Transport of Gases

Question 1

What is the function of plasma?

Answer 1

Contains digested food particles, eg glucose and amino acids.
It transports hormones, antibodies and other proteins as well as distributing heat around the body

Question 2

Name the 3 types of blood cell

Answer 2

1. Leucocytes (white blood cells)
2. Thrombocytes (platelets)
3. Erythrocytes (red blood cells)

Question 3

What 2 groups of immune cells can leucocytes be divided into?

Answer 3

Granulocytes - granular cytoplasm and lobed nuclei
Agranulocytes - clear cytoplasm and spherical nucleus

Question 4

What is the function of granulocytes?

Answer 4

Engulf pathogens by phagocytosis

Question 5

What is the function of agranulocytes?

Answer 5

Produce antibodies and antitoxins

Question 6

What are thrombocytes involved in?

Answer 6

Blood clotting

Question 7

Erythrocytes (RBCs) have 3 important features which allow them to efficiently transport oxygen. What are they?

Answer 7

1. Biconcave discs - giving them a large surface area so more oxygen can diffuse across the membrane
2. Mammalian RBCs have no nucleus - more room for haemoglobin which means more oxygen can be transported
3. Flexible - they can fit through the very narrow lumen of the capillaries

Question 8

One molecule of haemoglobin is able to bind to ___ molecules of oxygen to form ______________

Answer 8

4, oxyhaemoglobin

Question 9

When the partial pressure of oxygen is high, haemoglobin has a ____ __________ for oxygen and so oxygen _________ with haemoglobin to form _____________

Answer 9

High affinity, associates, oxyhaemoglobin

Question 10

What is meant by cooperative binding

Answer 10

The ease with which a haemoglobin molecule binds a 2nd and 3rd oxygen molecule, compared with the 1st and 4th

Question 11

Explain how cooperative binding results in the oxygen dissociation curve being a sigmoid curve

Answer 11

Once the 1st molecule of oxygen has associated with haemoglobin, it causes a change in the shape of the protein making the 2nd and 3rd binding site more available, increasing haemoglobin affinity for oxygen. The 2nd and 3rd oxygen molecules associate more easily the first. It’s then more difficult for an oxygen molecule to bind to the last binding site. Biding of oxygen to haemoglobin is not directly proportional to oxygen concentration.

Question 12

The oxygen saturation of haemoglobin measured in a healthy person is 98%, why not 100%?

Answer 12

• The rate of blood flow through the pulmonary capillaries is too fast for all oxygen to diffuse into blood
• Some oxygen is used by the respiring cells of the alveoli

Question 13

Foetal haemoglobin has an oxygen dissociation curve shifted to the ____ of the adult curve.

Answer 13

Left

Question 14

Why is important that the foetal haemoglobin oxygen dissociation curve is shifted to the left of the adult curve?

Answer 14

It has a higher affinity for oxygen and therefore can load oxygen from the mothers blood at all partial pressures of oxygen

Question 15

Why does a baby not retain its foetal haemoglobin once its born?

Answer 15

Foetal haemoglobin has a higher affinity for oxygen so not enough oxygen would be released to the respiring tissue of an adult
If female, when having own children, the adult needs its haemoglobin to have a lower affinity for oxygen than the foetal haemoglobin

Question 16

Explain why a llamas oxygen dissociation is shifted to the left of an adult

Answer 16

Llamas live at high altitudes. With an increase in altitude, there is a drop in atmospheric pressure and therefore a reduction in the partial pressure of oxygen.
To compensate for this, a llamas haemoglobin has a higher affinity for oxygen and therefore picks up oxygen more readily at the lungs.

Question 17

Why do animals living at high altitude have more red blood cells?

Answer 17

There is more haemoglobin so more oxygen can be loaded and transported

Question 18

Why is lugworms oxygen dissociation curve shifted to the left?

Answer 18

Lugworms live in burrows in the sand on the seashore. They absorb oxygen from the seawater they pump through their burrows.
In order to cope with the low oxygen concentration of seawater their haemoglobin has a higher affinity for oxygen so the haemoglobin more readily takes up oxygen.

Question 19

What is the function of myoglobin?

Answer 19

Acts as an oxygen store in muscle tissue

Question 20

Describe the position of myoglobin’s oxygen dissociation curve

Answer 20

Very far to the left of haemoglobin
At every partial pressure of oxygen, myoglobin has a higher percentage oxygen saturation than haemoglobin

Question 21

What is the Bohr Effect?

Answer 21

When the partial pressure of CO2 is high (due to CO2 production in respiring tissues) the conditions inside the red blood cell become more acidic. This causes a slight change in the shape of the haemoglobin so it now has a lower affinity for oxygen, unloading this oxygen to the respiring tissues more readily