Block 2 - HTN Physiology Flashcards
What is HTN?
High BP resulting from atherosclerosis that block blood flow in major arteries and create excess pressure on arterial walls
How is systemic arterial pressure measured?
Conventional cuff over brachial artery
What is the major cause of first strokes, MIs and heart failures?
HTN
What is arteriosclerosis and how does it cause embolism?
Thickening of arterial walls → arteries lose elasticity losing ability to constrict or dilate → plaque forms → lumen narrows → pressure builds against walls and plaque breaks off → embolism
What is normal BP?
<120/<80
What is elevated BP?
120-129/<80
What is HTN stage 1
130-139/80-89
What is HTN stage 2?
140+/90+
What is HTN crisis?
180+/120+
What is primary HTN (essential)? Factors?
No known cause
90% of cases
1. Genetics
2. Age
3. Diet
4. Smoking and alcohol
5. Sedentary
What is secondary HTN? How is it treated?
Identifiable cause associated with hyperthyroidism, CKD, tumors of adrenal gland
Remove underlying cause
What are the factors that affect? Figure
- Hormones: RAAS, plasma adiponectin (reduce HTN)
- Nervous system
How does HTN affect the RAAS?
Disruptions of the RAAS → heightens presence of angiotensin II
What is angiotensin? How is important in maintaining HTN?
- Potent vasoconstrictor
- Affects growth and maturation of adipocytes
Adipocytes → cardioprotective adiponectin → regulates energy balance, anti-inflammatory, and anti-plaque → decreasing risk for HTN
Low adiponectin levels in HTN
What does obesity lead to?
- Increased angiotensin II in adipocytes of visceral fat
- Reduced plasma levels of adiopectin
What is endothelial dysfunction? Risk factors?
Dysfunction in endothelium that regulates BP of vasoactivity (dilators: NO)
Reduced amount of NO from smoking, aging, HTN
How is the sympathetics NS affected in HTN?
- Increased in HTN
- Increased HR, blood flow, renal retention of Na+
- NE raises BP
- E promotes vasoconstriction
How can alcohol consumption contribute to HTN?
- Activates RAAS → increased renin and angiotensin II
- Vasoconstriction → depletes NO
- Activates SNS
How can lifestyle factors contribute to HTN?
- Increased stress
- High salt intake
- Lack of PE
- Obesity
How can genetics contribute to HTN?
- Increased in E and NE seen in a family history of HTN
- African Americans have the highest rate of HTN
What are the clinical manifestation of HTN?
- Asymptomatic → damage is progressively occurring
- Symptoms are rare until BP is really high (DZ, nosebleeds, HA, facial flushing, blood spots in eyes)
What are the long term consequences of HTN?
- MI
- Stroke
- CKD
- Vision loss
- ED
What is the difference between HTN crisis and urgency?
Crisis: Organ damage in CV, kidneys, and brain (aggressive. immediate treatment)
Urgency: No organ damage
What are the signs of severe HTN?
- Retinal hemorrhage
- Papilledema (edema in retina)
Signs and symptoms of HTN?
- Dyspnea
- Acute LHF
- Diminished renal function
- Stroke
- HTN encephalopathy (leaky brain capillaries, seizures, paralysis, coma, HA)
What are the secondary causes of HTN crisis?
- Pheochromocytoma
- Cocaine use
- Preeclampsia and eclampsia
- Acute aortic dissection
- Renovascular HTN
- Hyperthyroidism (thyroid storm)
What is pheochromocytoma? Etiology?
tumor of chromatin tissue in the adrenal medulla
Rare
Sympathetic nerve cells release catecholamines→ vasoconstriction → HTN
Clinical manifestations of pheochromocytoma?
- Paroxysmal (periodic episodes)
- Whole body: flushing, HBP, sweating, DZ, fatigue
- Heart: tachycardia
- Marked variability in BP between episodes