2. Gas exchange in mammals

Question 1

What are the gas exchange organs in mammals? & what does it do?

Answer 1

Lungs, they help to get oxygen into the bloods (for respiration) and to get rid of carbon dioxide (mainly made by respiring cells) from the body

Question 2

What happens as your breath in?

Answer 2

As you breath in, air enters the trachea (windpipe) which then splits into two bronchi - one bronchus leading to each lungs. The bronchus then branch into smaller tubes called bronchioles. The bronchioles end in small ‘air sas’ called alveoli. There are lots of alveoli in the lungs to provide a large surface area for diffusion. The ribcage, intercostal muscle and diaphragm all work together to move air in and out.

Question 3

Role of goblet cells

Answer 3

Goblet cells (lining the airways) secrete mucus and traps microorganism or dust particles in the inhaled air , stopping them from reaching the alveoli

Question 4

Role of cilia

Answer 4

The cilia are hair like structures on the surface of epithelial cells lining the airways. They beat the mucus secreted by the goblet cells. This moves the mucus (plus the trapped microorganism and dust) upward away from the alveoli towards the throat, where its swallowed. This helps prevent lungs infections.

Question 5

Role of elastic fibres

Answer 5

Elastic fibres in the walls of the trachea, bronchi, bronchioles and alveoli help the process of breathing out. On breathing in, the lungs inflate and the elastic fibres are stretched. Then, the fibres recoil to help push the air out when exhaling.

Question 6

Role of smooth muscle

Answer 6

Smooth muscle in the walls of the trachea, bronchi and bronchioles (except the smallest bronchioles) allow their diameter to be controlled. During exercise the smooth muscle relaxes, making the tubes wider. This means theres less resistance to airflow and air can move in and out of the lungs more easily.

Question 7

Role of cartilage

Answer 7

Rings of cartilage in the walls of the trachea and bronchi provide supports. Its strong but flexible - it stops the trachea and bronchi collapsing when you breath in and the pressure drops.

Question 8

Structure of Trachea

Answer 8

a

Question 9

Structure of Bronchus

Answer 9

a

Question 10

Structure of bronchiole

Answer 10

s

Question 11

Structure of alveolus

Answer 11

a

Question 12

Hows the cartilage in 
> Trachea
> Bronchi
> Alveoli 
> Bronchiole

Answer 12

Trachea - large c -shaped pieces
Bronchi - smaller pieces
Bronchiole - none
Alveoli - none

Question 13

Is smooth muscle present in
> Trachea
> Bronchi
> Alveoli 
> Bronchiole

Answer 13

> Trachea - yes
Bronchi - yes
Alveoli -no
Bronchiole - yes (larger and smaller) no ( smallest)

Question 14

Is elastic fibres present in 
> Trachea
> Bronchi
> Alveoli 
> Bronchiole

Answer 14

yes for all of them

Question 15

Are goblet cells present in
> Trachea
> Bronchi
> Alveoli 
> Bronchiole

Answer 15

> Trachea - yes
Bronchi - yes
Alveoli - no
Bronchiole yes (Larger) no (smaller & smallest)

Question 16

Hows the epithelium in
> Trachea
> Bronchi
> Alveoli 
> Bronchiole

Answer 16

> Trachea - Ciliated
Bronchi - Ciliated
Alveoli - no cilia
Bronchiole - ciliated (larger & smaller) no cilia ( smallest)

Question 17

Hows nose adapted to make gaseous exchange as effective as possible?

Answer 17

> Large sa with good bloody supply to warms the air to body temperature
Hairy lining secrete mucus which traps dust and bacteria, protecting delicate lung tissues from irritation and infection
Moist surfaces increase humidity of incoming air, reducing evaporation for exchange surfaces

Question 18

Hows trachea adapted to make gaseous exchange as effective as possible?

Answer 18

> Flexible cartilage that stops tube from collapsing
Has goblet cells which secrete mucus
Has cilia which beat and move mucus

Question 19

Hows bronchioles adapted to make gaseous exchange as effective as possible?

Answer 19

> Has goblet cells
Has smooth muscles which contract to close up bronchioles and relaxes to dilate them, changing the amount of air entering in them
> HAs a thin layer of flatted epithelium making some gas exchange possible

Question 20

Explain how alveoli adapted for gas exchange

Answer 20

> Large SA for gaseous exchange
Thin layers so short distance for diffusion
Good blood supply with large capillary of networks supplying alveoli bringing CO2 and picking up O2
Good ventilation as breathing moves air in and out of alveoli