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01:119:116 (653)
Lecture 25

01:119:116 Lecture 25: Lecture 25 - Circulation
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Department
Biological Sciences
Course
01:119:116
Professor
Dr.Christy Beal
Semester
Spring

Description
Lecture 25 - Circulation I. Basics of Circulatory Systems A. Types of Circulatory Systems ➢ What is a circulatory system used for? ➢ Why do you need one? ➢ Some animals do not have a circulatory system ○ Cnidaria - diploblastic, gastrovascular cavity ○ Flatworms - gastrovascular cavity ○ Nematodes - fluid in pseudocoelom ➢ Three basic components: ○ Fluid ○ Interconnecting vessels ○ Pump ➢ Two basic types of circulatory systems: ○ Open ■ Hemolymph ■ Bathes tissues ○ Closed ■ Blood ■ Straight to cells B. Vertebrae Circulation ➢ Closed system = cardiovascular system ➢ Blood ➢ Blood vessels (3 types) 1. Arteries - Away from heart 2. Capillaries 3. Veins ★ Not Distinguished by O2content ➢ Arteries → arterioles → capillaries → venules → veins ➢ Heart - 2 or more chambers ➢ Atria (sing. atrium) ○ Receives blood from tissues ➢ Ventricles ○ Pump blood to arteries ➢ Pericardium ○ Connective tissue sac ○ Encloses heart C. Comparison of Vertebrate Circulatory System ➢ Fish - low metabolic rate, slow system ○ Single circulation ○ Two-chambered heart - 1 atrium, 1 ventricle ■ Heart → Gills → Body → Heart ➢ Amphibian - low metabolic rate, slow system ○ Double circulation ■ Three-chambered heart - 2 atria, 1 ventricle ○ Pulmocutaneous circuit ■ O2picked up from skin ○ Systemic circuit → to body ■ Returns to right atrium ○ Ridge in ventricle - why? ➢ Mammals & Birds - endotherms ○ Double circulation - more vigorous blood flow ○ Four chambered heart - 2 atria, 2 ventricles ○ Systemic and pulmonary ■ Circuits completely separate ■ Fig 42.5 II. Human Heart A. Heart Structure ➢ Cardiac output - blood pumped/min by left ventricle ○ Heart rate x stroke volume ○ Heart rate = # of strokes/minute ■ ~60-100 bpm ○ Stroke volume - amt. Blood pumped in single contraction ➢ Four valves: ○ Prevents backflow ○ Between atrium & ventricle ■ Right AV (tricuspid) ■ Left AV (mitral) ➢ Semilunar - ventricles to heart exit ○ Pulmonary valve ○ Aortic valve ➢ The sound of a heartbeat ➢ Lub - low pitch ○ AV valves closing ➢ Dub - Higher pitch ○ Semilunar v
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