Topic 3 - Gas Exchange In Mammals

Question 1

What adaptions do the alveoli in the lungs have for gas exchange?

Answer 1

Provide a large surface area and thin walls to reduce the diffusion distance.
They are surrounded by dense capillary network, maintaining a steep diffusion gradient.

Question 2

What is the role of ventilation in gas exchange?

Answer 2

• Breathing movements maintain the flow of air, replenishing oxygen and removing carbon dioxide
• Blood flow through capillaries insures gases are constantly transported and from the alveoli.

Question 3

How do mammals minimise water loss?

Answer 3

– Moist surfaces are internal reducing exposure to the external environment.
– There is humidified in the nasal passage reducing operation from the lungs.

Question 4

Simply what is the structure of the human gas exchange system?

Answer 4

Lungs
Rib cage
Diaphragm

Question 5

What are the lungs?

Answer 5

• pair of lobes structures with a large surface area allowing for efficient gas exchange
• Enclosed in the thoracic cavity and protected by the rib cage.
• Lubricating fluid reduces friction between the lungs and rib cage during breathing.

Question 6

What is the rib cage?

Answer 6

• surrounds the lungs and provides protection
• External intercostal muscles to lift the rib cage during inhalation
• internal intercostal muscles contract to lower the rib cage during exhalation

Question 7

What is the diaphragm?

Answer 7

• A sheet of muscle separating the thoracic cavity from the abdominal cavity.
• Contracts and flattens during inhalation increasing long volume and reducing pressure.

Question 8

What is the pathway of air?

Answer 8

1. Nasal cavity
2. Trachea - a wide tube supported by C-shaped rings of cartilage preventing collapse during inhalation, ciliated epithelium trapping and moving mucus with debris away from the lungs
3. Bronchi - trachea divides into two bronchi leading to a lung
4. Bronchioles - contains smooth muscle and elastic fibre end in alveoli

Question 9

What are the five adaptions gaseous exchange of the alveoli?

Answer 9

1. Thin walls: one cell thick reducing the diffusion pathway.
2. Capillary network: surrounding capillaries are also one cell thick reducing the diffusion distance.
3. Large surface area: there are many tiny alveoli.
4. Steep concentration gradient: maintained by a constant blood flow in capillaries and ventilation of the lungs
5. Elastic fibres: allow alveoli to stretch and recoil during breathing helping to expel air effectively.

Question 10

What is the role of cartilage?

Answer 10

Supports the trachea and bronchi, keeping airways open.
The C-shaped rings in the trachea, allow the oesophagus to expand during swallowing

Question 11

What is the world of smooth muscle?

Answer 11

Can contract to restrict airflow controlling air movement in certain conditions.

Question 12

What is the role of elastic fibres?

Answer 12

Allow for expansion and recoil during inhalation and exhalation