can be active/passive. Ammonia: is a toxic by-product of protein metabolism. Diffuses into the lumen of the nephron. Hydrogen, Potassium and Penicillin: actively secreted into nephron. Urine Movement: There are pressures that force blood through filtration membrane to become filtrate, pressure which force filtrate to flow through the nephron. Peristalsis- urine through ureters to bladder- occurs constantly. Can be influenced by nervous system: - Parasympathetic stimulation: increases frequency. - Sympathetic stimulation: decreases frequency. Ureters enter the bladder obliquely through trigone. Pressure in bladder compresses ureter and prevents backflow. Urine: 1% of filtrate. 1-2L a day. Majority composed of water. Dilute or concentrate- depending on body needs (ADH and renin). Urea- protein metabolism. Uric Acid- amino acid metabolism. Ammonia Hydrogen Potassium Bile pigments Drugs and toxins: penicillin and morphine. Micturition Reflex: Flow of urine from ureters to bladder is continuous- bladder to urethra is not (elimination). Bladder capacity- max 1L. Process of elimination is micturition- going to bathroom. As bladder