Circulatory System
Oxygen and nutrient distribution to cells around the body through diffusion.
- Fish: single loop, 2 chambers
Problem: lack of O2 combat this with countercurrent exchange system in gills
1 ventricle, 1 atrium single loop circulation heart gills body aquatic challenge: lower O2 content
Non-polar O2 dissolves poorly in polar H2O
Gil countercurrent exchange: maximizes O2 diffusion
Problem: slow delivery of O2 fish an manage with the lack of O2 because it doesn’t take much energy to swim land animals would have a harder time going through this process
Amphibians and Reptiles: double loop, 3 chambers double circulation
2 atria, 1 ventricle
- New problems:
Dehydration
Mixing of O2 poor and O2 rich blood in the heart survive mixing because most breathe O2 through the skin birds and mammals can not survive the blood mix
- why not? energy needed for flight/ larger size brain/ endothermic animals/ need for more O2 and glucose to make ATP to fuel increased metabolic demands.
- Birds and Mammals: double loop, 4 chambers wall (septum) separates the two types of blood
2 atria, 2 vesicles Fast delivery of O2 rich blood
- Vascular System (mammals) arteries always carry blood away from the heart do not always carry oxygenated blood (pulmonary arteries) veins always carry blood to the heart d do not always carry deoxygenated blood (pulmonary veins) artery arteriole capillary venule vein pressure highest in the arteries, lowest in the veins
Artery walls stressed by surge of blood coming from pump
- systolic pressure: highest pressure from bulge of blood flow
- diastolic pressure: lowest pressure from heart at rest
• Low pressure = no blood flow
• High pressure = leaky vessels
• Receptors in the brain (baroreceptors) receive information about blood pressure
• Control Center- deep brain stem region
• Effectors:
- change cardiac output (pump faster/stronger)
- change vascular resistance (constrict/dilate arterioles)
- functional unit: capillary
• goal: deliver needed materials to body cells, pick up waste
• Big surface area of capillary beds- capillaries are micrometers from body cells
• Blood travels