Cardiovascular System Histology Quiz and Flashcards

Study Notes

Cardiovascular System Composition

The cardiovascular system is composed of arteries, arterioles, veins, venules, capillaries, and the heart.

Blood Vessel Layers

The walls of blood vessels consist of three concentric layers: tunica intima, tunica media, and tunica adventitia.
The tunica intima is the inner layer, abutting the vessel lumen.
The tunica media is the middle layer, sandwiched between the intima and adventitia.
The tunica adventitia is the outer layer, abutting the perivascular soft tissue.

Artery Structure

The tunica intima consists of endothelium, subendothelial connective tissue, and internal elastic membrane.
The tunica media is the thickest layer, composed of abundant elastic tissue and smooth muscles.
The tunica adventitia is composed of dense irregular connective tissue, separated from the tunica media by external elastic lamina.

Medium Arteries

Medium or muscular arteries distribute blood to all organs, using their thick muscular walls to maintain steady blood pressure.

Small Arteries and Arterioles

In small arteries and arterioles, the media is abundant in smooth muscle cells that vasoconstrict or vasodilate.
Smooth muscle contraction causes dramatic changes in lumen diameter.

Vein Structure

The walls of veins are thinner than the walls of arteries, while their diameter is larger.
The tunica intima is very thin, with only the largest veins containing notable amounts of subendothelial connective tissue.
Internal and external elastic laminae are absent or very thin.
The tunica media appears thinner than the tunica adventitia, and the two layers tend to blend into each other.

Capillaries

There are three types of capillaries: continuous, fenestrated, and sinusoid.
Continuous capillaries consist of endothelial cells resting on a basal membrane, with pericyte and pinocytotic vesicles.
Capillaries contain a single layer of endothelial cells and their basement membrane.
The lumen of capillaries is so narrow that red blood cells have to pass in singly.
Capillaries facilitate exchange of gases and small molecules between the bloodstream and surrounding tissue.

Heart Structure

The heart is a muscular organ that pumps blood through the blood vessels of the circulatory system.
The wall of the heart consists of three layers: endocardium, myocardium, and epicardium.
The endocardium is composed of a continuous endothelial lining, with attendant basement membrane.
The myocardium is a layer of cardiomyocytes that lies between the endocardium and epicardium.
The epicardium is lined by a layer of flat mesothelial cells that lie on top of a layer of collagenous tissue.

Heart Valves

The heart has four valves composed of connective tissue layered with endothelium on each side.
The valves consist of three layers: spongiosa, fibrosa, and ventricularis.

Description

Test your knowledge on the cardiovascular system's anatomy with a focus on arteries, veins, capillaries, and the heart. Understand the three layers of blood vessel walls and their functions. Prepared by Dr. Hassna Bader Jawad for 2nd-year Second Term students.