respiration 6 Flashcards
Amount of gas in solution is directly proportional to:
the partial pressure of the gas
Effects of depth on the body
- 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
Deep diving marine mammals
- No lung filling with gas under pressure
- Breath at surface, then dive
- Excess lung air expelled
- Change in cartilage distribution: more collapse
under pressure
=less trapped air
Fat absorbs excess nitrogen safely
Effects of heights on the body
- 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 !
acute mountain sickness (hypoxic hypoxia)
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
People living at high altitudes
Acclimatization
Acclimatization
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
Group of lung diseases with increased resistance:
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
Primary determinant of resistance to airflow is ____________
the radius of the conducting airway
_______ nervous system controls contraction of smooth muscle in walls of bronchioles (changes the radii)
Autonomic
Chronic obstructive pulmonary disease (COPD) abnormally increases airway resistance
Expiration is more difficult than inspiration
Chronic bronchitis
Asthma
Emphysema
Obstruction causes pressure changes that are unfavorable for gas exchange, leading to ________
bronchial collapse
“wheeze”
Airway collapse during forced expiration
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.
Associated with Obstructive Lung Diseases
Abnormal Spirogram
Barrel chested
More air in the lungs but less gas exchange
- More work required to “empty” lungs
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
Chronic bronchitis
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
Asthma
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
Emphysema
Lungs have elastic recoil
rebound if stretched
Emphysema decreases what?
Compliance
Heart failure and pulmonary oedema
- 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
Respiratory distress syndrome
- 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
