The Mechanism of Breathing (lesson 2)

Question 1

Explain voluntary and involuntary breathing

Answer 1

Voluntary: Short periods where someone can control the rate and deaths of breathing

Involuntary: Medulla oblongata controls breathing

Question 2

What are the five negative feedback mechanism of breathing?

Answer 2

1) Nerve impulses, muscles contract

2) Lungs inflate

3) Inflation of lungs stop respiratory centre from sending nerve impulses

4) Muscles relax and lungs deflate

5) Nerve impulses work again, muskie contract again

Question 3

What is inspiration (breathing in)?

Answer 3

Usually active.

High CO2 and H+ levels trigger muscle contraction, expanding the chest and drawing air in lungs

Question 4

Steps in inspiration?

Answer 4

1) Brain tells the diaphragm and muscles to work

2) Diaphragm moves down, and the chest gets bigger

3) Lungs fill with air becuase pressure drops

4) Air enters the lungs from outside

5) Air reaches tiny sacs (alveoli) where gas exchange happens

Question 5

What is expiration (breathing out)?

Answer 5

Usually passive but can be active if intercostal and abdominal muscles contract to help force air

Question 6

Steps in expiration?

Answer 6

1) Brain stops telling diaphram and muscles to work, so they relax

2) Sensors notice alveoli are stretched and send a “stop” message

3) Rib cage moves down, making chest smaller

4) Air gets pushed out of lungs

Question 7

Explain the breathing movements (inhale and exhaling)?

Answer 7

Inhale:
-Ribs move UP and OUT, diaphragm moves DOWN

Exhale: Ribs move DOWN and INWARDS, diaphragm moves UP