9) Hypertension Flashcards
Discuss the main causes of primary hypertension. (4 marks)
Smoking, Stress, high alcohol diet, high salt diet.
Describe how the SNS is involved in the normal regulation of blood pressure. (4 marks)
The SNS has nerves in the brain that stimulate sino-atrial node (SAN), increasing heart rate increasing which increases cardiac output (CO).
The SNS also has nerves in the brain which stimulate arterioles, causing them to contract increasing peripheral vascular rate (PVR) increasing CO.
State the two main factors that are known to regulate cardiac output and give an example of why each might fluctuate. (4 marks)
1) Heart rate- Heart rate may speed up due to exercise and slow down due to heart disease.
2) Stroke volume- amount of blood ejected from the heart when it contracts. During exercise the heart contracts more vigorously so there is more blood ejected, increasing SV.
State two different factors that can increase peripheral vascular resistance and explain the underlying physiological mechanism of each. (4 marks)
The SNS has nerves in the brain that stimulates arterioles, causing them to constrict and increasing peripheral vascular resistance increasing CO.
The hormone angiotensin 2 directly stimulates arterioles, causing them to constrict- this creates smaller volume space inside the arteriole and increasing the resistance because it is not more difficult for blood to pass through the blood vessel.
Discuss how continually high levels of stress may lead to hypertension. (4 marks
Stress causes action potentials sent rapidly from the hypothalamus to the adrenal glands. Catecholamines such as adrenaline and noradrenalin are released that bind to receptors in arterioles, leading to vasoconstriction & binding to receptors in the heart cells leading to increased HR. This increases CO & PVR therefore increasing BP.
Explain the steps of the normal RAAS pathway which lead to the production of angiotensin II. (4 marks)
Renin released by nephron in response to lowered BP.
Renin converts circulating inactive angiotensin produced by the liver into angiotensin 1.
Angiotensin 1 is converted by ACE (ANGIOTENSIN CONVERTING ENZYME) present on lung endothelial cells into angiotensin 2.
Explain how angiotensin II can increase blood pressure. (4 marks)
Angiotensin 2 causes vasoconstriction of arterioles to increase PVR. Angiotensin 2 causes the release of the hormone aldosterone from the cortex of the adrenal gland. This hormone causes nephrons in the kidney to reabsorb more sodium ions into the blood, water then follows by osmosis and increasing BV. Angiotensin 2 also binds to nephrons in the kidney causing them to reabsorb more sodium ions into the blood, water then follows increasing BV and therefore BP.
Describe the different roles of the kidney in regulating blood pressure. (4 marks)
1) Kidney produces renin which can initiate the conversion of angiotensin- angiotensin 1 - angiotensin 2.
2) Kidney responds to ADH from posterior pituitary gland to collect water in the collecting duct.
3) Kidney can respond to angiotensin2 to increase NA+ reabsorption from filtrate into the blood, water follows into the blood by osmosis.
4) Kidney can responds to aldosterone to increase NA+ reabsorption from filtrate into the blood, water follows into blood by osmosis.
Explain how baroreceptors mediate short-term blood pressure regulation. (4 marks)
In high stretch (high BP) baroreceptors cause a reduction ion SNS impulses- decreasing HR and decreasing vasoconstriction.
In low stretch (low BP) baroreceptors cause an increase in SNS impulses- increasing HR and increasing vasoconstriction.
- Discuss two of the main pathological complications of hypertension. State the name of each complication and how this complication is caused by hypertension. (4 marks)
