Cushing's Reflex and Cardiac Physiology Flashcards

Flashcards about Cushing's reflex and cardiac physiology.

Cushing's Reflex

A triad of hypertension, bradycardia, and respiratory depression caused by increased intracranial pressure.

Mechanism of Cushing's Reflex

Increased intracranial pressure constricts arterioles, leading to cerebral ischemia.

Result of Cerebral Ischemia

Cerebral ischemia leads to anaerobic respiration.

Central Sympathetic Activation in Cushing's Reflex

Raising mean arterial pressure to restore perfusion.

Hypertension's Effect on Baroreceptors

Increased stretch activates baroreceptors, triggering peripheral nervous system activation and bradycardia.

Effect of Decreased Blood Pressure on Baroreceptors

Less stretch on baroreceptors leads to increased sympathetic firing.

Effect of Decreased Blood Pressure on Parasympathetic System

It decreases.

Effect of Decreased Blood Pressure on Heart Rate

Increases.

Effect of Decreased Blood Pressure on ANP release

There will be less release of it.

Pulmonary Capillary Wedge Pressure (PCWP)

Approximate of left atrial pressure, except in mitral stenosis where PCWP is more than the left ventricular end-diastolic pressure.

Autoregulation

Blood flow to an organ remains constant over a wide range of perfusion pressures.

Autoregulation in Lungs

In the lungs, hypoxia causes vasoconstriction, directing blood flow to well-ventilated areas.

Autoregulation in Other Organs

Hypoxia causes vasodilation.

Skeletal Muscle Metabolites During Exercise (CHALK mnemonic)

Carbon dioxide, hydrogen, adenosine, lactate, and potassium.

PC

Capillary hydrostatic pressure, which pushes fluid out of the capillary.

PI

Interstitial hydrostatic pressure, which pushes fluid into the capillary.

Function of Plasma Oncotic Pressure

Plasma oncotic pressure, which pulls fluid into the capillary.

Function of Interstitial Fluid Osmotic Pressure

Interstitial fluid osmotic pressure, which pulls fluid out of the capillary.

Edema

Excess fluid outflow into the interstitium.

Edema in Heart Failure

Due to increased capillary hydrostatic pressure.

Increased Capillary Permeability

Toxins, infections, and burns increase it, causing edema.

Edema due to Increased Interstitial Fluid Oncotic Pressure

Caused by lymphatic blockage, which increases interstitial fluid oncotic pressure.

Edema due to Decreased Plasma Proteins

Decreased plasma oncotic pressure, seen in nephrotic syndrome, liver failure, and protein malnutrition.

Truncus Arteriosus

The ascending aorta and pulmonary trunk.