1.2b - The Respiratory system

Question 1

Describe the short term effects of exercise on gas exchange at the alveoli

Answer 1

1) During exercise ppO2 in the alveoli of the lungs is high and low in the blood
2) oxygen diffuses from an area of high pressure to a low pressure and therefore more oxygen diffuses from the alveoli to the blood.
3)There is also a higher ppCO2 in the blood capillaries and low in the alveoli
4) Therefore more CO2 diffuses from the blood to the alveoli.

Question 2

Outline how oxygen is transported in the blood(2marks)

Answer 2

1)Combines with haemoglobin
2)Dissolved in plasma

Question 3

Describe the process of oxygen diffusion at the alveoli during exercise(3marks)

Answer 3

1)During exercise, the alveoli have a high concentration of oxygen and low CO2
Bloodstream/capillary has a high concertration of CO2 low concentration of oxygen
3) High concentration of oxygen from the alveoli diffuses into the bloodstream
4) It attaches to the haemoglobin and therefore becomes oxyhaemoglobin

Question 4

define tidal volume

Answer 4

volume of air inspired and expired per breath

Question 5

define breathing rate

Answer 5

number of breaths per minute

Question 6

define minute ventilation

Answer 6

volume of air inspired or expired per minute

Question 7

what are the values for breathing rate during exercise and at rest

Answer 7

rest = 15
exercise = 40-60

Question 8

What are the values for tidal volume during exercise and at rest

Answer 8

rest = 500ml
exercise = 3000ml

Question 9

What are the values for minute ventilation during exercise and at rest

Answer 9

rest = 5 litres/min
exercise = 100-150 litres/min

Question 10

Explain inspiration at rest

Answer 10

• active process
• external intercostal muscles contract
• ribs move up and out (creates a greater chest cavity volume)
• diaphragm flattens
• Thoracic cavity volume increases
• thoracic cavity pressure decreases
• causing air to rush in

Question 11

Explain expiration at rest

Answer 11

• passive process
• muscles relax
• ribs move inwards
• thoracic cavity volume decreases
• thoracic cavity pressure increases
• CO2 moves out of lungs

Question 12

explain inspiration at exercise

Answer 12

• active process
• diaphragm and external intercostal muscles contract with more force than at rest
• extra muscles also contract (Sternocleido mastoid- in neck and lifts the ribs up, pectorals)
• ribs move up and out with more force
• thoracic cavity pressure decreases more than at rest
• thoracic cavity volume increases more than at rest
• more oxygen goes in

Question 13

Explain expiration at exercise

Answer 13

• now active process
• internal intercostal muscles contract causing the ribs to go down and in
• diaphragm relaxes and pushes lungs up with more force
• abdominal muscles contract
• thoracic cavity pressure increases more than at rest
• thoracic cavity volume decreases more than at rest

Question 14

Describe respiratory control in the body (refer to receptors in your answer)

Answer 14

chemoreceptors (detect an decrease in O2 and an increase in CO2)
Baroreceptors (increase in blood pressure)
Proprioceptors (increase in muscle movement)

sends impulse to the medulla oblongata
sends a nerve impulse down the phrenic nerve
to the respiratory muscles
triggers them to contract
faster and deeper breathing

Question 15

Describe the gas exchange for external respiration during rest

Answer 15

• between the alveoli and blood
• low partial pressure of o2 in the blood
• low partial pressure of C02 in alveoli
• pressure gradient
• CO2 move into alveoli and O2 moves into blood

Question 16

Describe the gas exchange for external respiration during exercise

Answer 16

• increases demand for O2 and increased production of CO2 during exercise
• Alveoli and blood
• higher PP of O2 in alveoli, low in blood
• Higher pp of CO2 in blood, low in alveoli
• diffusion gradients steepen so they both diffuse in an out quicker

Question 17

Describe the gas exchange for internal respiration during exercise

Answer 17

• increases demand for O2 and increased production of CO2 during exercise
• muscles and blood
• higher pp of O2 in blood, low in muscles
• higher pp of CO2 in muscles, low in blood
• diffusion gradient steepens so oxygen enters and CO2 leaves rapidly

Question 18

Describe the gas exchange for internal respiration during rest

Answer 18

• muscles and blood
• low partial pressure of O2 in muscles
• low partial pressure of CO2 in blood
• pressure gradient
• O2 moves into muscles, CO2 moves into blood

Question 19

Explain why more oxygen dissociates from the blood to the muscle cells during exercise (5)

Answer 19

• increased affinity of haemoglobin to oxygen at a higher temp
• haemoglobin becomes fully saturated
• working muscle utilise more O2
• haemoglobin gives up O2 more readily during exercise (Bohr shift)
• Increase O2 diffusion gradient
• increased removal of CO2

Question 20

Explain the role of the sternocleidomastoid muscle in respiration during exercise

Answer 20

• additional muscle (recruited to aid during exercise)
• assists external intercostal muscles to pull rib cage upwards and outwards
• increase in thoracic cavity volume and a decrease in thoracic cavity pressure
• increased O2 diffusion gradient
• increased tidal volume