University:
University of Virginia
Course:
BIOL 2200 | Introduction to Biology II: Organisms & Evolution
Academic year:

2024
Views:

389

Pages:

3
Author:

Zoe C.

31: circulation II Monday, April 15, 2024 1:27 PM why is a circulatory system adaptive? • directed and efficient distribution of O2 and nutrients and collection of CO2 and waste • found in most animals ○ essential for animals with large or complex body plans or high metabolism • some animals do without a circulatory system ○ animals with gastrovascular cavities exchange material through diffusion open circulatory system • heart pumps hemolymph through circulatory vessels to hemocoel • hemolymph exchanges resources directly with tissues • heart relaxes, hemolymph pulled through pores that close when heart contracts • pros: ○ less energetically costly ○ direct delivery of nutrients and waste between hemolymph and tissues • cons: ○ lower pressure and flow rate ○ resources delivery not directed at specific tissues • insects: gas exchange decoupled from circulation closed circulatory system • blood confined to vessels • heart(s) pump blood through vessels that branch and infiltrate tissues and organs • exchange between blood, interstitial fluid, and body cells • efficient delivery of O2 and nutrients to specific tissues single circulation • blood through heart once • 1 atrium, 1 ventricle • efficient delivery of O2 and nutrients to specific tissues single circulation • • • • blood through heart once 1 atrium, 1 ventricle moves from heart → gills → body → heart lower blood pressure through body double circulation • blood through heart twice • pulmonary circuit ○ start at R side of the heart → oxygen-poor blood to lungs/skin → oxygen-rich blood back to L side of heart ○ lower blood pressure • systemic circuit: ○ starts at L side of heart → oxygen/nutrient-rich blood to body → CO2-rich blood back to R side of heart ○ higher blood pressure differences in blood circulation • amphibians ○ 2 atria, 1 ventricle with a central ridge ○ gas exchange using both lungs and skin ○ can adjust circulation when lungs are not in use • turtles, snakes, and lizards ○ 2 atria, 2 ventricle with incomplete septum ○ can bypass pulmonary circuit when necessary (when underwater) • birds and mammals ○ 2 atria, 2 ventricles ○ as endotherms, require high rate of O2 delivery ○ also create more CO2 and waste the cardiac cycle • • • • • • contraction: systole relaxation: diastole blood returns from large veins to atria, then ventricles atrial contraction forces all blood into ventricles ventricles contract, pump blood into large arteries what happens to blood pressure after you exercise? • • • • • • relaxation: diastole blood returns from large veins to atria, then ventricles atrial contraction forces all blood into ventricles ventricles contract, pump blood into large arteries what happens to blood pressure after you exercise? what factors influence blood pressure?