Chapter 21: Blood Vessels

Flashcards for reviewing key vocabulary terms related to blood vessels and circulation.

Arteries

Efferent vessels carrying blood away from the heart.

Veins

Afferent vessels carrying blood toward the heart.

Capillaries

Microscopic vessels connecting small arteries to small veins, important for gas and nutrient exchange.

Tunica interna (intima)

The inner layer of arteries and veins, made of simple squamous endothelium, providing a slick lining for smooth blood flow and a selectively permeable barrier.

Tunica media

The middle layer of arteries and veins, containing smooth muscle, collagen, and sometimes elastin, responsible for vasoconstriction and vasodilation.

Tunica externa/adventitia

The outer layer of arteries and veins, made of loose connective tissue that anchors the vessel to its surroundings.

Vasa vasorum

A network of small vessels supplying large vessels like the aorta and vena cava.

Conducting (elastic) arteries

The largest arteries, like the aorta, that absorb some pressure but also maintain it.

Distributing (muscular) arteries

Midsized arteries that distribute blood to specific organs, like the femoral or hepatic artery.

Resistance arteries or arterioles

The smallest arteries leading up to capillary beds, containing a precapillary sphincter to control blood flow into capillaries.

Metarterioles

A subtype of resistance artery that links arterioles and capillaries.

Capillaries

Exchange vessels where nutrients, wastes, and hormones move between blood and tissue fluid; composed of only endothelium and basal lamina.

Continuous capillary

A capillary type with endothelial cells joined by tight junctions and some intercellular clefts, found in most organs.

Fenestrated capillary

A capillary type with endothelial cells having filtration pores, facilitating exchange, commonly found in the kidneys.

Sinusoid (discontinuous) capillary

A capillary type with irregular passages and wide gaps between endothelial cells, commonly found in the liver and spleen.

Precapillary sphincters

Control the blood flow into capillary beds; relax (open) when tissue is active and close when tissue is inactive.

Veins

Capacitance vessels that contain most of the blood at any given time in the circulatory system.

Postcapillary venules

Very porous veins that allow for some exchange.

Muscular venules

Veins with smooth muscle in their walls (tunica media).

Medium veins

Individually named veins that contain valves.

Skeletal Muscle Pump

Muscle activity squeezes veins and forces blood through one-way valves toward the heart.

Simple path

Circulatory route where blood flows from artery to capillary to vein.

Portal system

Circulatory route with a sequence of two capillary beds.

Anastomosis

Circulatory route involving a vessel merger without an intervening capillary bed.

Pulmonary trunk

Unpaired vessel from the right ventricle that starts the pulmonary circuit.

Pulmonary arteries

Carry oxygen-poor blood in the pulmonary circuit.

Pulmonary veins

Carry oxygen-rich blood back to the left atrium in the pulmonary circuit.

Ascending aorta

The initial section of the aorta that gives rise to the L. & R. Coronary arteries.

Aortic arch

The curved section of the aorta that branches into the brachiocephalic, L. common carotid, and L. subclavian arteries.

Descending aorta

The section of the aorta that descends, divided into the thoracic and abdominal aorta.

Common carotid artery

Artery in the head and neck that branches into the external and internal carotid arteries.

Vertebral artery

Artery in the head and neck that contributes to the basilar artery and cerebral arterial circle (of Willis).

Cerebral arterial circle (of Willis)

An arterial circle in the brain that includes the anterior cerebral, anterior communicating, posterior cerebral, and posterior communicating arteries.

Celiac trunk

Unpaired artery in the abdomen that branches into the common hepatic, L. gastric, and splenic arteries.

Superior mesenteric artery

Unpaired artery supplying blood to the small intestine and part of the large intestine.

Hepatic portal vein

Vein that carries blood from the GI tract to the liver before returning to the heart.

Arteriosclerosis

Stiffening of blood vessels, generally due to aging.

Atherosclerosis

Growth of lipid deposits in arterial walls, often due to poor lifestyle choices, hereditary diseases, or aging.

Foramen ovale

Fetal circulation: Allows blood bypass the lungs by flowing directly from the right atrium through the foramen ovale into the left atrium.

Ductus arteriosus

Fetal circulation: Allows blood bypass the lungs by flowing from the pulmonary trunk through the ductus arteriosus into the aorta.

Ductus venosus

Fetal circulation: Placental blood bypasses the liver by flowing through the ductus venosus into the inferior vena cava (IVC).