gas exchange in humans

Question 1

thorax

Answer 1

the part of the body which contains the heart and lungs within a rib cage

Question 2

alveoli

Answer 2

air sacs where gas exchange takes place between air and blood

Question 3

pleural membrane

Answer 3

-two thin, moist membranes which separate the lungs and the thorax
-form an airtight seal
-filled with a pleural cavity with pleural fluid to stop the lungs of sticking to the thorax when expanding

Question 4

diaphragm

Answer 4

-dome-shaped sheet of muscle which separates the thorax from the abdomen and moves in and out of the lungs when it contracts/relaxes

Question 5

trachea

Answer 5

-main windpipe
-supported by C-shaped cartilage which keeps it open

Question 6

bronchus

Answer 6

-a branch of the trachea through which air passes to reach the alveoli
-supported by rings of cartilage

Question 7

bronchiol

Answer 7

branches from the bronchi which air passes through to reach the alveoli, supported by rings of cargilage(may not be ring of cartilage not sure)

Question 8

intercostal muscles

Answer 8

-join each rib to the next
-move the ribcage when they contract

Question 9

ribs

Answer 9

enclose the lungs

Question 10

mucus

Answer 10

-in the trachea and bronchi
-secrets mucus to trap harmful substances, stops them entering the lungs and causing infection
-hair like cilia move the mucus up and out towards the mouth

Question 11

what happens to these when breathing in:
-external intercostal muscles
-internal intercostal muscles
-rips
-diaphragm muscles
-diaphragm

Answer 11

-external intercostal muscles contract
-internal intercostal muscles relax
-ribs move up
-diaphragm muscles contract
-diaphragm flattens

Question 12

what happens to these when breathing out:
-external intercostal muscles
-internal intercostal muscles
-rips
-diaphragm muscles
-diaphragm

Answer 12

-external intercostal muscles relax
-internal intercostal muscles contract
-ribs move down
-diaphragm muscles relax
-diaphragm raises

Question 13

where does air enter from in the bell jar model

Answer 13

-glass tube which represents the trachea
-model is air tight so

Question 14

how can the mechanism of ventilation be shown

Answer 14

-bell jar model

Question 15

explain how muscles move to allows for ventilation

Answer 15

-external intercostal muscles contract, internal intercostal muscles relax
-diaphragm muscles relax, flattening it, ribs moves out
-volume of thorax increases; pressure decreases
-pressure in lungs is less than atmospheric pressure; air rushes in the lungs

Question 16

how does the bell jar model work

Answer 16

-as the rubber sheet is pulled down, the volume of the jar increases and the pressure therefore decreases and air is dawn in through the glass rube inflating the balloons, which represent the lungs

Question 17

-emphysema (effect of smoking)

Answer 17

-the degeneration of alveoli
-the wall break down, decreasing the surface area for gas exchange and resulting in less oxygen in the blood
-mild exercise in severe cases cannot take place

Question 18

bronchitis (effect of smoking)

Answer 18

-inflammation of the airways
-substances in smoke damage cilia
-mucus is not swept away from the lungs
-more mucus is produced due to irritation of smoke in the airways
-results in ‘smokers cough’ irritation of airways and bacterial infections which inflames airways, blocking normal airflow and causing breathing difficulties

Question 19

coronary heart disease (effect of smoking)

Answer 19

-blockage of the narrow coronary arteries of the heart
-leads to cardiac arrest
-smoking increases blood pressure and makes blood clots more likely so it increases the risk of a heart attack

Question 20

cancer (effect of smoking)

Answer 20

-substances in the tar of cigarettes called carcinogens
-causes cells to mutate and divide uncontrollably, forming a tumor
-often cause no pain in lungs and not identified before cancer spreads to rest of body

Question 21

ulcer (effect of smoking)

Answer 21

-smoking increases the acidity of the stomach and duodenum, leading to ulcers

Question 22

carbon monoxide poisoning (effect of smoking)

Answer 22

-carbon monoxide is in cigarette smoke
-binds to haemoglobin instead of oxygen and forms carboxyhaemoglobin

Question 23

how does carbon monoxide poisoning affect fetus

Answer 23

-smoking during pregnancy reduces oxygen received by fetus, affecting its growth and development

Question 24

addiction (effect of smoking)

Answer 24

-caused by nicotine

Question 25

passive smoking

Answer 25

-non-smokers inhaling other people’s smoke are at risk of the effects of smoking

Question 26

effects of smoking mark scheme(5)

Answer 26

1. emphysema
2. less surface area/ damage to alveoli
3. bronchitis
4. bacteria/infection
5. cilia damaged
6. more mucus
7. cancer
   8.tar