Cardiovascular System Lecture

Vocabulary terms and definitions covering the anatomy, vessel structures, mechanics, and physiology of the human cardiovascular system from the lecture.

Heart

An organ that generates fluid flow by pumping blood out into the blood vessels.

Artery

A blood vessel that carries blood away from the heart and is structured to withstand high pressure.

Vein

A low-pressure blood vessel that returns blood to the heart and contains internal valves to prevent backflow.

Capillaries

Microscopic, delicate blood vessels lacking outer protective layers where gases, nutrients, and wastes enter and exit the blood.

Endothelium

The innermost, smooth cellular layer of a blood vessel that directly touches circulating blood.

Middle layer (blood vessel)

The layer in blood vessel walls composed of smooth muscle and elastic tissue, which is substantially thicker in arteries than in veins.

Elastic tissue

Connective tissue with elastic fibers that enables arteries to stretch under pressure and snap back to their original shape.

Heart attack

A failure of heart function occurring when heart muscle tissue is deprived of sufficient oxygen, often due to a blood clot or arterial plaque buildup.

Atherosclerosis

A condition in which arteries harden and lose their elastic tissue, compromising their ability to stretch and recoil.

Nitrous oxide

A gas released by medications such as nitroglycerin that causes blood vessels around the heart to relax and open up.

Baculum

A penis bone present in many mammals (such as dogs and walruses), but absent in humans.

Arteriole

A small artery that branches off larger arteries and leads into capillary beds.

Venule

A small vein that receives blood directly from capillary beds and channels it toward larger veins.

Precapillary sphincters

Tiny circular muscular rings that squeeze off or open capillary pathways to regulate blood flow into capillary beds.

Lumen

The open interior space of a tube or blood vessel through which fluid flows.

Venous valves

Flap-like structures within veins that prevent the downward backflow of blood, ensuring one-way transit back toward the heart against gravity.

Stroke

A medical emergency caused by a blood clot lodging in blood vessels of the brain, cutting off oxygen delivery.

Aneurysm

A weakening and bubble-like ballooning of the arterial wall layers that carries a risk of rupture under high blood pressure.

Right atrium

The upper right chamber of the heart that receives oxygen-poor blood returning from the rest of the body.

Right ventricle

The lower right chamber of the heart that pumps oxygen-poor blood to the lungs.

Left atrium

The upper left chamber of the heart that receives oxygen-rich blood returning from the lungs.

Left ventricle

The lower left chamber of the heart that pumps oxygen-rich blood out to the entire body.

SA node

The natural pacemaker consisting of specialized tissue in the upper right atrium that generates electrical impulses roughly 70 times per minute to coordinate heart contractions.