Physiology of Hypertension and Arterial Pressure

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Questions and Answers

Which of the following is NOT a mechanism by which angiotensin II increases arterial pressure?

Causing vasoconstriction of the arterioles

Increasing Na+ reabsorption in the proximal convoluted tubule

Increasing thirst

Increasing aldosterone secretion (correct)

What is the defining characteristic of benign hypertension?

A long, symptomless course with moderate blood pressure elevation (correct)

A rapid increase in blood pressure that leads to significant organ damage

A sustained increase in blood pressure caused by an underlying disease

A chronic condition with fluctuating blood pressure levels

What is the primary mechanism of arterial pressure control in the long term?

Renal-body fluid feedback mechanism (correct)

Hormonal regulation

Intermediate pressure controls

Nervous reflexes

How does aldosterone contribute to the regulation of arterial pressure?

By increasing sodium reabsorption in the distal tubule Signup and view all the answers

Which of the following is a characteristic of hypertension?

A sustained increase in arterial pressure Signup and view all the answers

What is the difference between primary and secondary hypertension?

Primary hypertension is caused by an unknown cause, while secondary hypertension is caused by an underlying disease. Signup and view all the answers

What is the role of thirst in the regulation of arterial pressure?

Thirst promotes fluid intake, which indirectly increases blood pressure. Signup and view all the answers

Which of the following is a consequence of angiotensin II's action on the proximal convoluted tubule?

Contraction alkalosis Signup and view all the answers

What is the typical change in blood pressure during a relaxed state in early sleep?

Decrease of 15-20 mmHg Signup and view all the answers

What physiological effect primarily causes a reduction in blood pressure during relaxed sleep?

General vasodilation Signup and view all the answers

In which body type is systolic blood pressure usually slightly higher?

Obese individuals Signup and view all the answers

Why might a standard arm cuff provide a falsely high blood pressure reading in an obese individual?

Tissue between the cuff and the artery dissipates some of the cuff pressure Signup and view all the answers

What range is the normal mean arterial pressure (MAP) typically maintained at?

95-100 mmHg Signup and view all the answers

Which of these is categorized as a rapid blood pressure control mechanism?

Baroreceptor reflexes Signup and view all the answers

How quickly do the rapid blood pressure control mechanisms typically respond to changes in blood pressure?

Within seconds to a few minutes Signup and view all the answers

Where are baroreceptors, which are involved in the regulation of blood pressure, located?

In the walls of the carotid sinus Signup and view all the answers

In a night worker, how does their typical physiological rhythm compare to that of a day worker?

Their rhythm is reversed. Signup and view all the answers

During muscular exercise, what is the general trend observed in systolic and diastolic blood pressure among most individuals?

Systolic pressure increases while diastolic pressure decreases. Signup and view all the answers

If an individual has a blood pressure of 120/80 mmHg at the brachial artery, what would be the approximate blood pressure at the dorsalis pedis artery, which is about 100 cm below the heart?

Approximately 200/160 mmHg Signup and view all the answers

Why should blood pressure measurements be taken at the heart level?

To counteract for hydrostatic effects of the blood column due to gravity. Signup and view all the answers

What immediate effect does standing up from a lying position have on venous return and cardiac output?

Decreased venous return, decreased cardiac output. Signup and view all the answers

What is the initial response of the baroreceptors due to the momentary fall in systolic blood pressure when standing up?

Decreased baroreceptor discharge, leading to an increase in diastolic pressure Signup and view all the answers

How long does the rise in diastolic blood pressure typically last after standing up from lying down?

For about 30–60 seconds. Signup and view all the answers

Why do normal individuals typically not experience any symptoms after the initial changes in blood pressure when standing up?

Because the baroreceptor reflexes quickly return blood pressure to normal. Signup and view all the answers

What is the primary role of the renal–body fluid feedback mechanism?

To maintain normal output of salt and water by the kidneys Signup and view all the answers

How long does it take for the renal–body fluid feedback mechanism to show a significant response?

Several hours to days Signup and view all the answers

What initiates the Renin–Angiotensin–Aldosterone System?

Decreased renal perfusion pressure Signup and view all the answers

What is the function of angiotensin-converting enzyme (ACE)?

To convert angiotensin I to angiotensin II Signup and view all the answers

What effect does angiotensin II have on the body?

It stimulates aldosterone secretion Signup and view all the answers

What happens when ACE inhibitors are administered?

Conversion of angiotensin I to angiotensin II is blocked Signup and view all the answers

What primarily happens if kidney function is unaltered over time?

Blood pressure regulation continues unaffected Signup and view all the answers

In which organ does the conversion of angiotensin I to angiotensin II largely occur?

Lungs Signup and view all the answers

What defines malignant hypertension?

A severe form characterized by rapid progression Signup and view all the answers

What is a common consequence of persistent high blood pressure?

Development of vascular, cardiac, or renal diseases Signup and view all the answers

Which condition is characterized by excessive secretion of catecholamines?

Pheochromocytoma Signup and view all the answers

Which type of hypertension is specifically associated with renal disease?

Renal hypertension Signup and view all the answers

What can be a result of hypertension during pregnancy?

Hypertension with convulsions in eclampsia Signup and view all the answers

How does atherosclerosis contribute to hypertension?

By hardening and narrowing blood vessels Signup and view all the answers

Which of the following is NOT a type of secondary hypertension?

Malignant hypertension Signup and view all the answers

What effect does low glomerular filtration rate have during pregnancy?

Causes water retention and elevated blood pressure Signup and view all the answers

Which of the following is a severe manifestation of primary hypertension?

Retinal hemorrhage Signup and view all the answers

What type of hypertension can be cured by treating the underlying disease?

Secondary hypertension Signup and view all the answers

Which class of antihypertensive drugs reduces blood pressure by causing vasodilatation?

Alpha adrenoceptor blockers Signup and view all the answers

What mechanism do calcium channel blockers primarily utilize to lower blood pressure?

Block calcium channels in myocardium Signup and view all the answers

Which of the following agents is used to prevent vasoconstriction by acting on the vasomotor center?

Depressors of vasomotor center Signup and view all the answers

What characterizes primary hypotension?

It develops without underlying disease Signup and view all the answers

Which of the following antihypertensive drugs blocks the formation of angiotensin?

ACE inhibitors Signup and view all the answers

What is considered hypotension in terms of systolic blood pressure?

Less than 90 mm Hg Signup and view all the answers

Study Notes

Blood Pressure

Blood pressure is the lateral force exerted by blood against vessel walls, typically measured in mmHg.
Arterial pressure is the most common type measured.
Systolic pressure is the peak pressure during ventricular contraction. Normal for young adults is 120mmHg (range 105-135).
Diastolic pressure is the lowest pressure occurring during ventricular relaxation. Normal for young adults is 80mmHg (range 60-90).
Pulse pressure is the difference between systolic and diastolic pressure. Normally 40 mmHg.
Mean arterial pressure (MAP) is the average pressure throughout the cardiac cycle. Approximately equal to diastolic pressure plus one-third pulse pressure. Normal 93 mmHg (range 90-100).
Arterial blood pressure (BP) is the product of cardiac output (CO) and total peripheral resistance (PR)

Determinants of Blood Pressure

Cardiac output (CO) is directly related to systolic pressure, increasing CO increases systolic pressure. CO is a function of heart rate and stroke volume.
Heart rate increases systolic pressure as cardiac output is increased.
Peripheral resistance (PR) is the resistance to blood flow in arterioles. Increasing resistance increases diastolic pressure
Blood vessels elasticity & viscosity affect peripheral resistance: stiff blood vessels increase resistance and increase diastolic pressure. High blood viscosity increases resistance.
Blood volume is a factor influencing blood pressure, higher volume = higher pressure; conversely, lower volume = lower pressure.

Factors Affecting Blood Pressure

Age: Blood pressure normally rises with age.
Sex: Pre-menopausal females have lower blood pressure than males at same age; post-menopausal females potentially higher than males.
Meals: Systolic blood pressure increases after eating (4-6 mm Hg) for ~1 hour.
Emotions: Stress, fear, and excitement increase cardiac output, leading to increased systolic blood pressure.
Temperature: Cold temperatures increase peripheral resistance and blood pressure, while heat causes vasodilation and reduces pressure.
Posture: Standing increases pressure in lower extremities and reduces upper body pressure.
Exercise: Typically increases systolic blood pressure and decreases diastolic blood pressure.
Sleep: Blood pressure often falls during sleep due to general vasodilation.
Body build: Obese individuals may show slightly higher systolic blood pressure readings using standard arm cuffs.

Physiological Control Mechanisms

Rapid (short-term): Baroreceptors, central nervous system ischemic response and chemoreceptor reflexes act rapidly (seconds to minutes) to correct changes in blood pressure.
Intermediate (minutes to weeks): Renin-angiotensin-aldosterone system and capillary fluid shift play more gradual, medium-term responses to blood pressure changes.
Long-term (days to months): The renal fluid feedback system (kidney function) is most important for long-term control of blood pressure. Increased pressure triggers more sodium and fluid excretion from the kidneys, reducing blood volume and pressure.

Hypertension

Hypertension (high blood pressure) is sustained high blood pressure (systolic above 140 mmHg and/or diastolic above 90 mmHg)
Primary (essential): unknown cause, no underlying disease.
Secondary: caused by another condition (e.g., kidney disease, endocrine problems).
Benign: Gradual, persistent elevation in blood pressure typically not life-threatening
Malignant: Rapid acceleration in blood pressure potentially life-threatening due to organ damage.

Hypotension

Hypotension (low blood pressure).
Primary: Unknown cause.
Secondary: Caused by other conditions (e.g. cardiac issues, problems with the nervous system, poor nutrition)
Orthostatic: Sudden drop in blood pressure when going from a sitting or lying down position to standing. Common cause is inadequate blood flow to the brain, and symptom is fainting.

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Description

This quiz explores key concepts related to hypertension and arterial pressure regulation. Questions cover mechanisms like angiotensin II, the role of aldosterone, and the difference between primary and secondary hypertension. Test your knowledge on the physiological aspects that influence blood pressure control.