Chapter 6- Gas Exhange

Question 1

In humans where does gas exchange take place?

Answer 1

In small air sacs called alveoli inside the lungs

Question 2

How does gas exchange happen between air in the alveoli and blood flowing in adjacent capillaries?

Answer 2

By diffusion- there is a concentration gradient - air in alveolus is higher conc of oxygen and a Lower concentration of carbon dioxide then the blood in the capillary- this process is called ventilation

Question 3

What are type I pneumocytes?

Answer 3

Are extremely thin alveolar cells that are adapted to carry out gas exchange

Question 4

What do the walls of each alveolus consist of?

Answer 4

A single layer of cells called the epithelium - most cells in there are type I pneumocytes - walls of adjacent capillaries are very close- adaption which increases the rate of gas exchange

Question 5

What type II pneumocytes?

Answer 5

Secret a solution containing surfactant that creates a moist surface inside alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension - helps prevent collapse of the lungs

Question 6

What is the route of air entering lungs?

Answer 6

1) Air enters through nose or mouth
2) Passes down the trachea
3) Trachea divers to form two bronchi, one bronchus leads to each lung
4) Inside lungs bronchi divides repeatedly to form a tree like stitcher of narrower airways called bronchioles
5) End of bronchioles are groups of alveoli where gas exchange takes place

Question 7

What do muscle contractions cause?

Answer 7

The pressure to change inside the thorax that forces air in and out of the lungs to ventilate them

Question 8

What is inspiration and expiration?

Answer 8

1) muscle contractions cause pressure inside thorax to drop below atmospheric pressure- causes air to be drawn into lungs until pressure has risen to atmospheric pressure
2) muscle contractions then cause pressure inside the thorax to rise above atmospheric , so air is forced out from the lungs to the atmosphere

Question 9

What are the 2 states muscles can be in?

Answer 9

Contracting and relaxing

Question 10

What happens to muscle when it contracts

Answer 10

Do work when they are contracted- become shorter

Question 11

What happens to muscles when they relax

Answer 11

Lengthen- don’t do any work

Question 12

What happens in an antagonistic pair of muscles?

Answer 12

And one muscle contacts the other second muscle relaxes - inspiration and expiration are examples

Question 13

Explain diaphragm as example of antagonistic pairs

Answer 13

Inspiration: moves downwards and flattens
Expiration: moves upwards and becomes more domed

Question 14

Explain rib age as example of antagonistic pairs

Answer 14

Inspiration: moves upwards and outward
Expiration: Moves downward and inwards

Question 15

Explain volume and pressure change as example of antagonistic pairs

Answer 15

Inspiration: volume in thorax increases and pressure decreases
Expiration: volume inside thorax decreases and pressure increases

Question 16

Explain movement of diaphragm as example of antagonistic pairs

Answer 16

Inspiration:
Diaphragm- contracts and moves downwards so pushes abdomen wall out
Abdomen wall- relaxes, allowing pressure from diaphragm to push it out
Expiration:
Diaphragm - diaphragm relaxes, so it can be pushed upwards to domed shape
Abdomen wall- contract pushing abdominal organs and diaphragm upwards

Question 17

Explain movement of ribcage as example of antagonistic pairs

Answer 17

Inspiration:
External intercostal muscles- contract, pulling ribcage up and outward
Internal intercostal muscles - relax, and are pulled back into their elongated state
Expiration :
External intercostal muscles- relax and are pulled back into elongated state
Internal intercostal muscles- contract, pulling ribcage a inwards and downwards

Question 18

Causes of lung cancer

Answer 18

1) tobacco
2) passive smoking
3) air pollution
4) radon gases- (radioactive gases)

Question 19

Consequences of lung cancer

Answer 19

Difficulties with breathing
Persistent coughing
Coughing up blood
Chest pain
Loss of appetite
Weigh loss
General fatigue

Question 20

Causes of emphysema

Answer 20

Smaller air sacs with much thicker walls
Total surface area is very reduced
Gas exchange is less effective
1) phagocytes inside alveoli

Question 21

What does ventilation do?

Answer 21

It maintains concentration gradients of oxygen and carbon outside between Air in alveoli and blood flowing in adjacent Capillaries