My_Ch42_lecture_rev09(2009050122140922)

My_Ch42_lecture_rev09(2009050122140922) - Chapter 42...

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Chapter 42: Circulation & Gas Exchange Purpose—to understand the structure and function of the circulatory and respiratory systems. What you MUST know in Ch 42: Open vs. closed systems Survey of vertebrate circulatory systems (read on your own) Mammalian heart circulation Role of lymphatic system Blood clotting reaction Gas exchange across respiratory surfaces Control of breathing in humans Oxygen vs. Carbon dioxide transport Circulatory system Transport system that distributes nutrients and oxygen to 2 o In larger, more complex animals a circulatory system is needed, because diffusion is not adequate for transport over long distances (slow; diffusion limits size of cells) Open circulatory system o “open” because blood is pumped into an internal cavity, and the “blood” then bathes the internal organs directly. There is a heart, but no blood vessels hemocoel (hemo = blood, coel = cavity) or sinuses (spaces) hemolymph (O 2 + nutrient fluid) bathes the internal organs fluid is returned to the heart via ostia (holes) o insects, most mollusks Closed circulatory system
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o “closed” because blood is enclosed or confined in blood vessels. Nutrient and gas exchange occurs through 1 cell thick capillaries (blood does NOT directly bathe cells) o Phylum Annelida (earthworms), certain mollusks (squid, octopus), and vertebrates Vertebrate circulatory system You really need to refer to diagrams to understand this! Use Campbell or http://www.texasheart.org/HIC/Anatomy/index.cfm Heart + arteries + veins, and smaller blood vessels in between o Heart —pumps blood to systemic and pulmonary circuits o Arteries —carry oxygenated blood away from the heart (systemic circuit) have thick walls, to withstand pumping pressure from the heart o Arterioles —carry oxygenated blood from arteries to capillaries (smaller than arteries, larger than capillaries) o Capillaries —microscopic vessels, 1 cell thick walls where nutrient and gas exchange occurs by diffusion from the circulatory system into interstitial fluid (that surrounds cells) and into cells (and from cells back into the capillaries). o Venules —carry deoxygenated blood from capillaries (larger than capillaries, smaller than veins) o Veins —carry deoxygenated blood from venules back to the heart Thinner walls than arteries, do not need to withstand pumping pressure
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Double circulation o Systemic circulation Oxygenated blood is pumped from the heart to the body tissues Deoxygenated blood from body tissues then returns to the heart o Pulmonary circulation Deoxygenated blood from the body is pumped by the heart to the lungs , where it becomes oxygenated Oxygenated blood from the lungs is then pumped out to the body tissues Both circuits are needed because animals need to get oxygen into the blood—and can only do so via the lungs. The anatomy of the heart and blood vessel
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My_Ch42_lecture_rev09(2009050122140922) - Chapter 42...

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