Ventilation and perfusion

Question 1

Describe the conducting zone of the respiratory system

Answer 1

trachea to the bronchioles

where there is no gas exchange

Question 2

Describe the respiratory zone of the respiratory system

Answer 2

respiratory bronchioles to the alveoli

where there is gas exchange

Question 3

How does inspiration occur

Answer 3

• Diaphragm contracts and flattens and moves caudally
• Ribs are pulled cranially and outwards by contraction of the external intercostal muscles
• Together these increase the volume of the thoracic cavity, decreasing the pressure of the air in the alveoli and causing air to be sucked in as air flows from high to low pressure

Question 4

How does expiration occur

Answer 4

• Is a passive response except during exercise
• The diaphragm relaxes and raises
• intercostal muscles relax and ribs and sternum go down

Question 5

Describe the composition of the diaphragm

Answer 5

central part= tendinous

Peripheral = muscular

Question 6

What is the diaphragm attached to

Answer 6

• xiphoid process
• lower costal cartilages
• ribs
• vertebral column

Question 7

Describe the crura of the diaphragm

Answer 7

right and left crus or fibromuscular bands arising from the ;lumbar vertebrae, insert into the central tendon of the diaphragm

Question 8

Name the 3 things that pass through the diaphragm

Answer 8

• oesophagus
• aorta
• vena cava

Question 9

What nerve innervates the diaphragm

Answer 9

phrenic nerve

Question 10

Where do external intercostal muscles lie

Answer 10

superficially and the fibres run caudoventrally between ribs

Question 11

where do internal intercostal muscles lie

Answer 11

lie underneath and fibres run in the opposite direction

Question 12

Name the 2 components of internal intercostal muscles

Answer 12

interosseous

interchondral

Question 13

Describe the interosseous part of the internal intercostal muscles

Answer 13

expiratory muscles between bones

Question 14

describe the interchondral part of the internal intercostal muscles

Answer 14

inspiratory muscles between cartilage

Question 15

Describe the parietal pleura

Answer 15

outer layer of pleura lying closer to the ribs and chest wall

Question 16

Describe the visceral pleura

Answer 16

inner layer of pleura lying closer to the lung tissue

Question 17

Describe the pleural cavity

Answer 17

the space between the folds of the pleura

Question 18

how does locomotion affect ventilation

Answer 18

stride cycle and ventilation cycle of galloping animals are synchronized, piston pendulum theory, movement of the limbs influences inspiration and expiration, inspiration only when the body is extended due to negative pressure in the thorax

Question 19

What are the factors influencing ventilation

Answer 19

• resistance to flow in the airways
• lung compliance
• alveolar surface tension

Question 20

What is the calibre or airways

Answer 20

internal diameter

Question 21

What are the smooth muscles of the airway walls

Answer 21

bronchial muscle- musculus spiralis

Question 22

describe the laminar flow

Answer 22

a smooth pattern of flow

Question 23

describe turbulent flow

Answer 23

irregular flow with random variations in pressure

Question 24

Where is turbulence greatest

Answer 24

in trachea and bronchi

Question 25

what is compliance

Answer 25

change in volume of a structure for eac unit change in pressure

Question 26

what is elastance

Answer 26

retractive (recoil) force that the distension of a structure generates

Question 27

How is surface tension in the alveoli reduced

Answer 27

surfactant

Question 28

how is the pressure inside the alveolus determined

Answer 28

by the surface tension of the lining fluid and the radius of the alveolus

Question 29

Why is surfactant more concentrated in smaller alveoli

Answer 29

the surface tension is higher in smaller alveoli

Question 30

Define tidal volume

Answer 30

Is the amount of air breathed in or out during a respiratory cycle. It can increase or decrease from normal depending on ventilation requirements

Question 31

Define inspiratory reserve volume

Answer 31

is the amount of air that can still be inspired after inhaling the tidal volume

Question 32

Define expiratory reserve volume

Answer 32

is the amount of air that can still be expired after exhaling the tidal volume

Question 33

Define residual volume

Answer 33

is the amount of air remaining in the lungs after the most forceful expiration

Question 34

Define inspiratory capacity

Answer 34

is the sum of the tidal and inspiratory reserve volumes

Question 35

Define vital capacity

Answer 35

the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath

Question 36

Define functional residual capacity

Answer 36

Is the sum of the expiratory reserve volume and the residual volume

Question 37

Define total lung capacity

Answer 37

Is the entire gas volume of the maximally spontaneously inflated pulmonary parenchyma and airways in the thorax

Question 38

Define respiratory rate

Answer 38

Is the rate at which breathing occurs. This is usually measured in breaths per minute

Question 39

Define minute ventilation

Answer 39

Is the total volume of gas moved in or out of the airways and alveoli in 1 minute

Question 40

Define dead space

Answer 40

Is the volume of air that is inhaled that does not take part in the gas exchange, because it either remains in the conducting airways or reaches alveoli that are not perfusion or poorly perfused

Question 41

Define alveolar ventilation

Answer 41

Is defined as the volume of air entering and leaving the alveoli per minute

Question 42

Describe the regional differences in ventilation

Answer 42

lower portions of the lung are ventilated more than upper zones

Question 43

What is pulmonary perfusion

Answer 43

blood flow to the alveoli allowing uptake of oxygen and removal of carbon dioxide

Question 44

list 4 factors affecting perfusion

Answer 44

- hypoxic vasoconstriction - disease - posture - cardiac function

Question 45

Describe hypoxic vasoconstriction

Answer 45

reduces blood flow to the alveoli that aren't being ventilated in order to send blood to ventilated areas

Question 46

What is ventilation and perfusion mismatch

Answer 46

where the ventilation and perfusion don't match and aren't even across the lung

Question 47

Describe the V/Q at base of lung

Answer 47

low as there is more blood flow than ventilation

Question 48

Describe the V/Q at apex of the lung

Answer 48

high as there is more ventilation than blood flow

Question 49

Describe mismatching of ventilation due to posture

Answer 49

ventilation is less in dorsal areas and can become restricted when the animal is lying down due to the lungs becoming crushed

Question 50

Explain how ventilation is regulated

Answer 50

Is regulated by the respiratory centre in the medulla, which generates action potentials, modulated by feedback from: - Chemorecptors - Mechanorecptors