11 Gas exchange in Humans

Question 1

Aerobic respiration

Answer 1

Chemical reactions in cells in which nutrient molecules are broken down using oxygen to release energy.

Question 2

The breathing system

Answer 2

The organ system that allows the body to obtain the oxygen it needs for aerobic respiration, and to remove the carbon dioxide produced as a waste product

Question 3

Aveoli

Answer 3

Tiny air sacs in the lungs that provide a large surface area to volume ratio for efficient gas exchange.

Question 4

How air gets to the lungs

Answer 4

nose/mouth → larynx → trachea → bronchi → bronchioles → alveoli

Question 5

Diffuse

Answer 5

The net movement of particles from a region of their higher concentration to a region of their lower concentration, down a concentration gradient, as a result of their random movement.

Question 6

Breathing

Answer 6

The process of moving air in and out th elungs

Question 7

Gas exchange

Answer 7

Oxygen diffuses into the blood stream from the aveoli

Question 8

Expiration

Answer 8

Mechanism to remove air from the lungs.(Exhaling)

Question 9

Inspiration

Answer 9

Mechanism to take in air to the lungs.(Inhaling)

Question 10

Where does gas exchange happen

Answer 10

Gas exchange happens at the surface of the alveoli, allowing oxygen to diffuse from the air into blood in the capillaries, and carbon dioxide to diffuse from the blood in the capillaries into the air

Question 11

Trachea

Answer 11

A tube made of cartilage that allows ventilation to the lungs from the mouth and nose.

Question 12

Thorax

Answer 12

The chest cavity that protects some of the main internal organs such as the heart and lungs. Muscle contractions in the thorax allows for ventilation.

Question 13

Diaphragm

Answer 13

A large dome-shaped muscle at the base of the thorax (chest) that helps to ventilate the lungs.

Question 14

Intercostal muscles

Answer 14

Muscle tissue between the ribs in the thorax. Contraction and relaxation of these muscles allows the lungs to be ventilated.

Question 15

What happens in the thorax when you breathe in (or inhale):

Answer 15

the volume of the thorax increases
the pressure inside decreases and becomes less than the pressure outside
air is pushed into the lungs.

Question 16

What happens to the thorax when you breathe out (or exhale):

Answer 16

the volume of the thorax decreases
the pressure inside increases and becomes more than the pressure outside
air is pushed out of the lungs.

Question 17

The changes in the volume of the thorax are caused by:

Answer 17

contraction and relaxation of the diaphragm
contraction and relaxation of the intercostal muscles resulting in movement of the ribs

Question 18

What happens to the structure of the thorax when breathing

Answer 18

Structure Breathing in/Breathing out
diaphragm: contracts/relaxes
internal intercostal muscles: relax/contract
external intercostal muscle: contract/relax
ribcage: moves upwards and outwards/moves downwards and inwards

Question 19

Inspired air

Answer 19

The air being inhaled into the lungs.

Question 20

Expired air

Answer 20

The air exhaled from the lungs.

Question 21

Compositions of inspired air and expired air.

Answer 21

Inspired air / Expired air
oxygen: 21% / 16%
carbon dioxide: 0.04% / 4%
water vapour level: variable (depends on the
relative humidity) / always high

Question 22

Why are there differences in the compositions between inspired and expired air

Answer 22

The differences in compositions of inspired air and expired air are related to the ways in which the body uses or produces the gases:

Oxygen is used by cells during aerobic respiration
Carbon dioxide is a waste product of respiration and must be removed from the body.

Expired air contains more water vapour than inspired air because moisture evaporates from the cells of the gas exchange surface.

Question 23

Effect of exercise on breathing

Answer 23

The cells of the body respire more during physical activity, to provide the energy needed by the muscles. This increased rate of respiration produces more carbon dioxide as a waste product. The increasing concentration of carbon dioxide in the blood is detected by the brain. It triggers the body to respond by increasing the rate and depth of breathing to expel the carbon dioxide from the body. These changes also increase the amount of oxygen obtained, needed for aerobic respiration to continue.

Question 24

How exercise and breathing can have an effect on the Ph of Blood

Answer 24

High levels of carbon dioxide in the blood can cause changes in its ​​​ pH level, making it more acidic. This is because the carbon dioxide dissolves to form carbonic acid, which in turn decreases the pH of the blood.

Question 25

What type of cells protect the breathing system

Answer 25

Goblet cells
​​​​​​Ciliated cells

Question 26

Goblet cells and how it helps protect the breathing system

Answer 26

Specialist cells in the lining of membranes that produce mucus.
Produce sticky mucus, which is secreted from these cells.
This mucus lines the inside of the trachea. Pathogens and particles in inspired air become trapped in the sticky mucus.

Question 27

Ciliated cells and how it helps protect the breathing system

Answer 27

Type of specialised cell with cilia (fine hairs) that sweep mucus out of the nose and throat.
Ciliated cells line the surfaces of the nose, trachea, bronchi and bronchioles.
They are specialised cells with very fine structures called cilia
Movements of the cilia sweep mucus out of the breathing system to the throat (where it is then swallowed).
This carries any trapped pathogens or particles away from the breathing system.
Smoking damages cilia, so mucus is less efficiently swept up.

Question 28

The four adaptation of the aveoli in the lungs

Answer 28

Large surface area
Moist surface
Thin lining
Good blood supply

Question 29

Properties of gas exchange surfaces

Answer 29

Thin- so gases only have a short diffusion distance
Large surface area- many molecules of gas can diffuse at the same time
Moist- prevent cell death, enable gases to dissolve
Ventilation- maintain concentration gradients by continually supplying oxygen and removing carbon dioxide
Blood supply- enable transport of gases to and from lungs when needed