gas exchange in lungs

Question 1

describe the pathway of airway

Answer 1

mouth
trachea
bronchi
bronchioles
alveoli
capillary

Question 2

explain the difference between respiration and breathing

Answer 2

respiration is a chemical reaction that takes place in cells that releases energy from glucose

breathing is the movement of air in and out of cells

Question 3

Explain why humans require an efficient gas
exchange system

Answer 3

Large volumes of CO2 and O2 need to be
exchanged

Because they have a high metabolic rate
(respiration)

Because they are large organisms with
large volume of living cells

Because they maintain high body
temperature linked to high metabolic and
respiratory rate

Question 4

what are alveoli

Answer 4

Alveoli - tiny air sacs at the end of bronchioles. made of epithelium with elastic fibres and collagen between alveoli

Question 5

what is the function of the bronchioles

Answer 5

Bronchioles - branches from bronchi, muscular walls control air flow to alveoli

Question 6

what is the function of the bronchi

Answer 6

produce mucus to trap air and dirt

cilia move mucus towards the throat

Question 7

what is the structure of the trachea

Answer 7

rings to cartilage prevent trachea collapsing due to air pressure

walls are made of muscle, lined with ciliated epithelium and goblet cells

Question 8

explain what happens during the process of inhalation

Answer 8

• external intercostal muscles contract while the internal intercostal muscles relax
• ribs are pulled upwards and outwards increasing the volume of the thoracic cavity
• diaphragm contracts and flattens which also increases the volume of the thoracic cavity
• pressure in lungs decreases
• there is less pressure in the lungs than in the atmosphere so air moves into the lungs

Question 9

explain what happens during exhalation

Answer 9

• internal intercostal muscles contract while external intercostal muscles relax
• ribs move downwards and inwards decreasing the volume of the thoracic cavity
• pressure in the lungs increases
• pulmonary pressure is greater than atmospheric so air moves out of the lungs

Question 10

define epithelium

Answer 10

lining layer of tissue

Question 11

what is the advantage of having many alveoli and capillaries

Answer 11

large surface area

Question 12

what is the advantage of red blood cells in the capillary being slowed

Answer 12

more time for diffusion

Question 13

what is the advantage of red blood cells being flattened against the wall of the capillary

Answer 13

distance between alveolar air and red blood cells is reduced

= short diffusion pathway

Question 14

what is the advantage of walls of the alveoli and capillary being thin

Answer 14

distance between alveolar air and red blood cells is reduced

= short diffusion pathway

Question 15

what is the advantage of constant ventilation

Answer 15

steep concentration gradient between alveoli and capillaries is maintained

Question 16

what is the advantage of constant heartbeat and constant flow of blood through pulmonary arteries

Answer 16

steep concentration gradient between alveoli and capillaries is maintained

Question 17

State the names of the two muscles in the thorax responsible for ventilation

Answer 17

Intercostal muscles, diaphragm

Question 18

Describe the relationship between volume and pressure in a closed container.

Answer 18

As volume increases pressure decreases

Question 19

With reference to pressure what determines the way in which gases move from one region to another.

Answer 19

Gases move from a region of higher pressure to a region of lower pressure

Question 20

define ventilation

Answer 20

movement of air in and out of the lungs

Question 21

define inspiration (in terms of pressure)

Answer 21

pressure in the atmosphere is greater than in the lungs - air moves in

Question 22

define exhalation (in terms of pressure)

Answer 22

pressure in the lungs greater than in the atmosphere - air moves out

Question 23

describe the diaphragm

Answer 23

sheet of muscle separating thorax from abdomen

Question 24

describe the function of the internal intercostal muscles

Answer 24

contraction leads to expiration

Question 25

describe the function of the external intercostal muscles

Answer 25

contraction leads to inspiration

Question 26

Explain what is meant by pulmonary ventilation and how it is calculated

Answer 26

Pulmonary ventilation rate is the total volume of air that is moved into the lungs during one minute.
Calculated by: tidal volume x breathing rate

Question 27

when blood enter the lungs what is the concentration of oxygen within it

Answer 27

low concentration of oxygen

Question 28

when blood exits the lungs what is the concentration of oxygen within it

Answer 28

high concentration of oxygen