structure of the gas exchange system

Question 1

where is the gas exchange system located?

Answer 1

in the thorax- the upper part of the body

Question 2

what happens when we breathe in?

Answer 2

• air passes down the trachea
• the trachea splits to form the 2 bronchi
• the bronchi divide into bronchioles which carry air into the thorax

Question 3

what is the trachea?

Answer 3

the windpipe

Question 4

what is the trachea surrounded by?

Answer 4

C- shaped rings of cartilage

Question 5

what do the C- shaped rings of cartilage surrounding the trachea do?

Answer 5

they keep the trachea open but make swallowing easier

Question 6

what are bronchi?

Answer 6

these tubes lead to the lungs

Question 7

what are the bronchi surrounded by?

Answer 7

cartilage rings

Question 8

what are bronchioles?

Answer 8

small tubes

Question 9

what is at the end of each bronchiole?

Answer 9

microscopic air sacs- the alveoli

Question 10

what are the site of gas exchange?

Answer 10

the alveoli

Question 11

what are alveoli?

Answer 11

microscopic air sacs

Question 12

what are the lungs surrounded by?

Answer 12

the pleural membrane

Question 13

what does the plural membrane form?

Answer 13

a double layer between the lungs and the thorax walls

Question 14

what is in between the membranes and what does it do?

Answer 14

• a thin layer of pleural fluid
• form an air tight seal and prevent the lungs from sticking to the thorax wall as they inflate and deflate

Question 15

what do the ribs do?

Answer 15

help protect the organs in the thorax

Question 16

what do the intercostal muscles do?

Answer 16

• help to connect the bones
• important in moving air into and out of the lungs

Question 17

where are the intercostal muscles located?

Answer 17

between the ribs

Question 18

where is the diaphragm located?

Answer 18

below the lungs, separating the organs of the thorax and the abdomen

Question 19

what is the diaphragm made out of?

Answer 19

• domed sheet of muscle
• fibrous tissue

Question 20

what does the diaphragm do?

Answer 20

moving air into and out of the lungs

Question 21

what features do gas exchange structures have that allow the maximum amount of gases across the surface in the smallest amount of time?

Answer 21

large SA to allow faster diffusion of gases along the surface
thin walls to ensure diffusion distance remains short
good ventilation with air so that diffusion gradients can be maintained
good blood supply to maintain a high concentration gradient so diffusion occurs faster

Question 22

what is the trachea?

Answer 22

windpipe that connects the mouth and nose to the lungs

Question 23

what is the larynx?

Answer 23

the voicebox- when air passes across here we are able to make sounds

Question 24

what are the passages down to the lungs lined with?

Answer 24

ciliated epithelial cells

Question 25

how are the alveoli specialised for gas exchange?

Answer 25

there are many rounded alveolar sacs which give them a large SA:V ratio
alveoli and the capillaries around them have thin, single layers of cells to minimise diffusion distance
ventilation maintains high levels of oxygen and low levels of carbon dioxide in the alveolar air spaces
a good blood supply ensures constant supply of blood high in carbon dioxide and low in oxygen
a layer of moisture on the surface of the alveoli helps diffusion as gases dissolve

Question 26

what is bad about nicotine?

Answer 26

narrows blood vessels-increased blood pressure
increases heart rate
can cause blood clots in the arteries leading to heart attack/stroke

Question 27

what is bad about tar?

Answer 27

linked to increase chance of cancerous cells developing
contributes to COPD- when chronic bronchitis and emphysema occur at the same time
chronic bronchitis is caused by tar which stimulates goblet cells