Chap 7) Respiration In Humans

Question 1

Function of larynx in gaseous exchange

Answer 1

Let’s air pass from the pharynx down to the trachea & into the lungs

Question 2

Function of trachea in gaseous exchange

Answer 2

The Trachea is supported by C-shaped rings of cartilage. The cartilage keeps the lumen of the trachea open. The membrane next to the lumen is the epithelium, which contains gland cells & ciliated cells.

Question 3

Function of bronchi & bronchioles in gaseous exchange

Answer 3

Each bronchus carries air into the lung.
Each bronchus branches repeatedly, giving rise to the numerous bronchioles.
Bronchioles are very fine tubes. Each bronchiole ends in a cluster of air sacs or alveoli

Question 4

Function of Alveoli in gaseous exchange

Answer 4

Gaseous exchange takes place through the walls of the alveoli.

Question 5

State the characteristics of the alveoli

Answer 5

Alveolar walls are very thin, moist & well supplied with blood capillaries.
Gas exchange between the alveoli & the blood capillaries takes place through the walls of the alveoli.
Alveolar walls are 1 cell thick, short diffusion distance
Alveolar cavity is surrounded by a thin film of moisture, oxygen dissolves in it to facilitate diffusion of gases.
Numerous alveoli, increases surface area to volume ratio, increases rate of diffusion.

Question 6

Describe the role of, the exchange surface area of alveoli in gaseous exchange

Answer 6

Gas exchange in the lungs occurs by diffusion.
Blood entering the lungs has a lower concentration of oxygen & a higher concentration of carbon dioxide than the atmospheric air entering the alveoli in the lungs.
A concentration gradient for oxygen & carbon dioxide is set up between blood & alveolar air.
- oxygen dissolved into the thin film of moisture on the walls of the alveolus.
- the dissolved oxygen then diffuses through the wall of the alveolus & the wall of the blood capillary into the red blood cells.
- the oxygen combines with haemoglobin to form oxyhemoglobin.
- carbon dioxide diffuses from the blood into the alveolar air.