mechanics of breathing

Question 1

how many cells do gases have to diffuse across

Answer 1

• 2
• endothelial cells of capillaries
• and epithelial cells of alveoli

Question 2

what are the two types of respiration

Answer 2

• internal

- external - removing co2, exchange and transports of gases around the body

Question 3

what is inspiration

Answer 3

• movement of air into the lungs

Question 4

in order for air to move into the lungs what must the pressure be of the lungs

Answer 4

• lungs must be at a negative pressure compared to the atmospheric pressure

Question 5

how are the lungs at a negative pressure

Answer 5

• due to active contraction and downward movement of diaphragm
• and the contraction of intercostal muscles causing ribs to move up
• therefore increasing volume of thorax

Question 6

when does inspiration end

Answer 6

• as lungs inflate the pressure difference between the atmosphere and intrapleural fluid decreases until at equilibrium with elasticity of lungs

Question 7

what factor determines elasticity of lungs

Answer 7

• surface tension of the alveoli

Question 8

what cells aid in the expansion of the lungs and what do they secrete

Answer 8

• type 11 cells

- secretes surfactant

Question 9

what does the fluid surfactant do

Answer 9

• fluid coats the alveoli and reduces the surface tension

Question 10

what is surfactant composed of

Answer 10

• lipids and proteins

Question 11

what is expiration

Answer 11

• movement of air out of the lungs
• diaphragm and intercostal muscles relax
• both muscles recoil back to original position
• volume of thorax decreases increasing the pressure
• expiration is a passive process

Question 12

what is ventilation

Answer 12

• exchange of gas between the atmosphere and alveoli

- airflow = pressure inversely proportional to resistance

Question 13

during ventilation what is the pressure gradient between

Answer 13

• pressure in alveoli and atmospheric pressure (alv - atm)

Question 14

where is the basic respiratory rhythm generated by

Answer 14

• centres in medulla

Question 15

what are two properties of breathing

Answer 15

• automatic

- rhythmical properties

Question 16

what are two respiratory groups found in the medullary centre

Answer 16

• dorsal respiratory group

- ventral respiratory group

Question 17

dorsal respiratory group

Answer 17

• controls inspiration by sending signals to the inspiratory muscles

Question 18

ventral respiratory group

Answer 18

• inactive during quiet respiration

- active during forced inspiration and expiration

Question 19

where do pons send stimuli to and what do they regulate

Answer 19

• medulla

- rate and depth of breathing

Question 20

pneumotaxic centre

Answer 20

• increase rate by shortening inspiration

- inhibitory effect

Question 21

apneustic centre

Answer 21

• decrease rate and increases depth by prolonging inspirations
• stimulates inhibitory centre

Question 22

purpose of stretch receptors

Answer 22

• control how far lungs expand

- when breathing chest expands

Question 23

what do chemoreceptors detect

Answer 23

• changes in ph and carbon dioxide

Question 24

where do central chemoreceptors monitor conditions

Answer 24

• cerbro - spinal fluid

Question 25

where are peripheral chemoreceptors found

Answer 25

• carotid body

- aortic arch

Question 26

what muscles does quiet inspiration require

Answer 26

• primary muscles; diaphragm and intercostal muscles

- leads to an increase in thoracic volume

Question 27

what muscles does forced inspiration require

Answer 27

• primary muscles and

- accessory muscles; scalene, back and neck muscles, upper respiratory tract muscles

Question 28

what muscles does quiet expiration require

Answer 28

• no primary muscles

- passive process using elastic recoil

Question 29

what 4 muscles are needed for forced expiration

Answer 29

• abdominal muscles
• neck and back muscles
• accessory muscles
• internal intercostal

Question 30

what is the purpose of pleural cavity

Answer 30

• prevents lungs from sticking to chest walls

- enables free expansion and collapse of lungs

Question 31

term used to describe collapsed lung

Answer 31

• pneumothorax

Question 32

what is compliance

Answer 32

• measure of elasticity - how easy lungs and thorax expand due to pressure changes

Question 33

how to calculate compliance

Answer 33

• change in volume / change in pressure

Question 34

what two factors affect airway resistance

Answer 34

• diameter of airway

- whether airflow is laminar or turbulent

Question 35

how many sub units does haemoglobin contain

Answer 35

• 4 sub units
• each unit consists of a haem unit and globin chain
• depending on hb type different combination of globing chains

Question 36

what state does iron have to be in for oxygen to bind

Answer 36

• fe2+

Question 37

what enzyme helps convert fe2+ to fe3+

Answer 37

• enzyme methaemoglobin reductase

Question 38

what two states does haemoglobin exist in

Answer 38

• tense - low affinity for oxygen

- relaxed - high affinity for oxygen

Question 39

what four factors result in dissociation of oxygen

Answer 39

• increased temp
• increase co2 production
• decrease in ph
• increase production of 2,3 DPG

Question 40

what 5 ways does blood carry co2 as

Answer 40

• dissolved co2
• carbonic acid
• bicarbonate
• carbonate
• carbamino compounds

Question 41

what two things need to match to ensure continuous delivery of oxygen and removal of co2

Answer 41

• alveolar ventilation (air reaching alveolus)

- pulmonary blood flow (blood reaching alveolus in capillaries)