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Comprehensive Exam - Histology

Terms in this set (54)

Elastic artery - Conducting vessels
● Low resistance
● Intima: endothelium; connective tissue (CT) with
smooth muscle (SM)
● Media: THICK ABUNDANT ELASTIC FIBERS ALTERNATING WITH LAYERS OF SMOOOTH MUSCLE
● Adventitia: connective tissue with vasa vasorum (microvasculature supplying the adventitia of large vessels)
● Defining characteristic=very large tunica media



Muscular artery
Intima: endothelium; CT with SM. PROMINENT INTERNAL ELASTIC LAMINA
● Media: MANY LAYERS OF SMOOTH MUSCLES LESS ELASTIC MATERIAL
● Adventitia: connective tissue, vasa vasorum may
be present
● Distinguishing feature: prominent internal elastic
lamina in the tunica intima
Prominent internal


Small artery
Compare with arterioles based on number of layers of smooth muscle in tunica media, small arteries have about 10, arterioles have about 1-3.


Arteriole
Resistance vessels, primary site of vascular resistance
● Compare with small arteries (1-3 layers)
● Intima: endothelium, NO CONNECTIVE TISSUE OR SMOOTH MUSCLE
● Media: 1-3 layers of SMOOTH MUSCLE
● Adventitia: very thin connective tissue (less/no
vasa vasorum)


Capillaries general
Exchange vessels
● Pericytes: small cells that surround the
endothelial cells
● Intima: endothelium only (like the arterioles)
● Media: "non" pericytes
● Adventitia: none

Continuous capillaries
Most common
● Uninterrupted vascular endothelium
● Continuous basement membrane



Fenestrated capillaries
-Numerous openings in the capillary wall
● Continuous basement membrane
● Found in: kidneys, intestine, choroid plexus,
endocrine glands




Discontinuous/si nusoidal capillaries
Large diameter and larger openings
● Intercellular gaps
● Discontinuous basement membrane
● Found in: liver, spleen, some endocrine glands,
bone marrow

Venule
<.01mm● Large diameter with relatively thin wall

Small, medium, large vein

Small: <1mm
● Medium: varied
● Large: 10mm
Luminal diameter exceeds thickness of wall
● Intima: well developed, forms valves
● Media: relatively thin, few layers of SM
● Adventitia: CONNECTIVE TISSUE, gets thicker as it advances

Valves (medium and large veins): folds of intima
and subendothelial CT, projects into lumen

● Differentiates from arteries with thing wall, less
SMOOTH MUSCLE, and valves (if present)


Lymphatic capillaries
-Close-ended, very thin
● Incomplete basal lamina
● Interstitial fluid enters openings between endothelial cells