3. Gas Exchange in Humans

Question 1

Define Gas exchange

Answer 1

Process of taking gases in that are needed for life processes and getting rue of waste gases

Oxygen into blood for respiration
Co2 out made my respiring cells

Question 2

Name the 8 components of gas exchange system

Answer 2

Trachea
Bronchi 
Lung
Bronchioles 
Alveoli 
Ribcage
Intercostal muscles 
Diagram

Question 3

What is the pathway of air into body ?

Answer 3

Air enters trachea
Splits into 2 bronchi 1 in each lung.
Bronchioles which then end in alveoli.

Ribcage/ intercostal muscles and diaphragm all work together to move air in and out

Question 4

Where does gas exchange occur in mammals ?

Answer 4

Alveoli

Question 5

Location of intercostal muscles

Answer 5

Between ribs

Interlaced intercostal muscle

External intercostal muscles

Question 6

Define ventilation

Answer 6

Inspiration - breathing in
Expiration - breathing out

Controlled by ribcage/ Internal&external intercostal muscles and ribcage

Question 7

Inspiration

Answer 7

External intercostal muscles and diaphragm contract.
Ribcage moves up and out.
Diaphragm falters - increasing volume of thoracic activity.
This causes lung pressure to decrease below atmospheric pressure.
As air flows down pressure gradient from high to low pressure air flows into trachea and lungs

Question 8

Is inspiration active / passive

Answer 8

Active

Atp needed

Question 9

Expiration

Answer 9

External intercostal muscles and diaphragm muscles relax.
Ribcage down and in
Diaphragm curves up again
Volume of thoracic cavity decreases causing air to increase above atmospheric pressure.
Air forced down pressure gradient out of lungs

Question 10

Normal expiration

Answer 10

Passive

No energy

Question 11

Forced expiration

Answer 11

Blowing out candles
External intercostal mucked relax and internal intercostal muscles contract pulling ribcage further down and in

Antagonistic pairs

Question 12

Alveoli location

Answer 12

Gas exchange system

Millions of them

Microscopic

In lung

Surrounded by capillary network

Question 13

What causes the change in lung pressure?

Answer 13

Movement of ribcage and diaphragm

Question 14

Alveoli structure

Answer 14

Wall made from single layer of thin / flat cells called alveolar epithelium

Walls contain protein called elastin - helps alveoli Return ( recoil ) to Normal shape after inhaling & exhailing I

Question 15

What are the walls of capillary made from ?

Answer 15

Capillary endothelium

Question 16

Movement of co2 and o2

Answer 16

Both by diffusion and down pressure gradient

Co2 moves down its own diffusion and pressure gradient in opposite direction to oxygen - breathed out

Question 17

How does o2 get into the blood

Answer 17

O2 diffuses out of alveoli across the alveolar epithelium and the capillary endothelium into compound called haemoglobin in blood

Question 18

Where does the pressure gradient start and stop

Answer 18

Trachea
Bronchi
Bronchioles
Alveoli

Question 19

Where does diffusion gradient start and stop

Answer 19

Alveoli
Alveolar epithelium
Capillary endothelium
Blood

Question 20

What features for the alveoli have that speed up diffusion

Answer 20

Thin exchange surface - alveolar epithelium only 1 cell thick. So short diffusion pathway

Large surface area - millions of alveoli so for gas exchange

Steep conc gradient of oxygen and carbon dioxide between alveoli and capillaries which increases diffusion