RS. gas pressure

Question 1

what is the point of breathing?

Answer 1

maintain blood gas homeostasis

Question 2

how do gases move in alveoli and capillaries?

Answer 2

down conc gradients by diffusion

Question 3

what is the partial pressure of co2 and o2 in the alveolar sacs?

Answer 3

co2 = 40
o2 = 102

Question 4

what is the partial pressure of co2 and o2 in the trachea?

Answer 4

co2 = 0
o2 = 150

Question 5

what is the partial pressure of co2 and o2 in the in the capillaries coming into the lungs?

Answer 5

co2 = 40
o2 = 102

Question 6

what is partial pressure?

Answer 6

pressure that gas exerts in particular enviroments

Question 7

what is the partial pressure of gas equal to? (pGas)

Answer 7

fraction of gas (Fgas) in gas mixture X barometric pressure

Question 8

what do you have to take into account while working out the partial pressure?

Answer 8

in airways air warmed and humidified become saturated with water

Question 9

what is the partial pressure of water vapour?

Answer 9

47mmHg

Question 10

what happens as you go down divisions in the reparatory tract?

Answer 10

airways brach into small more numerous bronchioles until terminating to a group of alveoli

Question 11

what do bronchi contain?

Answer 11

contain cartilage and non-respiratory bronchioles

Question 12

how much of breath will always be in conducting airways?

Answer 12

150ml
30%

Question 13

what does not participate in gas exchange?

Answer 13

conducting airways (top)

Question 14

what is the respiratory airways?

Answer 14

bronchioles with alveoli where gas exchange occurs (from terminal bronchioles to alveoli)

Question 15

what is a reparatory unit/ gas exchanging unit?

Answer 15

basic physiological unit of the lung consisting of respiratory bronchioles, alveolar ducts and alveoli.

Question 16

how many alveolar sacs in a healthy adult?

Answer 16

300-400 million

Question 17

what is the shape of alveoli?

Answer 17

polygonal
250um in diameter

Question 18

what type of epithelial cells are alveoli composed of?

Answer 18

type 1 and 2

Question 19

in images what colour are the arteries and veins?

Answer 19

veins red
arteries blue

Question 20

what are conducting airways?

Answer 20

anatomic dead space not involved in gas exchange

Question 21

what are type 1 epithelial cells?

Answer 21

primary site of gas exchange
97% of surface area of alveoli

Question 22

what are type 2 epithelial cells?

Answer 22

septal cells
3% of surface area
produce pulmonary surfactant (reduces surface tension)

Question 23

what is a big problem in premature babies born at around 22 weeks?

Answer 23

no type 2 epithelial cells
therefor unable to expand lungs

Question 24

what do alveolar macrophages do?

Answer 24

remove debris

Question 25

what characteristics of alveoli make it good for gas exchange?

Answer 25

thin walls
large surface area 100m2
good diffusion characteristics

Question 26

what does the pulmonary circulation of the lung do?

Answer 26

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

Question 27

what does the bronchial circulation of the lung do?

Answer 27

bring oxygenated blood from lung to parenchyma

Question 28

what does the lymphatics system do?

Answer 28

defence and removal of lymph fluid

Question 29

how much of the total blood is in pulmonary circulation?

Answer 29

500ml
10%

Question 30

how do the arteries in pulmonary circulation compare to systemic circulation?

Answer 30

pulmonary
- thin walls
- highly compliant
- large diameter
- low resistance

Question 31

where does gas exchange occur in capillaries and alveoli?

Answer 31

through dense mesh like networks

Question 32

how fast do red blood cells pass through capillaries?
what happens in this time?

Answer 32

less than 1 second
(sufficient time for co2 and o2 gas exchange)

Question 33

what happens in the pulmonary circuit and the systemic circuit?

Answer 33

pulmonary: o2 enters blood and co2 leaves
systemic: o2 leaves blood and co2 enters

Question 34

is co2 or o2 more diffusible?

Answer 34

co2

Question 35

does pulmonary circulation have high or low pressure?

Answer 35

low pressure

Question 36

where does co2 and o2 move from?

Answer 36

co2 = from capillary to alveoli
o2 = from alveoli to capillary