Semester 2; L4 - The control of respiration

Question 1

what are the three examples of patterns of forced expiration?

Answer 1

Normal
Obstructive
Restrictive

Question 2

what parts of the brain are responsible for respiratory system?

Answer 2

sphenoidal air sinus
pituitary body
pons
medulla oblogata

Question 3

what is the main function of central and peripheral chemoreceptors?

Answer 3

regulate respiratory activity

Question 4

Where are central chemoreceptors located?

Answer 4

in the medulla

Question 5

what can central chemoreceptors maintain?

Answer 5

pH

arterial blood pO2, pCO2

Question 6

Can a change in pH alone stimulate central chemoreceptors?

Answer 6

no

Question 7

Where are peripheral receptors located?

Answer 7

cardiac and aortic bodies

Question 8

What are the functions of peripheral receptors?

Answer 8

response to changes in blood molecule concentrations

helps to maintain cardiorespiratory homeostasis

Question 9

What stimulates the peripheral chemoreceptors?

Answer 9

The firing will be stimulated by a reduction in PaO2

The reduction may be caused by lack of pH or increase of CO2

Question 10

What does the firing of those neurones from peripheral chemoreceptors result in?

Answer 10

Stimulates medullary respiratory neurones

Increased firing of motor neurones to respiratory muscles (principally diaphragm and ext. intercostals)

Increased ventilation

Question 11

What stimulates the central chemoreceptors?

Answer 11

an increase in PaCO2, csf PaO2, and a reduction of pH stimulates firing of neurones

Question 12

What does the firing of those neurones from central chemoreceptors result in?

Answer 12

Stimulates medullary respiratory neurones

Increased firing of motor neurones to respiratory muscles (principally diaphragm and ext. intercostals)

Increased ventilation

Question 13

What is oxyhemoglobin dissociation curve?

Answer 13

relates oxygen saturation (SO2) and partial pressure of oxygen in the blood (PO2)

Question 14

What is oxyhemoglobin dissociation curve determined by?

Answer 14

hemoglobin’s affinity for oxygen

Question 15

What is hemoglobin’s affinity for oxygen?

Answer 15

how readily hemoglobin acquires and releases oxygen molecules from its surrounding tissue

Question 16

What is hypercapnia?

Answer 16

A condition of abnormally elevated carbon dioxide (CO2) levels in the blood

Question 17

How does hypercapnia stimulate the central chemoreceptors?

Answer 17

This is due to CO2s ability to easily diffuse across the blood-brain barrier
The build up of CO2 in the csf, stimulates the central chemoreceptors to fire

Question 18

Why is pH buffering lower in CSF than in blood?

Answer 18

Due to much lower protein content

Question 19

what is hypoxia?

Answer 19

the oxygen pressure in the blood going to the tissues is too low to saturate the hemoglobin

Question 20

In the carotid body, what do the Peripheral chemoreceptors react when hypoxia occurs?

Answer 20

They release neurotransmitters onto the carotid sinus nerve, which branches on to the glossopharyngeal nerve

The glossopharyngeal nerve connects to the brain stem, in which alerts the respiratory centres.

Question 21

What are the pontine respiratory group (PRG) important for?

Answer 21

Important in regulating inspiration time

Damage here causes long inspiration time

Question 22

What are the Dorsal respiratory group (DRG) important for?

Answer 22

Primarily inspiratory, connect to contralateral phrenic nerve motor neurones

Question 23

What are the ventral respiratory group (VRG) important for?

Answer 23

Both inspiratory and expiratory, connect to respiratory motor neurones or to DRG

Question 24

what does the central respiratory rhythm generator consist of?

Answer 24

Dorsal Respiratory Neurons and Ventral Respiratory Neurons

when one is active, the other is dormant

Question 25

What does the central respiratory rhythm generator stimulate?

Answer 25

lower respiratory neurones, which in turn stimulate phrenic and intercostal nerves

Which eventually stimulate the respiratory muscles

Question 26

What pattern does inspiration incur on a graph?

Answer 26

a ramp,

activity intensifies, however when expiration occurs the activity stops.

Question 27

Why is it harder to breathe at a high altitude?

Answer 27

the atmospheric pressure is much less

And the total O2 content in the atmosphere is reduced at higher levels

Question 28

What happens to the body at a high altitude?

Answer 28

Driven by low alveolar PO2 (NB: at low total barometric pressure, PO2 is still ~20%)
↑Ventilation allows the body to expel more CO2
This causes CSF pH to rise (initially)
As HCO3 is transported out of CSF pH falls
Stimulates ventilation (in addition to hypoxic drive)