Transport In Animals

Question 1

What happens during atrial systole

Answer 1

Walls of atria contract thus vol. of atria decreases and pressure increases –> pressure in atria rises above that in ventricles thus AV Valves are forced open so blood flows into ventricles

Question 2

Thus how does the atria contract and atrial systole even occur

Answer 2

Sino-Atrial Node (SAN) becomes electrically excited thus sends a wave of exciation to the atria–> causing atria to contract which is known as ATRIAL SYSTOLE

Question 3

what happens during ventricular systole

Answer 3

walls of ventricles contract thus vol. of ventricles decrease and pressure increases making pressure rise above that of atria therefore AV valves are closed and both valves are closed momenterially and SL valves are eventtually open to empty blood

Question 4

What is the AVN

Answer 4

It is connected to conductive fibres called the purkyne fibres with purkyne fibres rudding down septum down to the apex and up walls of ventricle

Question 5

Thus how do the ventricles contract with reference to the cardiac output

Answer 5

The AVN detects wave of exciation passing over it and purkyne fibres conducts electrical exciation down septum to apex and up walls of ventricles –> so during ventricular systole blood contract from base pushing blood upwards and outwards

Question 6

What happens during diastole

Answer 6

Both atria and ventricles are relaxed making prssure in ventricles drop below that in atria thus SL valves closed, blood returns to atria causing AV valves to open as pressure in atria rise above that in ven. so blood flows passively into the ventricles. The cycle then continues again with Atrial Systole

Question 7

Why do the 2 valves close momenterially

Answer 7

To allow atria to fully contract so that the ventricles do not contract too early

Question 8

Why doesn’t the wave of exication pass down to the ventricles

Answer 8

Non- Conductive tissues seperate the 2 sides

Question 9

What is the role of haemoglobin

Answer 9

Haemoglobin has a high affinity for oxygen thus it binds to the haemoglobin in the alveoli which forms oxyhaemoglobin. Oxygen is then released where there is low pressure

Question 10

What happens after CO2 diffuses into the blood

Answer 10

C02 fuses with h20 to form carbonic acid (H2C03) enzyme carbonic anhydrase catalyses the reaction and the enzyme carbonic anhydrase catalyses the reaction

Question 11

What happens after cabrobinc acid is formed

Answer 11

It dissasociated to form hydeogen carbonate and hydrogen ions. H+ binds w/ haemoglobin to form haemoglobonic acid which prevents H+ from lowering pH

Question 12

What happens after haemoglobin acid is formed

Answer 12

Hydrogen carbonate ions diffuse out of RBC and into blood plasma where they are transported in solution

Question 13

what is haemoglobin in

Answer 13

erythocrytes

Question 14

what happens when PO2 of oxygen is low

Answer 14

saturation of haemoglobin is low as haemoglobin unloades oxygen at tissues/muscles

Question 15

What happens when PO2 of oxygen is rising

Answer 15

Oxygen is loaded onto haemoglobin in the lungs

Question 16

Why does the curve of haemoglobin level off at high PO2?

Answer 16

As there is a shortage of binding sites

Question 17

Why does foetal haemoglobin have a higher affinity for oxygen than that of an adult

Answer 17

To allow the foetus to obtain the mother’s blood at the placenta

Question 18

How does arteries withstand high pressure

Answer 18

Wall is thick with a layer of collagen which provides strength and Endothelium is folded

Question 19

how do arteries maintain high pressure

Answer 19

Thick layer of elastic tissue to cause recoi
Thick layer of smooth muscle which constricts lumen

Question 20

What substances remain in capillaries and why

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Answer 20

Plasma Proteins as they are to large to fit through gaps in capillary/endothilial walls

Question 21

What occurs at the venuole end in tissue fluid

Answer 21

Fluid acted on by osmotic pressure which pushes fluid back into the capillaries
In terms of wate potential. as the capillaries contain solutes it has a lower water potential than that of tissue fluid thus causing water to move down water potential gradient so water moves bacmk into the capillaries

Question 22

State what trachycardia bradychardia fibrilation and ectopic heartbreat is

Answer 22

Trachycardia –> Too Fast
Bradychardia –> Too slow
Fibrilation –> Irregular
Ectopic –> Extra Heartbeat before 4th heartbreat

Question 23

Why is reduced heart rate seen in people who are aerobically fit

Answer 23

Increases vol. of ventricles
Increased strength of heart muscle