Transport in animals

Question 1

describe the chloride shift process?

Answer 1

1. during respiration co2 released
2. co2 travels onto tissue fluid -> plasma -> RBC
3. in RBC co2 combines with water through the enzyme carbonic anhydrase catalysing the reaction , co2 and water forms carbonic acid
4. carbonic acid weak and unstable so broken down into hydrogen and hydrogen carbonate
5. hydrogen carbonate very negative molecule, RBC rejects it and diffuses into plasma
6. but to maintain electrical neutrality chloride ions diffuse into the RBC

Question 2

What is meant by myogenic in relation to cardiac muscle?

Answer 2

the heart can contract on its own without the need for external signals from the nervous system

Question 3

Outline the sequence of events in the cardiac cycle, including the roles of the valves and pressure changes. (6 marks)

Answer 3

1. Atrial systole: Atria contract, increasing pressure above ventricles → AV valves open (1 mark)
2. Blood flows into ventricles, filling them (1 mark)
3. Ventricular systole: Ventricles contract, pressure rises above atria → AV valves close (1 mark)
4. Ventricular pressure exceeds aortic/pulmonary artery pressure → semilunar valves open, blood forced out (1 mark)
5. Ventricular diastole: Ventricles relax, pressure falls → semilunar valves close to prevent backflow (1 mark)
6. Atria begin to fill again → pressure in atria > ventricles, AV valves reopen → cycle restarts (1 mark)

Question 4

Carbon dioxide release during respiration can affect the % oxygen saturation of haemoglobin.
The tertiary structure of haemoglobin is affected when carbon dioxide reacts with water to form carbonic acid.
This reaction releases hydrogen ions.
what affect would this have on the ph of and what would happen to the affinity for oxygen?

Answer 4

Ph fall, decrease haemoglobin affinity for oxygen