Vascular system

Question 1

BV walls have 3 tunics

Answer 1

Tunica adventitia- outer (CT)
Tunica media- variable, SMCs and CT
Tunica intima- inner- an endothelium and endo thelial cells (simple squamous and basal lamina, continous or discontinous

Question 2

The hear tunics

Answer 2

Endocardium (tunica intima- simple squamous endothelium/basal lamina)

Myocardium (Myocytes and fibroblasts, attaches to a dense CT skelton)

Epicardium (simple squamous)- During devlopment, epicardium over the monocellular covering

Question 3

Large vessels

Answer 3

Large elastic arteries:
Adventitia (external elastic membrane) thick wall (external elastic membrane)

Media: thickest (circular SMCs with 40-70 elastic lamellae), lamellae increase with age hypertension

Initima :ECs (continouous): tight junction and pinocytotic vesicles

Function: elastic recoil to maintain BP during diastole
Clinical Aneurysm

Large veins: thin wall, the adventitia is the thickest tunic in large veins

Question 4

Medium Vessels

Answer 4

Medium (muscular) arteries (adventitia, media (prominent 40 layers SMC, less elastin), intima (internal elastic lamina)

Function SMCs regulate BP

Atherosclerosis: intimal plaques caused by foam cells, macrophages ingest LDL, SMCs migrate ti the intima and ingest LDL

Plaques calcify, platlets attach–> thrombus–> MI/stroke

Question 5

Small vessels

Answer 5

Small arteries and arterioles in the capillary bed
t media: 8 layers in small artery 2 layers in arterioles

Function: SMCs regulate blood flow to the capillary bed

Lipid uptake by SMCs narrows the lumen–> hypertension

Question 6

Capillaries

Answer 6

Diameter of the lumen accept (RBC-7.5um) 1 endothelial cell can make up the tube
Simple squamous endothelium w/ basal lamina (no media or adventitia)

Question 7

3 types of capillaries

Answer 7

Type 1: continuous (tight junctions pass proteins only), pinocytotic vesicles pass larger proteins

Type 2 fenestrated: 100 nm window= permanent pinocytotic vesicles

Type 3 sinusoidal- have discontinuities between adjacent ECs

Question 8

Functions of endothelial cells

Answer 8

Exchange gases and nutrients (gases: thru cell membrane, nutrients: thru pinocytotic vesicles, fenestrations, discontinuities)

Secrete regulatory molecules (vasoactive factors- endothelin is a constrictor NO is a relaxant)

GF: FGF-fibroblast, PDGF platelet derived frowth factor, VEGF_

Question 9

Angiogenesis

Answer 9

activation of EC receptors, inhibition of angiogenic growth
Vasculogenesis–embryonic BV development
Angiogenic activators (ECs are the Target) Ligands and receptors (VEGF, FGF, Angiopoietin, w/ VEGFR, FGFR, TIE-2). Angiogenic inhibitors (angiostatin, endostatin, Avastin)

Clinical therapies: Proangiogenic (for ischemia in heart and extremities (VEGF, FGF)

Antiangiogenic (combat tumors, 1 EC can support 50 tumor cells, Angiostatin and endostatin inhibit new BV growth)