Gas Exchange Humans

Question 1

The thorax is the human

Answer 1

chest cavity

Question 2

thorax consists of (8)

Answer 2

• ribs
• intercostal muscles
• diaphragm
• trachea
• bronchi
• bronchioles
• alveoli
• pluriel membranes

Question 3

gas exchange surface in humans are the

Answer 3

lungs

Question 4

adaptations of lungs for good gas exchange (4)

Answer 4

• large surface area
• thin walls
• good ventilation with air
• good blood supply

Question 5

ribs

Answer 5

bones that protect internal muscles like the lungs

Question 6

intercostal muscles

Answer 6

muscles between the ribs that control the ribs’ movement causing inhalation and exhalation

Question 7

diaphragm

Answer 7

sheet of connective tissue/muscle at bottom of thorax that helps change the volume of thorax to allow inhalation and exhalation

Question 8

trachea

Answer 8

windpipe that connects mouth and nose to the lungs

Question 9

bronchi

Answer 9

large tubes branching off of trachea with one connecting to each lung

Question 10

bronchioles

Answer 10

bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli

Question 11

alveoli

Answer 11

tiny air sacs surrounded by capillaries where gas exchange takes place

Question 12

pleural cavity

Answer 12

fluid filled space between pleural membranes which reduces friction and allows lungs to move freely

Question 13

when you breathe in, the diaphragm and intercostal muscles

Answer 13

contract

Question 14

when you breathe in thorax volume

Answer 14

increases

Question 15

when you breathe in, pressure _____ bringing air ___

Answer 15

decreases

in

Question 16

when you breathe out, intercostal muscles and diaphragm

Answer 16

relax

Question 17

thorax volume _____ when you breathe out

Answer 17

decreases

Question 18

when you breathe out, pressure ____ so air is forced ___

Answer 18

increases

out

Question 19

External intercostal muscles, pull the rib cage ___

Answer 19

up

Question 20

Internal intercostal muscles pull the ribcage ___

Answer 20

down

Question 21

During inhalation

Answer 21

The diaphragm contracts and flattens

The external set of intercostal muscles contract to pull the ribs up and out:

This increases the volume of the chest cavity (thorax)

Leading to a decrease in air pressure inside the lungs relative to outside the body

Air is drawn in

Question 22

during exhalation

Answer 22

The diaphragm relaxes it moves upwards back into its domed shape

The external set of intercostal muscles relax so the ribs drop down and in

This decreases the volume of the chest cavity (thorax)

Leading to an increase in air pressure inside the lungs relative to outside the body

Air is forced out

Question 23

adaptations of alveoli for gas exchange (5)

Answer 23

• thin, one cell thick walls to minimise diffusion distance
• surrounded by capillaries to ensure a good blood supply
• moist lining , A layer of moisture on the surface of the alveoli helps diffusion as gases dissolve
• walls are permeable, so gases can diffuse across easily
• well ventilated, maintains high levels of oxygen and low levels of carbon dioxide in the alveolar air space, meaning there is a steep concentration gradient for diffusion of gases

Question 24

smoking cigarettes can lead to

Answer 24

diseases in the lungs and can lead to coronary heart disease

Question 25

smoking damages ?

Answer 25

the walls inside the alveoli, reducing the surface area for gas exchange

Question 26

what effect does nicotine have on you ( 2– leading to another 2)

Answer 26

narrows blood vessels and increases heart rate leading to increased pressure

• increased blood pressure leads to blood clots forming in the arteries, potentially resulting in heart attack or stroke

Question 27

carbon monoxide effect on you (1 -1 - 1)

Answer 27

binds irreversibly to haemoglobin, reducing capacity of blood to carry oxygen
- puts more strain on the breathing system as breathing frequency needs to increase

• means that the circulatory system needs to pump blood faster, raising blood pressure and increasing the risk of coronary heart disease and stroke

Question 28

effect of tar on you

Answer 28

• increses chance of cancerous cells developing in lungs

damages the cilia ( little hairs) in lungs and trachea

these hairs catch dust and bacteria before it reaches the lungs so when the cilia are damaged then chest infections are more likely

Question 29

PRACTICAL EFFECT OF EXERCISE ON BREATHING

Answer 29

Work out student A’s breathing rate at rest

Count their number breaths for 15 seconds and multiply by 4

Repeat several times to calculate an average

Student A should then exercise for a set time (at least 4 minutes)

Immediately after exercising, count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute

Compare the result to the breathing rate at rest to work out the change in breathing rate as a result of exercise

Repeat this last step every minute after exercise for 5 minutes

Repeat the process for student B

Finally, repeat the whole investigation for each student after a period of rest

Question 30

results of practical should be

Answer 30

frequency of breathing increases when exercising

This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them

After exercise has finished, the breathing rate remained elevated for a period of time. because the lactic acid that has built up in muscles needs to be removed