BIOG 1440 Lecture Notes - Lecture 10: Pulmonary Circulation, Circulatory System, Coevolution
27 Apr 2018
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Prelim 1: Content through digestion-microbiota (Monday’s lecture--2/26)
- Practice exam available tomorrow or Friday
- Answers posted Sunday
Limitations of Diffusion
1. Diffusion has limitations
a. Diffusion is fine for small organisms (micrometers in length, etc)
b. But it is very bad for large organisms--slow and inefficient
2. Diffusion is a slow process that is sensitive to size
a. Fick’s Law of diffusion
i. Distance higher → flux will be lower
ii. Higher concentration change → higher flux
b. Concentration decays w/ distance quickly
3. All really large creatures have a closed system of tubes to circulate materials
a. Diffusion replaced by bulk flow in large animals
The Circuit(s) with a Muscular Pump: The Heart
1. Closed circulatory and respiratory systems have coevolved as a unit system
a. Fish: single circulation
i. Body → pump(atrium/ventricles) → gills → body
b. Amphibians: double circulation
i. Duplication/separation of atria into two separate chambers but only one
ventricle in pump
1. Ventricle → some goes to lungs, some goes to body
ii. Very inefficient → amphibians have wet skin so they do oxygen exchange
also from skin
c. Reptiles (except birds): double circulation w/ pulmonary circuit (lungs) and
systemic circuit (body)
i. Still slightly less efficient
d. Mammals: most efficient → two completely separate atria/ventricles
i. Bigger push of oxygenated blood out to body
2. Cardiac Anatomy and blood flow
a. Mammalian heart has four chambers
i. Two atria (L/R) → right ventricle is on left side when you look at it
ii. Two ventricles (L/R)
iii. Left connects to left, right to right
b. Left atrium/ventricle system pumps blood from lung into systemic arteries (aorta)
towards body. Receives and ejects blood rich in oxygen
find more resources at oneclass.com
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Document Summary
The circuit(s) with a muscular pump: the heart: closed circulatory and respiratory systems have coevolved as a unit system, fish: single circulation. Body pump(atrium/ventricles) gills body: amphibians: double circulation, duplication/separation of atria into two separate chambers but only one ventricle in pump, ventricle some goes to lungs, some goes to body. Very inefficient amphibians have wet skin so they do oxygen exchange also from skin: reptiles (except birds): double circulation w/ pulmonary circuit (lungs) and systemic circuit (body) Still slightly less efficient: mammals: most efficient two completely separate atria/ventricles. Bigger push of oxygenated blood out to body: cardiac anatomy and blood flow, mammalian heart has four chambers. Two atria (l/r) right ventricle is on left side when you look at it. Left connects to left, right to right: left atrium/ventricle system pumps blood from lung into systemic arteries (aorta) towards body.
