Lecture 6 - Neural And Chemical Control Of Respiration

Question 1

What part of the brain are the neurons supplying the diaphragm and intercostal muscles found?

Answer 1

Latter 2/3s of brainstem:
-Pons
-Medulla

Question 2

Via what nerves do the neurones in the pons and medulla sent impulses to the primary respiratory muscles?

Answer 2

Phrenic nerves
Intercostal nerve

Question 3

Look at the last slide and label the ventral viewe of the brain

Answer 3

1 = frontal lobe
2 = olfactory bulb
3 = optic chiasm
4 = optic nerve
5 = optic tract
6 = midbrain
7 = pons
8 = temporal lobe
9 = medulla oblongata
10 = cerebellum
11 = spinal cord

Question 4

What are the 3 types of neurones involved in respiration?

Answer 4

Ventral group

Dorsal group

Pontine group

Question 5

What does the ventral respiratory group of neurons control in respiration?

Answer 5

Expiration

Question 6

What does the dorsal respiratory group of neurons control in respiration?

Answer 6

Inspiration

Question 7

What does the pontine respiratory group of neurons control in respiration?

Answer 7

The rate and pattern of rhythm

Question 8

What group of respiratory neurones spontaneously and continuously fire without needing sensory information?

Answer 8

Dorsal respiratory group neurons

Question 9

What are the 2 groups of neurones that make up the Pontine Respiratory group?

Answer 9

Pneumotaxic center
Apneustic center

Question 10

What is the function of the Pneumotaxic centre in the Pontine respiratory group of neurones?

Answer 10

Limits inspiration by restricting Action potential transmission in the phrenic nerve

Question 11

What is the function of the Apneustic centre in the Pontine respiratory group of neurones?

Answer 11

Promotes inhalation by constantly sending signals to the medulla (dorsal group) delaying the inspiratory off switch

Controls the intensity of breathing

Question 12

What inhibits the Apneustic centre?

Answer 12

Pulmonary stretch receptors

Pneumotaxic center

Question 13

What part of the brain is responsible for voluntary breathing?

Answer 13

Motor cortex in the cerebrum

Question 14

What are the 2 types of chemoreceptors?

Answer 14

Peripheral chemoreceptors

Central chemoreceptors

Question 15

Where are peripheral chemoreceptors located?

Answer 15

Aortic bodies

Carotid bodies

Question 16

What nerve does the peripheral chemoreceptors in the aortic body send impulses down?

Answer 16

Via Vagus Nerve (Cranial nerve X)

Question 17

What nerve does the peripheral chemoreceptors in the carotid body send impulses down?

Answer 17

Via Glossopharyngeal nerve (Cranial nerve IX)

Question 18

What do peripheral chemoreceptors detect?

Answer 18

Changes in partial pressure of Oxygen (pO2)

Question 19

What happens when peripheral chemoreceptors detect low levels of oxygen?

Answer 19

Respiratory rate and tidal volume increased

Blood flow directed to kidneys and brain

CO increased

Question 20

What type of cells are found in peripheral receptors?

Answer 20

Glomus

Question 21

What happens to the carotid body glomus cells are exposed to a low partial pressure of oxygen?

Answer 21

Membrane depolarises

Stimulates neurotransmitter and ATP release activates nerves (CNIX) and sends signals to CNS + stimulating respiration

Question 22

How does the nerve firing rate from carotid body nerves change as arterial paO2 increases and why?

Answer 22

Decreased impulses since respiration does need to be stimulated anymore

Question 23

What is the speed of the response from the peripheral chemoreceptors?

Answer 23

First chemoreceptor to respond (rapidly respond)

Question 24

What do peripheral chemoreceptors detect?

Answer 24

Changes in partial pressures of oxygen

Question 25

What do central chemoreceptors detect?

Answer 25

Changes in partial pressures of CO2 Cant detect Hypoxaemia

Question 26

Where are central chemoreceptors located?

Answer 26

Brain side of the Blood Brain Barrier

Question 27

What is the response to a sudden increase in pCO2?

Answer 27

Ventilation rapidly increases

Question 28

What part of the brain are central chemoreceptors in?

Answer 28

Medulla in brainstem

Question 29

How does changes in pCO2 affect pH of the CSF?

Answer 29

Small decrease in pCO2 leads to inc in PH of CSF which causes the resp centre to decrease its ventilation (less CO2 needs to be lost) Small inc in pCO2 leads to dec in pH of CSF so resp centres inc vent rate

Question 30

What is the response to chronic hypercapnia when detected be central chemoreceptors?

Answer 30

Choroid plexus increases activate transport of HCO3- into the CSF

Question 31

What is the effect of stimulating stretch receptors in the smooth in the airways due to excessive stretching in the lungs during large inspirations?

Answer 31

Slows resp freq by increasing expiratory time

Question 32

What happens to CO2 levels in hypoventilation? PH?

Answer 32

Hypercapnia since removal of CO is less than its production The higher pCO2 leads to respiratory acidosis

Question 33

How does the body respond to low pH (respiratory acidosis)?

Answer 33

Kidneys reduce excretion of HCO3-

Question 34

What happens to pCO2 and pH with hyperventilation?

Answer 34

Removal of CO2 is more rapid than its production PH rises (Respiratory alkalosis)