initiation and control of breathing

Question 1

what initiates breathing?

Answer 1

Respiratory Centres

Question 2

what are the 3 groups of neurones that send impulses to the respiratory muscles?

Answer 2

• Medullary rhythmicity area
• Pneumotaxic Centre
• Apneustic centres

Question 3

what are inspiratory group nuclei predominantly called

Answer 3

Dorsal respiratory group

Question 4

what is contained in the ventral respiratory group

Answer 4

both inspiratory and expiratory nuclei

Question 5

when is the dorsal respiratory group used?

Answer 5

in basic breathing

Question 6

when is the ventral respiratory group used

Answer 6

during forced breathing like exercise

Question 7

what neurones are inhibited when you are inspiring

Answer 7

the expiratory neurones

Question 8

what neurones are inhibited when you are expiring

Answer 8

the inspiratory neurones

Question 9

where is medullary rhythmicity found

Answer 9

medulla oblongata

Question 10

where is pneumotaxic centre and apneustic centres found?

Answer 10

in the Pons

Question 11

what does the pneumotaxic centre do

Answer 11

helps smooth the inspiration and expiration cycle

Question 12

at does the Apneustic centers do?

Answer 12

Modulates aspects of the breathing cycle (eg gasping)

Question 13

what is 3 things is respiratory control needed for

Answer 13

1. to maintain homeostasis
2. to maximise mechanical efficiency
3. to adapt to needs

Question 14

outline the 4 stages of negative feedback to the central controllers in breathing and state the location of each stage

Answer 14

1. Cortical control (cortex)
2. brainstem control ( Pons and Medulla)
3. ventilatory pump (respiratory muscles)
4. Sensors ( Chemoreceptors and Mechanoreceptors)

Question 15

outline the 4 stages of negative feedback to the central controllers in breathing and state the location of each stage

Answer 15

1. Cortical control (cortex)
2. brainstem control ( Pons and Medulla)
3. ventilatory pump (respiratory muscles)
4. Sensors ( Chemoreceptors and Mechanoreceptors)

Question 16

what 2 things can alter basic respiratory rhythm

Answer 16

1. higher centres
2. Baroreceptors, thermoreceptors, mechanoreceptors etc

Question 17

what are the 2 higher centres that can alter basic respiratory rhythm

Answer 17

1. Cerebral Cortex
2. Hypothalamus & limbic system

Question 18

how does the 1.cerebral cortex and 2.hypothalamus & limbic system change basic respiratory rhythm

Answer 18

1. Cerebral cortex: voluntarily changes breathing patterns are overridden by stimuli of increased arterial [H+] and [CO2]
2. Hypothalamus & limbic system: due to emotional changes

Question 19

what are the 2 types of chemoreceptors in breathing

Answer 19

1. peripheral chemoreceptors
2. Central chemoreceptors

Question 20

where are peripheral chemoreceptors found

Answer 20

• Carotid and aortic bodies in the carotid arteries and the aortic arch respectively

Question 21

where are central chemoreceptors found

Answer 21

in the medulla of the brain

Question 22

where do peripheral chemoreceptors lie close to

Answer 22

close to carotid sinus & aortic baroreceptors

Question 23

what is another name for peripheral chemoreceptors?

Answer 23

carotid or aortic bodies (depending on where they are located)

Question 24

outline what happens when carotid or aortic bodies are triggered

Answer 24

1. action potential is sent up the glossopharyngeal nerve (for carotid bodies) or the vagus nerve (for aortic bodies)
2. action potential goes up to the Dorsal respiratory group in the medulla oblongata
3. medulla oblongata send signals down to your respiratory muscles, causing you to breathe.

Question 25

what is another name for the glossopharyngeal nerve

Answer 25

cranial nerve 9

Question 26

what does an increased amount of carotid bodies stimulated result in

Answer 26

it results in increased speed of action potentials propagated into the medulla oblongata

Question 27

what is another name for the vagus nerve

Answer 27

cranial nerve 10

Question 28

what do 3 things do carotid and aortic bodies respond to?

Answer 28

1. to decreased PaO2 2. more sensitive to changes in arterial pH 3. Elicit 20% response to PaCO2 before central chemoreceptors take over

Question 29

what type of peripheral chemoreceptor is mainly involved in the response to decreased PaCO2

Answer 29

carotid bodies

Question 30

if you have a state of acidosis (increased H+), do you have a bigger or smaller response to breathing than if you have alkalosis?

Answer 30

Bigger response

Question 31

what is hypercapnia

Answer 31

increase in PaCO2

Question 32

what type of bodies exert the predominant, immediate effect on ventilation

Answer 32

carotid bodies

Question 33

what type of bodies have more of an effect on the Cardio-Vascular system?

Answer 33

aortic bodies

Question 34

where are central chemoreceptors located?

Answer 34

they are located close to respiratory centres in the ventral lateral medulla in the medulla oblongata

Question 35

what elicit the main ventilatory change caused by hypercapnia

Answer 35

central chemoreceptors

Question 36

what are central chemoreceptors completely insensitive to?

Answer 36

- Hypoxia (not enough oxygen in tissues)

Question 37

how the central chemoreceptors response to changes in PaCO2 manifested?

Answer 37

manifested as changes in Cerebrospinal fluid pH caused by CO2 being hydrated after it passes the blood brain barrier.

Question 38

why do acid and base changes in the blood not affect central chemoreceptors?

Answer 38

because free protons cannot cross the blood brain barrier

Question 39

outline the mechanism for triggering central chemoreceptors

Answer 39

1. CO2 diffuses across the blood brain barrier because it is lipid soluble 2. CO2 gets into the cerebrospinal fluid, which contains carbonic anhydrase. 3. carbonic anhydrase catalyses the reaction between CO2 and H20 (this is hydration), turning it into carbonic acid (H2CO3) 4. Carbonic acid is quickly turned into H+ and HCO3- (bicarbonate ion) 5. The increase in H+ ions via this mechanism triggers central chemoreceptors.

Question 40

what does less buffers present in the brain mean

Answer 40

means a great pH change

Question 41

what is it called when chemoreceptors work together when you have hypoxia and hypercapnia?

Answer 41

it is called a synergistic effect