Blood, Oxygen And CO₂ Transport

Question 0

What does the cellular part of blood contain?

Answer 0

Red cells (erythrocytes)
White cells (leucocytes)
Platelets (thrombocytes)

Question 1

Outline the structure if blood.

Answer 1

Blood is a red viscous tissue fluid. 55% of which is plasma and 45% of which consists of blood cells.

Question 2

What does the blood plasma contain?

Answer 2

90% water dissolved in which are gasses, nutrients from digestion, ionized minerals, vitamins, hormones, blood proteins (heparin) and enzymes. The function of water is to act as a solvent

Question 3

What is the function of the blood proteins?

Answer 3

To increase blood viscosity.

Question 4

How is blood pH maintained?

Answer 4

The amount of ions and protiens is controlled to maintain an overall blood pH of 7.4

Question 5

What are the four functions of blood in a mammal?

Answer 5

Transport
Temprature regulation
Defense
Communication.

Question 6

What role does blood play in transport?

Answer 6

The blood acts as a transport medium for the end products of digestion e.g glucose and a wide range of other substances including gasses such as CO₂

Question 7

What role does blood play in temperature regulation?

Answer 7

The blood transports heat around the body and the blood system can control temperature by constricting or dilating blood vessels.

Question 8

What role does blood play in defense?

Answer 8

The blood contains white cells called phagocytes and lymphocytes which engulf pathogens and produce antibodies respectively. Platelets also help protect the body by releasing enzymes which cause blood clotting after wounding.

Question 9

What role does the blood play in communication?

Answer 9

The blood transports hormones and so acts as a chemical communication system.

Question 10

What are the adaptions of red blood cells for carrying oxygen?

Answer 10

They have a biconcave disc structure to increase the surface area for diffusion. They are about 7nm and have no nucleus to give more volume for hemoglobin(Hb).

Question 11

How much oxygen does one Hemoglobin molecule carry?

Answer 11

Four oxygen molecules (O₂)

Question 12

Describe water’s affinity for oxygen.

Answer 12

What’re dissolves oxygen very poorly/has a low affinity for oxygen.

Question 13

Describe Hb’s affinity for oxygen.

Answer 13

Hb has a very high affinity for oxygen.

Question 14

Why does Hb have such a high affinity for oxygen?

Answer 14

After one oxygen molecule has been taken up by one iron atom (in a heam group) the other three heam groups change their shape which results in the other three oxygen molecules being taken up very rapidly.

Question 15

What is the oxidation state of iron once it has taken up a oxygen molecule, and why is this important?

Answer 15

The oxidation state remains as +2 (I.e the iron atom remains as Fe²⁺) and is not oxidised. This is important as it allows oxygen to uncouple very rapidly in the tissues of the body.

Question 16

Why is Hb more efficient than water at taking oxygen around the body?

Answer 16

Because Hb clings on to its oxygen for much longer than water.

Question 17

What is the Bohr shift?

Answer 17

As CO₂ concentration increases the Hb curve shifts to the right and down (I.e it becomes less steep).

Question 18

Describe and explain the position of the oxygen dissociation curve for Hb in the lungs.

Answer 18

In the lungs CO₂ concentration is low. As a result the curve is steep and to the left allowing fast, efficient loading of oxygen.

Question 19

Describe and explain the position of the oxygen dissociation curve for Hb in the tissues.

Answer 19

In the tissues CO₂ level is high and the affinity of Hb for oxygen falls (the curve moves to the right and down) making unloading of oxygen fast and efficient.

Question 20

What is Myoglobin?

Answer 20

This is only found in the muscles and has a dissociation curve shifted far to the left of the Hb dissociation curve.

Question 21

When will myoglobin release it’s oxygen and what is it’s function?

Answer 21

Myoglobin releases it’s oxygen when conditions are nearly anaerobic and so acts as an oxygen reserve.

Question 22

Where is Oxygen concentration low (environment terms)?

Answer 22

At high altitudes, in mud and foetal blood.

Question 23

What effect does a low oxygen environment have on the position of the oxygen dissociation curve?

Answer 23

In low oxygen environments it is necessary for the Hb to have a greater affinity for oxygen than normal therefore the curve is shifted to the left and is very steep. This allows animals to live in low oxygen environments.

Question 24

What is the purpose of foetal heamaglobin having a higher affinity for oxygen than the mother?

Answer 24

This allows oxygen to diffuse across the placenta from the Maternal blood to the foetal blood.

Question 25

What is the Chemical explanation for the Bohr shift?

Answer 25

1. ) Tissue respiration produces CO₂ which diffuses into the plasma.
2. ) CO₂ diffuses into red cells because Carbonic anhydrase reacts CO₂ with water to produce carbonic acid.
3. ) Carbonic acid dissociates to produce negative Bicarbonate ions and positive Hydrogen ions.
4. ) Because the membrane is permeable to negative charge, bicarbonate ions diffuse into the plasma.
5. ) The Hydrogen ions are buffered through reacting with haemoglobin to produce haemoglobinic acid which has a low affinity for oxygen.
6. ) As a result Hb gives up it’s oxygen to the tissues when CO₂ level is high.

Question 26

Explain both the process and purpose of the Chloride shift.

Answer 26

This is the method by which red cells remain electrically neutral. It involves the active transport of Chloride ions from the plasma into the red cell to compensate for the loss of negative charge by diffusion.

Question 27

What is the main form in which CO₂ is stored in the blood?

Answer 27

As Bicarbonate ions.

Question 28

Outline the structure of a capillary network.

Answer 28

These networks begin at an arteriole, produce a capillary bed and are collected up by a venule.

Question 29

Describe the pressure at the arteriole end of the capillary bed.

Answer 29

Pressure is very high.

Question 30

What is the result of pressure being high in the arteriole end of the capillary bed?

Answer 30

Blood is filtered under high pressure through the capillary walls. This process called ultrafiltration produces a yellowish fluid called tissue fluid which contains everything in the plasma except plasma proteins and cells.

Question 31

Outline the Movement of tissue fluid.

Answer 31

Tissue fluid now loves between the living cells of the tissue or organ because it is under high pressure. Tissue fluid must then be returned to the blood. This return takes place towards the venule end of the capillary bed. It is returned in two ways :-

Osmosis
The Lymphatic system.

Question 32

What happens as tissue fluid passes the cells?/What is the function of tissue fluid?

Answer 32

It delivers nutrients, water and oxygen to the cells and removes CO₂ and urea from the cells.

Question 33

How does the tissue fluid return to the blood by osmosis?

Answer 33

There is much more water in the tissue fluid than there is in the capillaries at the venule end and so water moves by osmosis into the capillaries. In addition waste products pass into the blood by diffusion.

Question 34

Outline the process of returning tissue fluid to the blood through the lymphatic system.

Answer 34

The lymphatic system consists of a series of open ended lymphatic capillaries with cilia that beat inwards, pulling in the remaining tissue fluid. This fluid is eventually returned to blood in the jugular veins in the neck where the lymphatic system joins the blood system.

Question 35

What is Kwashiokor?

Answer 35

This is when the return of tissue fluid to the blood by osmosis is not possible because of a lack of protein in the blood resulting in high blood ψ which prevents the osmotic return of water. As a result, swelling of the abdomen and ankles occurs.