The Endothelial Cell

Question 1

The exact location of the endothelium in the cardiovascular system

Answer 1

In the endocardium layer of the heart; it lines the entire circulatory system

Question 2

What function does the endothelium play as a barrier between the blood and other structures of the circulatory system?

Answer 2

It is a thin barrier that allows blood to move more smoothly and therefore circulate more quickly through out the body

Question 3

List the four primary types of tissue in the body

Answer 3

1) Epithelium 2) connective tissue 3) nervous tissue 4) muscle tissue

Question 4

Describe why the endothelium has a selectively permeable membrane

Answer 4

It’s lipid structure permits lipid-soluble molecules such as O2, CO2, and anesthetics to cross between blood and tissue

Question 5

What role does the glycocalyx play as part of the endothelium

Answer 5

A coating of biopolymers on the lumen surface, forms a semipermeable layer, reflects plasma proteins but permits the passage of smaller solutes and water.

Question 6

List and describe the different functions of the endothelium (there are seven of them)

Answer 6

see individual cards for each function

Question 7

Function 1 of the endothelium

Answer 7

Regulates blood-tissue exchange through a semipermeable membrane that retains plasma & blood cells inside the circulation, yet permit nutrient transfer into the tissues.

Question 8

Function (1) of the endothelium

Answer 8

Regulates blood-tissue exchange through a semipermeable membrane that retains plasma & blood cells inside the circulation, yet permit nutrient transfer into the tissues.

Question 9

Function (2) of the endothelium

Answer 9

Regulates vascular tone; secretes vasoconstrictor peptide and three vasodilator agents: nitric oxide, endothelium-derived hyper-polarizing factor, and prostacyclin

Question 10

Function (3) of the endothelium

Answer 10

Surface enzymes modify vasoactive peptides in the blood stream, angiotensin-converting enzyme is a primary enzyme modifier of circulating vasoactive peptides.

Question 11

Function (4) of the endothelium

Answer 11

Secretes both anti-thrombotic and pro-clotting factors. Nitric oxide & prostacyclin, but also inhibit platelet aggregation. Also secretes von Willebrand factor (a component of the clotting cascade).

Question 12

Function (5) of the endothelium

Answer 12

Participates in the inflammatory defense against pathogens,

venular endothelium inserts adhesion molecules in an inflamed tissue in order to capture circulating leukocytes & promote their migration in the source of inflammation.

Question 13

Function (6) of the endothelium

Answer 13

Initiates new blood vessel formation (angiogenesis).

Question 14

Function (7) of the endothelium

Answer 14

Endothelial dysfunction contributes to atheroma (abnormal fatty deposit in an artery); this is the single biggest cause of morbidity and mortality.

Question 15

Differentiate and summarize functions of the endothelium

Answer 15

• angiogenesis (growth of new blood vessels), serve as a barrier
• control development of heart muscle in embryo
• regulate function of myocardium
• inflammation, immune response, atherosclerosis
• endothelial dysfunction, atherosclerosis
• loss of healthy endothelial function associated w/ smoking, CAD, diabetes, hypercholesterolemia, high BP

Question 16

What role does actin-myosin structure play as part of the endothelium?

Answer 16

actin-myosin cytoskeleton provides shape & structure: anchors surface molecules, anchors intracellular junction, resists the shearing effect of the blood stream.

Question 17

What are intercellular clefts?

Answer 17

Provides a pathway for water and nutrient transfer; small lipids-insoluble solutes, glucose, amino acids, and drugs can cross the endothelial barrier here

Question 18

What are gap junctions

Answer 18

arterial endothelium-transmit signal: homo-cellular - transmit ions, membrane potential, chemical messages between cells. Hetero-cellular conveys signals between endothelium & underlying vascular smooth muscle. Together, they cause ascending vasodilation along small arteries.

Question 19

Describe Intercellular cleft

Answer 19

20 nm wide and occupy only 0.2 - 0.4% of the capillary surface. Provides pathway for water and small, lipid-insoluble solutes

Question 20

Describe intercellular gap junction

Answer 20

proteins form holes between adjacent cells allowing ions and molecules to pass freely between cells

Question 21

Describe the function of the glycocalyx

Answer 21

negatively charged barrier to macromolecules. “Sugar coat” located on the outer surface, semipermeable membrane allows small solutes but not plasma proteins or LDL to pass through.
Functions: a) aids in attachment of some cells (b) binds antigens and enzymes to cell surface (c) facilitates cell-cell recognition (d) protects cells from injury (e) assists T cells and antigen-presenting cells to align with each other

Question 22

Describe why the basal lamina is an important part of the endothelium

Answer 22

prevents capillary rupture by blood pressure.

Question 23

What are ion channels

Answer 23

channels that influence intracellular Ca2+ ion concentration & regulate functions: nitric oxide production & hyper-permeability of inflammation

Question 24

Describe EDRF and its relationship to nitric oxide

Answer 24

Endothelium-Derived Relaxing Factor: nitric oxide. Acetylcholine stimulates the release of this vasodilator.

Question 25

Describe why endothelin’s are an important part of the cardiovascular system

Answer 25

Endothelin: vasoconstrictor peptide. Contributes to basal vascular tone.

Question 26

List and describe the effects of nitric oxide on the cardiovascular system

Answer 26

1) lowers vascular tone in veins, large arteries.
2) contributes to gap formation in venules during inflammation.
3) inhibits platelet aggregation; protects from thrombosis
4) inhibits vascular myocyte proliferation (component of atheroma)
5) inhibits transcription of leukocytes binding adhesion molecules
6) VCAM - vascular cell adhesion molecule - mediates the adhesion of lymphocytes, monocytes, eosinophils, and basophils to vascular smooth muscle.

Question 27

describe the relationship between renin-angiotensin-aldosterone system and the endothelium

Answer 27

When BP drops ACE converts angiotensin I into angiotensin II (strong vasoconstrictor) in the lungs. Decrease in renal perfusion from the low BP will stimulate this.

Question 28

Describe how the endothelium reacts and responds to the inflammatory process

Answer 28

redness & heat (result of vasodilation: vacillation),
swelling (rapid escape of plasma from circulation through gaps in venular endothelium),
migration of leukocytes (pus formation).

Question 29

Describe how the endothelium contributes to angiogenesis

Answer 29

endothelial cells can multiply rapidly, forming a simple endothelial tube in a few days that can mature into an artery, vein, or capillary.

Question 30

Define atheroma

Answer 30

a patchy cholesterol-rich deposit in the sub-endothelial intima of large arteries. Also known as atherosclerosis (atheroma with hardening).

Question 31

Describe how atheroma contributes to heart attacks and strokes

Answer 31

The atheroma forms a plaque that narrows the artery lumen, leading to tissue ischemia and thrombosis. In the brain it causes transient ischemic attacks and thromboembolic strokes.

Question 32

List 5 chief predisposing factors of endothelial atheroma

Answer 32

1) high LDL
2) high plasma fibrinogen
3) smoking
4) diabetes
5) hypertension

Question 33

What structure forms a barrier between the blood and the other structures of the circulatory system and allows blood to flow more smoothly and therefore circulate more quickly throughout the body?

Answer 33

Endothelium

Question 34

Of the three distinct Actin-myosin systems, which one helps, resists the shearing effect of the blood stream by gluing the cell down?

Answer 34

Basal stress fibers

Question 35

List THREE of the seven Endothelium functions mentioned in this module

Answer 35

1) Regulates vascular tone
2) Regulates blood-tissue exchange
3) Secretes both anti-thrombotic and pro-clotting factors

Question 36

True/False - Loss of endothelial dysfunction is associated with smoking

Answer 36

True

Question 37

What cell structure allows various ions and molecules to pass freely between cells?

Answer 37

Gap Junctions

Question 38

What are the multiple effects of nitric oxide?

Answer 38

1) Lowers vascular tone
2) contributes to gap formation
3) inhibits platelet aggregation

Question 39

Which of the two angiotensin is a strong vasoconstrictor?

Answer 39

Angiotensin II

Question 40

True/False - Angiogenesis contributes to cancer growth

Answer 40

True

Question 41

What is the commonest cause of serious morbidity and death in the Westernized society?

Answer 41

Atheroma

Question 42

List three chief predisposing factors of endothelial atherosclerosis

Answer 42

1) High LDL
2) smoking
3) diabetes