RESP- Neural Control of Breathing

Question 1

why is there a need to modulate ventilation rate

Answer 1

acid base regulation
conservation of energy
achieve getting more / less oxygen during excercise

Question 2

what circumstances will increase oxygen demand or carbon dioxide production

Answer 2

excercise - increased activity = increased ATP production = increase in volume of oxygen consumed 
infection
injury
metabolic dysfunction
altitude

Question 3

how does breathing change to modulate rate of ventilation

Answer 3

tidal volume and breathing frequency increase together resulting in an increase in minute volume

Question 4

what is minute volume

Answer 4

amount of gas inhaled / exhaled from a persons lungs in one minute

Question 5

in healthy individuals how is increased oxygen delivery achieved

Answer 5

by increasing cardiac output - NOT increasing partial pressure of oxygen

Question 6

what are the physiological processes behind initiating breathing

Answer 6

neural innervation

Ach is released - binds to receptors, causes an influx of calcium, initiating contraction

Question 7

where is the neurological stimulus initiated which triggers muscle contraction

Answer 7

brainstem, central pattern generator, transferred to CNS then synapses with the muscle - triggers contraction

Question 8

in quiet breathing, which muscles are utilised

Answer 8

diaphragm

Question 9

in higher rates of breathing, what muscles are utilised

Answer 9

an increased tidal volume and rate of respiration may required further muscles such as external intercostal, and other accessory muscles such as pecs, abdominal etc..

Question 10

outline how the basic breathing pattern is generated by a neuronal system within the brainstem

Answer 10

rhythmic breathing is initiated by the respiratory centre in the medulla oblongata of the brain stem

the dorsal group of neurones are self-excitatory and switch on and off acting as a pacemaker - on for 2 seconds off for 3 ~ 12 breaths per minute

the inspiratory neurones stimulate nerves to the breathing muscles leading to the expansion of the thorax

the ventral group of respiratory neurones become active during forces respiration

the pontine respiratory group of neurones are responsible for ensuring that the lungs are not overinflated by sending inhibitory signals to inspiratory centre to limit inspiration

Question 11

how does the central pattern generator determine depth and rate of breathing

Answer 11

CPG integrates data from various neuronal inputs to regulate ventilation

central chemoreceptors
peripheral chemoreceptors
hypercapnic drive
hypoxic drive

Question 12

what do central chemoreceptors respond to

Answer 12

central respiratory chemoreceptors monitor changes in arterial pCO2 and can respond to H+ ions within cerebrospinal fluid

Question 13

what do peripheral chemoreceptors respond to

Answer 13

peripheral chemoreceptors respond to changes in arterial oxygen, carbon dioxide and pH

they are activated by a decrease in ppO2 and increase in ppCO2

Question 14

how is ventilation different during sleep

Answer 14

ventilation decreases during sleep

decrease in metabolic rate - decrease in respiratory demands
postural changes alter mechanics of breathing
decrease in SNS and increase in PNS tone - decrease in heart rate, blood pressure and cardiac output
decrease in tidal volume, decrease in breathing frequency
decrease in minute volume
decrease in SaO2, increase in PaCO2
decrease in upper airway calibre

Question 15

how can the physiological processes involved in breathing be impacted by trauma

Answer 15

damage to respiratory centres in brain stem

Question 16

how can the physiological processes involved in breathing be impacted by stroke

Answer 16

ischaemia - induced brainstem tissue injury

Question 17

how can the physiological processes involved in breathing be impacted by drugs

Answer 17

opioids - suppression of neuronal activity

Question 18

how can the physiological processes involved in breathing be impacted by congenital hypoventilation syndrome

Answer 18

people with this syndrome take shallower breaths

Question 19

how can the physiological processes involved in breathing be impacted by altitude

Answer 19

control system is unable to cope with abnormal atmospheric environment - low O2 and low CO2

Question 20

how can the physiological processes involved in breathing be impacted by Cheyne-strokes

Answer 20

can happen whilst awake - usually during sleep

period of quick shallow breathing followed by a period of slow heavier breathing with periods of no breathing at all

Question 21

what is sleep apnoea

Answer 21

the stopping and restarting of breathing during sleep

Question 22

how does sleep apnoea affect health

Answer 22

tiredness (poor sleep quality)
cardiovascular complications (stress and increases SNS tone)
obesity / diabetes (inflammation and metabolic dysfunction

Question 23

Explain the cycle of Cheyne-strokes

Answer 23

peripheral chemoreceptors detect hypercapnia and there is compensatory hyperventilation which produces hypocapnia and alkalosis which is sensed by the central chemo receptors which triggers a decrease in respiratory drive and compensatory hypoventilation which produces hypoxaemia and the cycle repeats