Blood Vessels

Which layer of the blood vessel contains smooth muscle and elastic fibers?

• Tunica intima

• Tunica media

• Tunica externa

• Basement membrane

What is the function of the valve in the vein as shown in the diagram?

• To prevent the backflow of blood.

• To increase the speed of blood flow.

• To filter impurities from blood.

• To supply oxygen to the blood.

Which blood vessel has the thickest tunica media?

• Artery

• Vein

• Capillary

The capillary wall is composed of ________ and ________.

• endothelium, basement membrane

• smooth muscle, connective tissue

• epithelium, elastic fibers

• fibroblasts, collagen

Which part of the diagram serves as a vascular shunt when precapillary sphincters are closed?

• Arteriole

• Precapillary sphincter

• Metarteriole

• Arteriovenous anastomosis

What are the features of continuous capillaries?

• Tight junctions + desmosomes

• Fenestrations + pores

• Discontinuous basement membrane

• Large intercellular gaps

Where are continuous capillaries found?

• Muscle, lungs, adipose, in CNS no intercellular channel

• Liver, spleen, bone marrow

• Kidney glomeruli, intestinal villi, endocrine glands

• Skin, gastrointestinal tract, lymph nodes

What are the features of fenestrated capillaries?

• Wide pores covered by mucoproteins – more open for more exchange

• Thick basement membrane with no pores

• Completely impermeable to water and solutes

• Lined with cilia for active transport

Where are fenestrated capillaries found?

• Kidneys, endocrine glands, intestines – areas of filtration

• Liver, spleen, bone marrow – areas of blood cell production

• Skin, muscles, lungs – areas of gas exchange

• Heart, brain, spinal cord – areas of neural activity

What is the order of vessels?

• Artery → Arterioles → Capillaries → Venules → Veins

• Vein → Venules → Capillaries → Arterioles → Artery

• Capillaries → Arterioles → Artery → Veins → Venules

• Arterioles → Artery → Capillaries → Veins → Venules