mechanism of breathing

Question 1

what occurs during inspiration ?

Answer 1

-Phrenic nerve fires > diaphragm flattens

-intercostal nerve fires > chest wall moves up and out

Parietal pleura adhering to chestwall ->↑intrathoracic volume->↓intrathoracic pressure -> air moves from atmosphere to thorax, down
the pressure gradient -> lungs fill

Question 2

What occurs during expiration ?

Answer 2

• Phrenic nerve stops firing > diaphragm domes
• Intercostal nerve stop firing > chest wall moves down and in
• Parietal pleura adhering to chestwall->↓intrathoracic volume->↑intrathoracic pressure -> air moves from thorax to atmosphere, down the pressure gradient -> lungs empty

Question 3

what is a reflex ?

Answer 3

rapid, involuntary response to a damaging stimulus

Question 4

what do respiratory tracts contain to help with cough reflex ?

Answer 4

mechanoreceptors and chemorecptors

Question 5

during cough reflex what do mehchanorecptors and chemorecptors do ?

Answer 5

send afferent signals to vagus nerve (CN X)

Question 6

during the cough reflex what occurs when the vagus nerve is triggered ?

Answer 6

-> short inspiratory phase
-> expiratory phase (accentuated by contraction of the abdominal walls against a closed glottis)
-> foreign material expired

Question 7

what law is important when describing the mechanism of breathing ?

Answer 7

Boyles law

Question 8

explain boyles law

Answer 8

gases will travel from high pressure to low pressure