arteries and capillaries

Elastic Arteries

Large arteries closest to the heart that contain lots of elastic fibers, allowing them to stretch during systole and recoil during diastole.

Characteristics of Muscular Arteries

Medium-sized arteries that deliver blood to specific organs, containing more smooth muscle and less elastic tissue than elastic arteries.

Function of Elastic Arteries

Smooth out blood pressure fluctuations and maintain continuous blood flow from the heart.

Arterioles

Smallest arteries that control blood flow into capillary beds and are responsive to neural, hormonal, and chemical influences.

Vasoconstriction

Narrowing of blood vessels, which reduces blood flow.

Continuous Capillaries

Most common type of capillary, found in skin and muscles, characterized by tightly joined endothelial cells allowing limited passage.

Fenestrated Capillaries

Capillaries with pores in endothelial cells, making them more permeable for fluids and small molecules.

Sinusoid Capillaries

Leaky capillaries with large gaps, allowing the passage of large molecules and cells, found in the liver, spleen, and bone marrow.

Microcirculation

The circulation of blood in the smallest blood vessels, including capillary beds between arterioles and venules. True Capillaries: Where exchange occurs.

Precapillary sphincters

Sphincters that regulate blood flow into true capillaries.