Lec 16 - Control of Breathing

Question 1

what factors are responsible for generating alternating insp/exp rhythm

Answer 1

respiratory centres in the brainstem

Question 2

what factors regulate magnitude of ventilation to match needs

Answer 2

chemoreceptors

Question 3

list the inspiratory muscles

Answer 3

diaphragm, external intercostal muscles

Question 4

list the expiratory muscles

Answer 4

abdominal muscles, internal intercostal muscles

Question 5

where is the respiratory control centres

Answer 5

in the brain stem

Question 6

what is the primary RCC

Answer 6

the medulla

Question 7

what is the medulla

Answer 7

a cluster of neuronal cell bodies - output to respiratory muscles

Question 8

what does the Pons infleunce

Answer 8

output from the medulla (primary RCC)

Question 9

what are the two parts making up the Pons

Answer 9

the apneustic centre and the pneumotaxic centre

Question 10

the medulla is made of two neuronal clusters, what are these?

Answer 10

DRG and VRG

Question 11

when the DRG fires it causes

Answer 11

inspiration

Question 12

when the DRG neurones cease firing it causes

Answer 12

expiration

Question 13

the DRG communicates with the

Answer 13

VRG

Question 14

The DRG is primarily

Answer 14

inspiratory neurons

Question 15

the VRG consists of

Answer 15

inspiratory and expiratory neurones

Question 16

the VRG is ____ during quiet breathing

Answer 16

inactive

Question 17

The VRG is important in

Answer 17

active expiration

Question 18

What sets the respiratory rhythm

Answer 18

the pre-Botzinger complex - the upper end of VRG

Question 19

the pre-Botzinger complex at the upper end of VRG display

Answer 19

pacemaker activity

Question 20

the synaptic input of the pre-Botzinger complex (upper end of VRG) drives the rate of firing of

Answer 20

DRG inspiratory neurones

Question 21

how many pontine centres are there

Answer 21

2

Question 22

what is the function of the pontine centres (pons)

Answer 22

fine tuning of output from primary RCC for smooth inspirations/expirations

Question 23

the pneumotaxic centre sends impulses to the

Answer 23

DRG

Question 24

when the pneumotaxic centre sends impulses to the DRG it does what?

Answer 24

switches off inspiratory neurons, limits duration of inspiration, allows expiration to occur normally

Question 25

what does the apneustic centre do?

Answer 25

stops inspiratory neurons being switched off, boots inspiratory drive

Question 26

which of the pontine centres are dominant

Answer 26

the pneumotaxic centre

Question 27

apneusis is a

Answer 27

unique pattern of breathing

Question 28

when is the Hering-Breuer Reflex triggered?

Answer 28

when the tidal volume is large, e.g. during exercise

Question 29

what does the Hering-Breuer Reflex prevent

Answer 29

over inflation of the lungs

Question 30

if the tidal volume exceeds 1litre, what happens to the pulmonary stretch receptors

Answer 30

they get activated

Question 31

when the pulmonary stretch receptors are activated what happens

Answer 31

APs travel via afferent nerves to primary RCC, inhibit inspiratory neurons, stops inspiration prevents over inflation

Question 32

the arterial blood gas content is highly regulated, how?

Answer 32

ventilation is varied to match the bodys needs

Question 33

what chemical factors increase ventilation?

Answer 33

decreased pO2, increased PCO2, increased H+

Question 34

chemoreceptors detect chemical changes, which types

Answer 34

peripheral and central

Question 35

where are the peripheral chemoreceptors?

Answer 35

carotid and aortic bodies

Question 36

the carotid and aortic bodies send afferent impulses to the

Answer 36

medullary RCC

Question 37

what is the main stimuli for peripheral (carotid and aortic bodies) to respond to

Answer 37

a decreased pO2 in arterial blood

Question 38

where are the central chemoreceptors

Answer 38

in the medulla

Question 39

why does an increased H+ have no effect on the central chemoreceptors

Answer 39

because H+ cannot penetrate BBB so not noticed

Question 40

what has the greatest effect on central chemoreceptors

Answer 40

the increased CO2 generating H+ in the brain ECF

Question 41

an increased CO2 generated H+ in the brain causes the medulla to recognise it and

Answer 41

increase ventilation

Question 42

what is the dominant control in pCO2

Answer 42

the central chemoreceptors (CO2 induced H+)

Question 43

what is the most important in regulating ventilation at rest

Answer 43

arterial pCO2

Question 44

arterial PO2 doesnt play a role in

Answer 44

normal ongoing respiration

Question 45

what are some involuntary factors that influence ventilation

Answer 45

protective (coughing/sneezing), emotional, swallowing, hiccups