Human Gas Exchange

Question 1

Name the parts of the human gas exchange system

Answer 1

lungs
trachea
bronchi
bronchioles 
alveoli

Question 2

Why are large volumes of gas needed?

Answer 2

Relatively large organism (large number of cells)

maintain a high body temp. due to high metabolic and respiratory rate.

Question 3

Why is the human gas exchange inside the body?

Answer 3

air not dense enough to support and protect this delicate structure
body would lose a great deal of water and dry out

Question 4

Describe the lungs

Answer 4

pair of lobed structure made up of bronchioles and alveoli
supported by the ribcage
ventilated by tidal stream of air

Question 5

Describe the trachea

Answer 5

flexible airway supported by rings of cartilage (prevents collapse and pressure drops when breathing in)
wall = ciliated epithelium and goblet cells

Question 6

Describe the bronchi

Answer 6

1=bronchus
produces mucus to trap dirt particles
has cilia
supported by cartilage, the smaller the bronchi gets the less cartilage

Question 7

Describe the bronchioles

Answer 7

walls=muscle lined with epithelial cells so they can contact to control airflow in/out of the alveoli

Question 8

Describe the alveoli

Answer 8

minute air sacs
between them is collagen and elastic fibre ( allows stretch) lined with epithelium
diameter 100nm-300um
at the end of the bronchioles
the alveolar membrane is the gas exchange surface

Question 9

What is breathing also known as?

Answer 9

breathing is also known as ventilation

Question 10

What causes the pressure changes in the lungs?

Answer 10

the movement of the muscles:
the diaphragm
the intercostal muscles

Question 11

Where are the intercostal muscles?

Answer 11

between the ribs

Question 12

Where is the diaphragm?

Answer 12

separates the thorax from the abdomen

Question 13

Describe the process of Inspiration/inhalation

Answer 13

external intercostal muscles contract
internal intercostal muscles relax
ribs move upwards and outwards which increases the volume of the thorax
Diaphragm contacts and further increases the volume of the thorax
increased volume = reduction in pressure in the lungs
atmospheric pressure > pulmonary pressure
air forced into the lungs

Question 14

Describe the process of expiration/exhalation?

Answer 14

external intercostal muscles relax
internal intercostal muscles contract
ribs move inwards and downwards which decreases the volume of the thorax
diaphragm relaxes and further decreases the volume of the thorax
decreased volume = increase in pressure in the lungs
pulmonary pressure >atmospheric pressure
air forced out of the lungs

Question 15

Is expiration active?

Answer 15

No it is mostly passive

the recoil of elastic tissue causes the expel of air

Question 16

What is the equation for the pulmonary ventilation rate?

WITH UNITS

Answer 16

tidal volume x breathing rate = pulmonary vent. rate

dm3 min-1

Question 17

Where is the site of gas exchange in the lungs?

Answer 17

epithelium of the alveoli

Question 18

How is the alveoli adapted for gas exchange?

Answer 18

single layer of epithelial cells= short dif. pathway
good blood network supply
distance between air and red blood cell
alveoli and capillaries have a large SA: VOL
Sharp diffusion gradient = breathing (ventilation) and heart (circulation)

Question 19

How are capillaries adapted for gas exchange?

Answer 19

capillaries have a large SA: VOL
blood capillaries are one cell thick as well
blood cells are slowed in pulmonary artery= more time 4 diffusion
blood flattened against capillary wall= reduced distance between air and red blood cell

Question 20

What are the risk factors for lung disease?

Answer 20

smoking 
genetic makeup
air pollution
infection
occupation

Question 21

Define vital capacity

Answer 21

total vol. of air in the lungs at the end of a maximal inhalation

Question 22

Define residual volume

Answer 22

volume of gas remaining in the lungs after the end of maximal exhalation

Question 23

Define tidal volume

Answer 23

volume of air inspired when at rest