Anatomy & Physiology Fundamentals Flashcards

The Frank-Starling mechanism of the heart states that increased ventricular preload leads to:

Answer: Increased stroke volume due to enhanced myofilament overlap

The Frank-Starling law describes how greater ventricular filling stretches myocardial fibers, optimizing actin-myosin overlap and increasing the force of contraction and stroke volume.

Nitrogen narcosis experienced by divers at depth is thought to result from nitrogen's effects on which cellular targets?

Answer: Lipid membranes and GABA-A/NMDA receptors in neurons

Nitrogen narcosis is primarily attributed to dissolved N₂ disrupting neuronal lipid membranes and modulating GABA-A (potentiation) and NMDA (inhibition) receptors, mimicking anesthetic effects.

Which pulmonary condition is characterized by destruction of alveolar walls, reducing surface area for gas exchange and causing air trapping, and is a contraindication to hyperbaric therapy due to risk of pulmonary barotrauma?

Answer: Emphysema

Emphysema destroys alveolar walls creating air-trapping bullae that cannot decompress during ascent, posing a severe risk of pulmonary over-inflation injury in a hyperbaric chamber.

The lymphatic system returns interstitial fluid to the bloodstream and plays a role in wound healing relevant to HBOT. Lymph ultimately drains into venous circulation primarily via which structure?

Answer: Thoracic duct emptying into the left subclavian vein

The thoracic duct, the largest lymphatic vessel, drains most of the body's lymph into the venous system at the junction of the left subclavian and internal jugular veins.

Vasoconstriction induced by hyperoxia during HBOT helps reduce edema in crush injuries. This vasoconstriction is mediated primarily by:

Answer: Inhibition of nitric oxide (NO) production and action

Hyperoxia quenches nitric oxide (a potent vasodilator) via superoxide-mediated inactivation, leading to vasoconstriction that reduces edematous fluid accumulation.

The oxygen dissociation curve shifts to the right (Bohr effect) under conditions of increased CO₂ and decreased pH, meaning hemoglobin:

Answer: Releases oxygen more readily to metabolically active tissues

The Bohr effect describes a rightward shift of the oxyhemoglobin dissociation curve in acidic, high-CO₂ environments, facilitating O₂ release where it is most needed.

Which type of hypoxia would be MOST effectively treated with hyperbaric oxygen therapy because HBOT can supply oxygen independent of red blood cell transport?

Answer: Anemic hypoxia from severe hemorrhage or CO poisoning

Anemic hypoxia (including CO poisoning) is ideally addressed by HBOT because dramatically increased dissolved plasma O₂ can sustain tissues even when hemoglobin is unavailable or blocked.