❤️‍🔥2- gas exchange (human)

Question 1

the lungs are

Answer 1

the gas exchange surface in humans

Question 2

all gas exchange surfaces have features which allow maximum amount of gas in the smallest space, these are-

Answer 2

large surface area to allow faster diffusion of gases across the surface, thin walls to ensure diffusion distances remain 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 3

ribs

Answer 3

bone structure that protects internal organs such as the lungs

Question 4

intercostal muscle

Answer 4

muscles between the ribs which control their movement causing inhalation and exhalation

Question 5

diaphragm

Answer 5

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

Question 6

trachea

Answer 6

windpipe that connects the mouth and nose to the lungs

Question 7

larynx

Answer 7

also known as the voice box, when air passes across this we are able to make sounds

Question 8

bronchi

Answer 8

large tubes branching off the trachea with one bronchus for each lung

Question 9

bronchioles

Answer 9

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

Question 10

alveoli

Answer 10

tiny air sacs where gas exchange takes place

Question 11

pleural cavity

Answer 11

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

Question 12

the passages down to the lungs are lined with

Answer 12

ciliated epithelial cells

Question 13

cilia cells have

Answer 13

tiny hairs on the end of them that beat and push mucus up the passages towards the nose and throat where it can be removed

Question 14

the mucus is made by

Answer 14

special mucus producing cells called goblet cells because they are shaped like a goblet (cup)

Question 15

mucus traps

Answer 15

particles, pathogens like bacteria or viruses and dust and prevents them for getting into the lungs and damaging the cells there

Question 16

the alveoli are

Answer 16

highly specialised for gas exchange

Question 17

why are alveoli specialised for gas exchange

Answer 17

• there are many rounded alveolar sacs which give a very large surface area to volume ration
• alveioli 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 space
• 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 18

muscles are only able too

Answer 18

pull on bones not push on them. this means there must be two sets of intercostal muscles to work antagonistically to facilitate breathing

Question 19

external intercostal muscles

Answer 19

pull the rib cage up

Question 20

internal intercostal muscles

Answer 20

pull the rib cage down

Question 21

the diagphram is

Answer 21

a thin sheet of muscle that separates the chest cavity from the abdomen

Question 22

during inhalation

Answer 22

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 the outside and so air is drawn in

Question 23

during exhalation

Answer 23

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 and so air is forced out

Question 24

the external and internal muscles work as

Answer 24

antagonistic pairs (different directions)

Question 25

when we need to increase the rate of gas exchange in humans

Answer 25

the internal intercostal muscles will also work to pull the ribs down and in to decrease the volume of the thorax more, forcing air out more forcefully and quickly. this is called forced exhalation, it allows a greater volume of gases to be exchanged

Question 26

smoking causes

Answer 26

chronic obstructive lung disease, coronary heart disease, and increased risks of several different types of cancer, including lung cancer

Question 27

chemicals in cigarettes include

Answer 27

tar, nicotine, carbon monoxide

Question 28

nicotine affect on the body

Answer 28

nicotine narrows blood vessels leading to an increased blood pressure, it also increases heart rate. both of these effects can cause blood clots to form in the arteries leading to a heart attack or stroke

Question 29

carbon monoxide affect on the body

Answer 29

carbon monoxide binds irreversibly to haemoglobin reducing the capacity of blood to carry oxygen. this puts strain on the breathing frequency and depth need to increase in order to get the same amount of oxygen into the blood. it also puts more strain on the circulatory system to pump the blood faster around the body and increases the risk of coronary heart disease and strokes

Question 30

tar affect on the body

Answer 30

tar is carcinogen and is linked to increased chances of cancerous cells developing in the lungs. it also contributes to COPD which occurs when chronic bronchitis and emphysema occur together

Question 31

chronic bronchitis is caused by

Answer 31

tar which simulates goblet cells and mucus glands to enlarge, producing more mucus

Question 32

chronic bronchitis affect on body

Answer 32

it destroys cilia and dirty, bacteria and virus containing mucus builds up, blocking the smallest bronchioles and leading to infections. a smokers cough is an attempt to remove said mucus

Question 33

emphysema develops as a result of

Answer 33

a frequent infection, phagocytes that enter the lungs release elastase, an enzyme that breaks down elastic fibres in the alveoli. this means that alveoli becomes less elastic and cannot stretch so many of them burst. the breakdown of alveoli reduces the surface area for gas exchange and as it progresses patients become breathless and wheezy-they may need a constant supply of oxygen to stay alive.

Question 34

apparatus needed to investigate breathing in humans

Answer 34

stop watch, two students

Question 35

method to investigate breathing in humans

Answer 35

1) work out student As breathing rate at rest
2) student A should then exercise for a set time (at least 4 mins)
3) immediately after exercising count the breaths taken in 15 seconds and multiply by 4 to find breathing per min
4) work out the change in breathing rate
5) do the last step every minute after exercise for 5 mins
6) repeat process for student B
7) finally repeat the whole investigation for each student after a period of rest

Question 36

results and analysis of investigating breathing in humans

Answer 36

frequency of breathing increases when exercising because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with energy demand. if they can’t keep up this energy demand that will also respire anaerobically producing lactic acid. after exercise has finished the breathing rate remained elevated for a period of time this is because the lactic acid has built up in muscles needs to be released as it lowers the ph of cells and can denature enzymes catalysing cell reactions.

Question 37

limitations of investigating breathing in humans

Answer 37

it is difficult to control all variables in relation to students being treated etc fitness/food before exercise- solution is to find students of a similar size, general fitness, age, gender and provide each with the same meal before exercise
activity is hard to replicate exactly for each reading- solution is to give students exercise where intensity is easier to control etc runing on a treadmill at a specific speed
breathing rate can vary substantially and changes quickly after exercise finishes- solution is to begin counting the breathing rate as soon as the time interval begins and only measure for 15s or less and then multiple by 4 to get breathing rate per minute