.

Question 1

Galen’s open system

Answer 1

Blood is produced in liver
Arteries and veins are distinct
Arteries carrying both blood (derived from venous
blood through invisible interventricular
holes) and pneuma (derived from the
lungs).

Question 2

Harvey’s closed circularity system

Answer 2

Heart centered
Blood circulates

Question 3

….. introduced the term
endothelium

Answer 3

Wilhelm HIS

• He recognized the physiological difference between endothelial
and epithelial cells. However, His did not recognize the
participation of ECs in blood vessel formation

Question 4

Largest endocrine gland

Answer 4

Endothelium

Question 5

Endothelium imple monolayer structure BUT has many important roles to maintain vascular
homeostasis.
• It regulates:

Answer 5

• Blood flow
• Vascular tone
• Vascular smooth muscle cell proliferation
• Thrombosis, thrombolysis, platelet adherence
• Inflammatory responses
• Haemostasis
• It produces and releases vasoactive, thrombo-regulatory and growth factor substances.

Question 6

Vascular endothelial cells, like
most cells, release different
types of membrane vesicles,
including ……………….. in response to
cellular activation or
apoptosis.

Answer 6

microparticles (MP) and exosomes

Question 7

Endothelial microparticles (EMP) (~100
nm to 1 µm in diameter) result from
endothelial plasma membrane blebbing
and carry endothelial proteins such as;

Answer 7

vascular endothelial cadherin, platelet
endothelial cell adhesion molecule-1,
intercellular cell adhesion molecule
(ICAM)-1, endoglin, E-selectin, S-endo
or αv integrin, Endothelial NO synthase
and vascular endothelial growth factor
receptor (VEGF-R2).

Question 8

cells from different locations in the same person express different

Answer 8

surface antigens and receptors

Question 9

…….. between
endothelial cells act as a selective
barrier (e.g. blood–brain barrier)

Answer 9

Tight junctions

Question 10

Endothelium respond to circulating
vasoactive mediators such as

Answer 10

bradykinin and thrombin

Question 11

VASODILATORS

Answer 11

Nitric oxide
✔ Prostacyclin: vasodilator
synthesized from arachidonic acid by endothelial cells
in response to inflammatory mediators
✔ Endothelial‐derived hyperpolarizing factor

Question 12

VASOCONSTRICTORS

Answer 12

✔ Endothelin (ET)
✔ Angiotensin-II (A-II)
✔ Thromboxane-A2 (TXA2)
✔ Free radicals

Question 13

Endothelins

Answer 13

Three members: ET-1, ET-2 and ET-3.
• Regulate vasomotor tone, cellular
proliferation and hormone production.
• ECs produce only ET-1, also syntesized by
vascular smooth muscle cells.
• Production is induced by hypoxia,
ischemia.
• ET-1 binds to specific receptors on smooth
cells→ vasoconstriction.

Question 14

Prostacyclin (PGI2)

Answer 14

• Synthesis is induced by disturbances in endothelial function or
vascular haemodynamics.
• Released from ECs and acts in a paracrine manner. • Binds to a specific receptor on platelets and vascular smooth
muscle cells to limit vasoconstriction and influence platelet
deposition.

Question 15

Nitric Oxide (NO)

Answer 15

• NO is the most abundant free-radical in the body
• It is lipophilic and can diffuse rapidly across biological membranes.
• Short lived, usually degraded or reacted within a few seconds
• The natural form is a gas

Question 16

NO synthesis

Answer 16

L-arginine → L- citrulline
No syntheses

Question 17

3 isoforms of NOS

Answer 17

1.Inducible NOS (iNOS) and
constitutive ones:
2. endothelial NOS (eNOS)
3. neuronal NOS (nNOS)
• eNOS and nNOS are
regulated
by Ca2+ and calmodulin

Question 18

Endothelial cells secrete adhesion molecules:

Answer 18

• E-selectin (expressed by endothelial cells),
• P-selectin (expressed by platelets and endothelial cells),
• intercellular adhesion molecule (ICAM)
• vascular cell adhesion molecule (VCAM)
Endothelial cells regulate leucocyte movement

Question 19

firm cellular adhesion to the endothelial wall

Answer 19

Activation of the leukocytes by
endothelial cell-bound chemokines leads
activation of leukocyte integrins,
another class of adhesion molecules

Question 20

Endothelial cells maintain anticogulant activity:

Answer 20

• Express heparan suphate- stimulates antithrombin III.
• Express tissue factor pathway inhibitor (TFPI)- prevents t thrombin formation

Question 21

Thrombomodulin-thrombin interaction activates

Answer 21

protein C-
strong anticoagulant activity.
• Synthesis of protein S, a cofactor for activated protein C.

Question 22

•Loss of NO bioactivity in the vessel wall causes

Answer 22

an
impairment in endothelium-dependent vasorelaxation

Question 23

NO deficiency in the vessel wall promotes

Answer 23

• Inflammation
• Oxidation of lipoproteins
• Smooth muscle proliferation
• Accumulation of lipid rich material
• Platelet activation and thrombus formation
Finally results in atherosclerosis