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Unit VII: Animal Structure and Function, Part I Animal Nutrition, Circulation and Gas Exchange, and Immunity Unit Objectives • Observe how animals adjust to the environment over the long term by adaptation due to natural selection and over the short term by physiological responses. + How do animals obtain energy from the environment? + How do animals obtain O2 for cell respiration while disposing of the waste gas CO2? + How do animals respond to pathogens? Epithelial Tissue The Cell • basic unit of structural organization for all living things + tissue (Latin, weave) - groups of cells with a common structure and function • Epithelial Tissue + surface tissue- covers every surface of the body - squamous - cuboidal - columnar Connective Tissue Live cells in a non-living matrix Connective Tissue (con’t) Blood • RBC/WBC in water based fluid plasma Bone • osteocytes living in calcified hard matrix Ligaments • fibroblasts in a matrix of collagen fibers + bone-to-bone connection Tendons • fibroblasts in a matrix of less elastic fibers + muscle-to-bone connection Cartilage • chondrocytes in a soft/pliable matrix Adipose tissue • mostly cells (little matrix) Loose connective tissue • tissue glue of the body Muscle Tissue Muscle Tissue • muscle fibers capable of contracting when stimulated by nerve impulses + Skeletal Muscle - striated (striped) - voluntary movements - multinucleated + Smooth Muscle - branched, tapered - involuntary actions + Cardiac Muscle - striated, branched - no neurons Muscle Contraction Skeletal Muscle • two kinds + fast-twitch (white meat) - tend to go anaerobic + slow-twitch (dark meat) - myoglobin-rich • “twitch” + contraction of protein filaments causes muscles to shorten - thin (actin) and thick (myosin) bands - interleaved with each other + myosin grabs actin and pulls - sliding filament theory of muscle contraction Muscle Contraction Sliding Filament Theory • relaxed muscle + length of each sarcomere is greater - Z-line to Z-line • Contracting Muscle + actin/myosin slide past each other - shortening the sarcomere • Contracted Muscle (maximum) + actin filaments overlap each other - sarcomere is very short Nervous Tissue Organ Systems • Digestive System: mouth … anus • Circulatory System: heart, blood vessels, blood • Respiratory System: lungs, trachea, other breathing tubes • Immune and Lymphatic System: marrow, lymph nodes, spleen, WBC • Excretory System: kidneys, ureters, bladder, urethra • Endocrine System: hormone-secreting glands • Reproductive System: ovaries, testes, etc. • Nervous System: brain, spinal cord, nerves • Integumentary System: skin and its derivatives • Skeletal System: bones, tendons, ligaments, cartilage • Muscular System: skeletal muscles Bioenergetics Overview • animals derive chemical energy from the environment in food • digestion breaks down food into nutrient molecules + some energy returns to environment as feces • nutrient molecules enter body cells + convert to useful form (ATP) • use ATP for cellular work and biosynthesis + some energy lost as heat • metabolic rate + amount of energy an animal uses in a unit of time + BMR Energy Content of Food Calorimeter • instrument used to measure the amount of energy in a food sample + food sample is burned, and the heat produced is measured • calorie + unit commonly used in measuring energy content of food - amount of heat that is needed to raise the temperature of 1 gram of water 1ºC + 1 calorie = 4.2 joules + 1 Calorie = kilocalorie (1000 calories) Regulating the Internal Environment Homeostasis • the process of controlled and regulating the internal environment + interstitial fluid Homeostasis Feedback Mechanisms • negative/positive + receptors detect a change in a variable - response depends on the type of change • thermometer (receptor) • variable (room temperature) • response (heat produced) Human Digestive System Alimentary Canal • “tube-within-a-tube” + mouth + pharynx + esophagus + stomach + small intestine + large intestine + rectum + anus • 27 feet long!!! + Take the tour! • accessory organs + salivary glands + liver + pancreas Mouth and Pharynx Mechanical Digestion • teeth and tongue Chemical Digestion • salivary glands + two types - thin, watery - thick, mucous + salivary amylase - digests starch Swallowing Reflex • tongue pushes bolus to pharynx • epiglottis closes off trachea Esophagus Peristalsis • alternate waves of relaxation and contraction + moves food through alimentary canal • sphincter + ring of muscle - cardiac sphincter - pyloric sphincter The Stomach Thick-walled, muscular sac • bolus is stored temporarily + 2+ liters of food/liquid + 20 minutes or less • mechanical breakdown + churning and contracting • chemical digestion of proteins + gastric juices - hydrochloric acid (ulcers) - pepsin • bolus changed into chyme + thin, soup liquid The Small Intestine Small Intestine • 6.5 meters long, 2.5 centimeters diameter + coiled, folded + lined with villi • three regions + duodenum, jejunum, ileum • site of chemical digestion and absorption + pancreatic juice - amylase, protease, trypsin, lipase + bile + intestinal juice - peptidase, maltase Stomach Secretions How does our body know when to secrete these enzymes? Feedback Mechanisms Intestinal Secretions Large Intestine Large Intestine • 1.5 meters long, 6 centimeters diameter • four regions + ascending, transverse, descending, and sigmoid colon • three functions + reabsorption of water - diarrhea/constipation + absorption of vitamins from bacteria - E. coli bacteria produce vit. K + elimination of feces • appendix + vestigial structure with no function Circulation and Gas Exchange Transport Systems • functionally connect the organs of exchange with the body cells + diffusion alone is not adequate + circulatory system solves this problem - chemicals are transported b/n the blood and interstitial fluid + O2/CO2, nutrients/waste Open and Closed Circulatory Systems + animals having many layers of cells - open: no distinction b/n blood and interstitial fluid + hemolymph - closed: blood is confined to vessels and is distinct from interstitial fluid Vertebrate Circulatory System Cardiovascular System • heart, blood vessels, and blood + heart - atria (1 or 2) and (1 or 2) ventricles + blood vessels - arteries/arterioles: carry blood away from the heart - veins/venules: carry blood towards the heart - capillaries: microscopic vessels with very thin, porous walls + capillary beds: networks of capillaries infiltrating tissue Single circuit flow in fish: blood must pass through two capillary beds Double circuit flow in amphibian: blood is pumped through two circuits Double circuit flow in mammals: O2-rich blood segregated from O2-poor The Mammalian Heart Atria • thin-walled collection chamber Ventricles • thick-walled pumping chamber Heart Valves • atrioventricular (AV) valve + b/n each atria/ventricle - tricuspid/bicuspid • semilunar valves + at the each exit of heart The LEFT side of the heart services O2-rich blood only • pumps blood through systemic circulation The RIGHT side of the heart services O2-poor blood only • pumps blood through pulmonary circulation (1) Right Ventricle + semilunar valve (2) Pulmonary arteries + right/left (3) Lungs (Pulmonary Circulation) + pulmonary veins (4) Left Atrium + bicuspid valve (5) Left Ventricle + semilunar valve (6) Aorta (7) Systemic Circulation + head/forelimbs (8) Systemic Circulation + abdominal organs/legs (9) Anterior Vena Cava (10) Posterior Vena Cava (11) Right Atrium + tricuspid valve “Lub-dup” The Cardiac Cycle • caused by the closing of valves + lub: AV valves + dup: semilunar valves - heart murmur Pulse • rhythmic stretching of the arteries caused by the pressure of blood driven by heart’s contractions + heart rate - cardiac cycle + systole/diastole The Cardiac Cycle (con’t) Sinoatrial (SA) node • specialized muscle tissue that sets the rate at which all cardiac muscle cells contract + atrioventricular (AV) node - relay point: delayed for about 0.1 sec. + electrocardiogram (ECG/EKG) Structure of Blood Vessels Arteries and Veins and Capillaries • arteries: thick layer of smooth muscle and elastic connective tissue + carry blood AWAY from the heart • veins: thin layer of smooth muscle + valves promote unidirectional flow of blood - varicose veins • capillaries + site of exchange; only epithelial tissue - thin-walled; 1 RBC pass through at a time • blood pressure + blood travels 1000x faster in the aorta than the capillaries - law of continuity: if a pipe’s diameter changes over it’s length, a fluid will stream through narrower segments of the pipe faster than the wider segments + but, with so many capillaries… Blood Pressure • Systolic/diastolic + measured in mm of mercury - sphygmomanometer + systolic pressure created when ventricles contract + diastolic pressure is the background pressure - blood is constantly under some pressure in a closed circulatory system Lymphatic System Lymph • plasma leaks out of capillaries + some of it reabsorbed by blood vessels (veins) - body’s drainage system + lead back to vena cava through network similar to veins + WBC fight infection + filaria infection Blood Components of Blood • Plasma (55%) + water (91%) + dissolved ions,hormones, proteins, nutrients - fibrinogen, albumin, prothrombin, globulin • RBC + erythrocytes (no nucleus) - transport O2/CO2 • WBC + leukocytes - defense/immunity • Platelets + thrombocytes - blood clotting Stem Cells • bone marrow or embryo + stem cell research + luekemia Blood Clotting Red Blood Cells Hemoglobin • 2.8 x 108 per RBC + each hemoglobin can carry 4 O2 • uptake of O2 affected by pH + CO2 combines with H2O in plasma - carbonic acid (H2CO3) + muscles produce a lot of CO2 - pH around muscles is low (acid) + lower pH causes hemoglobin to let go of O2 Why do we need to carry these gases? Respiratory System Gas Exchange • acquire O2, dispose CO2 + cell respiration - uses O2, produces CO2 • respiratory medium + source of O2 - water vs. air • respiratory surface + where O2/CO2 exchange takes place - must be moist + earthworm uses skin - high ratio of surface area to volume Gills • outfoldings of the body surface specialized for gas exchange for aquatic animals • countercurrent exchange + blood flows in opposite direction of water - creates diffusion gradient Tracheal Systems Tracheal Systems • respiratory adaptations for terrestrial animals + air tubes that branch throughout the body - extend to the surface of nearly every cell Lungs Respiratory System • nasal passages + filtered by hair • through pharynx to trachea + rings of cartilage + larynx (voice box) • trachea branches into two bronchi • bronchi branch into many bronchioles • bronchioles branch into bronchial tubes • bronchial tubes end in alveoli + clusters of air sacs - surrounded by blood vessels - moist, thin-walled Ventilating the Lungs Breathing • alternate inhalation and exhalation of air + negative pressure - suction pump • inhalation + diaphragm pulls downward + rib cage and muscles pull upward - increases lung volume - decrease pressure in lungs - fresh air rushes in • exhalation + diaphragm/rib cage and muscles relax - decreases lung volume Automatic Control of Breathing Breathing Control Centers • medulla oblongata and pons + sets basic breathing rhythm • monitors CO2 levels in blood + pH of blood - drop in pH, increase the rate/depth • O2 sensors in aorta and carotid arteries + sense severely depressed levels of O2 (high altitude) • hyperventilating + depletes CO2 and fools the brain/body into thinking it does not need to breath Transport of Gases Respiratory Pigments • hemoglobin + four polypeptide subunits each with a cofactor called a heme group - iron atom at center of group + binds to gases reversibly - most O2 carried by hemoglobin + loading and unloading dependent on partial pressure of gases - gases diffuse from a region of higher partial pressure to a region of lower partial pressure Carbon Dioxide Transport CO2 Transport 1. CO2 produced by tissues 2. CO2 diffuses into interstitial fluid and plasma 3. >90% enters RBC 4. 23% binds to hemoglobin 5. Most reacts with H2O to form H2CO3 6. H2CO3 dissociates into HCO3- + H+ 7. Hemoglobin takes away H+ 8. HCO3- diffuses into plasma 9. Carried to lungs 10-13. Opposite happens The Body’s Defenses Nonspecific defense mechanisms • not selective in their response + fight off everything the same way Specific Defense Mechanisms • Immune System + generates efficient and selective response Nonspecific Defenses Against Infection 1st Line of Defense • physical and chemical barriers + skin and mucous membrane + acid and lysozyme 2nd Line of Defense • phagocytosis + ingestion of invading organisms by certain types of WBC - neutrophils and monocytes - eosinophils and natural killer (NK) cells • antimicrobial proteins + complement system - serum proteins help to destroy (lyse) microbial cells + interferons - secreted by virus-infected cells + limit cell-to-cell spread of viral infection • inflammatory response + localized response to tissue damage (cut) or entry of microorganism - increased blood supply (redness/swelling/warmth) - histamine and prostaglandins + aid in delivering clotting elements and phagocytic cells Specific Immunity Immune System Response • lymphocytes + B cells and T cells - come from stem cells in bone marrow + mature in different locations before moving on to lymphoid tissue (lymph nodes, spleen, blood, lymph) - respond to specific antigens + clonal selection - effector cells and memory cells + primary and secondary immune response • self vs. non-self + autoimmune diseases - Type I diabetes, Multiple sclerosis Cell-Mediated Immune Response T cells • kill cells that have been infected, or parasites • response initiated through contact with cell or macrophage + divides into four cell lines - T memory cells - cytotoxic “killer” T cells - T4 helper cells + core of immune system; infected by HIV + “messenger” - T suppressor cells + protect our own tissues Humoral Immune Response B cells • fights infections of plasma (generally bacteria) • “antibody-mediated response” + antibody is quaternary protein (multiple polypeptide chains) - Y-shaped - can bind to variety of antigens + response to foreign antigen - divides into two different cell lines + memory cells + plasma cell - antibody factory - makes antigens easier to locate by phagocytes