Capillaries

Question 1

Capillaries are microscopic vessels that allow

Answer 1

For exchange of substances between blood and tissues

Question 2

Continuous capillaries

Answer 2

• consists of endothelial cells that completely encircle lumen surrounded by complete basement membrane
• function to move small nutrients and wastes through simple diffusion (gases)
• most common capillary found in muscles and skin

Question 3

Fenestrated capillaries

Answer 3

—similar to continuous but contain fenestrations (windows)

• allow more capillary exchange and slightly larger molecules to be absorbed into and filtered out capillaries
• typically found in small intestines and kidneys

Question 4

Sinusoidal capillaries

Answer 4

• consists of endothelial cells that do not completely encircle lumen with incomplete or absent basement membrane
• function to move large substances such as formed elements and plasma proteins
• typically found in red bone marrow, liver, spleen, and some endocrine glands

Question 5

Capillary bed

Answer 5

• made up of capillaries that serve the tissues of small area
• you cannot perfuse all capillaries at once
• capillaries generally alternate between state of receiving blood (perfusion) and state of little to no blood flow depending on tissue needs