6.4 - Gas Exchange

Question 1

What is ventilation

Answer 1

Ventilation is the exchange of gases between the atmosphere and the lungs - achieved via inhalation and exhalation

Question 2

What is Gas Exchange

Answer 2

Involves the transfer of gases between lungs and the blood stream - passive diffusion between alveoli and capillaries

Question 3

What is cell respiration

Answer 3

involves the release of energy (ATP) from organic molecules - enhanced by the presence of oxygen and produces CO2 as waste

Question 4

Explain the concentration gradient in ventilation

Answer 4

A ventilation system maintains the concentration gradient needed for passive diffusion of gases.

O2 - ALVEOLI (HIGH) — CAPILLARIES(LOWER)

Co2 - CAPILLARIES(HIGH)—- ALVEOLI(LOWER)

Question 5

What is the order of how the lung exchanges gas

Answer 5

Air enters via nose or mouth
Air travels down the trachea
Trachea splits into the bronchi
Bronchi forms bronchioles
Bronchioles end in alveoli
Alveoli exchange gases with the bloodstream (capillaries)

Question 6

What are pneumocytes

Answer 6

cells that line the alveoli and comprise the inner surface of a lung

Question 7

Describe the characteristics of Type I Pneumocytes

Answer 7

they mediate gas exchange with capillaries and cover 95% of the alveolar surface. Flat & Thin to minimise diffusion distance.

Question 8

Describe the characteristics of Type II Pneumocytes

Answer 8

Secrets pulmonary surfactant which reduces surface tension in the alveoli, stops the lung from collapsing and creates moist surface inside the alveoli

cuboidal in shape and possess many granules

Question 9

What is pulmonary surfactant?

Answer 9

decreases surface tension in the alveoli

Question 10

What does pulmonary surfactant do

Answer 10

enables smaller alveoli to expand, preventing collapse of air spaces

Question 11

What is Boyle’s Law

Answer 11

When volume in thoracic activity increases, pressure decreases (gas flows in)

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Question 12

What happens during inspiration/inhalation

Answer 12

1. External intercostal muscles contract
2. Internal intercostal muscles relax
3. Diaphragm contracts
4. Abdominal muscles relax
5. Pressure in the lungs decreases while volume increases, air enters

Question 13

What happens during expiration/exhalation

Answer 13

1. Internal intercostal muscles contract
2. External intercostal muscles relax
3. Diaphragm relaxes
4. Abdominal muscles contract
5. Pressure in lungs increases while volume decreases, air escapes

Question 14

How can exercise influence ventilation patterns?

Answer 14

It can increase ventilation rate (greater frequency of breaths)
It can increase tidal volume (amount of air per breath).

Question 15

What is lung cancer?

Answer 15

The uncontrolled growth of lung cells leading to tumour formation.

Question 16

Explain emphysema and the events that lead to emphysema

Answer 16

Emphysema occurs when the alveolar walls lose elasticity. This results in the abnormal enlargement of air spaces.

A major cause of emphysema is the smoking of cigarettes.

Chemical irritants trigger damage to the alveolar. Phagocytes are recruited to lungs and secrete elastase. Elastase breaks down elastin fibres in the alveolar wall.

Question 17

What is correlated with lung cancer

Answer 17

Genetics, Radiation, Pollution, Diseases, Asbestos and Tobacco