In Ohm's Law Flow = Pressure/
In Poiseulle's Law Flow is = to Delta P/
Where R= 8Ln/ pi r^4.
Therefore Flow = delta P x r^4, so Flow is proportional to both and radius but is inversely proportional to both the and viscosity of the fluid.
Aneuryms result in laminated thrombus formation because the velocity of flow is quicker at the edges of a vessel, which creates the impotence for viscous blood and therefor aggregation of platelets and thrombus formation.
Velocity = Flow/ cross sectional area
Length( cross sectional area, Resistance, Length ). This means when the radius of a vessel decreases
increases( decreases, increases ) such as during atherosclerosis there will be more damage occur as the Velocity will increase inversely
proportionately( inversely, proportionately ) to the reduction in cross sectional area. This may lead to increased damage to the endothelium of vessels.
The extends from the arterioles to the . Its main roles are:
- of tissues, with density being proportional to the metabolic activity of the organ
-Non- e.g. glomerular capillaries of kidneys, temperature regulation, , host-defence
are single layers of SMC's and are innervated
Meta-arterioles are larger than a capillary and short cut through the vascular bed
--> important for regulating blood flow
How many types of capillaries are there?
Which of these is not the role of a pericyte?
Endothelial support cell
regulate capillary flow
regulate wound healing through inflammation, fibrosis and angiogenesis
signal TH2 cells
The Resistance of the micro-circulation is the sum of the pre, capillary and post capillary resistance
Smooth Muscle Contraction:
Ca2+ entry through voltage gated calcium channels
Ca2+ release from SR ( here than in cardiac tissue)
Ca2+ entry through voltage independent channels e.g. NT binding receptors or stretch activated channels
Increased calcium activated calmodulin
The calcium- complex activates myosin light chain kinase
Phosphorylation of myosin light chain allows the myosin to interact with the actin, producing contraction.
Relaxation occurs when MLC phosphatase dephosphorylaes MLC.
Apart from myogenic stretch, activating stretch channels, local factors which can impact arteriole resistance are?
ATP, Adenosine, Lactic Acid
The equation for net filtration pressure = delta P - delta (colloid osmotic pressure)
If the hydrostatic pressure is 52 and the albumin levels are 36 in the plasma and the tissue pressure is -2 but the albumin levels are 13, what is the filtration.
The mechanism of vasculitis is infection leading to antigen-antibody complexes and complement activation, which causes a dense infiltration of acute and chronic inflammatory cells. Common symptoms are
Involvement of tunica intima and media
Which of these describes essential hypertension?
Due to a causative agent i.e. essential such as OSA, Renal artery disease, Hyperaldosteronism, Parenchymal Renal Disease, Cushing's Syndrome or Drugs.
Unknown cause and is believed to be a byplay between genetic, lifestyle factors, diet, obesity, smoking, reduced exercise and stress.
Renal HTN involves changes in systemic system caused by activation.
Endocrine disorders such as Cushing's causes excess production of cortisol which has the action of maintain vascular responsiveness to circulating vasoconstrictors.
Primary aldosteronism refers to a non-suppressible hypersecretion of aldosterone which promotes sodium reabsorption in the and therefore volume expansion.
Pheochromocytoma is a secreting tumor that arises from chromaffin cells of the adrenal medulla and increases NA, A.
Which of these is not a common end artery?
ACE-Inhibitors end in pril and are used to treat HTN, CHF, post AMI, Diabetic nephropathy. Main mechanism is to inhibit conversion of ANG 1 to ANG 2. This will lead to all but the following. They are contra-indicated in pregnancy.
Reduced sympathetic activation
The reason people take sartans such as Candesartan and Ang 2 receptor blocker is that they cause less of a cough than ACE-Inhibitors
Diuretics (cholothalidone and Indapamide), inhibit the reabsorption of + at the proximal segment of the DCT, which means more Na+ is maintained in the collecting duct and less H20 will here, thus reducing plasma volumes. in HTN, in CCF. They have more of a vasodilatory effect in HTN.
Ca2+ channel blockers such as amlodipine inhibit the entry of Ca2+ ions through a subset of voltage gated calcium channels which promotes smooth muscle relaxation.
Olol- B-blockers competitively antagonise
agonise( antagonise, agonise ) B-adrenergic receptors throughout the body.
They reduce BP by inhibiting rate
speed( rate, speed ) and contraction of myocardium (B1) without reducing TPR. They also exert an effect on the CNS to decrease RENIN secretion. They reduce myocardial O2 demand by lowering HR, BP & Preload.
What type of diet and activity regime would you recommend to a patient with HTN?
high sodium, low potassium, moderate exercise
low sodium, high potassium, moderate exercise