Physiology

Question 1

Boyles Law

Answer 1

Volume of gas up, pressure down.

Question 2

Three pressures important in ventilation:

Answer 2

atmospheric, intra-alveolar and intra-pleural pressures.

Question 3

What is the active and inactive process of breathing

Answer 3

Inspiration is an active process and normal resting expiration is a passive process

Question 4

Inspiratory muscles include:

Answer 4

Diaphragm, external inter coastal muscle (bucket handle)

Question 5

Law of Laplace means that:

Answer 5

smaller alveoli have a higher tendency to collapse (P = 2T/r)

Question 6

What is in pulmonary surfactant

Answer 6

Lipids and proteins

Question 7

Resp. distress syndrome caused by premature babies..

Answer 7

not producing enough surfactant.

Question 8

What is pulmonary compliance?

Answer 8

A measure of effort that goes into stretching lungs

Question 9

What % of energy is used in breathing

Answer 9

3%

Question 10

Four factors which influencing gas transfer across the alveolar membranes:

Answer 10

• Partial pressure gradient of O2 and CO2
• Diffusion coefficient for O2 and Co2
• Surface area of alveolar membrane
• thickness of alveolar membrane

Question 11

Dalton’s Law of partial pressures:

Answer 11

Total pressure = sum of each pressure

Question 12

Flick’s Law of Diffusion:

Answer 12

The amount of gas that moves across a tissue is proportional to the area of the sheet BUT inversely proportional to its thickness. (so thicker = less exchange)

Question 13

Henry’s Law:

Answer 13

The amount of a gas dissolved in a iquid is proportional to the partial pressure of the gas in equilibrium with the liquid.

Question 14

What % of oxygen in the blood is carried by Hb?

Answer 14

98.5%

Question 15

How many haem groups are in haemoglobin?

Answer 15

4

Question 16

What does a blood cell look like?

Answer 16

Contains alpha and beta subunits with 4 haem molecules

Question 17

Bohr effect:

Answer 17

Lower blood pH stimulates haem to release O2

Question 18

HbF (foetal) is different to adult in what way?

Answer 18

Contains 2 alpha 2 gamma subunits, more affinity for O2 than alpha beta.

Question 19

When is myoglobin released

Answer 19

When muscles are damaged

Question 20

What percent of CO2 is carried by bicarbonate?

Answer 20

60%

Question 21

What percent of CO2 is carried by carbamino compounds?

Answer 21

30%

Question 22

What percent of CO2 is found dissolved in solution?

Answer 22

10%

Question 23

The Haldane Effect:

Answer 23

removing O2 from Hb increases ability of Hb to pick up CO2 and CO2 generated H+.

• Increasing pH
• works with bohr to maintain buffer

Question 24

What comes from type 1 resp failure?

Answer 24

Hypoxia + normal/low CO2

Question 25

What comes from type 2 resp failure?

Answer 25

Hypoxia + hypercapnia

Question 26

What things control respiration?

Answer 26

Pons, Medulla Oblongata and Spinal Cord

Question 27

What does the pre-botzinger complex do?

Answer 27

Causes breathing rhythm - excites dorsal for passive expire and if increase firing, excite ventral and do active expiration.

Question 28

What do chemo receptors do?

Answer 28

Sense gas tensions

Question 29

What do peripheral chemo receptors do?

Answer 29

sense O2, CO2 and H+ values in blood

Question 30

What do centeral chemoreceptors do?

Answer 30

respond to H+ in CSF. - CO2 diffuses into CSF readily, H+ doesnt so High H+ indicates high CO2.

Question 31

What are some chronic adaptations to hypoxia? (altitude eg)

Answer 31

More RBCs, more capillaries, more mitochondria, kidneys conserve acid