respiration 6

Question 1

Amount of gas in solution is directly proportional to:

Answer 1

the partial pressure of the gas

Question 2

Effects of depth on the body

Answer 2

• Every 10 m, the pressure increases by 1 atmosphere (760mmHg)
• Gas enters the lungs at higher pressure, blood holds more gas
• 79% N2 -> dissolving in neuronal membranes -> decrease in excitability

Nitrogen: euphoria, dizziness, loss of judgement, impaired motorfunctions
Oxygen: lung injury, CNS damage
Nitrogen narcosis, rapture of the deep

Question 3

Deep diving marine mammals

Answer 3

1. No lung filling with gas under pressure
2. Breath at surface, then dive
3. Excess lung air expelled
4. Change in cartilage distribution: more collapse
   under pressure
   =less trapped air
   Fat absorbs excess nitrogen safely

Question 4

Effects of heights on the body

Answer 4

• Decrease in partial pressure
  (5486m)
  50% atmospheric pressure (380mmHg)
  Partial pressure ratio remains the same (80 mmHg) PO2 At alveolar level: 45 mmHg !

Anything above 10 000 feet (3048 m) unfavourable portion of binding curve !

Question 5

acute mountain sickness (hypoxic hypoxia)

Answer 5

Hypuokapnia induced alkalosis
(increased breathing to compensate, loss of Co2)
Symptoms: fatigue, nausea, rapid heart rate, loss of appetite, dizziness, poor judgement
End of the climb

Question 6

People living at high altitudes

Answer 6

Acclimatization

Question 7

Acclimatization

Answer 7

compensatory mechanisms to assure adequate oxygen supply and normal acid base balance

• Red blood cell production
  (erythropoiesis via erythropoietin)
  –> increase in Hg carrying capacity and O2 binding
  capacity
  –> Synthesis of Diphosphoglycerate/DPG
  (right shift), promoting unloading at tissue level
• Increased capillarization - diffusion distance
  decreased
• Endothelia cells promote 10x higher NO release
  (nitrangin) - vasodilation - increase in blood flow
• Increase in mitochondrial number - increased
  intracellular respiration capacity
  BUT: trade-off: increased viscosity - increased resistance - increased heart work required

Question 8

Group of lung diseases with increased resistance:

Answer 8

chronic obstructive pulmonary disease (COPD)
F=ΔP/R
Air Flow Rate = pressure gradient atmospheric to intra-alveolar / resistance of airways determined by the radius

A larger pressure gradient must be established = more work is required

COPD: Chronic bronchitis, Asthma, Emphysema

Question 9

Primary determinant of resistance to airflow is ____________

Answer 9

the radius of the conducting airway

Question 10

_______ nervous system controls contraction of smooth muscle in walls of bronchioles (changes the radii)

Answer 10

Autonomic

Question 11

Chronic obstructive pulmonary disease (COPD) abnormally increases airway resistance

Answer 11

Expiration is more difficult than inspiration

Chronic bronchitis
Asthma
Emphysema

Question 12

Obstruction causes pressure changes that are unfavorable for gas exchange, leading to ________

Answer 12

bronchial collapse

“wheeze”

Question 13

Airway collapse during forced expiration

Answer 13

In obstructive lung disease, premature airway collapse occurs for two reasons:

(1) the pressure drop along the airways is magnified as a result of increased airway resistance, and
(2) the intrapleural pressure is higher than normal because of the loss, as in emphysema, of lung tissue that is responsible for the lung’s tendency to recoil and pull away from the thoracic wall. Excessive air trapped in the alveoli behind the compressed bronchiolar segments reduces the amount of gas exchanged between the alveoli and the atmosphere. Therefore, less alveolar air is “freshened” with each breath when airways collapse at higher lung volumes in patients with obstructive lung disease.

Question 14

Associated with Obstructive Lung Diseases

Answer 14

Abnormal Spirogram

Question 15

Barrel chested

Answer 15

More air in the lungs but less gas exchange

- More work required to “empty” lungs

Question 16

Cigarette smoke, air pollution, allergens
Narrowed airways
edematous thickening of the airway lining
Overproduction of thick mucus
bacterial infections:
Irritants immobilize ciliary action: mucus remains stationary

Answer 16

Chronic bronchitis

Question 17

Obstruction due to:
Inflammation and histamine-induced edema  wall thickening
Excessive secretion of thick mucus
Airway hyperresponsiveness: profound constriction due to smooth muscle spasms

Treatment: bronchodilator

Answer 17

Asthma

Question 18

Chronic exposure to irritants, cigarette smoke

Characterized by collapse of smaller airways
Breakdown of alveolar walls
Irreversible condition!
Excessive release from alveolar macrophages of protein digestive enzymes: trypsin (excessive  overwhelming protective anti-trypsin)

Huge energetic cost: You don’t get air easily in AND you don’t get air easily out

Answer 18

Emphysema

Question 19

Lungs have elastic recoil

Answer 19

rebound if stretched

Question 20

Emphysema decreases what?

Answer 20

Compliance

Question 21

Heart failure and pulmonary oedema

Answer 21

• Left heart weakened
• Accumulation of fluid in the lung due to increase in hydrostatic pressure in capillaries
• Increased pulmonary blood pressure > capillary filtration exceeds fluid absorption (colloid osmotic pressure) > oedema

Question 22

Respiratory distress syndrome

Answer 22

• When surfactant (pneumocytes II) is missing in the
  new born premature baby
• Collection of symptoms
• Continuous tendency towards alveolar collapse
• The lungs cannot be filled enough, as it is too
  much work against the resistance

Huge effort to inflate the lungs, due to low compliance
Blowing up a balloon, the beginning phase
Alveoli collapse after each expiration (start anew with each breath)
May require a transmural pressure gradient of 20-30 mmHg (normal: 4-6 mmHg)
Weak muscles of the new born
Treatment: surfactant replacement until pneumocytes mature