D.6-Transport of respiratory gases

Question 1

The degree to which Haemoglobin binds to O2 is determined by what?

Answer 1

Partial Pressure of O2 (PO2) in the blood

Question 2

What is the PO2 in air?

Answer 2

160 mm of mg

Question 3

What is the PO2 in the lungs?

Answer 3

40 mm of mg

Question 4

Haemoglobin has high affinity for?

Answer 4

O2

Question 5

Haemoglobin likes dropping off passengers (dissociation of O2) when?

Answer 5

There are LOTS of passengers

Question 6

What happens to the dissociation of Haemoglobin once it is getting to its last passenger?

Answer 6

It doesn’t want to drop it off

→ it holds on to it until the end!

Question 7

% of O2 carried in blood:

1) Bound in Haemoglobin
2) Dissolved in blood plasma

Answer 7

1) Bound to Haemoglobin = 98.2% of all O2 in blood

2) Dissolved in blood plasma = 1.5%

Question 8

What are the 3 forms and the percentage of CO2 that is carried in blood?

Answer 8

1) Dissolved as CO2 = 7%
2) Reversibly converted to bicarbonate (hydrogen carbonate ions = HCO3 -) that are dissolved in bl. plasma = 70%
3) Bound to plasma proteins = 23%

Question 9

At what pH does blood need to be kept between?

Answer 9

7.35-7.45

Question 10

What does the binding of Haemoglobin to CO2 makes?

Answer 10

Carbaminohaemoglobin

Question 11

Haemoglobin also binds to H+ to make what?

Answer 11

Haemoglobonic acid

Question 12

What is the Chloride shift?

Answer 12

+ When the cell is negatively charged because of the formation of the Hydrogen carbonate ions
= don’t want the positive ions to rush in so RBC cell:
→ pumps Cl- ions INto it’s cell
→ forces the HCO3- OUT of the RBC through a protein channel
Hydrogen carbonate ion is a buffer, so it doesn’t like change

Question 13

Chemo-receptors in which area of the body can detect change in blood CO2? (3)

Answer 13

1) Medulla
2) Aorta
3) Carotid artery (supplying blood to the brain)

Question 14

Why does high level of CO2 in blood trigger an increase in ventilation rate?

Answer 14

In order to rid the body of CO2 buildup

→ CO2 diffuses into the alveoli and ventilation expels the CO2 from the body

Question 15

What regulates the rate of ventilation?

Answer 15

The respiratory control centre in the Medulla oblongata

Question 16

What are the 2 sets of nerves that travel from to the lungs from the respiratory centre?

Answer 16

1) Intercostal nerves = stimulate the intercostal muscle and thorax
2) Phrenic nerves = stimulate the diaphragm

Question 17

When the lungs expand due to the stimulation from the nerves = what happens?

Answer 17

+ Stretch receptors in the walls of the chest and lungs = sends signals to the respiratory centre = triggers an end of the signals
→ leading to inspiration until the animal exhales
+ Then a new signal is sent

Question 18

In the Kidney the H+ ions can be secreted into the urine bound to what and what does it lead to?

Answer 18

Bound to buffers. To raise the pH

→ leads to greater amt of bicarbonate to be reabsorbed from the tubules to neutralise the acid

Question 19

If the blood becomes too basic = what happens?

Answer 19

Bicarbonate ions can be secreted into the distal convoluted tubules of the Kidney

Question 20

Chemical buffers = exist within the extracellular fluid = these can’t remove the acids or bases BUT what can they do?

Answer 20

Can minimise the effect

Question 21

At high altitude there’s low pO2 in the air what happens as a consequence?

Answer 21

Haemoglobin may not become fully saturated → tissue may not be adequately supplied w/ O2

Question 22

What physiological changes happen at high altitudes? (3)

Answer 22

+ RBC production increases
→ increases total vol. of circulating haemoglobin
+ Ventilation rate increases to increases gas exchange
+ Muscles produce more Myoglobin to ensure delivery of oxygen to the tissues

Question 23

Populations living permanently in higher altitudes have greater what?

Answer 23

+ Mean lung surface area
+ Larger vital capacity
Than ppl living at sea level
→ O2 dissociation curve shifts to the RHS

Question 24

Emphysema patients have a “barrel chest”, what does that mean?

Answer 24

Large areas of trapped air in the lungs

→ leading to the lungs being in ‘inspiration’ position in the ventilation cycle

Question 25

What is the main cause of Emphysema?

Answer 25

Long-term exposure to airborne irritants

Question 26

Most common airborne irritants (4)

Answer 26

+ Tobacco smoke
+ Air pollution
+ Coal
+ Silica

Question 27

3 factors that causes the damage to the lungs

Answer 27

1) Oxidation reactions by high conc. of chemicals = free radicals in tobacco smoke
2) Inflammation due to body responding to irritating particulates within smoke
3) Free radicals and other components of tobacco smoke impair the activity of enzyme A1AT = normally block activity of elastase.

Question 28

Rare genetic diseases that causes Emphysema?

Answer 28

Deficiency in the enzyme A1AT (alpha-1-antitrypsin)