BIO 311D 2nd Edition Lecture 28 Outline of Last Lecture I. Partial Pressure Differences Affect DiffusionII. Hemoglobin in red blood cells binds O2III. Clicker quiz questions about hemoglobinIV. Circulatory system Outline of Current Lecture I. How are circulatory systems organized?II. Evolution of the heart in vertebratesIII. Introduction to blood and lymphIV. In-class exercise: index card questions Current LectureI. Circulatory SystemsA. 3 major types of blood vessels: artery, capillary, and vein a. Artery: smooth muscles b. Exchange of gases and solutes between blood and other tissues occurs: capillaries only B. In the vertebrates, respiratory systems are closely related to the circulatory system, including heart structure, are closely related. II. Evolution of the heart in vertebratesA. The closed circulatory system of vertebrates has evolved from a two-chambered heart in fish B. Frogs have an extra pulmonary circulation loop and a 3-chamebered heart. What is the adaptive advantage of having blood return to the heart before going out to the systemic circulation? – Extra push on the heart C. Birds and mammals have 4-chambered heart with two pathways by which blood leaves and returns to the heart. Oxygenated and deoxygenated blood totally separated. 1. Blood in the pulmonary circuit passes through the lungs and becomes oxygenated, then returns to the left side of the heart. 2. Oxygenated blood in the systemic circuit is pumped to all other tissues of the body, providing them with O2. This blood becomes deoxygenated and returns to the right side of the heartD. Pathway of blood through the heartIII. Introduction to blood and lymph A. Describe how blood pressure and blood velocity change as blood travels through the circulatory system and explain these changes. What is the advantage of slow blood flow through the capillaries?a. Pressure drops as blood travels from the arteries to the capillaries. Pressure never picks up again b. Speed (velocity) drops, but does pick up again. Slowing down blood flow allows greater gas exchange through diffusion. B. Water a. Reduces blood volume, pushes water out – fluid pressureb. Draws water back at the venous end – solute concentration C. Control of local blood flow through the capillaries by adjusting sphincter musclesa. Sphincter relaxb. Sphincter contracts D. A drop of blood is in an artery in your left arm flowing out towards your fingers. Aminimum of how many capillary beds will it pass through before it gets to the same location in your arm again? – 2 - In the artery therefore is already oxygenated - Capillary beds in arm or fingers (initial meeting)- Vein heart (right atrium) lungs (capillaries) E. What is the sequence of heart contraction?1. Pacemaker generates wave of signals to contract2. Signals are delayed at AV node3. Signals pass to heart apex4. Signals spread throughout ventricles a. Pacemaker cells in the SA node are autorhythmic, fire spontaneously initiates heartbeat b. Cardiac muscles cells are connected by gap junctions and desmosomes F. If removed from the body, the heart will keep beatingG. Heart rate can be affected by input from outside the heart: when you exercise, when you’re nervous, etc. H. Composition of blood: 55% plasma, 45% cellulara. Blood plasma composition is usually at equilibrium with the interstitial fluidIndex
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