3.2.7- Transport Of Oxygen

Question 1

What does ‘dissociation’ mean?

Answer 1

Releasing the oxygen from the oxyhemoglobin.

Question 2

What is feral haemoglobin?

Answer 2

The type of haemoglobin usually only found in the fetus.

Question 3

Explain that ‘haemoglobin’ is.

Answer 3

A protein that is the red pigment used to transport oxygen in the blood and is found in erythrocytes.

Question 4

When, haemoglobin takes up oxygen, what does it become?

Answer 4

Oxyhemoglobin.

Question 5

Explain the structure of a haemoglobin molecule.

Answer 5

It is a protein with four subunits- each of which consist of a polypeptide chain and a harm group that contains a single iron (Fe2+) ion.

Question 6

What is the function of the Fe2+ ion in the haem group of haemoglobin?

Answer 6

To attract and hold the oxygen.

Question 7

Each haem group can hold ______ oxygen molecule.

Answer 7

One.

Question 8

How many oxygen molecules can be held in one haemoglobin molecule?

Answer 8

Four- one on each of the four haem groups.

Question 9

The haem group in haemoglobin had a High ________ for oxygen molecules.

Answer 9

Affinity.

Question 10

Oxygen binds _________ to haemoglobin.

Answer 10

Reversibly.

Question 11

Explain the sequence of events simply that describe the transport of oxygen in the body.

Answer 11

Oxygen passes from the alveoli, to blood plasma and diffuse into RBC’s. Oxygen molecules bind to haemoglobin reversibly to make oxyhemoglobin that travels to the bodies tissues. Here oxyhemoglobin dissociates to release oxygen to body tissues.

Question 12

Explain how the formation of oxyhemoglobin helps to allow more oxygen to flow into the blood from the alveoli.

Answer 12

It helps to maintain the steep concentration gradient as it removes oxygen from the blood when they diffuse into erythrocytes so more oxygen can diffuse in.

Question 13

What does the ability of haemoglobin to associate with and release oxygen depend on?

Answer 13

The concentration of oxygen in the surrounding tissues.

Question 14

What is the concentration of oxygen in the surrounding tissues measures in?

Answer 14

By the relative pressure it contributes to a mixture of gases- the partial pressure of oxygen (pO2)- aka the oxygen tension. Measured in kPa (units of pressure).

Question 15

Explain what the haemoglobin dissociation curve is.

Answer 15

The partial pressure of oxygen in kPa (x) plotted against percentage saturation with oxygen (y).

Question 16

What shape if the haemoglobin dissociation curve?

Answer 16

An S Shaped Curve.

Question 17

At low oxygen tension, the haemoglobin does not…

Answer 17

Readily associate with oxygen molecules.

Question 18

Explain why haemoglobin doesn’t readily associate with oxygen molecules at low oxygen tension.

Answer 18

Because the haem groups that attract the oxygen are at the centre of the haemoglobin molecule, making it difficult for the oxygen molecule to reach the haem group and associate with it.

Question 19

As the oxygen tension rises, what else does?

Answer 19

The diffusion gradient into the haemoglobin molecule.

Question 20

Explain what happens to the haemoglobin molecule once one oxygen molecule enters it and associates with one of the haem groups.

Answer 20

It causes a slight shape change in the haemoglobin molecules shape- called a conformal change.

Question 21

Explain what affect the conformal change of the haemoglobin molecule will have on it.

Answer 21

It will allow more oxygen molecules to enter the haemoglobin molecule and associate with other haem groups relatively easily- this accounts for the steepness of the haemoglobin dissociation curve as oxygen tension rises.

Question 22

What happens as the percentage saturation with oxygen approaches 100% saturation?

Answer 22

The haemoglobin dissociation curve starts to level off.

Question 23

Why is the oxygen tension in respiring tissues low?

Answer 23

To cause oxygen to readily dissociate from oxyhemoglobin.

Question 24

Compare the affinity for oxygen of adult and fetal haemoglobin.

Answer 24

Fetal has a higher affinity for oxygen than adult does.

Question 25

Compare the positioning of the s shaped curve of the haemoglobin dissociation curve of adult and fetal haemoglobin.

Answer 25

For fetal, it is slightly to the Left of that of adult haemoglobin.

Question 26

Explain why the haemoglobin dissociation curve for fetal haemoglobin is slightly to the left of the one for adult haemoglobin.

Answer 26

The fetal haemoglobin has a higher affinity for oxygen , therefore fetal haemoglobin is able to associate with oxygen in an environment where the oxygen tension is low enough to make adult haemoglobin dissociate with oxygen.

Question 27

In the placenta, oxygen tension is ________.

Answer 27

Low

Question 28

Explain the sequence of events that take place in the placenta, relating to oxygen tension and haemoglobin and why these things happen.

Answer 28

Oxygen tension’s low in the placenta- f.haemoglobin absorbs oxygen from the surrounding blood fluid, further lowering oxygen tension- causing oxygen to diffuse from the mothers blood into the placenta, which reduces the mothers blood’s oxygen tension to make the maternal haemoglobin dissociate with more oxygen, releasing it into her blood.

Question 29

Define what ‘affinity’ means.

Answer 29

A strong attraction.