Bio Midterm 3 Notes PDF

Nutrition and Digestive System The Three Steps of Animal Digestion 1. Ingestion (eating) 2. Digestion (breakdown of food) 3. Absorption (Nutrient Uptake) 4. Elimination (Undigested Waste) The Three Main Categories of Animal Nutrition - Herbivore - Plant Eaters - Carnivo...

Nutrition and Digestive System The Three Steps of Animal Digestion 1. Ingestion (eating) 2. Digestion (breakdown of food) 3. Absorption (Nutrient Uptake) 4. Elimination (Undigested Waste) The Three Main Categories of Animal Nutrition - Herbivore - Plant Eaters - Carnivore - Meat Eaters - Omnivore - Eats both plants and meat Autotrophs Vs. Heterotrophs Autotrophs produce their own food (ex. Plants through photosynthesis) while heterotrophs (ex. humans) are unable to produce their own food and need to consume other organisms for energy. Three Nutritional Needs Chemical Energy - Used for cellular processes Building Blocks - For building macromolecules - Ex. Amino acids for proteins Essential Nutrients - Nutrients that are required and cannot be assembled for simpler organic molecules and must be obtained through an animal's diet. Four Classes of Essential Nutrients 1. Minerals a. Simpler Inorganic Nutrients usually required in small amounts. b. If ingested in large amounts will upset homeostatic balance 2. Vitamins a. Organic molecules that are required in very small amounts. b. There are 13 vitamins that are essential for humans c. There are two categories i. Fat-soluble (ADEK) 1. Vitamin A: Vision, Reproduction, Bond Health Immune System, Skin 2. Vitamin D: Strengthens Bones, Calcium Absorption, Immune System  3. Vitamin E: Immune System, Flushes Toxins 4. Vitamin K: Blood Clotting and Bone Health ii. Water Soluble 3. Essential Fatty Acids a. Must be obtained through diet and include unsaturated fatty acids. 4. Essential Amino Acids a. Animals require 20 amino acids and can only synthesize about 10 which means the rest must be obtained through their diet. Malnutrition Vs. Undernourishment - Malnutrition: A failure to obtain adequate nutrition like not ingesting the essential amino acids and fatty acids that your body cannot produce from simpler molecules. - Undernourishment: When a diet does not provide enough chemical energy and therefore your body cannot perform the normal cellular processes needed to survive. Food Processing Ingestion - Feeding and Eating - When food enters the mouth. Digestion - The process of breaking down food into small enough molecules so they can be absorbed - Types of Digestion - Mechanical digestion: The act of chewing and grinding to increase the surface area of the food making digestion easier. - Chemical Digestion: Splitting food into smaller molecules that pass through membranes, These are then used to build larger molecules like proteins. - Intracellular Digestion: Phagocytosis and Pinocytosis - Extracellular Digestion: When molecules are broken down outside the cell so that cells can uptake them. - Some animals with simple body plans have a gastrovascular cavity where both digestion and absorption occur but most animals don’t have this to prevent from the animals cells and tissues being digested. - Parts of the Digestive System - Oral Cavity: Where food processing begins - Teeth: Break down food - Salivary Glands: Secrete saliva to lubricate food. Saliva contains… - Mucus - Water - Salts - Cells - Glycoproteins - Amylase: Breaks down starch  - Only breaks down polysaccharides into smaller polysaccharides and maltose. - Stomach: Stores food and makes it into chyme (gastric juice and ingested food) - Gastric Juice - Hydrochloric Acid: Has a pH of about 2 that kills bacteria and denatures proteins. - Pepsin: Protease which breaks down peptide bonds in proteins making them into smaller peptides. - Both of these work together aka. Pepsin is pepsinogen secreted by chief cells and is inactive until parietal cells secrete HCl that turns it into pepsin. Absorption/Nutrient Uptake - Small Intestine - Villi and Microvilli: Increase the surface area (brush border) of the small intestine allowing for nutrient absorption. - Depending on the nutrient transport across epithelial cells can be passive or active. - Hepatic Portal Vein: Carries nutrient rich blood from the villi, to the liver and then to the heart. - The liver regulates nutrient distribution. - Liver: Produces bile that is released into the small intestine. - Bile contains salts that help breakdown fats. - Digestion of Fats - Fatty acids and monoglycerides are changed into triglycerides by epithelial cells - These fats are coated with phospholipids, cholesterol and proteins to form water-soluble chylomicrons. - These are transported into a lacteal (in each villi) - Lymphatic vessels are used to deliver chylomicron-containing lymph to large veins that return blood to the heart. Elimination - The Large Intestine - Colon: Completes the revvery of water that began in the small intestine. - Cecum: Aids in fermentation of plant material and connects the large and small intestine. - Appendix: An extension of the cecum that plays a role in immunity. - Microbiome: A mutualistic symbiotic relationship between bacteria in our digestive tract that aid in digestion. The differences in the microbiome are caused by diet, disease and age. System Adaptations of the Stomach - Herbivores - Herbivores have fermentation chambers where microorganisms digest cellulose in order for the herbivore to digest the nutrients in the plants completely.  - Longer alimentary canals since a longer time is needed to digest vegetation. - Carnivores - Have expandable stomachs - Omnivores - Have longer alimentary canals (small intestine). Hormonal Control - Hormones - Leptin: Produced by fat cells to suppress appetite and regulate fat levels. - Insulin: Triggers the uptake of glucose after a person eats. - Both trigger the brain satiety center. - PYY: Secreted by the small intestine after meals that suppress appetite. - Ghrelin: Hormone secreted by the stomach wall that triggers feelings of hunger. - Gastrin: Triggers the production of gastric juices. - Hormonal Digestion of Chyme - CCK (Cholecystokinin): Releases digestive enzymes from the pancreas and bile from the gallbladder - Secretin: Stimulate the release of HCO3 by the pancreas to neutralize chyme. - Hormonal Digestion of Fat - CCK and Secretin inhibit peristalsis to slow the movement of chyme when there is a high fat concentration. This allows the body to properly digest fast that may take longer to break down. - Homeostatic Glucose Regulation - Insulin (Beta Cells) and Glucagon (Alpha Cells) are both made in the pancreas and are both used to regulate glucose. - Glucagon causes the liver to produce glucose and works against insulin in times where glucose is low. Circulation and Gas Exchange Circulatory Systems and Exchange - These are essential to ensure that all cells receive the needed materials to maintain homeostasis. Diffusion although an option does not work over long distances and the time a particle takes to diffuse is proportional to the square of the distance it must travel. - Tissue specialization is crucial as it links exchange surfaces with all the cells throughout the body. - Smaller organisms like flatworms who have a gastrovascular cavity do not use tissue specialization as they are in direct contact with their environment and use structures to minimize diffusion distances. - The circulatory system and gas exchange are the link between the environment and the cells of complex organisms. Role of Partial Pressure - The pressure exerted by a particular gas in a mixture of gases. - How does gas diffusion work? - Gas goes from a region of higher partial pressure to a region of lower partial pressure. - In the alveoli of the lungs oxygen has a higher partial pressure which allows for it to diffuse into the blood which has a lower oxygen content and therefore a lower partial pressure. The opposite goes for carbon dioxide which then diffuses out of the blood into the alveoli. - This same idea works for cells and blood where in the cells oxygen has a lower partial pressure compared to blood so it diffuses in. Carbon dioxide has a higher partial pressure in the cells compared to the blood so it diffuses out. The Circulatory System Three Basic Components - Circulatory Fluid - Blood - Hemolymph - Interconnecting Vessels - Muscular Pump aka. The Heart Open vs. Closed Systems - Closed circulatory system: Blood is confined to vessels and is distinct from interstitial fluid - Allows organisms to be larger and more active due to effective oxygen and nutrients delivery. - Regulates the distribution of blood to different organs. - Annelids, cephalopods and vertebrates - Called the cardiovascular system in humans - Open circulatory system: Circulatory fluid surrounds all organs constantly and directly - Allows organisms to use less energy than needed. - Insects, arthropods and molluscs. Double Circulation - Oxygen-poor blood flows into the lungs into the alveoli capillaries, is oxygenated then moves through the pulmonary veins into the heart (left side) then to systemic arteries, into capillaries and oxygen diffuses into the cells. At the same time that this occurs CO2 rich blood (oxygen-poor) diffuses out of cells into capillaries, through systemic veins back into the heart (right), into pulmonary arteries and then back into the lungs into the alveoli where CO2 diffuses out and oxygen diffuses in. - Vein:Toward the heart - Artery: Away from the heart - Mammals and birds have 4 chambered heart - 2 atria and 2 ventricles. Arteries - Have thick elastic walls to handle high pressure blood pumped from the heart. Veins - Do not need thick walls instead they have valves to maintain unidirectional blood flow. Both have an endothelium, smooth muscle and connective tissue. Area Vs. Speed - The velocity of blood is slowest in the capillary beds as due to high resistance and large area. - The blood flow in capillaries is slow to allow for the exchange of materials. - Blood flows from high pressure to low. To regulate blood flow… - Vasoconstriction: Narrowing the arteriole walls to increase blood pressure. - Vasodilation: Widening the arterioles to decrease blood pressure. The respiratory system Respiratory surfaces should be… - Thin - Have a large surface area - Moist - Permeable The alveoli has all of these things. Oxygen diffuses through the moist film of the epithelium and into capillaries, CO2 diffuses out of the capillaries, across the epithelium into the air space. This is the gas exchange. Ventilation - Air flowing into the lungs during inhalation. - Air flowing out of the lungs during exhalation. Respiration - Exchange of oxygen and carbon dioxide at the cellular level and used in the mitochondria during respiration. Inhalation - Diaphragm contracts and negative pressure breathing is used to pull oxygen into the lungs. Exhalation - Diaphragm relaxes and CO2 is released from the lungs. BOTH are controlled by the medulla oblongata aka. The brain stem. Homeostatic Control - The normal blood pH is around a 7.4 - When the blood pH falls the cerebrospinal fluid also experiences a decrease in pH. The brain stem senses this and causes the body to breathe, to exhale the excess CO2 and inhale oxygen. (The opposite for when the blood pH is high). - Cerebrospinal fluid acts as a buffer for acidity levels in the brain while also detecting any acidity changes in the blood and alerting the brain. Function of Blood Components - Respiratory Pigments - Since O2 has a low solubility in water many organisms use pigments that allow for a greater transport of oxygen. - Hemoglobin (iron) and Hemocyanin (copper) are two major examples. - Hemoglobin Dissociation Curve - 1 hemoglobin molecule can carry up to four molecules of O2. The cool thing about hemoglobin is that it can change its affinity for oxygen. So if one molecule of O2 is added the affinity for three more molecules increases and if only one molecule of O2 detaches the hemoglobin's affinity for oxygen will decrease and detach the other three molecules. - The curve demonstrates that a slight change in the partial pressure of O2 will greatly affect the amount of Oxygen that hemoglobin delivers to the rest of the tissues. - Greater partial pressure means a greater oxygen content in the tissues. The opposite would leave the tissues deprived of oxygen. - Bohr Shift - Right Shift: When there is a lower blood pH then hemoglobin has a lower affinity for oxygen and there will be a higher concentration of CO2. - Left Shift: When there is a higher blood pH then the hemoglobin will have a greater affinity for O2 and there will be a higher contraction of O2 compared to CO2. Cardiovascular Adaptations - Double vs. single circulation - Double Circulation: When there are pulmonary and systemic circuits that pump blood depending on O2 content to and from the heart. - Single Circulation: Two chambered heart where the blood passes through two capillary beds and then returns to the heart. - Amphibians can have what is called a 3 chambered heart where instead of the four ventricles like humans they have only one ventricle where the oxygen poor and oxygen rich both flow into. These are called intermittent breathers and when they are underwater almost all blood flow to the lungs is such off. - Respiratory Adaptations - Aquatic Animals - Gills - Infoldings of the body that create a large surface area for gas exchange between water and the lungs of the fish.  - Gills use a countercurrent exchange system in which blood flows in the opposite direction of the water flow. - High Altitude Animals - Hemoglobin - Some animals have adapted to have hemoglobin that has a higher affinity for oxygen which allows them to breathe in higher altitudes with lower amounts of oxygen. - Fetal Hemoglobin binds to oxygen more strongly than adult hemoglobin so that the baby can receive oxygen from the mother. Immune System - Functions - Protects against pathogens (bacteria, viruses and parasites) - Protects against foreign molecules (ex. toxins) - Removes dead or damaged cells - Recognizes and removes abnormal cells - Innate Immunity - All animals have innate immunity. The different parts of this immunity are… - First Line Defenders (Physical): Skin, mucous, saliva and tears defend against foreign pathogens. The skin and digestive system also gave a low pH to prevent the growth of bacteria. - Sensor Systems (Pattern Recognition Receptors): Sentinel cells use PRR in cell membrane and cytoplasm along with the complement system. - Innate Defenses Effectors: Work to destroy invaders - Interferons - Phagocytosis - Inflammation and Fever Blood Cells Involved - Hematopoiesis: Stem cells that form blood cells - Cytokines induce the maturing of HSC cells - Red Blood Cells [Granulocytes]: Carry O2 - Neutrophils: Use phagocytosis to engulf and destroy bacteria. - Basophils: Used in allergic reactions which release histamines causing inflammation. - Eosinophils: Fight parasites and allergic reactions. - Platelets [Mononuclear Phagocytes]: Used for clotting - Monocytes:Develop as they leave the bloodstream. - Dendritic and Macrophages: Differentiate from monocytes. - White Blood Cells [Lymphocytes]: In charge of defenses against invaders - B and T Cells: Recognize antigens - Natural Killer: Destroy certain types of cells - Mast Cells - Immune cells that release histamines that dilate the blood vessels and make them more permeable. Phagocytosis - The ingestion and digestion of a foreign substance by a cell. - The cell membrane envelopes the bacteria, a vacuole is created, a lysosome connects the vacuole and digests the bacteria and then releases the debris. - Used by Neutrophils (circulate in the blood) and Macrophages (reside in organs and tissues). Inflammatory Response- Cascade of Events 1. Dilation of small blood vessels a. Greater blood flow=Heat and redness b. Leakage of Fluids=Swelling and Pain 2. Migration of Leukocytes a. Endothelial cells grab phagocytes which then squeeze between the cells of the vessel (diapedesis) 3. Clotting Factor 4. Dead Neutrophils a. Once the neutrophils are done eating the bacteria they then release the non harmful debris into the surroundings and die off. This accumulates as pus. 5 Cardinal Signs of Inflammation - Swelling - Redness - Heat - Pain - There can also be a loss of function. Local vs. Systemic Inflammatory Response Local aka. Acute Inflammation - Short term - Mainly neutrophils - Macrophages clean up damage by ingested dead cells and debris. But if the acute response fails… Systemic aka Chronic Inflammation - Macrophages and giant cells accumulate - Granulomas form How do invaders/pathogens evade the innate immune response? There are multiple ways that pathogens or antigens can evade the innate immune response. One way is by mutating to be able to withstand higher temperatures. Since inflammation is a component of the innate immune response and causes a fever if the antigen has a higher threshold for temperature then it will survive. The same thing goes for mutating to withstand a low pH like that of the skin or stomach acid to get past the first line defenses. Another option is mimicking host molecules so that they aren't recognized by their receptors. Adaptive Immunity There are two parts to this… 1. Humoral Immune Response: Meant to protect the blood using B cells 2. The Cell-Mediated Immune Response: Meant to destroy infected host cells Different Blood Cells Used - B Cells - Mature in the bone marrow - Used in the humoral response - Contains a constant and variable region for varying degrees of recognition of different antigens. - How does it work? - A B cell must bind to an epitope (the part of an antigen that is accessible and binds to the antigen receptor). - This causes antibodies to be made that will also help to fight and kill the antigens that they recognize. - How do you activate it? - An antigen binds to the B cell, receptor mediated endocytosis occurs. The MHC protein of the b cells then presents the antigen fragment to the helper T cell. The helper T then releases cytokines which cause the B cells to proliferate and then release antibodies which mark the antigens in the blood for destruction. - T Cells - Mature in the thymus - Used in the cell mediated response - Has three types - Cytotoxic - Induces apoptosis and releases cytokines to alert other cells. - To activate you need… - Signal from Helper T - Interaction with an antigen representing cell. - Helper T Cells - Activate macrophages and B cells - Activate both the humoral and cell mediated adaptive immune responses. - Produce cytokines to direct and support T cells - To activate… - A foreign molecule must be present - The antigen must be displayed on the surface of the antigen presenting cell. - Natural Killer Cells - Killing cells tagged with antibodies. - Secrete IFN-gamma to stimulate macrophages. - Antibodies - Used not for the killing of antigen host cells or other antigens in the blood but are used to mark them to be killed or digested by the cytotoxic cells. - They use neutralization which is where they bind to the surface proteins of viruses so that they cannot affect host cells. - They also use opsonization which is the promotion of phagocytosis. Immunological Memory - Responsible for the response to and memory of long-term diseases. - Primary Immune Response: When the body is first exposed to an antigen. - This is when a clone of the lymphocytes are formed and memory B cells are made. - Secondary Immune Response: Memory cells facilitate a faster response to an antigen the second time it is introduced into the body. Naturally and Artificially Acquired Immunity Naturally Acquired Immunity - The adaptive immunity is formed through the body fighting the antigen without any outside help. - Active Immunity: Antigens enter the body naturally and the body induces antibodies and lymphocytes (memory B cells). - Passive Immunity: Antibodies pass from the mother to the fetus through the placenta or breastfeeding. Artificially Acquired Immunity - When the adaptive immunity is formed using outside help either through a vaccine or previous monitored exposure. - Active Immunity: An antigen is introduced into the body through a vaccine and the body produces the antibodies and lymphocytes. - Passive immunity: Antibodies are injected. B and T Cell Diversity - Gene Rearrangement - The genes that code for the antigen receptors on both B and T cells are randomly arranged allowing for a wide variety of different B and T cell antigen receptors. - Alternative Splicing - This is when a protein is being coded for and not all the introns and cut out and not all the exons are included leading to a wider variety of proteins. Misregulation of Adaptive Immunity - Allergies - Exaggerated responses to certain antigens (or things that the body believes are antigens but are allergens). Autoimmune Diseases - Immune system is activated against the molecules within the body. This is a wide range with many possibilities for severity. HIV - The HIV virus attacks and kills helper T cells to a decreased immune response not only to the virus but also to other viruses making a patient more susceptible to something like the flu. Osmoregulation and Excretion Overcoming Osmoregulation Challenges - Osmoregulation Vs. Excretion - Osmoregulation is meant to control solute concentration and balance water loss and gain. - Excretion is meant to rid the body of nitrogenous metabolites and other waste products. - Osmoregulation depends on the osmolarity of internal fluids. - Conformers Vs. Regulators - Osmoconformers - Organisms that are isosmotic with their surroundings and do not regulate their osmolarity. They tend not to gain or lose water. - They are marine animals. - Osmoregulators - Expend energy to control water loss and gain. - These are freshwater and terrestrial animals. - Some examples of adaptations to osmoregulation are.. - Marine Fish - Hypoosmotic to saltwater. - Offset their water loss by drinking large amounts of water and eliminating salts through gills and kidneys. - Freshwater Fish - Hyperosmotic to freshwater. - Take in water by osmosis and release salts through diffusion. These salts are then replaced through food and uptake in the gills. - THEY BARELY DRINK WATER - Land Animals - Lose water through urine, feces, skin and gas exchange. - They have evolved with kidneys that are made to conserve as much water as possible. Excretion of Nitrogenous Waste - The origin of nitrogenous waste is the breakdown of nucleic acids and proteins. The three different forms of this waste are.. - Ammonia - Lots of water lost - Usually aquatic fish - Highly Toxic - Urea - Middle ground for water loss and conservation - Mammals, most amphibians, and some ocean life. - Uric Acid - The most water conservative - Birds, reptiles, insects, and land snails  - The least toxic The Vertebrate Excretory System Structure - Kidneys - Function in both excretion and osmoregulation. - The Nephron is the functional unit of the kidney - Includes tubules and ducts that carry urine out of the kidney and out of the body. - The Nephron - The Blue arrows are passive transport - The red arrows are active transport - The filtrate includes a multitude of things such as water, urea, salts, hydrogen, glucose, amino acids and some drugs. - The four steps of the excretory process 1. Filtration 2. Reabsorption 3. Secretion 4. Excretion - Filtration (BOWMAN'S CAPSULE) - Filtrate produced in the capsule contains… - Water - Glucose - Amino acids - Urea (Nitrogenous waste) - Some drugs - Hydrogen - Reabsorption (PROXIMAL TUBULE)  - Surrounded by interstitial fluid the point of this tubule is to reabsorb water, ions and nutrients like glucose. - The downs use passive transport while active transport is used on the hills. - Anything actively or passively transported enters the interstitial fluid and then gets reabsorbed by capillaries. - This step causes the contents of the filtrate to be more concentrated. - Reabsorption (Descending Loop of Henle) - Used for the reabsorption of water that is present in the filtrate using aquaporins. - Driven by the high osmolarity of the interstitial fluid which is hyperosmotic to the filtrate. - Reabsorption(Ascending Loop of Henle) - Salt is able to diffuse into the surrounding interstitial fluid through first passive and then active transport. This is to maintain the osmolarity of the interstitial fluid. - Reabsorption (DISTAL TUBULE) - Regulates Nacl and K contractions in body fluids. - pH is regulated through the controlled movement of Hydrogen and bicarbonate. - Everything is actively transported except for water. - Reabsorption (Collecting Ducts) - Process filtrate into urine which is then carried to the renal pelvis. - As the urine passes to the renal pelvis hormonal control of permeability and transport is used to determine how concentrated the urine becomes. - This reabsorption is the final place where any water or salts can be reabsorbed. THE TWO PRIMARY SOLUTES AFFECTING OSMOLARITY - NaCl - Urea Hormonal Control of Water Balance and Blood Pressure - ADH (Vasopressin) - The hormone released by the posterior pituitary that controls blood pressure and blood volume. - When the osmolarity of blood decreases (the concentration of the solutes in our blood is low) ADH is released - When the osmolarity drops to a certain point ADH secretion reduces. This point is around 285-295. - Control Collecting Duct Permeability - ADH is released - ADH binds and activates membrane receptors on collecting ducts cells. - Signal cascade - Insertion of aquaporin proteins into the membrane lining of the collection duct. - Increase in water recapture - Reduced urine volume Endocrine System