Physiology: Control of Ventilation Flashcards Preview

System 1: Respiratory AM > Physiology: Control of Ventilation > Flashcards

Flashcards in Physiology: Control of Ventilation Deck (35)
Loading flashcards...
1

Which nerves are stimulated in ventilation?

Stimulation from skeletal muscles of inspiration - ie the phrenic nerve to the diaphragm and intercostal nerves to the external intercostal muscles

2

Where are the respiratory control centres?

Pons and the medulla

3

Is respiration subconscious?

Normally yes however can be voluntarily modulated

4

Where does signalling to the respiratory system occur on the spinal cord?

C3-5

C3,4,5 keeps the diaphragm a alive

5

What is the function of the Respiratory centres?

Set automatic rhythm by co-ordinating firing smooth and repetitive action potentials in the Dorsal Respiratory Group (DRG) which travel to the inspiratory muscles

Adjusting the rhythm to stimuli

6

What modulates the Respiratory Centres?

1. Emotion (Limbic System)
2. Voluntary Over-ride (Higher brain centres)
3. Mechano-sensory input from thorax (stretch sensitive)
4. Chemical composition of blood (chemoreceptors)

7

What is the most significant modulator of respiratory centres?

Chemoreceptor input

8

What does the Dorsal Respiratory Group of neurons (DRG) supply?

Inspiratory muscles through phrenic and intercostal nerves

9

What does the Ventral Respiratory Group of neurons (VRG) supply?

Tongue
Pharynx
Larynx
Expiratory Muscles

10

What are the 2 types of Chemoreceptors?

Peripheral (Secondary Ventilatory Control) and Central (Primary Ventilatory Control)

11

Where are the Central Chemoreceptors found?

Medulla

12

What do Central Chemoreceptors Detect?

Changes in H+ concentration in CSF of the brain

13

What does a rise of H+ ions caused by raised PCO2 ie hypercapea?

Stimulates Ventilation

14

Does Ventilation directly respond to changes H+ concentration in plasma?

No

15

Can CO2 cross the blood brain barrier?

Yes

16

Can H+ cross the blood brain barrier?

No

17

How do central chemoreceptors monitor partial arterial pressure of CO2?

The monitor PCO2 indirectly

18

What products are formed when CO2 crosses the blood brain barrier?

Bicarbonate and H+
The receptors respond to H+

19

What does increased arterial PCO2 do the ventilation?

Increases Ventilation Rate

20

What does decreased arterial PCO2 do to ventilation?

Slows Ventilation Rate

21

Define the condition Hypoxic Drive?

De-sensitivity to PCO2 and instead relys on PO2 to stimulate ventilation

22

What Disease can cause hypoxic drive?

Chronic Lung Disease due to the elevated PCO2

23

Where are the Peripheral Chemoreceptors found?

Carotid and aortic bodies

24

What do peripheral chemoreceptors detect?

Changes in arterial PO2 (ie arterial oxygen pressure not total oxygen content) and H+ concentration (related to PCO2 in arteries)

25

How do Peripheral Chemoreceptors have an effect of ventilation?

Reflex stimulation of ventilation after a fall of PO2 or rise in H+ concentration

26

How does a fall in plasma pH affect ventilation?

Peripheral chemoreceptors detect increase [H+] and ventilation will be stimulated due to acidosis

27

How does increase in plasma pH affect ventilation?

Peripheral chemoreceptors detect decrease in [H+] (through vomiting) and ventilation will be inhibited due to alkalosis

28

How can we control our breathing?

Neural pathway from cerebral cortex to Resp motor neurons allows voluntary control

29

Are we able to overide our involuntary control?

No due to our chemoreceptors take primary control

30

When is ventilation reflexly inhibited?

Increase in PO2 in arteries and decrease in arterial PCO2 causing Hyperventilation