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Unit VIII- Homeostasis Chapter 32*, 33*, 34* Chapter 32 Homeostasis What you must know: Three categories of nitrogenous waste, which animal groups produce each, and why. The components of a nephron, and what occurs in each region. How hormones affect water balance by acting on the nephron. Control of the Internal Environment Feedback control maintains the internal environment in many animals Multicellularity allows for cellular specialization with particular cells devoted to specific activities Specialization requires organization and results in an internal environment that differs from the external environment Organ Systems Homeostasis Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level Regulation of room temperature by a thermostat is analogous to homeostasis Figure 32.4 Response: Heating stops. Room temperature decreases. Sensor/ control center: Thermostat turns heater off. Stimulus: Room temperature increases. Set point: Room temperature at 20C Stimulus: Room temperature decreases. Room temperature increases. Response: Heating starts. Sensor/ control center: Thermostat turns heater on. Animals achieve homeostasis by maintaining a variable at or near a particular value, or set point Fluctuations above or below the set point serve as a stimulus; these are detected by a sensor and trigger a response The response returns the variable to the set point Homeostasis in animals relies largely on negative feedback, a control mechanism that reduces the stimulus Homeostasis moderates, but does not eliminate, changes in the internal environment Set points and normal ranges for homeostasis are usually stable, but certain regulated changes in the internal environment are essential Osmoregulation: control solute concentrations and balance water gain/loss Excretion: removal of nitrogenous wastes from body Types of Nitrogenous Wastes: 1. Ammonia – water soluble, very toxic; aquatic animals 2. Urea – produced by liver; less toxic, conserves water; most vertebrates 3. Uric acid – excreted as paste or crystals; birds & reptiles Types of Nitrogenous Wastes Various forms of excretory systems Protonephridia - Platyhelminthes (Planaria) Metanephridia - Annelida Malpighian tubules – Insects, arthropods Kidneys - Vertebrates Least Most Complex: Protonephridium: closed tubes lacking an internal opening capped by a cellular unit called flame bulb. Urine passes out of small pores. 2. Metanephridia: internal openings collect body fluids into a long tube surrounded by capillaries. Urine exits out pores. 3. Malpighian tubes: remove N waste from hemolymph, located near digestive tract. Secretes dry waste with feces. 4. Kidneys: compact organs containing tubules surrounded by capillaries. Functions in water and blood filtration, excretion of N waste and salt 1. How to make urine: Water and solutes enter filtrate; blood cells and proteins remain in body fluid. Reclaim glucose, vitamins, hormones Add toxins and excess ions Filtrate leaves body as urine Mammalian Excretory System Nephrons: functional units of the kidney • Glomerulus: filtrate forced into Bowman’s capsule. • Blood cells and proteins DO NOT enter filtrate Processing of blood filtrate: 1. Proximal tubule: secretion & reabsorption change 2. 3. 4. 5. volume and composition of filtrate Bicarbonate, NaCl, water is absorbed Descending loop of Henle: reabsorb water Ascending loop of Henle: reabsorb salt Distal tubule: K+ and NaCl levels regulated Collecting duct: filtrate becomes more concentrated; minimize water loss From blood filtrate to urine SECRETION FILTRATION REABSORPTION EXCRETION Hormones Antidiuretic Hormone (ADH): urine concentration, reduce H2O loss Also called vasopressin Renin/angiotensin II: raise blood pressure Aldosterone: Na+ reabsorption, H2O retention, blood volume, pressure Blood Pressure Regulation Urine exits kidney through Ureters Bladder: stores urine Urethra: urine exits body Believe it or not… Your kidneys are only 4 in long and weigh about 5 oz (weight of ½ unfinished can of pop) Usually we urinate 1.5-2.5 liters/day 44 gallons of blood is filtered by kidneys everyday-2 bathtubs full Fresh urine is cleaner than spit, cleaner than your hands after they have been washed and cleaner than the sandwich you will eat for lunch Gandhi drank urine every day (Tantric Yoga practice) Gladiators brushed their teeth with it Colonial housewives cleaned their home with it 1st football=pig bladder Thermoregulation: Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range Conduction is the process by which heat moves from a place of higher temps to a place with lower temps Convection is heat transfer caused by airflow Evaporation is the process by which water leaves our bodies in the form of water vapor Radiation is the loss of heat through ejection of electromagnetic waves Figure 32.6 Radiation Convection Evaporation Conduction Endothermy and Ectothermy Endothermic animals generate heat by metabolism; birds and mammals are endotherms Ectothermic animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and nonavian reptiles Figure 32.8 Sensor/control center: Thermostat in hypothalamus Response: Sweat Response: Blood vessels in skin dilate. Stimulus: Increased body temperature Body temperature decreases. Homeostasis: Internal body temperature of approximately 36–38C Body temperature increases. Stimulus: Decreased body temperature Response: Blood vessels in skin constrict. Response: Shivering Sensor/control center: Thermostat in hypothalamus Endocrine signals trigger homeostatic mechanisms in target tissues There are two major systems for controlling and coordinating responses to stimuli: the endocrine and nervous systems In the endocrine system, signaling molecules released into the bloodstream by endocrine cells reach all locations in the body In the nervous system, neurons transmit signals along dedicated routes, connecting specific locations in the body Figure 32.9 (a) Signaling by hormones (b) Signaling by neurons Stimulus Stimulus Endocrine cell Cell body of neuron Nerve impulse Hormone Axon Signal travels to a specific location. Signal travels everywhere. Blood vessel Nerve impulse Axons Response Response WARM-UP 1. What is the principle of countercurrent exchange? 2. (Review) What are the 4 classes of macromolecules? 3. You eat a piece of candy. List the structures it passes through as it travels through your alimentary canal. 4. Where does most of the digestion of the candy in #3 happen? Chapter 33: Animal Nutrition What you need to know: Major compartments of alimentary canal (organs) – and their contributions to animal nutrition. Digestive glands: salivary, pancreas, liver, gall bladder – and their contributions to animal nutrition. Digestion of carbs, proteins, fats, nucleic acids. Essential Nutrients: required by cells, obtained through food Four classes of essential nutrients: Essential amino acids (8) Essential fatty acids Vitamins (13) - fat-soluble, water-soluble Minerals Dietary Deficiencies Undernourished: diet is deficient in calories, not enough energy Malnourishment: missing 1+ essential nutrients Herbivore licks exposed salts and minerals lacking in plants. The main stages of food processing: 1. Ingestion: eating 2. Digestion: breakdown of food into small 3. 4. molecules Mechanical (chewing, grinding) Chemical (enzymes) amylase in saliva Absorption: cells take up nutrients Elimination: pass undigested materials from digestive system Digestive Compartments Most animals process food in specialized compartments Intracellular: digestion of food inside cells by food vacuoles Ex. phagocytosis, pinocytosis, sponges Extracellular: food broken down outside of cells Gastrovascular cavity (simple) or alimentary canal (complex) Specialized organs for digestion in Humans Digestive system = alimentary canal + glands Glands = salivary glands, pancreas, liver, and gallbladder Q: Can you name the organs of the human alimentary canal in order? Peristalsis: push food through rhythmic contractions of muscles in the wall of the canal Esophageal Sphincters: valves (trapdoors) regulate the movement of material between compartments Digestion of Macromolecules: Mouth = carbs Stomach = proteins Small Intestine = carbs, proteins, fats, nucleic acids Digestion in the Mouth Oral cavity: mechanical, chemical digestion Salivary glands: saliva lubricates food Teeth chew food into smaller particles Salivary amylase: breakdown glucose polymers Saliva contains mucus, a viscous mixture of water, salts, cells, and glycoproteins Pharynx: back of throat Epiglottis: flap of cartilage, covers trachea when swallowing Esophagus: food tube (pharynx stomach) Digestion in the Stomach The stomach stores food and secretes gastric juice, which converts a meal to acid chyme HCl: pH 2, kills bacteria & denatures proteins Pepsin: enzyme (protease) that hydrolyze proteins into smaller peptides Pepsinogen (inactive) pepsin (active) by HCl Mucus: protects lining of stomach Gastric ulcers: lesions in the lining, caused mainly by bacterium Heliobacter pylori Digestion in the Small Intestine SI = major organ of digestion and absorption Pass through the Panama Canal of the body: the PYLORIC SPHINCTER Duodenum: first section, digestive juices, major chemical digestion Digestive juices: Pancreas: bicarbonate (basic), trypsin & chymotrypsin (proteases); lipase (fats); amylase (carbs); nuclease (DNA, RNA) Bile: made in liver, stored in gall bladder Emulsify fats (make smaller droplets) Hormones that coordinate digestion: Gastrin: produced by stomach, production of gastric juices Entrogastrin: produced by SI (duodenum), peristalsis to allow time for fat digestion Secretin & CCK (cholesystokinin): secreted by SI (duodenum), flow of digestive juices from pancreas & gall bladder Absorption in the Small Intestine Villi and microvilli increase surface area Villi capillaries hepatic portal vein liver heart Liver: distribute nutrients, detox, glucose storage (glycogen) Absorption in the Large Intestine LI = colon Function = compact waste, reabsorb water Cecum: pouch where SI & LI meet, ferment plant material Appendix = extension of cecum, role in immunity Rectum: end of LI, feces stored until elimination Evolutionary adaptations of vertebrate digestive systems correlate with diet Dentition: teeth correlate with diet Herbivores: longer alimentary canal, longer cecum Mutualistic Adaptations Many herbivores have fermentation chambers, where mutualistic microorganisms digest cellulose (ruminants) Homeostatic Mechanisms Vertebrates store excess calories as glycogen in the liver and muscle cells, and as fat in adipose tissue Overnourishment can lead to obesity Leptin: hormone, suppresses appetite Glucose Homeostasis Closing questions List the locations where each of the 4 macromolecules are chemically digested. 2. Where do vertebrates store excess calories? 3. Draw and label the structure of a human heart. 4. List the pathway of a single red blood cell through the heart. 1. Circulation & Gas Exchange Chapter 34 What you need to know: Circulatory vessels, heart chambers, route of mammalian circulation Evolution of the heart from 24 chambers How RBC’s demonstrate structure/function Blood pressure Cardiovascular disease (Roles of diet, BP, genetics) General characteristics of a respiratory surface How O2 and CO2 are transported in blood Pathway of O2 from airRBCtissues Transport systems (circulation) linked with gas exchange (respiration) Diffusion of gases only rapid across small distances Basic: Cells in direct contact with environment Ex. sponges Gastrovascular Cavity: For digestion & distribute substances Ex. jellies, flatworms Circulatory System: Moves fluid to tissues & cells for exchange Ex. larger animals Circulatory System = Blood + Vessels + Heart Open circulatory system: blood bathes organs directly • Blood + lymph = hemolymph • Heart pumps hemolymph into sinuses • Ex. arthropods, mollusks Closed circulatory system: blood contained in vessels & pumped around body • Blood and fluid separate • Ex. annelids, cephalopods, vertebrates Figure 42.10a Valve Basal lamina Endothelium Smooth muscle Connective tissue Endothelium Capillary Smooth muscle Connective tissue Artery Vein Arteriole Venule Types of Blood Vessels arterioles venules ARTERIES CAPILLARIES VEINS Blood away Connect Blood back from heart High pressure Thick, strong walls Pulse arteries Single-cell thick walls Exchange of O2/CO2 heart Low pressure Thin-walled, large diameter Valves prevent backflow Blood enters through an atrium and is pumped out through a ventricle Fish = single circulation pathway, 2 chambers Double circulation: amphibians, reptiles, mammals Double circulation pathways in vertebrates Pathway of blood through heart Figure 42.6 Capillaries of head and forelimbs Superior vena cava Pulmonary artery Capillaries of right lung Pulmonary vein Right atrium Right ventricle Pulmonary artery Aorta Capillaries of left lung Pulmonary vein Left atrium Left ventricle Aorta Inferior vena cava Capillaries of abdominal organs and hind limbs Cardiac cycle Systole: contraction or pumping phase Diastole: relaxation or filling phase Heart rate: # beats/minute (72 bpm resting) Stroke volume: amount of blood pumped by L. ventricle during contraction (~70 ml) Figure 42.8-3 2 Atrial systole and ventricular diastole 1 Atrial and ventricular diastole 0.1 sec 0.4 sec 0.3 sec 3 Ventricular systole and atrial diastole Valves: prevent backflow of blood The atrioventricular (AV) valves (tricuspid, bicuspid) separate each atrium and ventricle The semilunar valves control blood flow to the aorta and the pulmonary artery “Lub-dup” sound = blood against closed AV valves (lub) / the semilunar (dup) valves Heart murmur: backflow of blood through a defective valve Sinoatrial (SA) node: pacemaker of heart, in right atrium The pacemaker is regulated by two portions of the nervous system: the sympathetic and parasympathetic divisions The sympathetic division speeds up the pacemaker The parasympathetic division slows down the pacemaker The pacemaker is also regulated by hormones (epinephrine) and temperature Blood Pressure BP = systolic/diastolic pressure Systolic: heart contracts Diastolic: heart relaxed Normal: 120/70 Pulse: rhythmic bulging of artery walls with each heartbeat Using a Sphygmomanometer Blood pressure reading: 120/70 1 3 2 120 120 70 Artery closed Sounds audible in stethoscope Sounds stop Figure 42.13 Direction of blood flow in vein (toward heart) Blood returning to heart through veins and venules Valve (open) Skeletal muscle Valve (closed) Lymphatic System: returns lost fluid and proteins to blood as lymph Lymph Nodes: filter lymph, house WBC’s Immune system role Blood Plasma (55%) – water, ions, proteins, gases, nutrients, wastes, hormones Cells (45%) – RBC, WBC, platelets Develop from stem cells in bone marrow Red blood cells (erythrocytes): O2 transport via hemoglobin White blood cells (leukocytes): fight infection Platelets (cell fragments): blood clotting Figure 42.17 Cellular elements 45% Plasma 55% Constituent Water Solvent for carrying other substances Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering, and regulation of membrane permeablity Plasma proteins Albumin Fibrinogen Leukocytes (white blood cells) Separated blood elements 5,000–10,000 Functions Defense and immunity Lymphocytes Basophils Eosinophils Neutrophils Osmotic balance, pH buffering Monocytes Platelets 250,000–400,000 Clotting Immunoglobulins Defense (antibodies) Substances transported by blood Nutrients Waste products Respiratory gases Hormones Number per L (mm3) of blood Cell type Major functions Erythrocytes (red blood cells) 5–6 million Blood clotting Transport of O2 and some CO2 Figure 42.18 2 1 3 Collagen fibers Platelet plug Platelet Fibrin clot Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Enzymatic cascade Prothrombin Thrombin Fibrinogen Fibrin Red blood cell Fibrin clot formation 5 m Cardiovascular Disease Atherosclerosis: buildup of plaque deposits within arteries Heart attack (myocardial infarction): blockage of one or more coronary arteries Stroke: rupture or blockage of arteries in the head Hypertension: high blood pressure; promotes atherosclerosis and increases the risk of heart attack and stroke Figure 42.20 Lumen of artery Endothelium Smooth muscle 1 LDL Foam cell Macrophage Plaque 2 Extracellular matrix Plaque rupture 4 3 Fibrous cap Cholesterol Smooth muscle cell T lymphocyte Closing questions How does the heart beat? 2. What are the 3 types of blood cells and their function? 3. What is the function of the lymphatic system? 4. List the pathway of one molecule of O2 from the air into your pinky toe. 1. Respiration Gas exchange supplies O2 for cellular respiration and disposes of CO2 Partial pressure = pressure exerted by a particular gas in a mixture of gases Gases always diffuse from higher partial pressure lower partial pressure Respiratory media: O2 in air or water Respiratory surface: body wall, skin, gills, tracheae, lungs Characteristics: Moist Large surface area-to-volume ratio Larger animals: associated with vascular system Gills in aquatic animals Coelom Gills Parapodium (functions as gill) (a) Marine worm Gills Tube foot (b) Crayfish (c) Sea star Fish gills: absorb O2 through countercurrent exchange (blood flows opposite of water) Tracheal systems in insects Respiratory system in birds (lungs + air sacs) Mammalian respiratory system Pathway of O2 Nose/mouth: filtered, warmed, humidified Pharynx Larynx: contains vocal cords Trachea: windpipe; lined with cartilage Bronchi: branches to lungs Bronchioles Alveoli: air sacs for gas exchange Mucus: traps particles Cilia: sweeps particles up to pharynx Alveoli Figure 42.30a 1 Inhaled air 8 Exhaled air Alveolar epithelial cells 2 Alveolar spaces CO2 O2 Alveolar capillaries 7 Pulmonary arteries 3 Pulmonary veins 6 Systemic veins 4 Systemic arteries Heart CO2 O2 Systemic capillaries 5 Body tissue (a) The path of respiratory gases in the circulatory system Diaphragm: dome-shaped muscle separating thoracic/abdominal cavities Control of Breathing in Humans Control center = medulla oblongata Responds to pH changes in blood High CO2 carbonic acid forms lowers pH Sensors in the aorta and carotid arteries Adaptations for gas exchange Hemoglobin: respiratory pigment in vertebrates 4 subunits, each with heme group with iron (Fe) Can carry 4 molecules of O2 Bohr shift: O2 dissociates from hemoglobin when blood pH is low Arthropods, mollusks: blue hemocyanin pigment contains copper (Cu) How CO2 is transported 1. 2. 3. Bicarbonate ions (70%) Hemoglobin (23%) Dissolved in plasma (7%) Respiratory Adaptations of Diving Mammals Diving mammals have evolutionary adaptations that allow them to perform extraordinary feats For example, Weddell seals in Antarctica can remain underwater for 20 minutes to an hour For example, elephant seals can dive to 1,500 m and remain underwater for 2 hours High blood to body volume ratio Stockpile O2 and deplete it slowly Store oxygen in their muscles in myoglobin proteins Respiratory Disorders Asthma: airways constricted Bronchitis: bronchi swollen and clogged Pneumonia: inflammation of lung caused by infection Tuberculosis (TB): infectious disease caused by M. tuberculosis Emphysema: lose elasticity of lung tissue Lung Cancer: abnormal cell growth in lungs