The Respiratory System

Question 1

What happens during inhalation?

Answer 1

• The diaphragm contracts (flattens)
• External intercostal muscles contract
• Rib cage moves out and upwards
• Chest cavity enlarges
• Lungs expand
• Pressure inside decrease
• Air rushes into lungs to equalise pressure

Question 2

What happens during exhalation?

Answer 2

• Diaphragm relaxes (moves upward)
• Internal intercostal muscles contract
• Rib cage moves down and inwards
• Volume of chest cage decreases
• Lung volume decreases
• Pressure inside lungs increases
• Air passively flows out of lungs due to pressure

Question 3

Tidal volume

Answer 3

Volume of air breathed in and out in a single breathing cycle

Question 4

Approximate tidal volume

Answer 4

0.5 litres

Question 5

Inspiratory reserve volume

Answer 5

Volume when breathing in as deeply as possible

Question 6

Approximate inspiratory reserve volume

Answer 6

2 litres

Question 7

Exploratory reserve volume

Answer 7

Volume when breathing as forcibly as possible

Question 8

Approx exploratory reserve volume

Answer 8

1.5 litres

Question 9

Residual volume

Answer 9

Air remaining in lungs after maximal exhalation

Question 10

Approximate residual volume

Answer 10

1.5 litres

Question 11

Vital capacity

Answer 11

The maximum amount of air that can be moved into and out of the lungs in one breath

Question 12

Approximate vital capacity

Answer 12

4 litres

Question 13

Short term effects of exercise on ventilation

Answer 13

• Taking more breaths (increase in ventilation rate)
• Deeper breaths (increase in tidal volume)
-> respiration, more oxygen in

Question 14

Long term effects of exercise on ventilation

Answer 14

• Increase in lung volume

-> respiration, more oxygen in

Question 15

What effects does tar have on the human body?

Answer 15

• Lung cancer - tar contains carcinogens (substances that can cause cancer)
• Emphysema - chemicals in tar damage alveoli (decreased SA/V ratio)
• Lung infections, bronchitis
- cilia in bronchi(oles) get paralysed
- build up of mucus
- debris in lungs not removed
- build up of bacteria

Question 16

What effects does nicotine have on the human body?

Answer 16

• Addictive substance in cigarettes - stimulates neurotransmitters in brain leading to heightened activity
• Strokes and heart attacks
- constricts arteries reducing blood flow
- fat deposited in blood vessels
- increased blood pressure

Question 17

What effects does carbon monoxide have on the human body?

Answer 17

• Tiredness, dizziness, increased heart rate
- binds irreversibly to haemoglobin
- reduces oxygen-carrying ability of red blood cells
• reduced birth mass - foetus gets less oxygen

Question 18

What is the function of the respiratory system?

Answer 18

Gas exchange

• intake of oxygen (for respiration)
• release of carbon dioxide (waste product)

Question 19

Adaptations of the respiratory system for efficient gas exchange

Answer 19

• Large SA/V ratio - making diffusion efficient.
• Higher concentration gradient (breathing in makes the concentration of oxygen high and constant blood flow also does this).
• Short diffusion distance (walls of the alveoli are very thin, as are the walls of the capillary).
• Lots of moisture helps gases to dissolve.
• Surfactant keeps bubbles inflated and prevents the alveoli from collapsing.