Transport In Animals Flashcards
3 factors influencing need for transport system
Size
SA/V Ratio
Level of metabolic activity
Why do multicellular organisms such as mammals require a transport system?
they are large
Therefore
They have a small SA/V, so the body surface is not large enough to supply all innermost cells with nutrients & remove waste via diffusion alone
Also they are endotherms; maintain their own body temp so highly metabolically active
Single vs double circulatory system
Single: blood flows through heart once for each circuit of the body
Double: blood flows through heart twice for each circuit of the body
5 Features of an efficient transport system?
- Fluid/medium to carry dissolved nutrients & waste
- A pump to create pressure to push the fluid around the body
- Exchange surfaces to allow substances to enter and leave the fluid
To make it more efficient:
- Tubes to carry the fluid by mass flow
- Two circuits; one to pick up oxygen & one to deliver it to the tissues
Why is double circulation better than single
In single, Blood pressure drops towards the body
So slower
Rate of exchange is slower
Explain the difference in pressures of systemic circulation & pulmonary circulation
Pulmonary is low pressure as doesnt need to travel very far and cant damage the delicate capillaries in lungs
Systemic is higher as needs to travel around the whole body; left ventricle walls are thicker than right ventricles
Why are atrial walls much thinner than ventricle walls
Only need to pump blood to the chamber below, whereas the right ventricle needs to pump blood to lungs, and left ventricle needs to pump blood around whole body
What is the septum
Wall of muscle separating the ventricles, ensuring oxygenated blood is on left and deoxygenated on right, otherwise they would mix & pO2 would be too low to meet demands of all cells
What is a heart attack and how does it occur?
When the heart is starved of oxygen and nutrients; due to a blockage in coronary arteries supplying it
Contrast with reasons the difference in composition of capillaries, arteries and veins
Lumen:
is smaller for arteries so blood is higher pressure
Endothelium: same
Elastic tissue: thicker in arteries to withstand high pressure; evens out fluctuations
Smooth muscle: thicker in arteries to reduce diameter of lumen
Collagen: thicker in arteries to withstand high pressure
CAPILLARIES ONLY ONE SQUAMOUS ENdothelial CELL THICK FOR SHORT DIFFUSION DISTANCE & very narrow lumen (same as RBC so that they are squeezed against the walls as they pass through, reducing oxygen diffusion distance)
Benefits of closed circulatory system than open
Closed is where blood stays inside vessels
This means higher pressure so meets demand quick enough
Removes waste quicker to prevent toxic build up
Transport doesnt depend on body movements, as it does in insects for example
Adaptions of capillary walls
Lumen as narrow as an RBC so it is squeezed against the walls as passes through; shorter diffusion distance for o2
Wall is single layer of squamous endothelium; short diffusion distance
Fenestrations in walls; leaky to allow plasma & dissolved substances to leave blood
Tissue fluid formation 6 marker
Hydrostatic pressure @ arteriole end higher than oncotic pressure so NFP (HP-OP) = positive
; fluid moves out
Hydrostatic pressure @ venule end = dropped due to fluid leaving; is now lower than OP so NFP = negative; fluid moves back in
10% enters lymphatic system
O2 transport (4 marks)
At high pO2, Hb has high affinity for O2, eg in alveolar capillaries
Once the 1st o2 binds to Hb, CONFORMATIONAL change in tertiary structure makes it easier for more to combine
At low pO2, HbO8 unloads O2 (respiring tissues) as has low affinity for O2
What is conformational change
Once 1 O2 binds to Hb, it is much easier for others - so soons the first binds at high enough pO2, saturation increases quickly
HENCE THE S SHAPED HB SATURATION CURVE
