L16 - Respiration 3

Question 1

What are alveoli surrounded by?

Answer 1

elastic fibres and capillaries

Question 2

What are Type I alveolar cells?

Answer 2

very thin cells used for gas exchange

Question 3

What are Type II alveolar cells?

Answer 3

surfactant releasing cells used to break down surface tension

Question 4

How thick is the exchange surface of alveoli?

Answer 4

0.1 - 1.5µm

Question 5

What is pulmonary oedema?

Answer 5

when there is a build up of fluid in the exchange surface of alveoli, a greater diffusion distance and therefore, a decreased rate of gas exchange

Question 6

What is the order of pulmonary circulation?

Answer 6

right ventricle (low O2 blood) -> pulmonary trunk (divides into 2 pulmonary arteries) -> lungs -> pulmonary veins (oxygenated blood) -> left atrium

Question 7

Does the systemic or pulmonary system have higher resistance?

Answer 7

the systemic system

Question 8

What is the blood pressure of the pulmonary system in comparison to the systemic system?

Answer 8

blood pressure is lower in the pulmonary system

Question 9

What are three properties of pulmonary circulation?

Answer 9

1. 10% of blood volume (0.5 litres) at any given time
2. pulmonary blood pressure low (25/8 mmHg)
3. resistance of pulmonary circulation low

Question 10

What is normal ventilation-perfusion (V/Q) matching?

Answer 10

when an alveolus is constricted and is not able to carry out gas exchange, bronchioles to this alveolus will constrict and blood will be rerouted to nearby alveoli which are able to carry out gas exchange

Question 11

When oxygen content of pulmonary interstitial fluid decreases, pulmonary arterioles do what?

Answer 11

constrict

Question 12

Why is it called ventilation-perfusion matching?

Answer 12

because the amount of gas exchange able to occur in the alveolus is matched with the amount of blood flow provided to the alveolus

Question 13

What happens when partial pressure of CO2 increases?

Answer 13

bronchioles dilate, pulmonary arterioles constrict weakly and systemic arterioles dilate

Question 14

What happens when partial pressure of CO2 decreases?

Answer 14

bronchioles constrict, pulmonary arterioles dilate weakly and systemic arterioles constrict

Question 15

What happens when partial pressure of O2 increases?

Answer 15

bronchioles constrict weakly, pulmonary arterioles dilate weakly and systemic arterioles constrict

Question 16

What happens when partial pressure of O2 decreases?

Answer 16

bronchioles dilate weakly, pulmonary arterioles constrict and systemic arterioles dilate

Question 17

What is the partial pressure of oxygen at sea level?

Answer 17

160 mm Hg

Question 18

Is the oxygen concentration in lungs lower or higher than oxygen concentration in the atmosphere?

Answer 18

lower in lungs

Question 19

Which factors affect diffusion?

Answer 19

constants such as surface area, membrane thickness and diffusion distance + the most important factor which is concentration / pressure gradient

Question 20

Why does oxygen flow into venous blood and peripheral tissue?

Answer 20

because venous blood and peripheral tissue usually have lower partial pressures of oxygen resulting in oxygen moving down the pressure gradient

Question 21

Is oxygen or carbon dioxide more soluble in water?

Answer 21

carbon dioxide

Question 22

How much oxygen is carried in plasma and how much oxygen is carried by hemoglobin?

Answer 22

3 mL O2/L blood (plasma)

197 mL O2/L blood (Hb)

Question 23

What is the partial pressure of oxygen in the alveoli compared to a resting cell? Why is this important for oxygen-hemoglobin dissociation?

Answer 23

100 mm Hg in alveoli and 40 mm Hg in a resting cell
this is important because a drop in partial pressure is required for oxygen to dissociate from hemoglobin in resting cells

Question 24

What is the partial pressure of oxygen in exercising cells? Why is this important for oxygen-hemoglobin dissociation?

Answer 24

25 mm Hg

this is important because large amounts of oxygen will dissociate from Hb