Chapter 18 - Disorders of Blood Flow and Blood Pressure Flashcards
How many layers (tunica) do blood vessels have?
Three.
What is the name of the outermost layer of a blood vessel?
Externa or Adventitia.
What is the outermost layer of a blood vessel made of?
Loosely woven collagen fibers that protect the blood vessel and anchor it to surrounding structures. It is also infiltrated with nerve fibers, and sometimes vasa vasorum.
What is the middle layer of a blood vessel called?
Tunica media.
What is the middle layer of a blood vessel made of?
Circularly arranged smooth muscle cells and sheets of elastin.
What is the innermost layer of a blood vessel called?
Tunica intima.
What is the innermost layer of a blood vessel made of?
A single layer of flattened endothelial cells with minimal underlying subendothelial connective tissue.
What are the functions of endothelial cells of the blood vessels? (6)
Controls transfer of molecules across the vessel wall.
Plays a role in modulation of blood flow and vascular resistance.
Controls platelet adhesion and blood clotting.
Metabolism of hormones.
Regulation of immune and inflammatory reactions.
Elaboration of factors that influence the growth of other cell types, especially vascular smooth muscle cells.
What are the risk factors for endothelial dysfunction?
Smoking, hypercholesteremia, hypertension, insulin resistance, diabetes, obesity, and aging. (All related to the pathogenesis of atherosclerosis).
What do dysfunctional endothelial cells produce? (5)
Proinflammatory cytokines.
Growth factors. (eg. vascular endothelial growth factor).
Reactive oxygen species.
Procoagulant or anticoagulant substances.
Other disease producing products.
How do dysfunctional endothelial cells influence the reactivity of underlying smooth muscle cells?
Production of relaxing factors (eg. nitric oxide).
Production of contracting factors (eg. endothelins).
What is the role of vascular smooth muscle cells?
They produce vasoconstriction and vasodilation.
What do vascular smooth muscle cells do besides controlling vessel radius?
Collagen, elastin, and other components of the extracellular matrix.
Elaborate growth factors and cytokines.
Migrate into the intima and proliferate after an injury.
What stimulates the migratory and proliferative activities of smooth muscle cells?
Growth promoters and inhibitors.
What are some growth promoters that effect vascular smooth muscle cells? (4)
Platelet derived growth factor.
Thrombin.
Fibroblast growth factor.
Cytokines such as interferon-y and interleukin-1.
What growth inhibitor effects vascular smooth muscle cells?
Nitric oxide.
What are other regulators of vascular smooth muscle? (Besides growth promoters and growth inhibitors).
Renin-angiotensin system (Angiotensin II).
The catecholamines.
What are the five categories of lipoproteins?
Chylomicrons Very low density lipoprotein (VLDL) Intermediate density lipoprotein (IDL) Low density lipoprotein (LDL) High density lipoprotein (HDL)
What are the components of HDL?
5% triglycerides
20% cholesterol
50% protein
What are the components of LDL?
10% triglycerides
50% cholesterol
25% protein
What are the components of VLDL?
55%-65% triglycerides
10% cholesterol
5%-10% protein
What are the components of chylomicrons?
80%-90% triglycerides
2% protein
What are the functions of apoproteins?
Increase the stability and solubility of a lipoprotein.
Activate certain enzymes required for normal lipoprotein metabolism.
Serve as reactive sites that specific receptors on peripheral tissues can recognize and use in the endocytosis and metabolism of the lipoproteins.
What is the role of apoproteins in atherosclerosis?
Research suggests that genetic defects in the apoproteins may be involved in hyperlipidemia and accelerated atherosclerosis.
Where does lipoprotein synthesis take place?
The liver and the small intestine.
Where are chylomicrons synthesized?
The wall of the small intestine.
What is the role of chylomicrons?
They are involved, through the exogenous pathway, in the transport of dietary triglycerides and cholesterol that have been absorbed from the gastrointestinal tract. They transfer triglycerides to the cells of adipose and skeletal muscle tissue.
How are chylomicrons broken down?
Taken up by the liver and their cholesterol is used in the synthesis of VLDL or excreted in the bile.
Which two lipoproteins are synthesized by the liver?
VLDL and HDL.
Which lipoprotein is the main carrier of cholesterol?
LDL.
What is the role of HDL?
It participates in the reverse-transport of cholesterol. (i.e. it carries cholesterol away from the tissues back to the liver).