Lecture chapter 42 circulation and gas exchange 4 12 12 Overview Gills are an ex of a specialized exchange system in animals Gastrovascular cavity This cavity functions in both digestion and distribution of substances throughout the body Open and closed circulatory system More complex animals have either open or closed circulatory systems Both systems have 3 basic components A circulatory fluid blood or hemolymph A set of tubes blood vessels A muscular pump the heart Single circulation Fishes figure Double circulation Amphibians reptiles birds and mammals Figure Mammalian circulation Figure 42 6 The mammalian heart A closer look at the mammalian heart provides a better understanding of how double circulation works The cardiac cycle The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle The contracting or pumping phase is called systole The relaxation or filling phase is called diastole Impulses that ravel during the cardiac cycle can be recorded as a electrocardiogram ECG or EKG The pacemaker is influenced by nerves hormones body temp and exercise Blood pressure is the hydrostatic pressure that the blood exerts against the wall of a vessel In rigid vessels blood pressure is maintained less rigid vessels deform and blood pressure is lost Blood pressure and gravity Blood pressure is generally measured for an artery in the arm at the same time height as the heart Blood pressure for a healthy 20 year old at rest is 120mm Hg at systole and 70 mm Hg at diastole Lecture chapter 42 gas exchange 4 17 12 Fluid return by the lymphatic system The lymphatic system Returns fluid to the body from the capillary beds Aids in body defense Blood clotting When the endothelium of a blood vessel is damaged the clotting mechanism begins A cascade of complex reactions converts fibrinogen to fibrin forming a clot A blood clot formed within a blood vessel is called a thrombus and can block blood flow Figure 42 18 Stem cells and the replacement of cellular elements The cellular elements of blood wear out and are replaced constantly throughout a person s life Erythrocytes leukocytes and platelets all develop from a common source of stem cells in the red marrow of bones The hormone erythropoietin EPO stimulates erythrocyte production when oxygen delivery is low Cardiovascular disease Are disorders of the heart and the blood vessels Account for more than half of the deaths in the US One type of cardiovascular disease atherosclerosis is caused by the buildup of LDL cholesterol within arteries Gills in aquatic animals Gills are outfoldings of the body that create a large surface area for gas exchange Tracheal systems in insects The tracheal system of insects consists of tiny branching tubes that penetrate the body The tracheal tubes supply O2 directly to body cells Mammalian respiratory systems a closer look Figure 42 24 Lecture chapter 42 gas exchange 4 19 12 How a bird breathes Besides lungs birds have 8 or 9 air sacs that function as bellows that keep air flowing through the lungs Control of breathing in humans Sensors in the aorta and carotid arteries monitor O2 and CO2 concentrations in the blood These sensors exert secondary control over breathing Figure 42 28 Carbon dioxide transport Hemoglobin also helps transport CO2 and assists in buffering CO2 from respiring cells diffuses into the blood and is transported either in blood plasma bound to hemoglobin or as bicarbonate ions HCO3 Elite animals athletes Migratory and diving mammals have evolutionary adaptations that allow them to perform extraordinary feats Deep diving air breathers stockpile O2 and deplete it slowly also have myoglobin in their muscles which helps to store more O2 You should know Compare and contrast open and closed circulatory systems Compare and contrast the circulatory systems of fish amphibians non bird reptiles and mammals or birds Distinguish between pulmonary and systemic circuits and explain the function of each Trace the path of a red blood cell through the human heart pulmonary circuit and systemic circuit Define cardiac cycle and explain the role of the sinoatrial node Relate the structures of capillaries arteries and veins to their function Define blood pressure and cardiac output and describe two factors that influence each Explain how osmotic pressure and hydrostatic pressure regulate the exchange of fluid and solutes across the capillary walls Describe the role played by the lymphatic system in relation to the circulatory system Describe the function of erythrocytes leukocytes platelets fibrin Distinguish between a heart attack and stroke Discuss the advantages and disadvantages of water and of air as respiratory media For humans describe the exchange of gases in the lungs and in tissues0 Chapter 44 Osmoregulation and excretion Osmosis and osmolarity If 2 solutions are isoosmotic the movement of water is equal in both directions If 2 solutions differ in osmolarity the net flow of water is from the hypoosmotic solute concentration lower than environment to the hyperosmotic solute concentration higher than environment solution Most animals are stenohaline they can t tolerate substantial changes in external osmolarity Euryhaline animals can survive large fluctuations in external osmolarity Figure 44 4 Land animals Land animals manage water budgets by drinking and eating moist foods and using metabolic water Desert animals get major water savings from simple anatomical features and behaviors such as a nocturnal life style Transport epithelia in Osmoregulation Figure Forms of nitrogenous waste Different animals excrete nitrogenous wastes in different forms Ammonia fish Urea mammals Uric acid birds reptiles Diverse excretory systems Most excretory systems produce urine by refining a filtrate derived from body fluids Key functions of most excretory systems Filtration pressure filtering of body fluids Reabsorption reclaiming valuable solutes Secretion adding toxins and other solutes from the body fluids to the filtrate Excretion removing the filtrate from the system Structure of the human excretory system Figure 44 14 Solute gradient and water conservation Figure 44 15 Countercurrent multiplier system Figure 4 16 Antidiuretic hormone Figure 44 19 You should know Distinguish between the following terms isoosmotic hyperosmotic and hypoosmotic osmoregulators and osmoconformers stenohaline and euryhaline animals Define osmoregulation excretion anhydrobiosis Compare the osmoregulatory challenges of freshwater