13) Respiration and gas exchange

Question 1

Adaptation of trachea

Answer 1

-Lined with ciliated epithelial cells and goblet cells
-Goblet cells secretes sticky mucus to trap dust and pathogens
-Cilia beats to sweep the mucus out of the lungs back to throat and into stomach to be killed by acids

Question 2

Cartilage

Answer 2

Keeps trachea open to prevent it from collapse to allow continuous air flow into lungs

Question 3

Adaptation of alveoli

Answer 3

1. Many alveoli:
   - For larger surface area, for faster gas rate of diffusion for faster gas exchange
2. Thin wall (one cell thick):
   - For shorter diffusion distance, faster gas exchange
3. Well ventilation, good blood supply
   -To maintain steep conc. gradient for faster gas exchange
4. Moist lining
   - To dissolve gases and prevent dryness of alveolar wall
5. Surrounded by many capillaries:
   -To carry gas to and from cells

Question 4

Inhalation (mechanism of ventillation)

Answer 4

-External intercostal muscle: Contract
-Diaphragm: Contracts, flattens
-Internal intercostal muscle: Relaxes
-Ribcage : Outwards and upwards
-Volume of chest cavity: increases
-Pressure of air in lungs: decreases
-Direction of air movement: into the lungs

Question 5

Exhalation

Answer 5

-External intercostal muscles: Relax
-Diaphragm: Relax, ,moves upwards
-Internal intercostal muscles: Contracts
-Ribcage: Down and inwards
-Volume of chest cavity: Decreases
-Pressure of air in lungs: Increases
-Direction of air movement: Out of lungs

Question 6

Composition of oxygen in inhaled & exhaled air

Answer 6

Inhaled air: 21%
Exhaled air: 16%
Explanation:
Oxygen is used in aerobic respiration by cells to release energy

Question 7

Composition of carbon dioxide in inhaled & exhaled air

Answer 7

Inhaled air: 0.04%
Exhaled air: 4%
Explanation:
Product from aerobic respiration in cells, diffuses out across alveoli

Question 8

Composition of moisture in inhaled & exhaled air

Answer 8

Inhaled air: variable
Exhaled air: Higher moisture
Explanation:
Water is a product of respiration AND
Some of moisture surrounding alveoli evaporate into air

Question 9

Composition of Temperature in inhaled & exhaled air

Answer 9

Inhaled air: Variable
Exhaled air: Higher temp
Explanation:
Heat is generated from respiration

Question 10

Composition of Nitrogen in inhaled & exhaled air

Answer 10

Inhaled: 78%
Exhaled: 78%
Explanation:
Nitrogen is insoluble and unreactive

Question 11

Respiration

Answer 11

Chemical reaction that involves the breakdown of food to release energy

Question 12

Aerobic respiration

Answer 12

Total break down of glucose using oxygen to release a energy
C6H12O6 + 6O2 —> 6CO2 + 6H2O

Question 13

Anaerobic respiration in muscles

Answer 13

Incomplete breakdown of glucose in absence of oxygen releasing a small amount of energy
C6H12O6 —> 2 C3H6HO3
Takes place in mitochondria

Question 14

Advantages of anaerobic respiration

Answer 14

Releases energy for cells in absence of oxygen

Question 15

Disadvantages of anaerobic respiration

Answer 15

1.Building up lactic acid in muscle causes muscle fatigue
2. Releases small amount of energy
3. Builds up oxygen debt
takes place in cytoplasm

Question 16

Explain the effect of exercise on heart and ventilation

Answer 16

During beginning of exercise:
-There is an increase in breathing and heart rate to supply more oxygen for more aerobic respiration to release more energy for muscle contraction

As exercise strength increase:
- Insufficient supply of oxygen, so muscles will respire anaerobically, producing lactic acid and building oxygen debt

After exercise:
-Breath and heart rate still high to pay off oxygen debt and remove lactic acid

Question 17

Explain the changes taking place during exercise on heart and breathing

Answer 17

-Increase in heart rate and both breathing rate and depth
-Muscles respire aerobically for more energy for more contraction
- to increase blood supply to muscles for more oxygen and glucose supply
- for more aerobic respiration, for more muscle contraction
- for rapid removal of more carbon dioxide
- rapid removal of excess heat

Question 18

Explain why the heart rate and breathing rate remains high after exercise

Answer 18

-As during exercise there was an insufficient supply of oxygen
- so muscles respired anaerobic to meet high demand of energy by muscles
-Producing lactic acid and building oxygen debt
- So body recovers by keeping heart rate high for rapid removal of lactic acid from muscles, to diffuse into blood, to be transported to liver, to be broken down by using oxygen debt into co2 and water
-AND breathing rate remains high to provide enough oxygen to pay off oxygen debt, needed to break down lactic acid produced from anaerobic resp

Question 19

How to remove oxygen debt

Answer 19

-Heart and breathing rate remains high to pay off oxygen debt
-To supply enough oxygen needed to break down the lactic acids
- where lactic acid is removed from muscles into blood to liver
- to be broken down/ oxidised
- into carbon dioxide and water

Question 20

Explain increase in lactic acid concentration during exercise

Answer 20

-high demand of energy by muscles during exercise
-Insufficient supply of oxygen
-So muscles respired anaerobically
- producing lactic acid

Question 21

What stimulates the increase in heart and breathing rate during exercise?
How the increase in heart rate and breathing rate is coordinated during exercise?

Answer 21

-During exercise, there is an increase in energy demand
-So rate of aerobic respiration increase
-Increasing carbon dioxide concentration, increasing acidity
-Lowering blood pH
-Detected by chemoreceptors in brain
- Brain sends signals to pacemaker to increase heart rate
- Brain sends signals to intercostal muscles and diaphragm to contract more frequently, increasing breath rate and depth