Gas exchange & ventilation in humans

Question 1

In order, name the structures involved in gas exchange in humans

Answer 1

Trachea → bronchi → bronchioles → alveoli

Question 2

Ciliated epithelium is located in the respiratory system. What two cells does this epithelium consist of and what are their functions?

Answer 2

Goblet cells - Produce and secrete mucus that traps dust and microbes
Ciliated epithelial cells - Wafts the mucus by their cilia upwards to the mouth to be swallowed

Question 3

Name 2 adaptations of the trachea and state the function of these adaptations

Answer 3

C shaped rings of cartilage - keeps the airway open & prevents collapsing

Lined with ciliated epithelial cells and goblet cells - Protects against inhaled particles & pathogens

Question 4

How does the alveoli carry out gas exchange?

Answer 4

• Oxygen diffuses across the alveolar epithelium into the capillaries
• Carbon dioxide dissociates from haemoglobin and diffuses from the blood into the alveoli

Question 5

Name 4 adaptations of the alveoli for gas exchange and state the function of these adaptations

Answer 5

Consists of one layer of sqamous epithelial cells - allows for rapid diffusion

Large surface area - increases rate of gas exchange

Surrounded by network of capillaries - brings blood close to alveoli for gas exchange

Moist inner surface - allows gases to dissolve

Question 6

What is ventilation?

Answer 6

The movement of air into and out of the lungs, providing the body with oxygen and removing carbon dioxide

Question 7

What are the 3 main muscles involved in ventilation?

Answer 7

• The diaphram
• The external intercostal muscles
• The internal intercostal muscles

Question 8

What effect does the diaphram have on the ribcage when it contracts?

Answer 8

Moves the ribcage up and out

Question 9

What effect does the external intercostal muscles have on the ribcage when it contracts?

Answer 9

Moves the ribcage up and out

Question 10

What effect does the internal intercostal muscles have on the ribcage when it contracts?

Answer 10

Pulls the ribcage down and in

Question 11

Is inhalation an active or a passive process?

Answer 11

Active as it requires energy for muscle contraction

Question 12

Describe the mechanism of inhalation at rest

Answer 12

• The diaphram contracts and moves in the downwards direction
• The external intercostal muscles contract , moving the ribcage up and out
• This increases the volume and decreases the pressure of the thoracic cavity
• This creates a pressure gradient between the atmosphere and the alveolus
• Air flows into the lungs down this pressure gradient in the alveolus

Question 13

Is exhalation an active or passive process?

Answer 13

Passive as no energy is required unless exhalation is forced

Question 14

Describe the mechanism of exhalation at rest

Answer 14

• The diaphram relaxes and moves in the upwards direction
• The internal intercostal muscles contracts, moving the ribcage down and in
• This decreases the volume and increases the pressure of the thoracic cavity
• This creates a pressure gradient between the alveolus and the atmosphere which results in the movement of air down the pressure gradient into the atmosphere