Histology Flashcards
What are the 3 layers of every macroscopic vessel?
tunica adventitia
tunica media
tunica intima
What’s tunica adventitia?
Collagenous connective tissue, loose to dense
Role of tunica adventitia?
Anchorage, support (transgenic mice deficient in type I collagen gene prematurely die with ruptured arteries), elasticity
Carries nerve + blood supply to vessel (vasa vasorum in larger vessels)
What’s tunica media?
smooth muscle
Role of tunica media?
Support, elasticity, contractility (tone).
Physical regulation of blood flow.
Smoothing of blood flow of elastic arteries
What’s tunica intima?
Endothelium, over a little dense connective tissue
Role of tunica intima?
Selectively permeable barrier to blood.
Regulated adhesion of platelets + leukocytes
Makes mediators controlling vessel tone (maintained by tunica media), eg NO, endothelins
Makes mediators of inflammation
Diff between 3 layers in artery vs vein?
Artery: thick T.media>T.adventitia, round, wall>internal diameter
Vein: thin T.media, oval, internal diameter>wall
Diff types of arteries?
elastic (conducting arteries)
muscular
arterioles
eg of elastic (conducting arteries)?
aorta, pul arteries + their largest branches: brachiocephalic, common iliac
Features of elastic (conducting arteries)?
Thick T.media with many elastic laminae (sheets of elastin/lamellae)
Role of elastic (conducting arteries)?
Absorb systolic flow by stretching + continue blood flow in diastole by elastic recoil
How do elastic arteries look with H/E stain?
Smooth muscle cells: purple nuclei, pink cytoplasm
Elastic laminae: darker pink
How do elastic arteries look with EVG (elastic-Van Gieson) stain?
collagen: red
cytoplasm: yellow
elastin: brown/black
elastic laminae: brown
What damage happens in AAA?
Partial rupture of arterial wall, with blood entering T.media, fatal if T.adventitia also ruptures.
Features of muscular (distributing) arteries?
0.3mm diameter (40 🔴 wide)
Contractile - regulate blood flow + BP
How diff types of arteries merge into another?
Elastic -> muscular -> arterioles
How do muscular (distributing) arteries look with EVG (elastic-Van Gieson) stain?
collagen: red
cytoplasm: yellow
elastin: brown/black
Prominent internal elastic lamina, single, between intima and media
Thick T.media with some elastic fibres but no elastic laminae
External elastic lamina, several thin, discontinuous laminae, in adventitia at inner edge
Adventitia: red collagen
Main diff between elastic vs muscular arteries?
ELASTIC: many elastic laminae in T.media
MUSCULAR: single internal + external elastic laminae at edges of T. media.
Where are atheromas?
in T.media
Role of muscular (distributing) arteries?
Contractile to regulate BP + flow
Features of arterioles?
Microscopic, < 0.3 mm wide.
Difference from small arteries is arbitrary, there’s a continuum of sizes.