Ozzoo Flashcards
Describe lung pressure volume relationship. Draw a diagram.
Transmural pressure= Intraalveolar pressure - pressure outside lung.
Pressure decrease outside lung leads to increase in its volume. The curve is S-shaped and has three components.
Increase in pressure leads to small increase in volume (low compliance).
Further increase in the pressure, linear increase in volume (high compliance)
Finally, increase in the pressure causes small increase in volume (low compliance) flat curve.
Deflation curve different than inflation curve, it has low compliance.
Resistance to lung to inflation is due to
Elastic tissue and surface tension. This decrease by surfactant. When filled with saline, it causes very high compliance due to low surface tension.
Outline vascular compliance in artery and vein.
Pressure volume curve
Large arteries has elastic and stiff collagen fibers.
at lower volume, gradual increase in volume leads to gradual increase in pressure (linear relationship high compliance due to stretch of elastic fibers)
At higher volume, small increase in volume leads to marked increase in pressure (steep relationship low compliance) due to stiff collagen fibers
In atherosclerosis, same volume of blood causes marked change in pressure
Veins wide lumen, thin wall and poor elastic fibers.
Large increase in volume results in very little increase in pressure (very high compliance). At higher volume, small increase in volume lead to marked increase in pressure, results in low compliance.
State Law of Laplace and give two physiological applications.
Relation between distending pressure, radius and tension of hollow organs.
In sphere P=2T/r
In cylinder (blood vessel) P=T/r
Two examples:
Urinary bladder: Volume from 50-400 will increase T and r so pressure remains constant. (high compliance)
In stomach: stretch of the wall increases T and r which leads to constant pressure. (High compliance)
State Posieuli equation and describe its importance in vascular system.
The law describes the factors affecting blood flow in the vascular system.
Flow=∆P/Resistance
∆P: change in pressure from high to low across the blood vessels. Increase in ∆P increase in blood flow.
In healthy elastic blood vessels, increase in P leads to decrease in Resistance which leads to increase in flow. In rigid blood vessels, has less flow compared to healthy.
Resistance: affected by:
Increase radius, decreases the resistance
Length: increase length increase resistance (positive relation)
Viscosity: Increase in viscosity will increase the resistance.
Acclimatization to high altitude.
Adjustment to chronic hypoxia via compensatory mechanisms to increase PO2 and O2 supply to tissue.
Hyperventilation:
Primary: hypoxia —> +peripheral chemoreceptor—-> hyper ventilation. Hyperventilation can lead decrease in PCO2 negative respiratory center.
Secondary: gradual correction of decrease of CO2 –> increase inhibition of respiratory center—> hyperventilation.
Pulmonary hypertension: Vasoconstriction of pulmonary vessels to improve gas exchange.
Increase HR and CO through stimulation of peripheral chemoreceptor.
Increase RBCs: due to activation of erythropoietin
At cellular level: increase number of mitochondria. Increase 2,3 DPG in RBCs. Increase number of capillaries in skeletal and cardiac muscle.
Stagnant hypoxia definition
Inadequate blood flow to the tissue
causes: generalized cardiac failure or circulatory shock. Localized obstruction by embolus or thrombus.
Characterized by: in arterial blood normal PO2, O2 content and hemoglobin saturation. In venous blood, low PO2, O2 and hemoglobin saturation.
Cyanosis generalized or localized
Hypoxic hypoxia
inadequate oxygenation of arterial blood.
Causes: decrease O2 in inspired air. Impaired ventilation (obstructive or restrictive lung disease or respiratory center depression). Impaired diffusion (pulmonary edema or pulmonary fibrosis). V/Q imbalance.
Character: in both venous and arterial PO2, O2 and Hb content low.
Cyanosis is visible.
Anemic hypoxia
due to decrease hemoglobin available to carry oxygen.
Causes: decrease in hemoglobin and abnormal hemoglobin (like CO poisoning)
Treatment: hyperbaric oxygen.
Character of hypoxia: no cyanosis. In arterial blood PO2 normal, normal Hb saturation, decrease O2 content. In venous blood all is low.
Changes in w
