4.3 Gas Exchange (humans)

Question 1

define ventillation (breathing)

Answer 1

movement of air into and out of the lungs

Question 2

what is respiration

Answer 2

the chemical reaction to release energy in the form of ATP.

Question 3

gas echange

Answer 3

Oxygen diffuses from the alveoli to the blood in the capillaries, and Carbon Dioxide diffuses from the capillaries to the alveoli.

Question 4

structure of human gas exchange

Answer 4

alveoli
bronchioles
bronchi
trachea (wind pipe)
lungs

Question 5

what does trachea have

Answer 5

cartilage rings- (c shaped rings), helps support the trachea to keep the wind pipe open.

Question 6

what are the two key structures of ventilation

Answer 6

diaphragm (underneath the lungs)
antagonistic interaction between the external and internal intercostal muscles
this means that one muscle will contract and the other will relax

the external intercostal muscles (muscles between the ribs) contraction leads to inspiration (pulls rib cage up and outwards)

the internal intercostal muscle contraction leads to expiration (pulls rib cage back in and pull down)

Question 7

inspiration

Answer 7

the external intercoastal muscles- contract (pull ribs upwards and outwards)
the internal intercostal muscles - relax
diaphragm- contracts (downwards from dome position)
air pressure in lungs- decrease in pressure of lungs as the lung volume has increased
Air moves from high to low pressure and so will move in because the pressure is low

Question 8

expiration

Answer 8

external intercoastal muscles- relax
internal intercoastal muscles- contract (pull ribs downwards and inwards)
diaphragm- relaxes (returns to domed position)
air pressure in lungs- initially greater than atm, drops as air moves out
lung volume- decreases
how does air move out- air will move out as the pressure is lower in the atmosphere

Question 9

Gas exchange in alveoli

Answer 9

the alveoli are air sacs right at the end of the bronchioles
short diffusion distance- alveoli and capilary is made up of a single layer of cells
diffusion- high concentration of carbon dioxide compared to low so will diffuse out
oxygen will diffuse from the alveoli across the epithelium and into the blood

Question 10

alveolar epithelium

Answer 10

once gases are in the alveoli, gas exchanges occur between the epithelium and blood.

alveoli are tiny air sacs, 300 million in eac human lung wich creates very large surface area for gas exchange

the alveoli is made up of one layer of epithelium cells , to minimise diffusion distance

each alveolus is surrounded by a network of capillaries to remove exchanged gases, and therefore mainatains a concentration distance

Question 11

Explain how other features of alveoli enable efficient diffusion in the lungs.

Answer 11

alveoli are one cell thick so have short diffusion distance
bloody supply maintains concentration gradient
surfactant allows gases to dissolve