Human respiratory system

Question 1

List the structures air passes through to reach the alveoli

Answer 1

Nostrils
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli

Question 2

Features of the larynx

Answer 2

Contains vocal cords

Question 2

What are the trachea and bronchi lined with

Answer 2

Gland cells: Secrete mucus that traps dust and bacteria

Ciliated cells: Have hair-like structures called cilia that sweep dust-filled mucus to the pharynx to be expelled

Question 3

Features of the trachea

Answer 3

Supported by C-shaped rings of cartilage that prevent the collapse of the tube

Question 3

What allows for breathing to occur

Answer 3

Movement of ribs and diaphragm to change the volume of chest cavity

Question 4

Which muscles are antagonistic

Answer 4

Internal intercostal muscles
External intercostal muscles

Question 5

What happens during inhalation

Answer 5

• Diaphragm contracts and flattens
• External intercostal muscles contract
• Internal intercostal muscles relax
• Ribcage moves upwards and outwards
• Lung volume increases
• Lung pressure decreases
• Air enters from higher atmospheric pressure to lower lung pressure

Question 6

What happens during exhalation

Answer 6

• Diaphragm relaxes and arches upwards
• External intercostal muscles relax
• Internal intercostal muscles contract
• Ribcage moves downwards and inwards
• Lung volume decreases
• Lung pressure increases
• Air expelled out from higher lung pressure to lower atmospheric pressure

Question 7

Explain adaptations of alveoli

Answer 7

1) One cell thick alveolar walls
- Provides shorter distance for faster rate of diffusion of gases

2) Thin film of moisture on inner alveolar walls
- Allows gases to dissolve in the moisture for faster rate of diffusion

3) Surrounded by numerous blood capillaries
- Continuous transport of gases maintains steep concentration gradient

4) Present in large quantities
- Provides larger SA:V for faster rate of diffusion

Question 8

Describe oxygen transport from lungs

Answer 8

• Alveolar air contains higher oxygen concentration than blood
• Oxygen dissolves in thin film of moisture on inner alveolar walls
• Dissolved oxygen diffuses through alveolar walls and through blood capillaries into the blood
• Oxygen diffuses into red blood cells
• Oxygen binds with haemoglobin to form oxyhaemoglobin
• Reaction is reversible and direction of reaction depends on oxygen concentration
• Oxyhaemoglobin releases oxygen when blood passes through oxygen-poor tissue

Question 9

Describe carbon dioxide transport from body cells

Answer 9

• Carbon dioxide diffuses into blood from tissue
• Most carbon dioxide enters red blood cells
• Some carbon dioxide is carried in plasma as dissolved carbon dioxide
• Carbon dioxide reacts with water in cytoplasm of red blood cell to form carbonic acid, and this reaction is catalysed by carbonic anhydrase
• Carbonic dissociates to form hydrogen and hydrogencarbonate ions
• Hydrogen ions remain in red blood cell
• Hydrogencarbonate ions diffuse out of red blood cell to be carried in plasma

Question 10

Describe carbon dioxide transport at lungs

Answer 10

• Hydrogencarbonate ions diffuse back into red blood cells
• Hydrogen and hydrogencarbonate ions combine to form carbonic acid
• Carbonic anhydrase catalyses conversion of carbonic acid to carbon dioxide and water
• Carbon dioxide diffuses out of red blood cell, into blood, through blood capillaries and alveolar walls

Question 11

What is the stimulus for breathing

Answer 11

Stimulus for breathing is a high concentration of carbon dioxide in blood or alveolar air

Question 12

Describe components of inhaled air

Answer 12

• 21% O2
• 0.03% CO2
• 78% N2

Question 13

Describe components of exhaled air

Answer 13

• 16% O2
• 4% CO2
• 78% N2
• High water vapour concentration
• Around 37 degrees Celsius

Question 14

What are some harmful components of tobacco smoke

Answer 14

• Nicotine
• Carbon monoxide
• Tar
• Irritant chemicals

Question 14

What are the properties and effects of nicotine

Answer 14

• Addictive stimulant drug that causes release of adrenaline
• Makes blood clot easily
• Increases heart rate and blood pressure
• Increases risk of blood clots in arteries that can lead to coronary heart disease

Question 15

What are the properties and effects of carbon monoxide

Answer 15

• Combines permanently with haemoglobin to form carboxyhaemoglobin
• Reduces ability of blood to carry oxygen

Question 16

What are the properties and effects of tar

Answer 16

• Carcinogenic
• Paralyses cilia lining air passages
• Increases risk of lung cancer
• Dust trapped in mucus along air passages cannot be removed due to paralysed cilia, increasing risk of chronic bronchitis and emphysema

Question 16

What are the properties and effects of irritant chemicals

Answer 16

• Causes gland cells to secrete more mucus
• Paralyses cilia lining air passages
• Dust trapped in mucus along air passages cannot be removed, increasing risk of chronic bronchitis and emphysema

Question 17

Explain chronic bronchitis

Answer 17

• Prolonged exposure to irritant particles can cause chronic bronchitis
• Epithelium lining of airways becomes inflamed
• Epithelium produces excessive mucus
• Cilia lining air passages become paralysed, unable to remove mucus
• Airflow becomes blocked, making breathing difficult
• Efficiency of gaseous exchange decreases
• Persistent coughing occurs to clear airways

Question 18

Explain emphysema

Answer 18

• Persistent and violent coughing from chronic bronchitis may lead to emphysema
• Alveolar walls break down, decreasing surface area for gaseous exchange
• Lungs lose elasticity and ability to expel air
• Build up of carbon dioxide in lungs occurs
• Severe breathlessness experienced

Question 19

What is it called when someone suffers from both chronic bronchitis and emphysema

Answer 19

Chronic obstructive lung disease