Gas Exchange

Question 1

what is the gas concentration gradient in alveoli and capillaries?

Answer 1

the gases move down concentration gradients by diffusion and the concentration gradients are the same as pressure gradients

Question 2

what structures are involved in the conducting airways?

Answer 2

bronchi containing cartilage and non respiratory bronchioles

Question 3

what structures are involved in the respiratory unit?

Answer 3

respiratory bronchioles and alveolar ducts

Question 4

as the airway divides from trachea - bronchioles - alveoli what occurs in each division

Answer 4

an increase in number, a decrease in diameter and an increase in surface area

Question 5

what forms the anatomic dead space?

Answer 5

conducting airways (bronchi and non-respiratory bronchioles)

Question 6

what structures do not take part in gas exchange?

Answer 6

conducting airways (bronchi and non-respiratory bronchioles)

Question 7

what is the approximate volume of the respiratory airways?

Answer 7

2500ml

Question 8

what is the approximate volume of the conducting airways?

Answer 8

150ml

Question 9

what is a respiratory unit?

Answer 9

gas exchanging unit, basic physiological unit of the lug consisting of respiratory bronchioles, alveolar ducts and alveoli

Question 10

what are the type 1 epithelial cells in the alveoli and what do they do?

Answer 10

occupy 97% of alveoli and are the primary site of gas exchange

Question 11

what are the type 2 epithelial cells in the alveoli and what do they do?

Answer 11

occupy 3% of the surface area and produce pulmonary surfactant

Question 12

what does surfactant do?

Answer 12

reduce surface tension

Question 13

what do alveolar macrophages do?

Answer 13

removal of debris

Question 14

what are the characteristics of alveoli which make it perfectly designed for gas exchange ?

Answer 14

large surface area, very thin walls, good diffusion characteristics

Question 15

what is the function of the pulmonary circulation?

Answer 15

brings deoxygenated blood from heart to lung and oxygenated blood from lung to heart and then rest of the body

Question 16

what is the function of the bronchial circulation?

Answer 16

brings oxygenated blood to lung parenchyma

Question 17

what does the lymphatic system do?

Answer 17

defence and removal of lymph fluid

Question 18

what are the two types of blood circulation in the lungs?

Answer 18

pulmonary circulation and bronchial circulation

Question 19

what is the total blood volume in the pulmonary circulation?

Answer 19

500ml

Question 20

at rest what is the volume of blood in the alveolar-capillary network?

Answer 20

75mls

Question 21

what happens to the volume of blood in the alveolar-capillary network during exercise?

Answer 21

increases to 150-200mls due to recruitment of new capillaries secondary to an increase in pressure and flow

Question 22

what is the difference between pulmonary arteries and systemic arteries?

Answer 22

pulmonary arteries are thin walled, highly compliant, large diameter and have low resistance

Question 23

what is the distance between the alveoli and a red blood cell

Answer 23

1-2upm

Question 24

what lies between an alveoli and a red blood cell?

Answer 24

alveolar epithelial cell, capillary endothelial cell and basement membrane

Question 25

in the pulmonary circuit what is the change in O2 and CO2?

Answer 25

O2 enters blood and CO2 leaves blood

Question 26

in the systemic circuit what is the change in O2 and CO2?

Answer 26

O2 leaves blood and CO2 enters

Question 27

what gradient do gases move down?

Answer 27

pressure gradients

Question 28

what is the difference between the O2 and CO2 pressure gradients?

Answer 28

the pressure gradient for O2 is much bigger and CO2 is more diffusible

Question 29

describe the pulmonary circulation in terms of volume and pressure

Answer 29

carries large volumes of blood at low pressures

Question 30

what exchange happens between the alveoli and the capillary in the pulmonary circulation?

Answer 30

CO2 moves from capillary to alveoli and O2 moves from alveoli to capillary