Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
|
Define peripheral runoff
|
Peripheral runoff: is the rate of outflow of blood from the arteries through the resistance vessels
dVa/dt= Qh-Qr dVa/dt: change in arterial blood volume per time Qh: cardiac output (inflow of blood in the arterial system) Qr: outflow of blood from the arterial system through the resistance vessels |
|
|
Define Resistance vessels
|
the small arteries and arterioles that regulate the blood flow throughout the body
|
|
|
What is a myoendothelial junction?
What is its significance? |
Myoendothelial junctions: progections of parts of the endothelial cells into the vascular smooth muscle layer in the arteriole --> suggests a functional interaction between the endothelium and adjacent vascular smooth muscles.
|
|
|
What is autoregulation?
|
is the act of maintaining a constant blood flow via changing the vascular resistance in face of changes in the arterial perfusion pressure at constant levels of tissue metabolism
|
|
|
Describe the myogenic mechanism.
|
Myogenic mechanism: states that the vascular smooth muscles contracts in response to ↑ transmural pressue, and relaxes in response to ↓ transmural pressure.
-->due to activation of the membrane Ca++ channels |
|
|
What does paracrine mean?
|
related to a hormon function in which the effects of the hormon are restricted to the local envirnoment.
|
|
|
What are the factors that contribute to the development of interstitial oedema?
|
nterstitial oedema occurs when: 1-the volume of fluid leaving the capillaries and entering the interstitial space is increased,
2-and/or the lymphatic drainage is reduced, 3-and/or the total ECF volume is increased |
|
|
What is oncotic pressure?
|
osmotic pressure due to non-diffusable particles
|
|
|
What main topic does interstitial oedema come under?
|
Tissue micro-circulation
|
|
|
What are the constituents of the 'micro circulation'?
|
1-arterioles
2-capillaries 3-venules |
|
|
Which constituent of the microcirculation regulate the blood flow into it?
|
the arterioles (or the resistance vessels)
|
|
|
What is the average velocity of the blood flow in the capillaries?
|
1 mm /s
(can vary from 0 to several millimeters/ second within the same capillary) |
|
|
What is wall tension?
|
Wall tension: is the force per unit length tangential to the vessel wall,tending to pull apart a theoretical slit in the vessel
T= Pr (= force/unit area . length= force. Length) |
|
|
What is Laplace's Law?
|
Laplace’s Law: for a hollow distensible structure:
• P= T/R1 + T/R2 o P: transmural pressure o T: tension in the wall o r1:radius in one direction o r2: radius in the other direction • For a cylinder (e.g. a blood vessel), one radius =infinity, therefore P = T/R • For a sphere, r1=r2, thus P=2T/r |
