Gas Exchange in Respiration

Question 1

what is the tidal volume

Answer 1

the volume breathed in and expired.

Question 2

how do gases move along pressure gradients

Answer 2

downward. from high to low

Question 3

on average, how many ml/min of oxygen are consumed

Answer 3

250

Question 4

on average, how many ml/min of carbon dioxide are expired

Answer 4

200

Question 5

what is the partial pressure of oxygen

Answer 5

150mmHg

Question 6

is partial pressure of oxygen in the blood greater before going into the lungs are after

Answer 6

after

Question 7

what do pressure gradients show

Answer 7

the direction of movement of oxygen and carbon dioxide in the respiratory system

Question 8

what is the partial pressure

Answer 8

pressure a gas exerts in a particular environment, taking into account if the environment is wet or dry

Question 9

what must the sum of partial pressures of a gas be equal to

Answer 9

total pressure

Question 10

what do pressure changes in the environment depend on

Answer 10

weather patterns and the time of day

Question 11

what is barometric pressure

Answer 11

the pressure outside the body

Question 12

what is the equation to calculate partial pressure

Answer 12

fraction of the gas in the gas mixture times by the barometric pressure

Question 13

what is the pressure of water vapour in the body

Answer 13

47mmHg

Question 14

how many ml of air breathed in per breath on average at rest

Answer 14

500ml

Question 15

how many ml of air remains in the airways after expiration

Answer 15

150ml

Question 16

describe the respiratory tree

Answer 16

trachea
bronchi
non respiratory bronchioles
respiratory bronchioles
alveolar ducts

Question 17

what happens at each division of the respiratory tree

Answer 17

increase in number, an increase in surface area

Question 18

do the conducting airways participate in gas exchange

Answer 18

no

Question 19

what are the respiratory airways

Answer 19

bronchioles with the alveoli where gas exchange occurs, from the terminal bronchioles to the alveoli

Question 20

what is a respiratory unit

Answer 20

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

Question 21

how many alveolar sacs in average adult

Answer 21

300-400 million

Question 22

describe alveoli

Answer 22

polygonal
type 1 and type 2 epithelial cells

Question 23

what feature of alveoli encourages gas exchange the most

Answer 23

its close connection with capillary networks

Question 24

describe type 1 epithelial cells in alveoli

Answer 24

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

Question 25

describe type 2 epithelial cells of the alveoli

Answer 25

septal cells 3% surface area produce pulmonary surfactant (this reduces surface tension) alveolar macrophages remove debris

Question 26

describe the key features of alveolar

Answer 26

large surface area of 100m2 very thin walls good diffusion characteristics

Question 27

what are the blood supplies of the lungs

Answer 27

pulmonary circulation bronchial circulation

Question 28

describe pulmonary circulation

Answer 28

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

Question 29

describe bronchial circulation

Answer 29

brings oxygenated blood to the lung parenchyma

Question 30

function of the lymphatic system

Answer 30

defence and removal of lymph fluid

Question 31

what is the total blood volume in pulmonary circulation

Answer 31

500ml

Question 32

how many ml of blood in the alveolar capillary network at rest

Answer 32

75ml

Question 33

what is the blood volume in the alveolar capillary network during exercise and how does this happen

Answer 33

increases from 75 to 200. recruitment of new capillaries secondary to an increase in pressure and flow

Question 34

describe arteries

Answer 34

thin walled highly compliant large diameter low resistance

Question 35

how does gas exchange occur

Answer 35

dense mesh like network of capillaries and alveoli

Question 36

how many seconds for blood cells to pass through capillaries

Answer 36

one second

Question 37

describe the gas gradient of pulmonary circulation

Answer 37

oxygen enters carbon dioxide leaves

Question 38

describe the gas gradients of systemic circulation

Answer 38

oxygen leaves blood carbon dioxide enters blood

Question 39

what are gas concentration gradients important for

Answer 39

direction of flow

Question 40

do blood and air have a close contact

Answer 40

yes

Question 41

how do the volumes of carbon dioxide and oxygen that move each minute differ

Answer 41

they are similar

Question 42

is the pressure gradient of oxygen lesser or greater than carbon dioxide

Answer 42

greater

Question 43

is carbon dioxide or oxygen more diffusable

Answer 43

carbon dioxide

Question 44

describe volume and pressure of pulmonary circulation

Answer 44

large volumes at low pressure

Question 45

what is ventilation

Answer 45

process by which air moves in and out of the lung

Question 46

what is perfusion

Answer 46

process by which deoxygenated blood passes through the lung and becomes oxygenated

Question 47

what is the level of partial pressure in oxygen and carbon dioxide related to

Answer 47

the relationship between ventilation and perfusion

Question 48

what is the V/Q ratio

Answer 48

the relationship between ventilation and perfusion

Question 49

describe the distribution of ventilation

Answer 49

not uniform due to gravity

Question 50

describe ventilation in the upright position

Answer 50

alveoli in the apex is more expanded than at the base

Question 51

describe graviy's impact on ventilation distribution in the lungs

Answer 51

gravity pulls the lung down and away from the chest wall pleural pressure is more negative at the apex than at the base transpulmonary pressure is greater at the apex than at the base increased alveolar volume in the apex

Question 52

what is compliance

Answer 52

this refers to how much effort is required to stretch the lungs and chest wall

Question 53

what does high compliance mean for breathing

Answer 53

it means that the lungs and the chest wall expand easily

Question 54

what is resistance

Answer 54

narrowing or obstruction of airways reduced lumen increased resistance that can lead to decreased ventilation

Question 55

what does decreased compliance mean for breathing

Answer 55

common feature when there are pulmonary conditions, leads to: - scarring in the lung tissue (like in TB) - lung filled with fluid (edema) - deficiency in surfactant production - destruction of elastic fibres (emphysema)

Question 56

what is an increased resistance a common feature in

Answer 56

pulmonary conditions

Question 57

what can increased resistance lead to

Answer 57

- asthma - COPD due to obstruction or collapse of airways

Question 58

is pulmonary influenced more or less by gravity compared to systemic circulation

Answer 58

more

Question 59

describe upright pulmonary blood flow

Answer 59

there is greater blood flow the base than the apex

Question 60

describe pulmonary circulation

Answer 60

low pressure and low resistance

Question 61

what defines the V/Q ratio of a single alveolus

Answer 61

alveolar ventilation divided by capillary flow

Question 62

what defines the V/Q ratio of the lung

Answer 62

total alveolar ventilation divided by cardiac output

Question 63

what is the average alveolar ventilation of healthy individuals

Answer 63

4-6 litres per minute

Question 64

what is the pulmonary blood flow on average in healthy individuals

Answer 64

5 litres per minute

Question 65

what is the V/Q for a lung in a healthy individual

Answer 65

0.8 to 1.2

Question 66

what is the V/Q ratio when the ventilation exceeds the perfusion

Answer 66

greater than one

Question 67

what is the V/Q ratio when perfusion exceeds ventilation

Answer 67

less than one

Question 68

what does V/Q mismatching lead to

Answer 68

arterial hypoxemia in patients with respiratory disorders

Question 69

what is the V/Q ratio a ratio of

Answer 69

ventilation to blood flow

Question 70

what does it mean if V/Q ratio is 1

Answer 70

this is the perfect model, where the inspired gas and cardiac output partial pressures are shared equally

Question 71

what does V/Q mismatching result in

Answer 71

varying alveolar and capillary gas contents

Question 72

what are the regional differences in ventilation and perfusion largely down to

Answer 72

gravity