11. Gas exchange in humans

Question 1

Uses of energy in living organisms

Answer 1

muscle contraction
protein synthesis
cell division
active transport
growth
the passage of nerve impulses
maintenance of a constant body temperature

Question 2

Describe aerobic respiration with equation

Answer 2

the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.

glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2 → 6CO2 + 6H2O

Question 3

Describe anaerobic respiration with equation

Answer 3

the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen,

releases much less energy per glucose molecule than aerobic respiration.

yeast-muscles equation

glucose → alcohol + carbon dioxide
C6H12O6 → 2C2H5OH + 2CO2

glucose → lactic acid

Question 4

After anaerobic respiration- detect and action

Answer 4

lactic acid builds up in muscles and blood during vigorous exercise because of anaerobic respiration causing an oxygen debt.

Brain senses that CO2 or lactic acid- excess in blood- sends nerve impulse to diaphragm and intercostal muscles- stimulate- frequent & harder contraction- faster rate of breathing rate and deeper breaths to remove oxygen debt

(a) continuation of fast heart rate to transport lactic acid in the blood from the muscles to the liver

(b) continuation of deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid

(c) aerobic respiration of lactic acid in the liver

Question 5

Features of a gas exchange surface in humans

Answer 5

large surface area- faster diffusion

thin walls- efficient diffusion

good blood supply- maintain high concentration gradient for diffusion

good ventilation with air- maintain diffusion gradient

Question 6

8 parts of the breathing system

Answer 6

1. ribs- bone structure that protects internal organs like lungs
2. larynx- voice box, air passes across here, sounds made
3. trachea- tube through which air travels to lungs
4. bronchus- one of the two tubes- TAF trachea into lungs
5. bronchioles- small tube- TAF bronchus to every part of lungs
6. alveoli and capillaries- tiny air spaces where gas exchange takes place
7. diaphragm- muscle that separates chest cavity from abdominal cavity
8. intercostal muscles- muscle bw ribs which raise and lower ribcage by C and R

Question 7

function of cartilage

Answer 7

trachea has rings of cartilage around it- prevents collapsing of it when air pressure inside is lower than air outside it.

Question 8

Breathing in and breathing out

Answer 8

IIM relax, EIM contract, pulling ribcage upward and outward
D contracts, so it is lowered
volume of thorax increases, air pressure inside falls so air flows into lungs along trachea and bronchi to equalise air pressure

IIM contract, EIM relax, pulling ribcage downward and inward
D relax, so it springs up
volume of thorax decreases, air pressure inside is more so air flows is forced out of lungs along trachea and bronchi to equalise air pressure

Question 9

composition between inspired and expired air

Answer 9

oxygen- 21% 16%
carbon dioxide- 0.04% 4%
water vapour- variable very high

aerobic respiration- reactant and product

Question 10

link between physical activity and breathing

Answer 10

an increased carbon dioxide concentration in the blood, which is detected by the brain, leading to an increased rate and greater depth of breathing

Question 11

role of goblet cells

Answer 11

protect the breathing system from pathogens and particles

goblet cells secrete mucus which trap bacteria and dust particles which are swept by cilia (found in trachea and bronchi) up to the back of the throat so that is does not block the lungs