Mammalian Gas Exchange System

Question 1

Describe features of the nasal cavity

Answer 1

-Hairy lining, secretes mucus to trap dust and bacteria, protecting delicate lung tissue from irritation and infection.

-Moist surfaces, which increase the humidity of the incoming air, reducing evaporation from the exchange surfaces.

-Large SA and good blood supply- heats air.

Question 2

Describe the trachea

Answer 2

-Main airway carrying clean, warm, moist air from the nose down into the chest.

-Wide tube supported by incomplete rings of strong, flexible cartilage, stops trachea collapsing. Rings are incomplete so that food can move easily down the oesophagus behind the trachea.

Question 3

What’s the trachea and it’s branches lined with

Answer 3

-Ciliated epithiulium, with goblet cells between and below the epithelial cells.

-Goblet cells secrete mucus onto lining of trachea, to trap dust and microorganisms that have escaped the nose lining.

-The cilia beat and move mucus , away from lungs, into throat- swallowed and digested.

Question 4

Describe bronchioles

Answer 4

Bronchi divide to form bronchioles- have no cartilage rings- walls contain small muscle-contracts- bronchioles constrict (close up), relaxes- bronchioles dilate (open up). Changes amount of air reaching lungs. Bronchioles lined with a thin layer of flattened epithelium, making some gaseous exchange possible.

Question 5

Describe alveoli

Answer 5

Tiny air sacs, which are the main gas exchange surface of the body. Consists of a layer of thin, flattened epithelial cells, along with some collagen and elastic fibres. These elastic tissue allow the alveoli to stretch as air is drawn in. When they return to their resting size, they help squeeze the air out- elastic recoil of lungs.