Gas Exchange - QUIZ

Question 1

Explain how the structure of the alveoli are adapted to its function.

Answer 1

Function: gas exchange
- O2 diffuses from alveoli to capillaries
- CO2 diffuses from capillaries to alveoli
- TRIM
- Thin walls (diffusion distance)
- Rich capillary network (conc. gradient)
- Increased SA:Vol ratio
- Moist

Question 2

Explain how the structure of type I pneumocytes are adapted to its function.

Answer 2

Function: carry out gas exchange
- Thin / flat to minimize diffusion distance
- Flattened to increase SA

Question 3

Explain how the structure of type II pneumocytes are adapted to its function.

Answer 3

Function: secrete surfactant
- Cuboidal to store materials for surfactant
- Reduces surface tension
- allows gases to diffuse in solution

Question 4

Review micrographs of red blood cells and pneumocytes in the alveoli.

Answer 4

Gas Exchange Part 1

Question 5

Explain the roles of the internal / external intercostal muscles, diaphragm and abdominal muscles in the process of inspiration.

Answer 5

• diaphragm / external intercostal muscles contract
  - moves the rib cage upwards and outwards
  - increases volume of the lungs
• decreasing pressure causes air to flow into lungs

Question 6

Explain the roles of the internal / external intercostal muscles, diaphragm and abdominal muscles in the process of expiration.

Answer 6

• relaxation of external intercostal muscles / diaphragm
• internal intercostal / abdominal muscles contract
• increased air pressure due to decreased volume in lungs causes expiration

Question 7

Explain the process of gas exchange in the alveoli of the lungs.

Answer 7

• O2 diffuses into blood and CO2 diffuses out of blood
• air in alveolus is high in O2/low in CO2
• diffusion is due to concentration gradients
• concentration gradients maintained by ventilation & blood flow
• large surface area created by spherical shape of alveoli = more efficient diffusion
• rich supply of capillaries = efficient exchange
• gases must dissolve in liquid lining of alveolus in order to be exchanged

Question 8

Explain the role of the ventilation system in maintaining concentration gradients of CO2 and O2 between the alveoli and the capillaries surrounding them.

Answer 8

• ventilation is exchange of gases between lungs and air
• air drawn into alveoli brings fresh supply of oxygen
• oxygen concentration in alveolar sacs is higher than in blood capillaries
• conc. gradient causes oxygen to diffuse out of alveoli into red blood cells in capillaries

Question 9

Explain the causes, consequences, and treatments of emphysema.

Answer 9

Cause: air pollution, genetics
Cons: alveoli rupture (reduces surface area), loss of elasticity in lung tissue
Treat: brochodialators, inhailed steroids

Question 10

Explain the causes and consequences of lung cancer.

Answer 10

Cause: air pollution, genetics
Cons: internal bleeding, respiratory distress, weight loss

Question 11

Define ventilation.

Answer 11

The exchange of air between lungs and atmosphere (through breathing).

Question 12

Define ventilation rate.

Answer 12

(Breaths Per Min) Number of breaths / peaks in a graph with volume.

Question 13

Define tidal volume.

Answer 13

Volume of air taken in/out with each inhalation/exhalation.

Question 14

Define myogenic.

Answer 14

Muscle can contract without signals from the brain.

Question 15

Define systole.

Answer 15

Pressure in the arteries when the heart muscles contract.

Question 16

Define diastole.

Answer 16

Pressure in the arteries when the heart muscles relax.

Question 17

Define antherosclerosis.

Answer 17

Thickening of the arteries caused by a buildup of plaque.

Question 18

Define occlusion.

Answer 18

Blockage of a blood vessel / hollow organ.

Question 19

Define coronary heart disease.

Answer 19

Plaque buildup in the wall of the coronary arteries.

Question 20

Explain the effects of increased exercise (changes in CO2/ pH) on ventilation rate and tidal volume.

Answer 20

• exercise increases rate of cellular respiration
  - increases production of CO2 which decreases pH (acidity)
• Chemoreceptors in aorta/medulla detect change in pH
• impulse sent to medulla
• impulse sent to diaphragm for frequent contraction
• increased ventilation rate / tidal volume = more gas exchange

Question 21

Explain how ventilation rate is controlled.

Answer 21

• Chemoreceptors in aorta/medulla detect change in pH
• impulse sent to medulla
• impulse sent to diaphragm for frequent contraction

Question 22

Explain how to use a spirometer to measure tidal volume.

Answer 22

• max - min for individual breaths
• repeat and find a mean

Question 23

Explain how to use a spirometer to measure ventilation rate.

Answer 23

• Count the peaks and multiply the seconds to find Breaths Per Minute

Question 24

Describe how the structure of hemoglobin is related to its function and its oxygen dissociation curve.

Answer 24

• oxyhemoglobin forms when parietal pressure of oxygen is high
• respiring tissues have low parietal pressure for O2
• y-axis: O2 saturation of hemoglobin // x-axis: parietal pressure of O2
• sketch
• steep part results in dissociation of oxyhemoglobin

Question 25

Explain the Bohr shift

Answer 25

• increase in CO2 lowers pH of blood
  - causes hemoglobin to release oxygen
  - oxygen is released in tissue where it is required
• lower pH decreases hemoglobin affinity for O2
• moves curve to the right (S-shaped)
• sketch curve
• Bohr effect important during exercise

Question 26

Explain why and how the body adapts to gas exchange at high altitudes.

Answer 26

Pros:
- improved performance at low O2 levels
- higher conc. of red blood cells
- more O2 transported
- improved gas exchange
Cons:
- altitude sickness
- effects not permanent
- unfair to competitors who can’t train at high altitude

Question 27

Describe the different ways that carbon dioxide is carried in the blood.

Answer 27

• Hemoglobin in red blood cells
• Dissolved in plasma
• in erythrocytes as carbonic acid