Lecture 28: Arteries and Arterioles Flashcards
What do the arterial components include?
-Smooth muscle(regulate vessel diameter)
-Endothelial cells(regulate smooth muscle functions, vessel permeability)
-Collagen fibres (impart rigidity)
-elastic laminae( impart elasticity to store energy)
What do the arteries do?
- conduits for movement of blood from the heart to the other tissues-thus the name conductance vessels
- its a pressure reservoir for blood movement when the heart relaxes, because it stores potential energy when the heart expands, and you store less and less as you get older.
During systole and diastole, which volume is greater, in or out, and does the delta P increase or decrease and what happens to the vessel walls
Systole: V.in> V.out, therefore Delta P increases and the vessel wall expands
Diastole: V.in<V.out, therefore Delta P decreases and the vessel wall contracts
What is another name for arterioles and they have a thick layer of what?
Resistance vessels
Arterioles feature a thick layer of smooth muscle.
What is arteriolar vasoconstriction?
-increased contraction of circular smooth muscle and arteriolar wall, which leads to increased resistance and decreased flow through the vessel
What is arteriolar vasodilation?
-decreased contraction of circular smooth muscle in the arteriolar wall, which leads to decreased resistance and increased flow through the vessel
What are some Vasoconstrictor hormones?
Norepinephrine
epinephrine
Angiotensin II
Vasopressin
What are some Vasodilator hormones?
Bradykinin
Histamine
What are included in the chemical intrinsic regulation of the Arteriolar radius?
-High O2 tension (low CO2)= vasoconstriction
-High CO2 tension(low O2)=Vasodilation
What is Active Hyperemia and how does it occur?
-ITs when oxygen is depleted, and since oxygen is required for ATP production, therefore smooth muscle contraction takes place to maintain vascular tone. flow to the tissues increases.
What are included in the physical intrinsic regulation of the arteriolar radius ?
Heat increased blood flow and cold decreases blood flow
Shear stress: a force induced by friction of blood flowing over the endothelium causing cells to release Norepinephrine
Myogenic response to stretch: VSMC responds to being passively stretched by increasing tone. When volume of blood delivered to an organ increases, it stretches the smooth muscle around the microvasculature.
What happens to the flow in reactive hyperemia ?
Blood flow to a tissue is totally restricted.
What happens during pressure autoregulation?
Decreased MAP reduces blood flow and stretching of the arterioles, and metabolites build up. Arterioles dilate to restore blood flow to the tissue maintaining blood flow.
