Mass Transport In Mammals

Question 1

Describe the structure of haemoglobin, and how it differs to load and unload oxygen

Answer 1

4 peptide chains
Each with a Prosthetic haem groups containing Fe2+
In high concentration of oxygen protein shape changes so the oxygen can bind easier (higher affinity) e.g. In the lungs. Also vice versa in tissues were [O2] is low

Question 2

Describe positive cooperativty

Why is the fourth O2 often hard to bind

Answer 2

First O2 to bind is difficult but this changes the shape making it easier for the second and third
Although protein structure favours it 4th to bind is harder as less chance of collision

Question 3

If a line was shifted to the right on an oxygen dissociation curve what would this mean in terms of the affinity for oxygen? What about left?

Answer 3

Lower affinity if shifted right

Higher affinity if shifted left

Question 4

Describe the bohr effect

Answer 4

In high [CO2] there will be a reduced affinity for oxygen hence unloading will occur. CO2 lowers pH and hence effects protein structure

Question 5

Name two environments where mamals would likey have haemoglobin with higher oxygen affinity

Answer 5

Underwater
High altitude
Anywhere where partial pressure of oxygen is lower

Question 6

Mammalian circulatory systems are referred to as being double circulatory systems. What does this mean and why is it important?

Answer 6

Passes heart twice

Blood needs to be re-pressurised after exchange with lungs

Question 7

Why is the muscle surrounding the right ventricle thinner?

Answer 7

Right ventricle pumps to the lungs, this is a shorter distance than to the whole body hence doesnt need to be as strong

Question 8

These vessels go from \_\_\_\_\_\_ to \_\_\_\_\_\_\_
Aorta
Vena cava
Pulmonary artery 
Pulmanory vein

Answer 8

Aorta connects the left ventricle to the body
Vena cava connects body to the right atrium
Pulmanory artery - right ventricle to the lungs
Pulmanory vein - lungs to left atrium

Question 9

What major vessel do coranory arteries branch off?

How may they cause a heart attack?

Answer 9

Branch of aorta
If clotted not enough oxygen delivered to heart
Hence heart muscles respire anerobically
Cant continue this so will stop

Question 10

What happens diastole?

Answer 10

“Heart relaxation”
Blood returns to atria via pulmaory vein (from lungs) and from body via vena cava
Atria fill

Question 11

What happens in atrial systole?

Answer 11

Atrial pressure is greater than ventricular pressure
Atrioventricular valves open
Ventricles recoil to increase their volume
Atria contract to push blood into ventricles

Question 12

What happens in ventricular systole?

Answer 12

Ventricles contract
Atrioventricular valves close prevent back flow
Forced put lf ventricles into aorta ( left) or pulmanory artery (right)

Question 13

Locate these valves:
Atrioventricular
Semi lunar
Pocket valves

Answer 13

Atrioventricular valves are between atria and ventricles
Semi lunar valves are in the blood vessels leaving ventricles
Pocket valves are within the veins ensuring blood goes to heart

Question 14

With an equation define cardiac output

Answer 14

Cardiac output (volume of blood pumped by one ventricle in one minute)=heart rate (bpm) X stroke volume (volume pumped out per beat)

Question 15

Describe with reasons the structure of arteries

Answer 15

Carry high pressure bloody from the heart (oxygenated)
Thick musclular layer - constrict to control volume
Thick elastic layer - keeps blood pressure high to reach extremities, also means pressure kept constant as adjustable dependant on volume
No valves - high pressure blood wont flow backwards

Question 16

Why do arterioles have thinner muscular layers?

Answer 16

Pressure in arterioles is smaller hence less risk of bursting

Question 17

Why in veins are the elastic layers and muscular layers thin? Why do they have valves?

Answer 17

Because the blood pressure is much lower in the veins as its taking blood back to heart. Therefore not going to burst
Have valves because lower pressure means back flow is more likely valves prevent this

Question 18

Relate the structure of capillaries to their function

Answer 18

Very thin = small diffusion pathway
High branching and many of them = large SA:V
Narrow lumen = red blood cells squeezed against side
Gaps in the endothelial tissue to allow white blood cells out

Question 19

What is in tissue fluid?

Answer 19

Water glucose amino acids fatty acids ions and O2

Basically everything a cell would need

Question 20

Describe how tissue fluid is removed from the blood whilst other contents of the blood arent

Answer 20

High hydrostatic pressure due to blood flow
Increases as blood vessels become smaller
But …
High hydrostatic pressure outside
Lower water potential of blood than surrondings
Both have an effect of pushing inwards

Hence only the tissue fluid is small enough to leave proteins + WBC will stay in as rhey are larger

Question 21

Describe how tissue fluid is returned to the blood in the venous end of the capillary bed. How is the tissue fluid that doesnt get back into blood removed?

Answer 21

Lower hydrostatic pressure in capillaries
Lower water potential due to lost water
Tissue fluid moves in with waste products it exchanged with cells
The un reabsorbed tissue fluid removed in the lymphatic system which drain into larger vessles and back to heart (moves purely due to hydrostatic pressures and muscle contraction as no heart beat to increase pressure