Normal Physiology

Question 1

What percentage of O2 bound to Hb is used in one pass of the bodies systems

Answer 1

25%

Question 1

An increase in [H+] causes what shift in the oxygen dissociation curve?

Answer 1

Right

Question 2

How can low oxygenation of the blood be compensated for?

Answer 2

Greater amounts of Hb

Greater CO

Question 3

How much CO2 does the body produce at BMR compared to while exercising?

Answer 3

At BMR: 200ml/min During exercise: >4000ml/min

Question 4

What does PaO2 stand for?

Answer 4

Partial pressure of arterial O2

Question 4

Why do small airways contribute low resistance?

Answer 4

Because there are a lot of them

Question 5

What does central cyanosis reflect in the blood?

Answer 5

Arterial blood is not well oxygenated

Question 6

How much O2 does the body use at BMR compared to while exercising?

Answer 6

At basal metabolic rate: 250ml/min During exercise: >4000ml/min

Question 7

What is the function of carbonic anhydrase?

Answer 7

It catalyses the reaction of CO2 + H2O > H2CO3

Question 8

An increase in PCO2 causes what shift in the oxygen dissociation curve?

Answer 8

Right

Question 9

What are the main functions of the lungs?

Answer 9

1. Oxygenate pulmonary arterial blood 2. Removed CO2 from pulmonary arterial blood 3. Maintain acid-base balance

Question 9

What do central chemoreceptors respond to? Where are they located?

Answer 9

H+ Ventrolateral medullary surface

Question 10

Why is diffusion of CO2 20x greater than O2 given that the driving pressure is greater for O2?

Answer 10

CO2 is more soluble

Question 11

What does PiO2 stand for?

Answer 11

Partial pressure of inspired O2

Question 13

What does PA02 stand for?

Answer 13

Partial pressure of alveolar O2

Question 14

An elevated PaCO2 is generally due to a ventilation or diffusion problem? Why?

Answer 14

Ventilation, because CO2 diffusion is very fast.

Question 14

How many branches are there of the lung airways?

Answer 14

23

Question 16

What drives O2 to bind to Hb?

Answer 16

Its concentration dissolved in plasma (PaO2 or PvO2)

Question 17

Apart from central and peripheral chemoreceptors, what factors effect respiration?

Answer 17

Stretch receptors in the chest wall

Muscle and joint receptor

Cortical control

Question 18

What are the main muscles of expiration?

Answer 18

Internal intercostals

Abdominals

Question 19

What are implications of a right shift in the oxygen dissociation curve during exercise?

Answer 19

O2 is more easily unloaded

Question 20

An increase in temperature causes what shift in the oxygen dissociation curve?

Answer 20

Right

Question 21

What type is air flow is seen in the small and large airways?

Answer 21

Laminar and turbulent respectively

Question 22

Which way will the oxygen dissociation curve shift if Hb’s affinity for O2 is increased?

Answer 22

Left

Question 23

What is the vital capacity?

Answer 23

The difference between total lung capacity and residual volume

Question 24

T/F Carbon monoxide has a greater affinity for Hb than O2

Answer 24

True, 240x greater

Question 25

What is the normal PaO2, PaCO2 and pH of arterial blood?

Answer 25

O2 - 100mmHg CO2 - 40 mmHg pH - 7.4

Question 26

What percentage of CO2 is bound to Hb for transportation?

Answer 26

30%

Question 26

What do peripheral chemoreceptor respond to? Where are they located?

Answer 26

H+, CO2, O2 Carotid and aortic bodies

Question 27

What nerves are important in stimulating inspiration?

Answer 27

Phrenic (diaphragm) Intercostal nerves (external intercostal muscle)

Question 29

What two factors contribute to the work of breathing?

Answer 29

Resistive - Overcoming airflow resistance Elastic - Pushing against elastic lungs (imagine blowing up a balloon) and expanding the chest wall

Question 30

What percentage of CO2 is dissolved in plasma?

Answer 30

10%

Question 32

True or false, in healthy individuals undergoing exercise, there is not enough time for Hb to be completely oxygenated in alveolar capillaries.

Answer 32

False, the time required is 0.25s which is the time spent by blood in the capillaries during exercise.

Question 34

What is the difference between residual volume and functional residual volume?

Answer 34

Residual volume is what is left after maximal expiration (1,200ml) while function residual volume is what is left after normal expiration (2,200ml)

Question 35

What does a low V/Q match indicate?

Answer 35

Ventilation doesn't match perfusion

Question 36

What are main muscles of inspiration?

Answer 36

Diaphragm External intercostals Sternocleidomastoids

Question 37

Why are more CO2 bound in the carboamino form in venous blood cf to arterial?

Answer 37

Because there is more reduced Hb (Hb without O2, H+ instead) with has a higher affinity for CO2 than HbO2

Question 38

What percentage of vital capacity is used at maximum exercise?

Answer 38

50%

Question 39

In what form is the majority of CO2 transported?

Answer 39

Bicarbonate: 60%