lung function

Question 1

define ventilation

Answer 1

movement of air in and out of lungs by bulk flow

Question 2

the lower respiratory tract is divided into 2 zones

Answer 2

1. conducting zone
2. respiratory zone - alveoli for gaseous exchange

Question 3

what are type I pneumocytes

Answer 3

cells that maximise gaseous exchange

Question 4

what are type II pneumocytes

Answer 4

secrete surfactant

Question 5

shape of type I pneumocytes

Answer 5

flat and very thin

Question 6

shape of type II pneumocytes

Answer 6

large and rounded

Question 7

how to work out minute ventilation (VE) measured in L/min

Answer 7

breathing rate (R) x tidal volume (VT)

Question 8

what happens when Patm and Palv is the same

Answer 8

no air flow, there has to be a pressure difference between the two

Question 9

what is Boyles law

Answer 9

pressure is inversely proportional to vol
-vol increase - pressure decrease
-vol decrease - pressure increase

Question 10

what is the main respiratory muscle causing change in volume

Answer 10

diaphragm

Question 11

what happens to diaphragm during inspiration

Answer 11

diaphragm contracts - pulls down

Question 12

what happens to diaphragm during expiration

Answer 12

diaphragm relaxes - moves up

Question 13

breathing at rest -
accessory muscles during inspiration

Answer 13

diaphragm + external intercostals contract

Question 14

breathing at rest -
accessory muscles during expiration

Answer 14

diaphragm relaxes + passive recoil of lungs

Question 15

forced breathing -
accessory muscles during inspiration

Answer 15

more forceful contraction of diaphragm
other accessory muscles also contract

Question 16

forced breathing -
accessory muscles during expiration

Answer 16

abdominals + internal intercostals contract

Question 17

what is the space between the pleural membranes called

Answer 17

pleural fluid

Question 18

function of the pleural membranes and pleural fluid inbetween

Answer 18

provides cohesion between the inner surface of the chest cavity and surface of the lungs

Question 19

as chest cavity expands, what happens to the intrapleural pressure (pressure between pleural membranes). leads to expansion of lungs

Answer 19

becomes more negative

Question 20

define compliance

Answer 20

how stretchable a tissue is

Question 21

how to measure lung compliance from the lung volume/ trans-pulmonary pressure (PTP) slope

Answer 21

gradient

Question 22

what is transpulmonary pressure (PTP)

Answer 22

force that makes the lungs expand - increases when PIP decreases

Question 23

how does elastin (connective tissue) influence lung compliance

Answer 23

-STRETCHABLE - stretches for inspiration
-passive recoil during expiration

Question 24

how does collagen (connective tissue) influence lung compliance

Answer 24

-RIGID - provides structural support but restricts stretching
-healthy alveoli have little collagen

Question 25

how does surface tension influence lung compliance

Answer 25

cohesive forces at air/water interface in alveoli reduces compliance

Question 26

how does too much collagen cause restrictive lung disease

Answer 26

low compliance, lung capacity is reduced, impaired gaseous exchange

Question 27

how does too little collagen cause obstructive lung disease

Answer 27

high compliance, bronchioles collapse easily during expiration, impaired gaseous exchange

Question 28

equation for working out alveolar air pressure (P)

Answer 28

P = 2T/r

Question 29

equal surface tension in both alveoli - which has greater pressure & what happens to compliance and gas exchange

Answer 29

smaller alveoli has greater pressure, compliance and gaseous exchange is impaired

Question 30

what reduces surface tension so that there's no pressure diff between both alveoli and compliance and gaseous exchange is maintained

Answer 30

type II pneumocytes secretes surfactant - smaller alveoli have more surfactant so surface tension is less than bigger alveoli. no pressure difference, compliance and gaseous exchange is maintained

Question 31

no surfactant restricts inspiration, what happens to lung compliance

Answer 31

low compliance, lungs are partially collapsed, impaired gaseous exchange

Question 32

how does bronchoconstriction affect resistance, and then air flow

Answer 32

resistance increased, air flow decreased

Question 33

what hormone causes bronchodilation of bronchioles

Answer 33

adrenaline binding to beta agonists

Question 34

what paracrine factor causes bronchodilation of bronchioles

Answer 34

CO2 from alveoli

Question 35

what neuronal factor causes bronchoconstriction of bronchioles

Answer 35

acetylcholine

Question 36

what paracrine factor causes bronchoconstriction of bronchioles

Answer 36

histamine released by inflammatory cells

Question 37

excessive narrowing of bronchioles (obstructive lung disease) is a feature of what disease

Answer 37

asthma - increased resistance, decreased airflow, impaired gaseous exchange