Cardiovascular and Respiratory Physiology Review

A comprehensive vocabulary review of cardiovascular blood flow, pericardial pathologies, cardiac electrophysiology, respiratory reflexes, and chemical control of ventilation based on the lecture transcript.

Pulmonary artery

The artery that carries less oxygenated blood from the heart to the lungs to participate in gas exchange.

Fibrous pericardium

The tough, loose-fitting, and elastic tissue layer that directly surrounds the heart.

Serous pericardium

The fluid-containing sac around the heart consisting of an inner parietal layer and an outer visceral layer.

Pericardial effusion

The abnormal accumulation of fluid, blood (such as from trauma), or pus (from infection) within the pericardial space.

Cardiac tamponade

A potentially fatal condition that occurs when fluid accumulation in the pericardial space becomes large enough to impair the pumping ability of the heart.

Pericarditis

Inflammation of the pericardium surrounding the heart.

Pulseless Electrical Activity (PEA)

A condition in which organized electrical activity is visible on a cardiac monitor, but cardiac mechanical contractions are insufficient to produce a palpable pulse or circulate blood.

Refractory period

The time interval following muscle contraction during which the heart muscle cannot contract again, even upon receiving a new electrical signal.

Synchronized cardioversion

The administration of an electrical shock synchronized to deliver outside of the heart's refractory period to avoid damaging cardiac tissue.

Saddle PE

A critical blood clot lodged at the bifurcation of the pulmonary artery that completely blocks perfusion to both lungs, causing a severe V/Q mismatch and rapid mortality.

Baroreceptors

Sensory receptors that detect vascular stretch and blood pressure changes, utilizing a negative feedback loop to decrease elevated blood pressure or increase low blood pressure.

Vasopressors

Medications that induce peripheral vasoconstriction to maintain systemic blood pressure and organ perfusion, with prolonged use risking peripheral tissue necrosis.

P wave

The electrocardiographic waveform corresponding to atrial systole.

Lub

The first heart sound, coinciding temporally with atrial systole.

Dub

The second heart sound, coinciding temporally with ventricular systole.

Hering-Breuer inflation reflex

A reflex triggered during high tidal volumes where pulmonary stretch receptors send an inhibitory signal via the vagus nerve to dorsal respiratory group ($\text{DRG}$) neurons to halt inhalation and prevent lung overexpansion.

Deflation reflex

A respiratory reflex triggered by the sudden collapse of the lung that stimulates the drive to inhale.

Irritant receptors

Receptors situated along large conducting airways that respond to dust or toxic fumes by triggering vagal sensory pathways to induce coughing, sneezing, bronchoconstriction, and tachypnea.

J receptors (Juxtacapillary receptors)

Sensory C-fiber endings in the lower lung parenchyma near pulmonary capillaries that respond to alveolar inflammation, congestion, or edema by stimulating rapid shallow breathing, a sensation of dyspnea, and glottic narrowing.

Peripheral chemoreceptors

Sensory cells located in the carotid bodies that respond rapidly to arterial hydrogen ions, decreased $PaO_2$, and increased $PaCO_2$, accounting for $20\%$ to $30\%$ of the ventilatory response to hypercapnia.

Central chemoreceptors

Receptors in the brainstem that respond to increases in hydrogen ions generated by $CO_2$ crossing into the cerebrospinal fluid, producing the dominant drive to breathe.

Hypoxic drive

A breathing drive triggered by decreased arterial oxygen, functioning as the primary stimulus to breathe in patients with chronic hypercapnia whose $CO_2$ receptors have become desensitized.

Oxygen-associated hypercapnia

A condition in chronically hypercapnic patients where high concentrations of supplemental oxygen satisfy the hypoxic drive, leading to hypoventilation and excessive retention of $CO_2$.

Target $SpO_2$ for COPD

An arterial oxygen saturation goal typically maintained between $88\%$ and $92\%$ to avoid blunting the hypoxic drive in carbon dioxide retainers.

Craniotomy

A surgical opening and removal of a section of the skull, sometimes temporarily stored within the patient's abdomen, to allow brain tissue to swell outward without causing fatal compression.