breathing mechanism

Question 1

What does pulmonary surfactant do??

Answer 1

It facilitates lung expansion by reducing water surface tension in the alveoli, prevent the alveoli from collapsing and reduces the energy required to expand the lungs.

Question 2

Pulmonary surfactant is secreted by

Answer 2

type II alveolar cells

Question 3

structural characteristic and function of Type I alveolar cells

Answer 3

-consist of simple squamous epithelial cells
- the walls are one cell thick
- forms a thin barrier which facilitates gas exchange between alveoli and blood capiliries.

Question 4

Descibe alveolar macrophages

Answer 4

• found within the alveolar lumen
  -engulf foreign particles such as dust particles and bacteria, keep the alveolar surface clean.

Question 5

What is the function of collagen and elastic fibres between the alveolar cells?

Answer 5

allow the alvoeli to expand during inhalation and recoil easily during exhalation.

Question 6

function of alveolar pores

Answer 6

allow collateral ventilation in which air flow between the adjacent alveoli.
- This provides alternative route if obstruction occurs.

Question 7

Breathing mechanism in humans include…..

Answer 7

mouth, nose, pharynx, larnyx , tranchea, bronchi, bronchioles and alveoli.

Question 8

Adaptation of alveoli for gaseous exchange

Answer 8

1. the alveoli wall is thin and permeable to respiratory gases.
2. The surface of alveoli is moist
3. millions of alveoli
4. the alveolus wall is elastic
5. the alveoli are surrounded by a dense network of blodd capillaries.
6. short distance between alveoli and blood capillaries
7. a steep concentration gradient

Question 9

explantion for the adaptation: alveolus wall is thin and permeable to respiratory gases. & the surface of the alveoli is moist

Answer 9

about 0.001 thick , the gas diffuses through alveolar wall fast and easily.
&
respiratory gases can dissolve in the water before diffusion can occur.

Question 10

A steep concentration gradient

Answer 10

• breathing brings supplies of fresh air into the lunggs, with a high O2 concentration and low CO2 concentration.
• Blood is transported to lungs with low concentration of O2 and a higher concentration of CO2.
• O2 diffuses down its