Bio Systems Notes - Aidan Kropf PDF

Nutrition: Why do we Eat? -​ Energy to maintain body functions -​ Growth -​ Social Interactions Food for Energy: -​ Nutrients provide the energy that fuels all biological processes -​ Light energy is converted to chemical energy through photosynthesis -​ Chemical energy can be store...

Nutrition: Why do we Eat? -​ Energy to maintain body functions -​ Growth -​ Social Interactions Food for Energy: -​ Nutrients provide the energy that fuels all biological processes -​ Light energy is converted to chemical energy through photosynthesis -​ Chemical energy can be stored in cells and released when needed -​ Chemical energy fuels growth and movement -​ Endothermic animals: energy maintains body temperature, converted into thermal energy and some is converted back to the environment Energy Requirements: -​ Endothermic animals need more food to maintain body temperature -​ Larger animals generally eat more (animals eat food relative to their size) Metabolism: (Chemical reactions) -​ Catabolism: breakdown of materials (chemical and physical breakdown during digestion) -​ Anabolism: building of larger more complex molecules from smaller molecules Metabolic Rate: Rate at which the body converts stored energy into working energy -​ Body Size: larger body = more energy required -​ Physical Activity: muscle burns more energy than fat -​ Sex: males have a larger proportion of muscles to females -​ Age: metabolic rate decreases with age -​ Heredity: genes Energy: -​ Energy is measured in joules or kilojoules -​ One calorie is the amount of energy to raise the temperature of 1g of water to 1 degree celsius -​ One kilocalorie is the unit usually on food labels -​ A calorie is a unit of energy (can apply to other things besides food) Basal Metabolic Rate: -​ Rate at which energy is used by an organism when it is at rest (no activity, just vital processes) Total Daily Energy Expenditure: Body Mass Index (BMI) -​ Medical screening tool that measures the ratio of height to weight to estimate the amount of body fat in a person -​ Doesn’t diagnose health, it is used with other tools to assess a patient's health status and risks (other methods for classifying weight: waist circumference, skinfold calipers, DEXA scan, ADP, etc.) -​ High body fat may lead to heart disease, stroke, high blood pressure, sleep apnea, certain cancers, depression, Type 2 diabetes (it is possible to have or not have these conditions with a high or low BMI) Limitations of BMI: -​ Doesn’t differentiate between lean body mass (muscle) and fat mass -​ Used for both genders even though females have more body fat than males -​ Hasn’t been adjusted for increasing average adult height over the years -​ Doesn’t measure the location or distribution of body fat -​ Doesn’t account for family history 3,500 calorie rule: -​ 3,500 calories = 1 lb of fat -​ Formula doesn’t consider composition of body fat and the nutritional value of food Sustainable Weight Loss: -​ Composition of Diet -​ Activity Levels -​ Pace of changes -​ Sustainability of changes Nutrients: Carbohydrates: -​ Main source of energy for the human body -​ Made of carbon, hydrogen, and oxygen -​ There are 3 different types of carbohydrates : Monosaccharides, Disaccharides, and Polysaccharides Monosaccharides: -​ The most basic carbohydrates (also known as simple sugars) -​ They are ringed shaped structures consisting of a single sugar molecule -​ Examples: Glucose, Fructose, etc. Disaccharides: -​ Ringed shaped structures consisting of two sugar molecules -​ Essentially two monosaccharides combined -​ Examples: Lactose, Sucrose, etc. Polysaccharides: -​ Ringed shaped structures consisting of sugar molecules -​ Essentially multiple sugar molecules joining together -​ Most complex form of carbohydrates -​ Examples: Starches, Cellulose, etc. What do we use Carbohydrates for: -​ Big part of cell structures -​ Plants use them to create complex molecules like cellulose -​ Carbohydrates consist of 55% of a healthy person's diet -​ Foods high in carbohydrates include: vegetables, potatoes, grapes, etc. -​ Cellulose provides Fiber and can’t be broken down -​ Plant starches are the main source of chemical energy in humans -​ Complex carbohydrates have to be broken down before the body can use them -​ Mostly stored in the liver and muscle tissues, can be converted into lipids and stored in the form of body fat Proteins: -​ One of the key building blocks of cells and provide a wide range of functions -​ Functions include: structural molecules, metabolic activities, generation of motion -​ Some can serve as hormones -​ Examples: Myosin in Muscle Cells, Hemoglobin in Red Blood Cells Amino Acids: -​ Most complex nutrients, made up of long chains of smaller molecules called amino acids that vary in size and shape -​ There are 20 different amino acids and the human body can make 12, the body acquires 8 elsewhere Sources of Amino Acids: -​ There are many plant and animals that contain protein -​ Sources include meat, eggs, fish, and cheese -​ Plant sources include beans, lentils, seeds, and nuts -​ Animal proteins contain all 8 amino acids, but plant proteins lack at least one, Vegetarians have to eat more varied plants to obtain all amino acids -​ Animal muscle has a higher concentration of protein than plant protein -​ When you eat proteins, the body separates them into different amino acids to be further constructed into important proteins Proteins and Diet: -​ Recommended daily diet for teenagers is 0.85g for every kg of body mass -​ Proteins also provide energy, excess protein can be converted into fat, usually smaller portions of energy in an individual's diet. -​ 10-20% of a human's diet should come from proteins Lipids: -​ They provide a concentrated source of chemical energy for the human body -​ They help the absorption of vitamins and are the main component of cell membranes and serve as insulation for the body -​ Certain hormones including sex hormones are lipids -​ Fats and Oils are examples of lipids -​ They are made up of three fatty acids and a glycerol molecule which make up a triglyceride Triglycerides: -​ A lipid made of glycerol and three fatty acids that are bonded together -​ Fatty acids contain long chains of carbon and hydrogen atoms -​ Unsaturated triglycerides are called oils and are usually liquid at room temperature -​ Plants and fish oils are common sources of unsaturated fats Saturated Fats: -​ Usually solid at room temperature -​ Meat and butter are common sources of saturated fats Unsaturated Fats: -​ Usually considered as “good fats” -​ Studies have shown that people who have a diet that consists of unsaturated fats are generally healthier than those who have a diet of saturated fats -​ Some fatty acids are considered essential and cannot be produced by the body, one is called Omega 3 Omega 3: -​ Unsaturated fats that are important in maintain good health and preventing diseases like heart diseases and arthritis -​ Found in a variety of foods such as fish, nuts, seeds, and leafy green vegetables Steroids: -​ A special group of lipids called steroids contain certain sex hormones like testosterone, estrogen, and cholesterol -​ Sex hormones control the development of male and female sex characteristics -​ Cholesterol is key component of all animal cell membranes, cholesterol has good and bad forms Fats: -​ Fats usually raise a warning sign when eating but are a key component of any diet -​ A healthy diet should consist of no more than 30% of energy intake of fats -​ Excessive consumption can lead to negative effects like heart disease and obesity -​ Trans Fats are a harmful type of lipid, they are a type of unsaturated fat, but perform like saturated fats -​ they pose a higher risk of heart disease by increase bad cholesterol levels and lowering good cholesterol levels Vitamins and Minerals: -​ Vitamin is a compound an organism needs only in small amounts -​ They regulate cell functions, growth, and development within our bodies -​ They are classified as fat soluble or water soluble (dissolves in fat or water) Vitamins: -​ Vitamins A,D,E, and K are fat soluble and can be stored in body fatty tissues for future use -​ These vitamins don’t dissolve in water and therefore are harder to get rid of when within the body -​ Taking high doses of these vitamins can lead to toxic levels within the body -​ Vitamins B and C are water soluble -​ They can’t be stored in the body in excess quantities and are excreted through urine, people need to take daily doses of these vitamins -​ We obtain most of our vitamins from our food, vitamins A,D, and K can be produced within our bodies -​ For example, the body can convert a chemical called beta carotene into Vitamin A -​ Vitamin D can be formed under our skin when exposed to sunlight -​ Vitamin K is synthesized by special bacteria found in the large intestine Minerals: -​ Minerals are naturally occurring elements that the body uses to carry out metabolic processes and repair tissues -​ Examples include Calcium and Phosphorus and are critical in bone formation -​ Sodium is involved in nerve impulse transmission and muscle contraction -​ Iron is a key component of the blood protein hemoglobin -​ Oxygen binds to the Iron component and is transported throughout the body -​ Calcium, Phosphorus, Sodium, and Iron are key parts of our body, but other minerals like Fluorine, Zinc, and Copper are found in smaller amounts The Digestive System: Functions of the Digestive System: -​ Break down large food molecules into smaller molecules -​ Absorb smaller molecules into the circulatory system to be carried to the rest of the body Human Digestive System: -​ Complete digestive system: Gastrointestinal Tract with accessory organs -​ Simple digestive system: opening and gastrovascular cavity Main Steps in Digestion: -​ Ingestion: taking in of nutrients -​ Digestion: physical and chemical breakdown of nutrients -​ Absorption: transfer of nutrients to the bloodstream -​ Egestion: removal of waste from the body Mechanical Digestion: -​ Physical breakdown of food -​ Increase surface area = increase absorption of nutrients -​ Occurs at mouth, esophagus, and stomach Chemical Digestion: -​ Chemical breakdown of food -​ Break macronutrients into smaller components -​ Glands produce hormones that regulate enzymes (chemicals that increase rate of chemical reactions -​ Occurs at mouth, stomach, and small intestine Mouth: -​ Receives food and begins digestion -​ Incisors and Canines grab and cut food -​ Premolars and Molars grind and crush food -​ Sight or smell of food / presence in mouth triggers salivary glands to release saliva -​ Saliva helps to moisten food particles and binds them into a bolus and helps us taste food -​ Amylase produces with saliva to digest starch into disaccharides -​ Mucus acts as a lubricant and aids in swallowing Swallowing: -​ Tongue pushes bolus to the back of the mouth (voluntary movement) -​ Food is pushed into the pharynx -​ The soft palate is raised to prevent food from entering the nasal passage -​ The epiglottis prevents food from entering the airway  -​ Involuntary phase of swallowing beings with the pharyngeal muscles contracting to force the bolus into the esophagus Esophagus: -​ Long, muscular tube that carries food from the pharynx to the stomach -​ Food stretches the walls of the esophagus, activating smooth muscles (involuntary) to undergo peristalsis (wave like contractions that move food down the esophagus and into the stomach -​ Circular muscles at the end of the esophagus / beginning of the stomach is called the gastroesophageal sphincter -​ Relaxes (opens) to allow food into the stomach -​ Prevents food and stomach acid from entering the esophagus from the stomach -​ Heartburn (acid reflux) is the result of acid escaping the stomach Stomach: -​ J-Shaped, muscular organ, can store up to 2L of food -​ 4 layers -​ Mucosa: excessively folded layer, secretes gastric juice (cells of mucosa divide and replace every three days) -​ Submucosa: Connective tissue, contains network of nerves and blood vessels -​ Muscularis: Smooth muscle, contract to churn and mix food with gastric juices (churning produces chyme, semi liquid material) -​ Serosa: Smooth, outermost layer, holds stomach in place and secretes lubricating fluid to eliminate friction between organs Chemical Digestion: -​ Nerves in submucosa detect food, initiate release of hormone called gastrin -​ Gastrin travels to gastric cells in stomach and stimulates the release of gastric juice -​ Gastric juice contains enzymes, acid, mucus, and intrinsic factor -​ HCL kills harmful microorganisms and converts pepsinogen into its active form (pepsin) and begins the breakdown of proteins into amino acids -​ Activation is a necessary step (if gastric glands made pepsin, stomach would digest itself) -​ Mucus: lubricates food, protects stomach walls from self digestion -​ Intrinsic Factor: needed for absorption of vitamin B12 from the stomach Mechanical Digestion: -​ Nerve endings in stomach are stimulated when food enters the stomach -​ Signals cause a increase in muscular contractions which mixes food with gastric juice Absorption: -​ Some absorption occurs through the lining of the stomach (small amounts of water, glucose, ions, and alcohol) Stomach Ulcers: -​ H. Pylori can survive acidic environment in the stomach by secreting acid neutralizing enzymes and burrowing through the mucosa -​ Limits the production of mucus which can expose the stomach lining to stomach acid and can create an ulcer -​ Can be eliminated with antibiotics -​ If not treated, can lead to bacteria entering the bloodstream and infecting the body Small Intestine: -​ A tube that is around 20 feet long and an inch in diameter -​ Major region of chemical digestion and nutrient absorption -​ Duodenum: Digestion -​ Jejunum: Digestion and absorption -​ Ileum: Majority of absorption -​ Inner surface of the small intestine is adapted to maximize absorption -​ Folded into ridges, finger like projections called villi increase the surface area -​ Epithelial cells making up the villi have microscopic projections called microvilli and increase the surface area by a factor of 500 -​ Within each villus is a network of capillaries that digest all nutrients except fats -​ Lacteals absorb digested fats Duodenum: -​ Pyloric Sphincter controls the passage of food from the stomach to the small intestine -​ Chyme enters the duodenum and is moved by peristalsis -​ 2 digestive juices are added in the duodenum Bile: -​ Produced in the liver, stored in the gallbladder -​ Released into the small intestine through the common bile duct -​ Aids in digestion by breaking down fat Pancreatic Juice: -​ Produced in the pancreas and released through the pancreatic duct -​ Contains pancreatic amylase which breaks down starch into maltose -​ Contains trypsin which breaks down proteins into peptides and into amino acids -​ Pancreatic lipase breaks down lipids into fatty acids and glycerol -​ Bicarbonate ions neutralize acidic pH from the stomach Jejunum and Ilium: -​ Digestion and absorption -​ Intestinal glands secrete intestinal juice containing carbohydrase (breaks down disaccharides and monosaccharides) and peptidase (breaks down peptides into amino acids) Liver and Gallbladder: -​ Liver removes excess glucose and stores it as glycogen -​ Removes amino acids from the bloodstream and produces bile -​ Bile contains bile salts which aid in digestion and absorption -​ All blood travelling through capillary beds of the intestines go to the liver before returning to the heart -​ Liver removes and breaks down toxins Pancreas: -​ Secretes enzymes that are critical in the digestive process -​ Secretes hormones that regulate the absorption and storage of glucose -​ Releases bicarbonate ions that neutralize acidic chyme from the stomach Large Intestine: -​ 1.5m in length and 7.6cm in diameter -​ Waste takes 4-72 hours to pass through -​ Small intestine joins the large intestine at the cecum -​ Appendix projects from the cecum (possible role of storing cultivating gut bacteria and immune function) -​ Large intestine hosts 500 species of bacteria and exists in a beneficial relationship -​ Colon has 4 segments (ascending colon, transverse colon, descending colon, and sigmoid colon) -​ Rectum is the last 20cm -​ Holds waste until eliminated through the anus  -​ Still contains some undigested and indigestible material (cellulose) that cannot be broken down by humans -​ As matter passes through the colon, most of the water is reabsorbed -​ 20L of fluid passes through every day -​ Vitamins B and K, sodium, chloride, are absorbed Egestion: -​ Indigestible components of food maintain full feeling to reduce overeating and retain water to aid in the elimination of digestive wastes -​ Absorption of water in large interesting changes liquid material in colon into feces -​ Too much water can result in constipation -​ Too little water can result in diarrhea which can lead to dehydration Anus: -​ Surrounded by two sphincter muscles -​ Internal anal sphincter is smooth muscle (involuntary) -​ External anal sphincter is skeletal (voluntary) SBI3U | Respiratory System Aerobic Cellular Respiration: The Need for Oxygen ​ All living cells need oxygen to survive - use oxygen to survive (use oxygen to obtain energy from food) ​ This process is called aerobic cellular respiration ​ Energy is released when glucose reacts with oxygen to form carbon dioxide and water ​ 64% of energy is released as thermal energy ​ The rest (approx. 36%) is stored in molecules called adenosine triphosphate (ATP) ○​ ADP + P + Energy → ATP ​ Cells use ATP to power almost all processes (growth, movement, building new molecules)  ○​ ATP → ADP + P + Energy Gas Exchange and Ventilation ​ Gas exchange - process by which oxygen diffuses into the body cells and carbon dioxide diffuses out of the cells ​ Simple organisms - oxygen diffuses directly from the surrounding environment, through the cell membrane, into the cells (vice versa for carbon dioxide - from cells to environment) ​ For larger, multicellular animals, because most cells do not come in contact with the external environment, they have special organ systems to supply oxygen to cells and remove carbon dioxide ​ Gas exchange occurs at two locations - cells and lungs ○​ Lungs - oxygen diffuses from the air into the bloodstream, where it is then transported to all the cells of the body ○​ Cells - surrounded by fluid called tissue fluid, oxygen diffuses from the blood, into the tissue fluid, then into the cells ○​ Carbon dioxide - from the cell, to tissue fluid, to bloodstream, to lungs, diffuses into the air ​ Ventilation (breathing) - process of moving oxygen rich air to the lungs, and carbon dioxide rich air away from the lungs. Respiratory Structures ​ Human respiratory system has 4 important structural features  ○​ Thin, permeable respiratory membrane through which diffusion can occur ○​ Large surface area for gas exchange ○​ Good supply of blood ○​ Breathing system for bringing oxygen-rich air to the respiratory membrane ​ Lungs ○​ Respiratory membrane, with large surface area, and good blood supply ○​ Enclosed within the thoracic cavity, protected by rib cage ​ Pathway of Air ○​ Nose & Mouth - air enters, is warmed and moistened in the nasal passages and mouth ​ Nasal passages lined with tiny hairs and mucus to filter out and trap dust and airborne particles ○​ Pharynx - glottis remains open (covered by epiglottis during swallowing of food) ○​ Trachea (windpipe) - semi-rigid tube of soft tissue, wrapped around c-shaped bands of cartilage (keep the trachea open) ​ Lined with mucus-producing cells and cilia - further protect lungs from foreign matter ​ Cilia - hair-like structures, wave-like motions sweep trapped material upwards through the trachea, where it is swallowed, or expelled through coughing or sneezing ○​ Bronchi - each bronchus connects to a lung ○​ Bronchioles - smaller branches of bronchi, continuously branches off into smaller and smaller bronchioles ○​ Alveoli - cluster of tiny sacs surrounded by a network of capillaries ​ Each alveolus is tiny - 0.1 - 0.2 micrometres in diameter ​ 150 million in each lung ​ All alveoli spread out would cover a tennis court Gas Exchange in the Alveoli ​ Air that reaches alveoli is 37 degrees celsius and saturated with moisture ​ Respiratory Membrane that forms the alveoli is also saturated with moisture ​ Oxygen cannot diffuse across the membrane unless dissolved in a liquid ​ Alveoli perfectly adapted for gas exchange ○​ Membrane is incredibly thin (one cell thick) - short distance from inside of alveoli and blood in the capillaries Partial Pressures ​ Air exerts pressure (measured in kilopascals kPa) depending on the density ○​ At sea level the air pressure is 101.3 kPa ○​ Top of Mount Everest (8850 m) air pressure is 31 kPa ​ Partial Pressure - pressure of each individual gas that makes up the total pressure ○​ Oxygen - makes us about 20.9% of air in the atmosphere  ○​ Carbon Dioxide - makes up about 0.0391% ​ Partial pressure of air at sea level ○​ Oxygen (PO2) - 20.9% of 101.3 kPa = 21.17 kPa ○​ Carbon Dioxide (PCO2) - 0.0391% of 101.3 kPa = 0.0397 kPa Oxygen Transport and Diffusion ​ Alveoli ○​ PO2 in the alveoli is about 13.3 kPa - less than surrounding air because residual or stale air remains in the alveoli ○​ PO2 in the alveoli is higher than the PO2 in the capillaries (5.33 kPa) ○​ Pressure gradient causes oxygen to diffuse from the alveoli into the liquid component of the blood - plasma ​ Hemoglobin - iron-containing protein in red blood cells that binds to oxygen to form oxyhemoglobin ○​ 98.5% of oxygen is carried by hemoglobin, 1.5% is dissolved in blood plasma ○​ Oxyhemoglobin gives blood its bright red colour ○​ Blood with hemoglobin carried 20 mL of oxygen per 100 mL of blood vs 0.3 mL without hemoglobin (70x better oxygen carrying capacity) ​ Cells ○​ At tissues cells, oxygen diffuses into body cells ○​ Oxygen in hemoglobin is not depleted before blood flows away - PO2 in the veins is 5.33 kPa - blood always contains some oxygen Carbon Dioxide Transport and Diffusion ​ Cells ○​ Carbon dioxide - by-product of cellular respiration, must be removed ○​ PCO2 of tissue fluid is 5.60 kPa - higher than PCO2 in capillaries which is 5.33 kPa ○​ Pressure gradient facilitates diffusion of CO2 from tissues to bloodstream ​ Transport ○​ 7% dissolved in plasma ○​ 20% attached to hemoglobin - carbaminohemoglobin ○​ 73% reacts with water in plasma to form carbonic acid ​ Carbonic acid separates into bicarbonate ions and hydrogen ions ​ Hydrogen ions increases acidity of plasma - which can be life-threatening ​ Decrease in pH triggers receptors to increase breathing rate - breathing is driven by our need to remove CO2 ​ Hydrogen ions attach to hemoglobin to prevent accumulation - carried back to lungs (bicarbonate remains dissolved in blood plasma) ​ In lungs bicarbonate and hydrogen ions reform to CO2 and water ​ Lungs ○​ PCO2 in capillaries is 5.60 kPa ○​ PCO2 in alveoli is 5.33 kPa ○​ CO2 diffuses from blood plasma to the air within the alveoli Altitude ​ 2000 m - atmospheric pressure is 80 kPa ​ 7000 m - 40 kPa ​ Above 7000 m - too low for humans to survive ​ Oxygen still makes up 20.9% of air, but density and partial pressure of oxygen are too low (not enough oxygen molecules in a given volume of air) ○​ At 2000 m - PO2 drops to 17 kPa (20.9% of 80) ○​ Pressure gradient between air and blood drops, rate of diffusion drops, supply of oxygen is reduced ○​ Decreased oxygen supply can cause altitude sickness - shortness of breath, headache, dizziness, tiredness, and nausea ​ When supply of oxygen is reduced, kidneys produce erythropoietin (EPO) ○​ EPO is a hormone that stimulates the production of red blood cells ○​ Increased number of red blood cell - increases amount of oxygen that can be absorbed and delivered to body cells ○​ Synthetic EPO exists - banned substance in competitive sports ​ Athletes will train at high altitude to increase red blood cell count ○​ In a few weeks - can increase red blood cell count from 5,000,000/mL to 7,000,000/mL ○​ Lifespan of red blood cells is 90-120 days Mechanism of Ventilation ​ Inspiration ○​ The external intercostal muscles contract ○​ Ribs move upward and outward ○​ Diaphragm contracts and moves down ○​ Volume of the thoracic cavity increases ○​ Pressure in lungs is decreased ○​ Air enters lungs to equalize pressure  ​ Expiration ○​ External intercostal muscles relax ○​ Ribs move downward and inward ○​ Diaphragm relaxes and moves up ○​ Volume of thoracic cavity decreases ○​ Pressure in lungs increases ○​ Air is forced out of the lungs to equalize pressure Lung Capacity ​ Total Lung Capacity: maximum volume of air held during a single breath ​ Tidal Volume: volume of a normal, involuntary breath ​ Inspiratory reserve volume: the volume of air that can be forcibly inhaled after normal inhalation ​ Expiratory reserve volume: the volume of air that can be forcibly exhaled after a normal exhalation ​ Residual volume: the volume of air remaining in the lungs after a forced exhalation (helps prevent lungs from collapsing) ​ Vital Capacity: the maximum amount of air that can be exhaled  ○​ Vital capacity = tidal volume + IRV + ERV SBI3U | Blood The Need for Circulation ​ Do all organisms need a circulatory system? ​ No - unicellular and some simple multicellular organisms have cells that are in direct contact with their environment- example: Sponges ​ Why do we need a circulatory system? ○​ Bring nutrients and oxygen to the cells and eliminate waste products ○​ Multicellular makeup where cells do not contact the environment directly to access oxygen and nutrients ​ 2 circuit system ○​ Systemic circuit - head and body  ○​ Pulmonary circuit - between the heart and lungs - to oxygenate blood ​ What colour is your blood ○​ Oxygen rich - bright red ○​ Oxygen poor - deep red Key Functions of the Circulatory System ​ Deliver oxygen from the respiratory system ​ Deliver nutrients from the digestive system ​ Deliver hormones from the endocrine system ​ Deliver chemicals or cells from the immune system ​ Remove metabolic wastes from the cells of the lungs and kidneys ​ Maintain body temperature for warm-blooded organisms Fundamental Features ​ A fluid that transports (circulates) materials through the body ​ A network of tubes in which the fluid circulates ​ A pump that pushes the fluid through the tubes Open Circulatory System ​ “Blood” contains hemolymph ​ Blood not always in vessels ​ No true heart ​ Requires less energy ​ Low blood pressure ​ Organs bathe in blood for nutrients and gas exchange ​ Examples: insects, lobsters, crabs, oysters Closed Circulatory System ​ Blood is pumped within a closed network of vessels  ​ Faster flow ​ Circulates in one direction ​ Suitable for larger organisms who have a faster metabolism and need to eliminate waste quickly ​ Examples: birds, mammals, fish, reptiles What is in Blood? ​ The human body contains 4-5L of blood ​ Blood is a connective tissue that consists of cells suspended in intercellular matrix ​ Human blood contains 2 components ○​ Cellular Components: red blood cells, white blood cells, platelets ○​ Intercellular matrix: plasma (yellow-coloured liquid) ​ The components can be separated through centrifuge Plasma  ​ Protein rich liquid consisting of oxygen, carbon dioxide, proteins, nutrient molecules (glucose, minerals, and vitamins) and waste ​ Mostly water (90%) ​ Proteins: albumins, globulin, fibrinogen ​ Carries dissolved ions (Na+, K+, Ca2+, Cl-, HCO3-) ○​ Sodium ion concentrations create osmotic pressure gradient that causes water to enter or leave blood - high salt causes water to enter blood, causing hypertension Red Blood Cells ​ Produced in the red bone marrow: spongy material in the centre of many bones in the body ​ Hemoglobin (Hb) is also formed within them ○​ Heme (iron containing red pigment) ○​ Globin (protein) ​ Very flexible : can travel through narrow capillaries to deliver O2 ​ Don’t normally leave the circulatory system except when they are broken down by the spleen ​ When they are old they are engulfed by macrophages (large phagocytic cells that are found in the spleen, liver and bone marrow) White Blood Cells ​ Neutrophils : Act to combat infection by ingesting small particles such as bacteria ​ Lymphocytes: They secrete antibodies which attack bacteria directly ​ Monocytes: Are the largest of the WBC; ingest foreign bodies ​ Eosinophils: Fight internal parasite infestations (worms), increase allergic response (asthma, hay fever) ​ Basophils: Release histamine in allergic reactions; release heparin, which can prevent blood clotting but is more likely used to fight infection SBI3U | Blood Vessels Arteries ​ Blood vessel that carries blood away from the heart ​ Aorta - single artery that leaves the heart ○​ Branches into major arteries that carry blood around the body ​ Artery walls - 3 layers of tissue ○​ Outer layer - connective tissues ○​ Middle layer - smooth muscle ○​ Inner layer (endothelium) - single layer of epithelial cells ​ Elastin fibres in artery walls give vessels elasticity ​ Allow them to slightly expand when blood is pumped through them ○​ Return to original size to push blood downstream ○​ Elasticity ensures continuous flow of blood Arterioles ​ Smallest artery ​ Diameter controlled by nervous system (smooth muscle in walls) - control blood flow ○​ Vasodilation - relaxation of smooth muscles, increasing diameter of blood vessels ○​ Vasoconstriction - contraction of smooth muscles, narrowing diameter of blood vessels ​ Controlling blood flow to skin - used to control body temperature ​ Without vasoconstriction - would need 200 L of blood to fill all blood vessels in the body Capillaries ​ When arterioles reach the body’s tissues, they branch further into capillaries ​ Networks of blood vessels supplying oxygen and nutrients to every cell throughout the body ​ No cell is more than 2 cells away from a capillary ​ Capillary walls are 1 cell thick Blood Flow in Capillaries ​ No smooth muscle in walls of capillaries - diameter cannot be controlled by nervous system ​ Precapillary Sphincter muscles contract and relax to increase or decrease blood flow to capillary network ​ Blood flow slows down as it enters capillary network ○​ Millions of capillaries in a network create a total cross-sectional area that is greater than the cross sectional area of the arterioles and artery from which the capillaries branch Venules and Veins ​ Capillaries merge into venules , which merge into veins ​ In systemic circulation, veins carry deoxygenated blood carrying CO2 and waste from body tissues back to the heart ​ Smooth muscle in veins is not as thick and walls are not as elastic, interior diameter is larger ​ Blood returns to the heart with the assistance of one-way valves and the skeletal muscle pump  Artery Vein Direction of Blood Flow Away from heart Towards heart Blood Pressure High Low Thickness of Wall Thick Thin Inner Circumference Small Large Elasticity Very elastic Lacks elasticity Presence of Valves No Yes Oxygen Content in Blood Oxygenated* Deoxygenated* **in pulmonary circulation, pulmonary artery carries deoxygenated blood from the heart to the lungs and the pulmonary veins carry oxygenated blood from the lungs to the heart** Varicose Veins ​ Blood vessels tend to become less elastic as we age ​ People who spend a lot of time sitting or standing may damage the valves in their veins ​ This leads to more blood in the veins, and since the vessels are less elastic, bulging occurs Spider Vein Removal ​ Spider veins are small damaged veins that can appear on the surface of legs or face. ​ Causes ○​ When valves stop working  ○​ In the face: increased pressure (forceful coughing, sneezing, vomiting) or sun damage (UV light can damage blood vessels) ​ Risk Factors ○​ Genetics ○​ Childbirth ○​ Age ○​ Gender - more often in female ○​ Overweight & during pregnancy - extra weight adds pressure on leg veins ○​ Lifestyle - sitting or standing for long periods of time Blood Pressure ​ Blood pressure is a measure of the force of blood against the walls of your arteries ​ Each cardiac cycle (heartbeat) consists of a contraction and relaxation of the heart ​ Systolic number (top) is a measure of the pressure force when your heart contracts and pushes out the blood ○​ Normal systolic pressure is about 120 mm Hg (millimeters of mercury) ​ Diastolic number (bottom) is the measure when your heart relaxes between beats ○​ Normal diastolic pressure is about 80 mm Hg Low Blood Pressure (Hypotension) ​ As long as you are not experiencing symptoms of low blood pressure, there is no need for concern ​ Most doctors consider chronically low blood pressure only if it causes noticeable signs and symptoms, such as: ○​ Dizziness or lightheadedness ○​ Nausea ○​ Fainting ○​ Cold, clammy, pale skin ○​ Dehydration or unusual thirst ○​ Rapid, shallow breathing ○​ Lack of concentration ○​ Fatigue ○​ Blurred vision ○​ Depression Healthy Blood Pressure ​ By keeping your blood pressure in the healthy range, you are: ○​ Reducing your risk of the walls of your blood vessels walls becoming overstretched and injured ○​ Reducing your risk of having a heart attack or stroke; and of developing heart failure, kidney failure and peripheral vascular disease  ○​ Protecting your entire body so that your tissue receives regular supplies of blood that is rich in the oxygen it needs High Blood Pressure (Hypertension) ​ Healthy arteries are made of muscle and a semi-flexible tissue that stretches like elastic when the heart pumps blood through them ​ The more forcefully that blood pumps, the more the arteries stretch to allow blood to easily flow ​ Over time, if the force of the blood flow is often high, the tissue that makes up the walls of arteries gets stretched beyond its healthy limit and damages ​ High blood pressure can lead to: ○​ Damage to the heart and coronary arteries, including heart attack, heart disease, congestive heart failure, aortic dissection and atherosclerosis (fatty buildups in the arteries that cause them to harden) ○​ Stroke ○​ Kidney damage ○​ Vision loss ○​ Erectile dysfunction ○​ Memory loss ○​ Fluid in the lungs ○​ Angina ○​ Peripheral artery disease Preventing High Blood Pressure ​ Eat a better diet, which may include reducing salt ​ Enjoy regular physical activity ​ Maintain a healthy weight ​ Manage stress ​ Avoid tobacco smoke  ​ Comply with medication prescriptions ​ If you drink, limit alcohol ​ Understand hot tub safety SBI3U | Cardiac Cycle Structure of the Heart ​ Muscular organ located in the middle of the chest, directly under the breastbone ​ Size of a clenched fist ​ Enclosed by pericardium - double-walled sac with fluid between layers ​ Septum - wall of muscle separating two parallel pumps ​ Each pump has an atrium and a ventricle ​ Atria - top of the heart, receive blood and pump it into the ventricles ​ Ventricles- bottom of the heart ○​ Right ventricle - pumps blood into pulmonary circulation (to the lungs) ○​ Left ventricle - pumps blood into systemic circulation (to the body) ○​ Ventricle walls thicker than atria, left ventricle walls thicker than right - needs to pump blood further distance ​ Valves - ensure blood flows in one directions through the heart ○​ Semilunar valves - between the ventricles and arteries ​ Pulmonary semilunar valve - right ventricle to pulmonary arteries ​ Aortic semilunar valve - left ventricle to aorta ○​ Atrioventricular valves - between the atria and ventricles ​ Left AV valve - bicuspid valve (2 flaps) ​ Right AV valve - tricuspid valve (3 flaps) ​ Chordae tendineae - prevent the AV valves from opening backwards into the atria during high pressure ventricular contractions Blood Supply ​ Heart has a high demand of oxygen and nutrients - requires over 10% of total oxygen load from blood ​ Has own supply of blood vessels - coronary blood vessels ○​ Network of arteries and veins provide oxygen and nutrients to the heart, and remove waste ​ Coronary arteries branch from the aorta ​ Coronary veins join to form the coronary sinus, which empties into the right atrium Circulation  ​ At rest, the heart can pump 5 L of blood in one minute ​ At maximum output, the heart can pump more than 25 L of blood in one minute Pathway of blood through the heart: 1.​ Deoxygenated blood enters right atrium via superior and inferior vena cava 2.​ Contraction of right atrium, with pull of gravity, moves blood into the right ventricle 3.​ Right ventricle contracts, forcing blood through pulmonary arteries and to the lungs 4.​ Gas exchange occurs at the lungs 5.​ Oxygenated blood returns to the left atrium via the pulmonary veins 6.​ Left atrium contracts to move blood to the left ventricle 7.​ Contraction of the left ventricle sends blood out of the heart and into the aorta 8.​ Blood moves through systemic circulation (arteries, arterioles, capillaries, venules, veins, vena cava) Cardiac Cycle ​ Cardiac cycle - complete heartbeat ○​ Contraction and relaxation of each chamber of the heart ○​ Takes 0.8 seconds under normal conditions ​ Diastole - relaxation of filling of the heart with blood ​ Systole - contraction and emptying of the heart Heart Sounds ​ lub-DUB sound of the heartbeat caused by closing of valves ​ lub - AV valves as ventricles start to contract (left slightly before the right) ​ DUB - when ventricles relax and semilunar valves snap shut ​ Murmurs - sound of blood leaking past or through valves that do not completely close  ○​ Not usually life-threatening, but result in a degree of inefficiency and require increased heart rate to compensate for decreased blood flow through the heart Regulation of Heart Rhythm ​ Heart is composed of myogenic - muscle that can contract and relax without external input ​ Heart rate can be influenced by the ​ Sympathetic (fight or flight) or ​ Parasympathetic(rest and digest) nervous systems ​ Conduction of the heart ○​ Heartbeat is initiated by a cluster of cells called the sinoatrial node (SA node) - pacemaker of the heart ○​ Signal passes over the atria in a wave, causing the muscles to contract ○​ Signal reaches the atrioventricular node (AV node) ○​ Signal is sent down purkinje fibres - conducting fibres through the septum, that initiate contraction of the heart from bottom to top Electrocardiograph (ECG/EKG) ​ Electrocardiograph detects and measures electrical signals and records them as an electrocardiogram ​ Analysis of an electrocardiogram can provide indication of abnormal heart conditions ○​ P wave - atrial depolarization (signal moving through atria) ○​ QRS complex - ventricular depolarization (signal moving through ventricles) ○​ T wave - ventricular repolarization (reset)