Cellular, Organ, and Hemodynamic Principles of the Cardiovascular System (copy)

Caenorhabditis elegans

A free-living nematode (roundworm) approximately 1 mm in length, lacking specialized circulatory and respiratory systems.

Hemolymph

The fluid in open circulatory systems, bathing the internal tissues directly before returning to the heart.

Ostia

Perforations in the heart that allow hemolymph to drain back into the heart in open circulatory systems.

Closed Circulatory Systems

Systems that maintain distinct blood and interstitial fluid compartments, with fluid exchange occurring across capillaries.

Bulk Flow

The mass movement of a fluid down an absolute pressure gradient, essential for nutrient and gas transport.

Poiseuille’s Law

The law that describes the volumetric flow rate of a fluid through a cylindrical conduit as influenced by pressure gradient, viscosity, and radius.

Cardiac Output (CO)

The total volume of blood pumped by a ventricle per unit time, calculated as heart rate multiplied by stroke volume.

End Diastolic Volume (EDV)

The maximum blood volume inside the relaxed ventricle at the end of diastole.

Baroreceptor Reflex Arc

The mechanism by which baroreceptors respond to changes in blood pressure to regulate autonomic outputs and maintain homeostasis.

Sympathetic Autonomic Pathway

The pathway that increases heart rate and vascular resistance through norepinephrine release, mainly acting on beta-adrenergic receptors.

Starling Forces

The forces governing fluid movement across capillary walls, encompassing hydrostatic and colloid osmotic pressures.

Lymphatic System

The network responsible for draining excess interstitial fluid, returning it to the venous circulation.

Fluid Filtration

The process by which fluid moves out of capillaries into the interstitium, driven by hydrostatic pressure.

Transcytosis

The process by which large molecules cross the endothelial barrier via vesicular transport.

Pacemaker Potential

The spontaneous depolarization that occurs in autorhythmic cells, leading to action potentials in the heart.

Ventricular Ejection

The phase of the cardiac cycle when blood is expelled from the ventricles into the arteries.

Vascular Resistance

The opposition to blood flow within the vasculature, primarily influenced by the diameter of blood vessels.

Elastic Arteries

Large arteries that expand during systole and maintain pressure through elastic recoil during diastole.

Isovolumetric Contraction

The phase when the ventricles contract but no blood is ejected due to closed valves, increasing pressure without changing volume.

Echocardiography

A diagnostic tool using ultrasound waves to create images of the heart structure and function. This can assess conditions such as heart failure.

Negative Chronotropy

The decrease in heart rate due to parasympathetic stimulation, primarily mediated through the vagus nerve.