vascular endothelium 1

Question 1

how does the anatomy of the heart arteries capillaries veins have function in the cardiovascular system?

Answer 1

• generates flow - stabilises pulse - facilitate gas and solute exchange - maintains unidirectional flow

Question 2

what is the vascular endothelium?

Answer 2

• a single cell layer that acts as the blood vessel interface

Question 3

what are the functions of the vascular endothelium?

Answer 3

• vascular tone (secretes and metabolises vasoactive substances) - thrombosis (prevents clotting or molecules sticking to the walls) - absorption and secretion ( allows active and passive transport via diffusion channels) - barrier (prevents atheroma development and impedes pathogens) - growth ( mediates cell proliferation)

Question 4

how can we asses vascular endothelial function?

Answer 4

• laser doppler flowmetry - flow mediated dilatation

Question 5

why are laser doppler flowmetry and flow mediated dilation not used in clinical practice?

Answer 5

too variable

Question 6

** what is the mechanism of arachidonic acid?

Answer 6

**

Question 7

what does nitric oxide do when released by the endothelial cells?

Answer 7

results in relaxation

Question 8

show the mechanism of relaxation of the endothelial cells?

Answer 8

***

Question 9

what is the mechanism of prostacyclin?

Answer 9

• PGI2 produced via COX1 -PGI2 diffuses into the vascular smooth muscle cell - PGI2 binds to the IP receptor - upregulation of adenylyl cyclase - AC converts ATP to cAMP - cAMP inhibits myosin light C kinase - the cell relaxes - the vessel dilates

Question 10

what is the mechanism of thromboxane A2?

Answer 10

• thromboxane diffuses through the apical and basement membrane - thromboxane binds to TP3 on the vascular smooth muscle cell - PLC migrates along the membrane - PLC converts PIP2 to IP3 - IP3 triggers ca2+ influx from the extracellular space and the SER - CA2+ upregulates myosin light chain kinase - VSMC contracts - vessel constricts - TXA2 binds to TP receptor on platelets - platelet becomes active and produces more TXA - the positive feedback potentiates response

Question 11

what sthe the synthesis pathway of angiotensin 2?

Answer 11

• angiotensinogen - angiotensin 1 - ACE - angiotensin 2

Question 12

what does angiotensin 2 do?

Answer 12

• ADH secretion - aldosterone secretion - tubular sodium reabsorption - sympathoexcitation - arteriolar vasoconstriction - overall increases blood pressure

Question 13

what is the role of the renin angiotensin aldosterone system?

Answer 13

• renin cleaves angiotensinogen to Ang 1 - ACE is expressed on endothelial cells in renal/ pulmonary circulation - Ang 1 is cleaved to form Ang 2 by ACE - Ang 2 diffuses across the endothelium - Ang 2 binds to AT1 receptor - PLC migrates along the membrane - PLC converts PIP2 to IP3 -IP3 triggers calcium infux - Ca upregulates myosin light chain kinase - cell contracts - ACE metabolises bradykinin - vasodilation is reduced - vessel constricst

Question 14

what is the mechanism of enothelin 1?

Answer 14

****

Question 15

what is the best way to treat hypertension?

Answer 15

using calcium channel blockers

Question 16

why might some drugs have side effects?

Answer 16

• our body uses the same biochemicals to regulate different processes - interaction between different systems in the body - unfortunately drugs are not always tissue specific - receptor expression varies between tissues - people can experience side effects

Question 17

*show a summary table of all of the key mediators o vascular endothelial cells :

Answer 17

**

Question 18

what does asprin do?

Answer 18

permenantly disables COX enzymes and subsequent prostaglandin / thromboxane synthesis this means the platelets cannot recover so the endothelial cells produce new enzymes