BAMS: Respiration (control of breathing)

Question 1

what can breathing be modulated by?

Answer 1

emotional events (crying, laughing)
vocalisation (singing)
reflexes (coughing)
volitional control (breath hold, hyperventilation)
physiological challenges (sleep, exercise)

Question 2

where does the brain receive neural signals from?

Answer 2

chemoreceptors and mechanoreceptors

Question 3

where does the brain send neural signals to?

Answer 3

respiratory muscles (to produce rhythmic breathing movements, e.g., diaphragm and intercostals)

upper airway muscles (e.g., laryngeal, pharyngeal and tongue)

produce reflexes to keep airways patent, e.g., cough, sneeze, gag

Question 4

what do chemoreceptors do?

Answer 4

provide feedback on the levels of O2 and CO2 in the blood and pH

Question 5

what do mechanoreceptors do?

Answer 5

detect changes in movement within the respiratory system

detect movement of lungs and chest wall
(e.g., during inspiration mechanoreceptors detect inflation of lungs and movement of chest)

Question 6

where are neuronal clusters found, involved in regulation of breathing?

Answer 6

in the medulla of the brainstem

Question 7

what is hypoxia?

Answer 7

decreases in O2

Question 8

what is hypercapnia?

Answer 8

increases in CO2

Question 9

what can chemoreceptors be classified into?

Answer 9

peripheral and central chemoreceptors

Question 10

where are peripheral chemoreceptors located?

Answer 10

in the aortic arch (nestled with baroreceptors - located perfectly) –> info sent via vagus nerve to brain

and in the bifurcation of the carotid artery (also with baroreceptors) –> info sent via the glossopharyngeal nerve to brain

Question 11

what region of the brain receives info from the peripheral chemoreceptors?

Answer 11

nucleus tractus solitarius (NTS) in brainstem

Question 12

what do peripheral chemoreceptors respond to?

Answer 12

decreases in PO2 (hypoxia)

(ventilation increases to restore PO2 levels)

Question 13

what is the relationship between ventilation and hypoxia (low PO2 levels)?

Answer 13

progressive reductions in inspired oxygen (from 100 to 60 mmHg) have little effect on ventilation

below 60mmHg, there is a progressive hyperventilation

–> body can withstand a fair drop in partial pressure in O2 before it kicks into action

Question 14

does oxygen play a big part in moment-to-moment control of breathing

Answer 14

no, it plays little part

Question 15

where are central chemoreceptors located?

Answer 15

in the CNS (specifically in the brainstem, mainly within the medulla)

Question 16

when are central chemoreceptors activated?

Answer 16

where there is a change in CO2 levels (i.e., hypercapnia - increase PCO2)

or pH decreases

Question 17

what happens if central chemoreceptors are activated?

Answer 17

signals are processed and info sent to neuronal clusters in brainstem involved in generated breathing.

these neuronal clusters then send signals to respiratory muscles in order to adapt breathing and restore PCO2 levels

Question 18

what is the ventilatory response to hypercapnia (increase in CO2)?

Answer 18

very small changes in PCO2 have large effects on ventilation (unlike O2)

Question 19

does CO2 play a big part in moment-to-moment control of breathing

Answer 19

yes

Question 20

where are mechanoreceptors located?

Answer 20

throughout the respiratory system

Question 21

when the mechanoreceptors are activated, how is the info sent and where is it sent to?

Answer 21

sent via vagus nerve to the nucleus tractus solitarius in brainstem

Question 22

what are certain movements that can influence change in breathing?

Answer 22

postural changes and locomotion

Question 23

what info does the nucleus tractus solitarius receive?

Answer 23

info from mechanoreceptors and peripheral chemoreceptors

Question 24

what are the two types of bilateral neuronal clusters in the brainstem?

Answer 24

(top neuronal cluster) = nucleus tractus solitarius

(bottom neuronal cluster) = respiratory neurons - produce rhythmic output of breathing and integrate info that is received by the mechano and chemoreceptors

Question 25

does a neuron always fire at the SAME POINT in a cycle?

Answer 25

yes (inspiratory neurons active during inspiration) (expiratory neurons active during expiration)

Question 26

what are PATTERN generating neurons?

Answer 26

associated with controlling the pattern of inspiration and expiration (but aren't setting the underlying rhythm of breathing)

Question 27

what are RHYTHM generating neurons?

Answer 27

can produce rhythmic output that underlies the breathing pattern can continue to produce respiratory-like rhythmic output even when isolated

Question 28

what can the rhythmic output from rhythm generated neurons be modulated by?

Answer 28

can be modulated by the inspiratory and expiratory PATTERN generating neurons

Question 29

where are rhythmic neural signals sent to?

Answer 29

spinal cord

Question 30

where does the phrenic nerve exit the spinal cord?

Answer 30

at cervical spinal cord level 3-5 (C3,4,5 keeps the diaphragm alive)

Question 31

what innervates the diaphragm?

Answer 31

phrenic nerve

Question 32

what nerves innervate intercostal muscles?

Answer 32

nerves exiting thoracic spinal cord

Question 33

what is the ventral respiratory group (in the brainstem)?

Answer 33

where the pattern and rhythm generating neurons are located

Question 34

what is the dorsal respiratory group (in the brainstem)?

Answer 34

where the nucleus tractus solitarius (NTS) is located

Question 35

what type of information does the NTS receive?

Answer 35

afferent information

Question 36

what is the motor homunculus?

Answer 36

somatotopic organisation of the primary motor cortex (area of motor cortex dedicated to a particular muscle is proportional to the number of motor neurons innervating the muscle)

Question 37

what is higher center modulation? (in terms of regulation of breathing)

Answer 37

input to the brainstem neurons from the cortex (volitional and emotional)w

Question 38

what do the pattern and rhythm generating neuronsn control?

Answer 38

the rhythmic output of breathing