Animal Transport Flashcards
Relate the structure of arteries to their function
- Thick, muscular walls to handle high pressure without tearing.
- Elastic tissue allows recoil to prevent pressure surges.
- Narrow lumen to maintain pressure
Relate the structure of veins to their function
- Thin walls due to lower pressure
- Require valves
- Less muscular and elastic tissue as they don’t have to control blood flow
Relate the structure of capillaries to their function
- One cell thick walls for a short diffusion pathway
- Numerous and highly branched proving a large surface area
Relate the structure of arterioles and venules to their function
- Branch off arteries and veins in order to feed blood into the capillaries
- Smaller than arteries and veins so that the change in pressure is more gradual, as blood passes through increasingly small vessels
What is tissue fluid?
A watery substance containing glucose, amino acids, oxygen and other nutrients.
It supplies these to cells while also removing any waste materials
What types of pressure influence the formation of tissue fluid?
Hydrostatic pressure - Higher at arterial end of the capillaries than the venous end
Oncotic pressure - The tendancy of water to move into blood by osmosis
How is tissue fluid formed?
- As blood is pumped through increasingly small vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances will the cells
How does tissue fluid differ from blood and lymph?
- Tissue fluid is formed from blood, but does not contain red blood cells, platelets or other solutes that are in blood
- After tissue fluid has bathed cells it becomes lymph, and therefore this contains less oxygen and less nutrients and more waste products
Describe what happens during cardiac diastole
- The heart is relaxed
- Blood enters the atria, increasing the pressure and pushing open the atrioventricular valves
- This allows blood to flow into the ventricles
- Pressure in the heart is lower than in the arteries, so semi lunar valves remain shut
How do you calculate cardiac output?
Cardiac output = heart rate x stroke volume
What does myogenic mean?
The heart’s contraction is initiated from within the muscle itself, rather than by nerve impulses.
Explain how the heart contracts
- SAN initiates and spreads impulse across the atria, so they contract
- AVN receives, delays, and then conveys the impulse down the bundle of His
- Impulse travels into the purkyne fibres which branch across the ventricles, so they contract from the bottom up
Describe the types of abnormal activity that may be seen on an ECG
Tachycardia - Fast heartbeat over 100bpm
Bradycardia - Slow heartbeat under 60bpm
Fibrillation - Irregular, fast heartbeat
Ectopic - Early or extra heartbeats
How does partial pressure of oxygen affect oxyhaemoglobin binding?
- As oxygen partial pressure increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin
- When partial pressure is low, oxygen is released from haemoglobin
Describe the Bohr shift
- As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape
- The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin
