Chapter 4: Exchange and Transport

Question 1

4.5-Transport of gases in the blood

What is an erothrocyte?

Answer 1

A red blood cell

Question 2

4.5-Transport of gases in the blood

Erothryctes have an affintiy for…

Answer 2

oxygen and are therefore vital in the transportation of oxygen around the body.

Question 3

4.5-Transport of gases in the blood

What is each heamoglobin made of?

Answer 3

Each haemoglobin molecule is a large globular protein made of four peptide chains (quarternary structure) with an iron prosthetic group.

Question 4

4.5-Transport of gases in the blood

What happens in the reaction involving oxygen and heamoglobin?

Answer 4

Pick up/drop off of oxygen in a reversible reaction forming oxyhaemoglobin.

Question 5

4.5-Transport of gases in the blood

What is the equation linking heamoglobin and oxygen?

Answer 5

Question 6

4.5-Transport of gases in the blood

Explain oxyheamoglobin formation and how the binding is for each group.

Answer 6

The binding of the first oxygen molecule to haemoglobin alters the molecule slightly which allows the second molecule to bind more easily.
Therefore the 4th molecule binds even easier than the first.
This also means the reverse is true, the 4th molecule will disassociate more easily/readily than the 1st.

Question 7

4.5-Transport of gases in the blood

Why is there always a steep concentration gradient between blood and the erethrocyte?

Answer 7

As blood enters the lung there is a large concentration gradient (blood is deoxygenated). Thus diffusion occurs quickly.
Because oxygen is diffused into the cytoplasm of the erythrocytes there is always a steep concentration gradient between the blood and the erythrocytes, maximising diffusion of oxygen into the blood.

Question 8

4.5-Transport of gases in the blood

Respiring tissue have low oxygen conc (relative to erythrocyte cytoplasm concentration)…

Answer 8

so will diffuse down its concentration gradient into the cells.

Question 9

4.5-Transport of gases in the blood

How is there a high reserve of oxygen bound to haemoglobin?

Answer 9

At rest only about 25% of oxygen disassociates from haemoglobin, meaning there is a reserve of 75% during periods of high aerobic activity/need/requirement.

Question 10

4.5-Transport of gases in the blood

What is haemoglobin uptake affected by?

Answer 10

proportion of carbon dioxide in the tissues (rate of respiration)

Question 11

4.5-Transport of gases in the blood

If high partial pressue of CO2 how is haemoglobin affected?

Answer 11

High partial pressure of CO2 the affinity of haemoglobin for oxygen is less, which means it disassociates more easily

Question 12

4.5-Transport of gases in the blood

If low partial pressue of CO2 how is haemoglobin affected?

Answer 12

Low carbon dioxide partial pressures (eg: in the lungs), which makes it easier for oxygen to bind to haemoglobin.

Question 13

4.5-Transport of gases in the blood

Draw a labelled oxygen dissociation curve

Answer 13

Question 14

4.5-Transport of gases in the blood

What is the other respiratory pigment?

Answer 14

Fetal haemoglobin and myoglobin

Question 15

4.5-Transport of gases in the blood

Why does a fetus need a high affinity for oxygen than the mother?

Answer 15

The fetus is dependent on the mother for oxygen as it cannot breath for itself. Oxygenated blood form the mother runs through the placenta close to the deoxygenated fetal blood. If the mothers and fetus blood had the same affinity, oxygen could not reach the fetus stopping respiration. Therefore a higher affinity forces the oxygen to dissociate from the mother’s heamoglobin.

Question 16

4.5-Transport of gases in the blood

Where is myoglobin found and what is itrs structure

Answer 16

Myoglobin – found in muscular tissue of vertebrates.
Small and bright red (gives meat it’s red colour).
Myoglobin has a structure similar to haemoglobin (contains a haem group that oxygen binds to).

Question 17

4.5-Transport of gases in the blood

What makes myoglobin different to haemoglobin

Answer 17

Myoglobin has a HIGHER affinity for oxygen than haemoglobin so becomes saturated with oxygen easily.
Myoglobin also binds to oxygen and does not dissociate, thus acting as oxygen store.
So during periods of exercise when oxygen levels are really low myoglobin dissociates when oxygen is required.

Question 18

4.6-Transfer between the circulatory sytem and cells

What is the medium of transfer in and out of cells?

Answer 18

The actual transfer into and out of cells occurs between the cells and the TISSUE FLUID which they are surrounded by. Tissue Fluid is formed from blood.