Blood Vessels

Tunica intima

The innermost layer of a blood vessel, composed of a single layer of endothelial cells.

Tunica media

The middle layer of blood vessels, composed primarily of smooth muscle and elastic fibers, responsible for vasomotor function.

Tunica adventitia

The outer layer of a blood vessel, made of loose connective tissue that anchors the vessel to surrounding tissues.

Capillaries

The smallest blood vessels where gas and nutrient exchange occurs between blood and tissues.

Arteries

Blood vessels that carry blood away from the heart, typically with thick walls and small lumens.

Veins

Blood vessels that carry blood back to the heart, typically with thinner walls and larger lumens, containing valves to prevent backflow.

Venule

Small blood vessels formed by the joining of capillaries, which merge to form veins.

Arteriole

Small blood vessels that branch from arteries and lead to capillaries, regulating blood flow.

Vasoconstriction

The narrowing of blood vessels, which increases blood pressure.

Vasodilation

The widening of blood vessels, which decreases blood pressure.

Mean Arterial Pressure (MAP)

The average pressure in a person’s arteries during one cardiac cycle, important for understanding blood flow to organs.

Blood pressure

The force exerted by circulating blood on the walls of blood vessels, measured in mmHg.

Net Filtration Pressure (NFP)

The difference between hydrostatic pressure and osmotic pressure in capillaries, determining the movement of fluid into or out of capillaries.

Hydrostatic pressure

The pressure exerted by a fluid due to gravity, affecting fluid movement in capillaries.

Colloid osmotic pressure

The osmotic pressure exerted by proteins in the blood plasma, important for fluid reabsorption in capillaries.

Epinephrine

A hormone secreted by the adrenal medulla that increases heart rate and blood pressure, causing vasoconstriction.

Renin-Angiotensin-Aldosterone System

A hormone system that regulates blood pressure and fluid balance, responding to decreased blood pressure.

Natriuretic peptides

Hormones released by the heart that lower blood pressure by promoting vasodilation and increasing salt and water loss in urine.

Chemicals affecting blood pressure

Substances like epinephrine, renin, and natriuretic peptides that regulate vascular resistance and volume.