Flashcards in HTN Deck (73)
Define Blood pressure.
The pressure exerted on the arterial walls by the blood.
What is systolic blood pressure?
The pressure exerted on the arterial walls by the blood during a contraction (systole).
What is diastolic blood pressure
The pressure exerted on the arterial walls by the blood during relaxation (diastole).
What are the two influencing factors affecting blood pressure?
Blood pressure= cardiac output x total peripheral resistance.
What is cardiac output and what are the contributing factors to cardiac output (Q).
Heart rate x Stroke volume
Contributing factors = blood volume, venous return and arterial/venous compliance.
What factors influence total peripheral resistance?
The structure and the function of the blood vessels - regulated by the neuroendocrine factors secreted from the kidneys.
What is the baroreceptor homeostatic feedback loop?
1. An increase in Blood pressure stimulates baroreceptors in the carotid sinuses and the aortic arch
2. Increased impulses from the baroreceptors stimulates the PNS and inhibits the SNS
3. Decrease in SNS causes a drop in HR, contractility and cardiac output
4. Vasodilation occurs
5. Blood pressure returns to the homeostatic range
1. A decrease in blood pressure inhibits the baroreceptors in the carotid sinuses and the aortic arch
2. Decreased impulses from the baroreceptors stimulates the SNS and inhibits the PNS
3. Increase in the SNS causes HR to increase, contractility and CO to rise
4. Vasoconstriciton occurs
5. Blood pressure returns to the homeostatic range
What is the Renin Angiotensin Aldosterone (RAAS) feedback loop?
1. Dehydration, Na+ deficiency or hemorrhage (for examples) cause a decrease in blood volume
2. This causes a decrease in blood pressure
3. The juxtaglomerular cells in the kidney are stimulated to release renin and angiotensin 1
4. The liver is stimulated to release angiotensinogen
5. At the lungs the angiotensin 1 gets activated (by angiotensinogen) to angiontensin 2
6. Angiotensin 2 causes vasoconstriction and the release of aldosterone in the adrenal cortex
7. Aldosterone stimulats Na+ and water absorption in the kidneys and increases secretion of K+ and H+ into the urine
8. Blood volume increases and combined with the vasoconstriction blood pressure returns to normal
Where are the baroreceptors found?
In the carotid sinus and the aortic arch.
What does increased baroreceptor activity stimulate?
The PNS system activity therefore causing a drop in heart rate and a drop in blood pressure.
What does inhibited baroreceptor activity stimulate?
The SNS system (inhibiting the PNS system) causing an increase in heart rate and thus an increase in blood pressure.
What could cause a drop in blood volume stimulating the RAAS feedback loop?
Dehydration, an Na+ deficiency or a hemorrage.
Which cells in the kidney does increased blood pressure stimulate and what substances do they release?
The juxtaglomeruler cells which release renin and angiotensin 1.
What enzyme converts inactive angiotensin 1 to it's active form (angiotensin 2) and where does this process occur?
Angiotensinogen causes the transformation - this occurs at pulmonary sites (the lungs).
What does the active form of angiotensin 2 stimulate?
It causes vasoconstriction and the release of aldosterone from the adrenal cortex.
What does aldosterone do?
It causes an increased uptake of Na+ and water into the kidneys and increases the secretion of K+ and H+ into the urine.
The transitory or sustained elevation of arterial blood pressure likely to induce cardiovascular damage or result in other adverse health consequences.
Classify the normal, prehypertension, Stage 1 hypertension and stage 2 hypertension values.
Normal = <120 mmHg / <80 mmHg
Prehypertension = 120-139 mmHg / 81-89 mmHg
Stage 1 hypertension = 140-159 mmHg / 90-99 mmHg
Stage 2 hypertension = >160 mmHg / >100 mmHg
What are the social contributory/risk factors for hypertension?
Housing, education, income, aging, urbanization and globalization.
What are the behavioral contributory/risk factors for hypertension?
Unhealthy diet, tobacco use, physical inactivity and harmful alcohol consumption.
What are the metabolic contributory/risk factors for hypertension?
Obesity, raised blood lipid profile and diabetes.
What are the co-morbdities and/or consequences of hypertension?
CVD, heart attack, strokes, heart failure and kidney failure.
Why are lifestyle modifications encouraged regardless of blood pressure?
Blood pressure naturally increases with age and these modifications can help act as a preventative measure.
At what stage are drugs used to treat hypertension?
Drugs are likely at stage 1 hypertension - at stage 2 hypertension a combination of drugs may be needed.
Lifestyle modification is of course still needed at both these stages.
What types of hypertension are there?
Primary Hypertension - this accounts for 95% of cases - it has no known universally established cause (idiopathic) - it can also be known as essential hypertension.
Secondary Hypertension - This accounts for 5% of cases where there is a rectifiable, known cause.
What are the known causes of hypertension (Secondary hypertension)?
Renal Hypertension - due to kidney disease/failure
Endocrine Hypertension - primary aldosteronism (aldosterone over production), Cushing's syndrome - high cortisol levels or even pill induced (in females).
What can hypertension sometimes be called?
A silent killer due to lack of any or consistant symptoms at the early stages.
What symptoms could one with high hypertension experience?
Headaches, dizziness, palpitations, fatigue or blurred vision.
When hypertensive what is the % increase risk of CVD from a 5 mmHg increase in DBP - who found this?
21% increased risk - MacMahon (1990)