T15 Gas Exchange in Humans

Question 1

describe order of thorax

Answer 1

trachea, bronchus, bronchioles, alveoli

Question 2

explain fucntion of the ribs

Answer 2

around lungs to provide protection for internal organs

Question 3

explain fucntion of the intercostal muscles

Answer 3

muscles between ribs that control inhalation/exhalation

Question 4

explain fucntion of the diaphragm

Answer 4

muscular dome - bottom of thorax - chanes pressure of lungs to control inhalation/exhalation

Question 5

explain fucntion of the trachea

Answer 5

windpipe - where air enters thorax and flows to lungs

Question 6

explain fucntion of the bronchi

Answer 6

trachea divides into 2 bronchi , into each lung

Question 7

explain fucntion of the bronchioles

Answer 7

bronchi further split into small tubes connected to alveoli

Question 8

explain fucntion of the alveoli

Answer 8

tiny air sacs - site of gas exchange

Question 9

explain fucntion of the pleural membranes

Answer 9

found on outside of lungs inside of chest cavity - to lunricate lungs, reducing friction when breathing

Question 10

how thorax does inhalation

Answer 10

1. intercostal muscles contract and ribs go up and out
2. diaphragm contracts downwards, creating larger volume of space for air to difffuse in
3. air pressure decreases
4. air moves in (air moves from area of high pressure to low pressure)

Question 11

how thorax does exhalation

Answer 11

1. intercostal muscles relax and ribs go down and in
2. diaphragm relaxes upwards, smaller volume of space for air
3. air pressure increases
4. air moves out

Question 12

why do we need to breathe in and out?

Answer 12

in = to get oxygen into blood for respiration through alveoli
out = remove waste products, carbon dioxide

Question 13

how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

Answer 13

1. folded - large syrface area to increase rates of diffusion
2. thin cell wall - one cell thick, short diffusion distance
3. large network of capillaries - increases concentration gradient between air in alveoli and blood, oxygen moves away in blood and carbon dioxide breathed out

Question 14

CONSEQUENCES OF SMOKING

how tar affects air passages

Answer 14

1. Tar in cigarettes destroy the Cilia (which carries away dust and microbes trapped in Mucus), therefore causing the buildup of Mucus and increasing risk of Bronchitis
2. Tar in cigarettes contain carcinogens that increases risk of Lung Cancer

Question 15

CONSEQUENCES OF SMOKING

how tar affects alveoli

Answer 15

1. Tar in cigarettes break down Alveoli walls and causes them to merge together, decreasing the surface area to volume ratio for gas exchange
2. Insufficient gas exchange will increase the risk of Emphysema - shortness of breath due to insufficient Oxygen transport in blood

Question 16

CONSEQUENCES OF SMOKING

how is emphysema caused?

emphysema=shortness of breath due to little oxygen transport in blood

Answer 16

1. caused by smoking and breathing in dust
2. due to frequent infection, enzyme released by phagocytes to break down elasticity in alveoli
3. alveoli become less elastic and cannot strecth to burst
4. brekadown of alveoli reduces surface area for gas exchange
5. patients become breathless and wheezy, may need constant supply of oxygen

Carbon Monoxide from cigarette smoking will bind irreversibly to Haemoglobin, reducing capacity of Oxygen transport by Red blood cells and hence increases the risk of Emphysema

Question 17

CONSEQUENCES OF SMOKING

how is coronary heart disease caused?

Answer 17

1. nicotine causes blood vessels to narrow - leads to build of fat globules (higher blood pressure) - damaging artery wall more likely and blood clots to form - fully blocking artery
2. creates blockage of coronary arteries - means heart has less supply of oxygen - can die as less aerobic respiration
3. may interfere with heart beat - causing heart attack

Question 18

CONSEQUENCES OF SMOKING

how is chronic bronchitis caused?

Answer 18

1. overporduction of mucus to catch tar from smoking, bronchi becomes inflamed and narrowed
2. mucus not produced as much
3. narrowed bronchus causes -> breathing is harder, damages alveoli further, leads to emphysema

Question 19

CONSEQUENCES OF SMOKING

how carbon monoxide affects people?

Answer 19

1. CO joins with haemoglobin in red blood cells in place of oxygen - less oxygen transported in blood
2. leads to low birth weight of mother - baby won’t have enough oxygen - won’t have oxygen for respiration to produce glucose for energy for growth

Question 20

practical: investigate breathing in humans, including the release of carbon dioxide and the effect of exercise

Answer 20

1. Measure and record the breathing rate (number of breaths per minute - 10 seconds x 6 - more accurate - less anomalies) of the participant at
   rest.
2. Carry out a specific exercise (eg. running/jumping) for a fixed period of time eg.1 minute.
3. Measure the breathing rate of the participant again.

Question 21

Explain why after exercise, the breathing rate increases

Answer 21

1. breathing rate increases to get more oxygen in blood
2. more oxygen to muscles
3. muscles more oxygen for aerobic respiration for more muscle contractions
4. more energy released, so more muscle contractions
5. less anaerobic respiration - so less lactic acid