Lecture 28: Cardiovascular Histology

Question 1

List the three tunics of the heart wall

Answer 1

Endocardium, Myocardium, Epicardium

Question 2

Endocardium

Answer 2

Innermost layer of heart wall which lines atria and ventricles; contains endothelium and subendothelial connective tissue. Continuous with tunic intima of blood vessels that enter/leave the heart.

Question 3

Subendocardium

Answer 3

Layer located between endocardium and myocardium; contains nerves and Purkinje fibers

Question 4

Myocardium

Answer 4

Contains cardiac muscle cells

Question 5

Epicardium

Answer 5

External surface covered by simple squamous epithelium (mesothelium). Mesothelium overlies fibroelastic connective tissue containing adipose cells, nerves, and coronary vessels

Question 6

Cardiac skeleton

Answer 6

Dense collagenous connective tissue; myocardial fibers originate and insert into cardiac skeleton

Question 7

Tunica intima

Answer 7

Contains endothelium and basal lamina, subendothelial connective tissue, internal elastic membrane

Question 8

Tunica media

Answer 8

Made up of circular smooth muscle tissue and fibroblasts; contains collagen and elastic fibers

Question 9

Tunica adventitia

Answer 9

Outermost layer; lacking in arterioles, consists of loose areolar tissue w/ irregular fibroelastic tissue and adipocytes; small vessels and nerves (vasa vasorum, nervi vasorum)

Question 10

Elastic arteries

Answer 10

Conducting arteries, stretch during systole/recoil during diastole; tunica media=layers of elastic fibers organized in to laminae

Examples: aorta, pulmonary trunk, large branches of aorta

Question 11

Muscular arteries

Answer 11

Distributing arteries; tunica media = smooth muscle responding to ANS stimulation/hormones (gradual transition from elastic to muscular artery)

Examples: all named arteries in body except elastic ones

Question 12

Arterioles

Answer 12

Small arteries that LACK a tunica adventitia; tunica media = 1-3 layers of smooth muscle; mean arterial pressure depends on proper tone of smooth muscle; give rise to metarterioles which have a DISCONTINUOUS layer of smooth muscle

Question 13

Continuous capillary

Answer 13

Found in muscle, brain, thymus, bone, lung, etc,
Caveolae/vesicles transport substances by transcytosis.

BASAL LAMINA and CYTOPLASM = continuous.

Question 14

Fenestrated capillary

Answer 14

Found in tissues that transport fluid (intestinal villi, choroid plexus, ciliary processes of eyes)
Fenestrae are present which make membrane leaky.

BASAL LAMINA = continuous

Question 15

Discontinuous capillary

Answer 15

Leakiest-larger gaps than in fenestrated; found in the spleen
BASAL LAMINA = discontinuous (sometimes fragmented or absent)

Question 16

Veins

Answer 16

Compared to arteries: larger lumen, thinner wall, valves present in many veins

Question 17

Atherosclerotic plaque development

Answer 17

Hypercholesterolemia causes LDL deposits in artery. Development in the tunica intima consits of atheroma core and fibrous cap; MMPs and cytokines produced that weaken fibrous cap. Thrombosis is caused by procoagulant tissue factor of macrophages, leading to obstruction/occlusion in lumen of artery

VCAMs, macrophages, LOLs, SR-As involved