Mass Transport In Animals 7 Flashcards
Right atrium
Receives deoxygenated bloody from body via vena cavae
Right ventricle
Contracts to move deoxygenated bloody into pulmonary artery leading to lungs
Left atrium
Receives oxygenates bloody from lungs via Pumonary veins
Left ventricle
Contracts to move oxygenated blood into aorta leading to rest of body
Atrio-ventricular valves
Open when atria contact and the pressure in atria is greater than in ventricles
Blood flows from atria into ventricles
AV valves close as ventricles contract, preventing back flow
Tendinous cords
Prevent the AV valves turning inside out as pressure in ventricles increases above that in atria
Semilunar valves
Open to allow blood into pulmonary artery and aorta as ventricles contract
They close as ventricles relax, preventing back flow of blood into ventricles
Cardiac output
Volume of bloody pumped out of one ventricle per minute
CARDIAC OUTPUT = STROKE VOLUME X HEART RATE
Arteries
Carry blood away from heart at high pressure
Elastic tissues stretches providing a smooth flow of blood
Thick wall and small lumen
Don’t possess valves
Carry oxygenated blood
Arterioles
Control flow of blood by contraction or relaxation of smooth muscle
VASOCONSTRICTION - reducing blood flow to capillaries
VASODILATION - increases blood flow to capillaries
Veins
Carry blood under low pressure back to heart
Thinner walls
Carry deoxygenated blood
Larger lumen
Semi lunar valves ensure blood flows in 1 direction
Capillaries
1 endothelial cell thick - short diffusion pathway
Gaps between endothelial cells increase permeability
Large numbers and highly branched - large SA
Total cross sectional area is high producing a large frictional resistance, reducing rate of blood flow, allowing more time for exchange of substances
Arteriolar divide to produce a large number of blood capillaries which supply all body tissues…
At arteriole end of capillary hydrostatic pressure is high
Pressure causes filtration of blood plasma
Small molecules diffuse through endothelial layer
Blood cells and large plasma proteins remain in capillary
Filtered plasma forms tissue fluid which surrounds body cells
How is Lymph formed?
Large plasma proteins that remain in blood make WP more negative, causing the osmotic uptake of water
Reduced hydrostatic pressure at venue end means osmotic potential is greater than blood pressure, and some of water for, tissue fluid is reabsorbed by osmosis into blood
Process too slow to reabsorb all filtered plasma and some tissue fluid enters lymph capillaries (lymph)
Eventually empty into subclavian veins returning tissue fluid to blood
Haemoglobin
Haemoglobin + oxygen = oxyhaemoglobin
Contains 4 haem units so can carry 4 oxygen molecules
If Hb has a HIGH affinity for oxygen - Hb will associate with oxygen easily, and disassociate reluctantly
If Hb has a LOW affinity for oxygen - Hb will associate reluctantly and disassociate easily
