Physiology of Endothelium and Hemostasis

Questions and Answers

What is the primary function of pericytes in the brain?

To maintain homeostatic and hemostatic functions

Which type of capillary is commonly found in muscles and bones?

Continuous

What is the primary function of capillaries in the brain?

To maintain the blood-brain barrier

Which type of capillary has gaps of 10-100 nm and is found in intestinal villi?

Fenestrated Signup and view all the answers

What is the function of pericytes in angiogenesis?

To promote new vessel formation Signup and view all the answers

What type of capillary is found in the liver and spleen?

Sinusoidal Signup and view all the answers

What is the main function of hemostasis in response to vascular damage?

To seal an injured vessel and prevent blood loss Signup and view all the answers

Which type of artery has a tunica media composed primarily of smooth muscle?

Muscular artery Signup and view all the answers

What is the function of the tunica adventitia in elastic arteries?

To supply nutritional needs to the tunica media Signup and view all the answers

What is the primary component of the tunica intima in arteries?

Endothelium and loose connective tissue Signup and view all the answers

What is the role of the endothelium in the body?

To facilitate fluid distribution and hemostasis Signup and view all the answers

What is the function of smooth muscle cells in the tunica media of arteries?

To regulate diameter and tone Signup and view all the answers

What is the arrangement of smooth muscle cells in the tunica media of arteries?

Circumferentially arranged Signup and view all the answers

What is the name of the stain used to visualize elastic fibers in arteries?

Van Giessen stain Signup and view all the answers

What is the innermost layer of a vessel made up of?

Endothelium, internal elastic membrane, subendothelial connective tissue Signup and view all the answers

What is the function of the endothelium in hemostasis?

To promote blood clotting Signup and view all the answers

What type of capillary is characterized by small pores that allow for the passage of small molecules?

Fenestrated capillary Signup and view all the answers

What is the outermost layer of a vessel composed of?

Collagen, blood vessels, nerves, capillaries Signup and view all the answers

What is the function of the endothelium in inflammation?

To modulate inflammation Signup and view all the answers

What type of capillary is characterized by a complete basement membrane and is found in muscles and connective tissue?

Continuous capillary Signup and view all the answers

What is the role of pericytes in capillaries?

To provide structural support to the capillary Signup and view all the answers

What is the function of the blood-tissue barrier?

To regulate the passage of substances between blood and tissue Signup and view all the answers

Study Notes

Endothelium

The endothelium acts as a physical barrier between intravascular and extravascular spaces and regulates fluid distribution, hemostasis, inflammation, and healing.
Hemostasis is a physiological response to vascular damage, providing mechanisms to seal an injured vessel and prevent blood loss.

Arteries

Elastic arteries (e.g., Aorta) have three tunics: tunica intima, tunica media, and tunica adventitia.
Tunica intima consists of endothelium and loose connective tissue.
Tunica media is composed of repeating elastic lamellae.
Tunica adventitia contains vasa vasorum to supply the nutritional needs of the thick tunica media.

Muscular Arteries

Tunica media is primarily composed of smooth muscle.
Thickest tunic is tunica media, giving them a round appearance.
Smooth muscle cells in tunica media regulate diameter and tone (vasodilation/vasoconstriction).

Pericytes

Pericytes help maintain homeostatic and hemostatic functions in the brain and sustain the blood-brain barrier.
They proliferate after injury and are a source of stem cells.
Important in angiogenesis and new vessel formation.

Capillaries

Classification of capillaries:
- Continuous: Most common, found in muscle, brain, bone, lung, etc.
- Fenestrated: In tissues with substantial fluid exchange, e.g., intestinal villi, choroid plexus.
- Discontinuous (Sinusoidal): Hepatic and splenic sinusoids, allowing large molecules to exit.

Vessel Structure

Tunics of vessels:
- Innermost: Tunica intima (endothelium, internal elastic membrane, and subendothelial connective tissue).
- Middle: Tunica media (smooth muscle and elastic lamellae/fibers).
- Outermost: Tunica adventitia (collagen, may contain blood vessels, nerves, capillaries).

Endothelium Function

Modulates perfusion.
Role in inflammation.
Role in hemostasis.

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Description

Learn about the role of endothelium in fluid distribution, hemostasis, inflammation, and healing, as well as the physiological response to vascular damage. Understand the mechanisms of hemostasis and its importance in the body.