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Flashcards in Vascular System - Lough Deck (18)

In order to avoid metabolic starvation, how close must a cell be to a blood supply?

Oxygen diffusion fails beyond 200µm.


What are the 3 tunics that surround blood vessels?

What do they each contain?

Which is outermost?

Tunica Adventitia (outer; connective tissue)

Tunica Media (middle; smooth muscle & CT)

Tunica Intima (inner; endothelial cells)


Which vascular tunic expresses PECAM?

What else does this molecule go by?

Tunica Intima; PECAM is expressed by endothelial cells?



Describe the composition of each of the 3 layers of heart tissue.

Endocardium (simple squamous epithelial with basal lamina)

Myocardium (myocytes & fibroblasts)

Epicardium (simple squamous; may house adult stem cells)


What do epicardial cells give rise to during development?

Cardiac fibroblasts

Coronary arteries

Cardiac myocytes (?)


Describe the composition and function of large vessels.

How many layers of SMC are present?

Large vessels have elastic adventitia (*thickest layer*), thick media, and nonpermissible intima (tight junctions).

Function is to be elastic to maintain blood pressure.

40-70 layers of SMCs here.


Describe the composition and function of medium vessels.

How many layers of SMC are present?

Thinner & less elastic media. Internal elastic intima. 

Function is regulation of blood pressure.

About 40 layers of SMCs here.


In a nutshell, how do foam cells cause atherosclerosis?

Where does this occur?

Foam cells (eg Macrophages, SMCs) ingest LDLs and form plaques which can calcify and obstruct or embolize.

Occurs in medium (& some large) vessels.


Contrast the composition of a vein's wall to that of an artery.

Adventitia tends to predominate. Media and intima layers are much smaller--SMC remains, but much less of it.


Describe the composition and function of small vessels.

How many layers of SMC are present?

Tunica media contains 8 or fewer SMC layers.

Function is to regulate bloodflow to capillary beds.


Describe the composition and function of capillaries.

How many layers of SMC are present?

Only a single squamous epithelial cell with basal lamina. Forms tight junctions with other endothelial cells (or itself) to circumscribe a lumen.

Functions (usually) to facilitate exchange of small molecules.

No smooth muscle here.



Distinguish between the vessel wall permeability of Types I, II, and III capillaries.

Type I has tight junctions which only gases and very small molecules may pass. Pinocytotic vesicles for anything substantial.

Type II has 0.1µm windows ("permanent pinocytotic vesicles") which are big enough to permit some proteins.

Type III has large discontinuities, and can permit whole cells to escape or enter.


Give the capillary type that best fits each description.

Found in CNS.

30µm in diameter.

Found in bone marrow.

Found in kidneys.

Type I

Type III

Type III

Type II


What are the two primary functions of endothelial cells?

1. Exchange gases, nutrients & wastes.

2. Secrete regulatory molecules.


What factors are secreted by endothelial cells? What do they do?

Endothelin: Vasoconstriction

NO: Vasorelaxation

FGF/PDGF/VEGF: Growth factors for injury repair & angiogenesis.


What is angiopoietin-1's function?

What receptor does it bind to?

What clinical benefit could this have?

Involved in angiogenesis signaling.

Binds TIE-2.

Controlling angiogenesis could increase perfusion of ischemia tissues (eg diabetic leg).


What factors classically inhibit angiogenesis?

What are some clinical applications of this?

Angiostatin, endostatin.

Combat tumors, which are metabolically limited & rely on angiogenesis to grow.


What class of drug is Bevacizumab?

What is its trade name?

What is its mechanism of action?

Monoclonal Antibody.


Targets and binds VEGF-A, inhibiting it.