Control Of Ventilation

Question 1

What’s reflexes are included as into the cycle of breathing

Answer 1

Chemoreceptors
- arterial and central

Lungs

Airways

Cardio system

Muscles/joints

Skin

Question 2

What is response for setting the basic unconscious rhythm of breathing?

Answer 2

The central pattern generator in the medulla
- takes readings from the chemoreceptors and sensory input from cranial nerves to generate breathing in respiratory muscles

Question 3

What does the peripheral chemoreceptors do?

Answer 3

Found in CN 10 and 9

Take readings from Partial pressures of CO2/o2 and pH. Uses thes readings to relay information back to the central pattern generator and allows it to either speed up or slow down breathing

note the central chemoreceptors in the brain also function to regulate the pattern generator, however they are only sensitive to CO2 and pH

Question 4

Vagal and phrenic effects on lung inhalation/exhalation (Hering-Breuer reflex)

Answer 4

Phrenic nerve is stimulated to contract diaphragm and allow lungs to inflate.

Before lungs reach max inflation, pulmonary stretch receptors are activated and use vagus nerve to send signals to the medulla inspiratory area. This turns off the inspiratory center and turns the phrenic nerve activity
- prevents the lungs from being overinflated naturally

Question 5

Where is the central hub for breathing located in the human body?

Answer 5

Medulla

- primarily DRG and nucleus tractus solitarius

Question 6

DRG

Answer 6

Dorsal respiratory group of neurons that control inspiration only with control of the phrenic nerve

Question 7

What is the pons affect one breathing?

Answer 7

Modulates breathing but is not essential for breathing

- no pons causes extended inspiration since it contains the apneustic center

Question 8

Apneustic center vs pneumotaxic center

Answer 8

Apneustic:
- promotes inspiration

Pneumotaxic:
- inhibts inspiration

Both are found in the pons

Question 9

Difference between DRG and VRG

Answer 9

DRG:
- contains only inspiratory neruons

VRG:
- contains both inspiratory and Expiratory neurons

Question 10

What is the most important chemical associated with establishing ventilation?

Answer 10

Partial pressure of CO2

There is a direct relationship between PCO2 and ventilation rates

Question 11

What happens to the ventilation centers when hypoxia is introduced?

Answer 11

Resting alveolar ventilation is naturally increased

Also, the ventilation rate is even more sensitive/ increases the relationship even more to PCO2 levels

Question 12

What do peripheral chemoreceptors respond to?

Carotid And aortic bodies

Answer 12

Hypoxia, hypercapnia and metabolic/respiratory acidosis

Question 13

The glomus cell

Answer 13

The chemo sensor cell inside the peripheral chemoreceptors

In response to hypoxia, hypercapnia and acidosis:

• inhibits K+ channels
• raises intracellular calcium
• releases neurotransmitters

Question 14

General step by step response in glomus cells

Answer 14

1) oxygen goes down
2) CO2 goes up and pH goes down
3) activates H+ channels and inhibits sodium channels
4) inhibits potassium channels
5) increases intracellular calcium
6) releases neurotransmitters to the glossopharyngeal nerve

Question 15

Central chemoreceptors

Answer 15

Take inputs from cerebral spinal fluid and secondary responses from peripheral chemoreceptors

• DOESNT contact the blood so doesn’t directly read blood
• really only directly pays attention to CO2 since it is the only molecule in blood that can pass the BBB