Hypertension and physics

In Ohm's Law Flow = Pressure/

In Poiseulle's Law Flow is = to Delta P/ [blank_start]R[blank_end] Where R= 8Ln/ pi r^4. Therefore Flow = delta P x r^4, so Flow is proportional to both [blank_start]driving pressure[blank_end] and radius but is inversely proportional to both the [blank_start]length[blank_end] 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/ [blank_start]cross sectional area[blank_end]. This means when the radius of a vessel [blank_start]decreases[blank_end] such as during atherosclerosis there will be more damage occur as the Velocity will increase [blank_start]inversely[blank_end] to the reduction in cross sectional area. This may lead to increased damage to the endothelium of vessels.

The [blank_start]microcirculation[blank_end] extends from the arterioles to the [blank_start]venules[blank_end]. Its main roles are: -[blank_start]Nutrition[blank_end] of tissues, with density being proportional to the metabolic activity of the organ -Non-[blank_start]nutritional[blank_end] e.g. glomerular capillaries of kidneys, temperature regulation, [blank_start]signalling[blank_end], host-defence [blank_start]Arterioles[blank_end] are single layers of SMC's and are innervated Meta-arterioles are larger than a capillary and short cut through the vascular bed [blank_start]Pre-capillary sphincters[blank_end]--> important for regulating blood flow

How many types of capillaries are there?

Which of these is not the role of a pericyte?

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 ([blank_start]poorer[blank_end] 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-[blank_start]calmodulin[blank_end] 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?

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

Which of these describes essential hypertension?

Renal HTN involves changes in systemic system caused by [blank_start]RAAS[blank_end] 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 [blank_start]cortical collecting duct[blank_end] and therefore volume expansion. Pheochromocytoma is a [blank_start]catecholamine[blank_end] 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.

The reason people take sartans such as Candesartan and Ang 2 receptor blocker is that they cause less of a cough than ACE-Inhibitors

[blank_start]Thiazide[blank_end] Diuretics (cholothalidone and Indapamide), inhibit the reabsorption of [blank_start]Na[blank_end]+ at the proximal segment of the DCT, which means more Na+ is maintained in the collecting duct and less H20 will [blank_start]reabsorb[blank_end] here, thus reducing plasma volumes. [blank_start]Low doses[blank_end] in HTN, [blank_start]higher doses[blank_end] 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 [blank_start]antagonise[blank_end] B-adrenergic receptors throughout the body. They reduce BP by inhibiting [blank_start]rate[blank_end] 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?