Date post: | 29-Dec-2015 |
Category: |
Documents |
Upload: | laureen-jennings |
View: | 216 times |
Download: | 0 times |
Circulation and Respiration
• Basic features– Distribute nutrients throughout body– Remove wastes from cellular activity– Exchange gases
• Advanced features– Defend against infection– Cell communication – hormones
Why is a circulatory system necessary?
• Rate of diffusion limits effective transfer of nutrients.
• Fluid carries nutrient and dissolved gases to cells.– Connects organs of exchange with the rest of the body– Organs of exchange in animals
• Nutrients – stomach, intestines
• Gases – gills or lungs
Simple Distribution in Radiates
• Fluid filled channels distribute nutrients
• Branching– Increases surface
area
– Allows rapid diffusion to all cells
Open Closed
• Blood and interstitial fluid the same - Hemolymph
• Exchange occurs at sinus
• Separate blood and interstitial fluid
• Exchange occurs at blood vessels
What Are the Features of Our Circulatory System?
• Fluid
• Vessels – tubes to carry fluid
• Pump to move fluid
• Valves to keep fluid moving in one direction
• Blood cells
Blood Vessels
• Arteries– Blood moves by pressure from heart
• Veins– Blood moves by action of valves and skeletal
muscles
• Capillaries– Many small branches to increase surface area
Vein vs. Artery
• Thin flexible wall• One way valves• Moved by skeletal
muscles
• Thick more rigid wall• No one way valves• Moved by heart
Effects of Blood Vessel Branching
• As cross-sectional area increases blood velocity decreases
• As surface area increases blood pressure decreases
Countercurrent flow
• Maximizes oxygen uptake
• Greatest difference in Oxygen content comes into contact with water
Hemoglobin
• Found in red blood cells
• Multiple protein complex with iron molecule
• Each hemoglobin binds to 4 oxygen or carbon dioxide molecules
• In general:– High oxygen/low carbon dioxide – releases carbon
dioxide and binds to oxygen– Low oxygen/high carbon dioxide – releases oxygen and
binds to carbon dioxide
Oxygen Dissociation
• Oxygen dissociation is greater at lower pH
• Metabolically active tissues have lower pH