Exam 5 Final Learning Objectives Chapter 42 Circulation and Gas Exchange Concept 42 1 Circulatory systems link exchange surfaces with cells throughout the body Explain how a gastrovascular cavity functions in part as a circulatory system o Fluid bathes both the inner and outer tissue layers facilitating exchange of gases and cellular waste Only the cells lining the cavity have direct access to the nutrients released by digestion but the body wall is very slim so nutrients only need to diffuse a short distance to reach the rest of the body Distinguish between open and closed circulatory systems List the three basic components common to both systems o Open Circulatory System the circulatory fluid bathes the organs directly with hemolymph which also acts as the interstitial fluid that bathes the body cells Allows blood and interstitial fluid to mix with each other arthropods mollusks o Closed Circulatory System blood is confined to vessels and is distinct from the interstitial fluid annelids cephalopods and all vertebrates o 3 basic components of both 1 Circulatory fluid blood 2 Set of tubes blood vessels 3 Muscular pumps heart List the structural components of a vertebrate circulatory system and relate their structure to their function o Arteries carry blood away from the heart to organs Has two layers of tissue surrounding the endothelium outer connective tissue containing elastic fibers which allow the vessel to stretch and recoil and a middle layer containing smooth muscle and more elastic fibers The walls of arteries are thick and strong accommodating blood pumped at high pressure by the heart Arterial walls also have an elastic recoil that helps maintain blood pressure and flow to the capillaries when the heart relaxes between contractions o Arterioles small blood vessels that convey blood to the capillaries o Capillaries microscopic vessels with very thin porous walls The thin walls which consist of endothelium and its basal lamina of capillaries allows for diffusion between blood and interstitial fluid o Capillary beds networks of capillaries that infiltrate every tissue the thin wall of capillaries allows for diffusion between blood and interstitial fluid o Veins vessels that carry blood back to the heart Has two layers of tissue surrounding the endothelium outer connective tissue containing elastic fibers which allow the vessel to stretch and recoil and a middle layer containing smooth muscle and more elastic fibers Only return blood back to the heart they have a lower pressure and do not require thick walls Veins have valves inside that maintain a unidirectional flow of blood despite the low pressure o Atria chambers that receive blood entering the heart o Ventricles responsible for pumping blood out of the heart Using diagrams compare and contrast the circulatory systems of fish amphibians non bird reptiles and mammals and birds Distinguish between pulmonary and systemic circuits and explain the functions of each o Pulmonary Circuit The right side of the heart delivers oxygen poor blood to capillary beds of the gas exchange tissues where there is a net movement of O2 into the blood and CO2 out of the blood o Systemic Circuit The oxygen enriched blood leaves the gas exchange tissues enters the left side of the heart contraction of the heart propels this blood to the capillary beds of tissues and organs gas exchange the now poor oxygen blood returns to the heart Concept 42 2 Coordinated cycles of heart contraction drive double circulation in mammals Define a cardiac cycle and distinguish between systole and diastole o Cardiac cycle One complete sequence of pumping and filling Systole contraction phase Diastole relaxation phase List the four heart valves describe their location and explain their functions o 1 o 2 o 3 o 4 the heart Define sinoatrial SA node and atrioventricular AV node and describe their location in o Sinoatrial SA node primary pacemaker It s a cluster of cells that sets the rate and timing at which all cardiac muscle cells contract Gap junctions between cardiac muscle cells allow impulses generated by SA to travel along atrial cells causing both atria to contract in unison These cells are located in the wall of the right atrium o Atrioventricular AV node secondary pacemaker cell cluster Pacemaker generates wave of signals to contract The signals from SA node are delayed here before spreading to the heart apex allowing the atria to empty completely before the ventricles contract These cells are located in the wall between the right and left atria o human heart Describe the origin and pathway of the action potential cardiac impulse in the normal o 1 Impulses from SA node spread through atria Signals are delayed at AV node wall between left and right atria Bundle branches pass signals to heart apex signals spread throughout ventricles Concept 42 3 Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels Relate the structures of capillaries arteries and veins to their function o Arteries Thick walled vessels with smooth muscle and connective tissue to withstand high pressure caused by accommodation of blood pumped at high pressure by the heart Arterioles branch off of arteries which are smaller in diameter to help control the distribution of blood flow Arterioles lead to the capillaries o Capillaries are the smallest blood vessels with very thin porous walls Networks of these vessels called capillary beds infiltrate every tissue Across the thin walls of capillaries chemicals like dissolved gases are exchanged by diffusion between the blood and the interstitial fluid of the tissue cells At their downstream end capillaries merge to form venules and venules merge to form veins o Veins Contain smooth muscle and connective tissue with thinner walls than arteries They do not require thick walls because they convey blood back to the heart at a lower pressure Explain why the velocity of blood flow through capillaries is substantially slower than it is through arteries and veins o Blood flow is slowest through capillary beds because of the large total cross sectional area The exchange of substances between the blood and intestinal fluid occurs only in capillaries because only capillaries have walls thin enough to permit this transfer The slower flow of blood is necessary to provide time for diffusion to occur Explain how blood returns to the heart even though it must sometimes travel from the lower extremities against gravity o 1st
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