Trigger 7 - Hypertension and Dementia Flashcards
Define: Homeostasis
Homeostasis is defined as the condition of constancy of the “internal environment” in terms of its cells, tissues, and organs.
Describe: Circulatory System
The circulatory system is a closed-loop system in which cardiac output is dependent upon adequate venous return.
Blood pressure is a function of: Cardiac output (CO) = __________ * __________.
Heart rate (70bpm) * Stroke volume (70ml)
Blood pressure is determined by which of the following factors?
A) Heart rate and stroke volume
B) Cardiac output and systemic vascular resistance
C) Sympathetic stimulation and parasympathetic stimulation
D) Renin and aldosterone levels
B) Cardiac output and systemic vascular resistance
True or False: Blood pressure homeostasis relies solely on positive feedback loops.
False
Describe: Neurohumoral Control of Blood Pressure
The neurohumoral control of blood pressure involves various systems such as autonomic baroreflex, renin-angiotensin-aldosterone system, and anti-diuretic hormone (ADH) or vasopressin. These systems detect changes in pressure, leading to responses such as increased sympathetic stimulation, vasoconstriction, and sodium and water absorption in the kidneys. All these systems operate through negative feedback loops, with no specific set point for triggering the loop.
Define: Baroreceptor Reflex
The baroreceptor reflex is a physiological mechanism that regulates blood pressure by sensing changes in arterial pressure and initiating appropriate responses to maintain homeostasis.
Baroreceptor reflex reacts to the tension of the __________.
Arteries
When the baroreceptor reflex is activated, which of the following occurs?
A) Decreased arteriolar tone
B) Reduced sympathetic nervous system activity
C) Increased parasympathetic activity
D) Decreased cardiac contractility
C) Increased parasympathetic activity
True or False: High blood pressure leads to increased sympathetic activity and decreased parasympathetic activity, resulting in decreased cardiac output and vasodilation.
True
Describe: Effect of High Blood Pressure on Baroreceptor Reflex
High blood pressure triggers a response opposite to the normal baroreceptor reflex. It leads to a depression of sympathetic activity and stimulation of parasympathetic activity, causing a decrease in cardiac output and vasodilation, ultimately reducing blood pressure.
Define: Renin-Angiotensin-Aldosterone System (RAAS)
The Renin-Angiotensin-Aldosterone System (RAAS) is a hormonal system that regulates blood pressure and fluid balance in the body by controlling the volume of fluids and electrolytes in the blood.
Renin is released in response to sympathetic nerve stimulation in JG cells, reduced NaCl concentration in the distal tubule, and reduced ___________.
Afferent arteriole pressure
Which of the following are functions of angiotensin II mediated by specific angiotensin II receptors (AT1)?
A) Decreasing systemic vascular resistance
B) Inhibiting sympathetic adrenergic activity
C) Decreasing aldosterone release
D) Stimulating thirst centers
D) Stimulating thirst centers
True or False: Angiotensin II stimulates sodium reabsorption by acting directly on renal tubules.
True
Describe: Action of Vasopressin (ADH)
Vasopressin, also known as Antidiuretic Hormone (ADH), stimulates water reabsorption by the kidneys by increasing water permeability in the collecting duct, thereby permitting the formation of concentrated urine. Additionally, it constricts arterial blood vessels, which helps to increase blood pressure.
Define: Renin
Renin is an enzyme produced by the kidneys that acts upon angiotensinogen to initiate the Renin-Angiotensin-Aldosterone System (RAAS).
Angiotensin-converting enzyme (ACE) cleaves off two amino acids from angiotensin I to form the octapeptide ___________.
Angiotensin II
What is the effect of angiotensin II on the adrenal cortex?
A) Decreases aldosterone release
B) Stimulates cortisol production
C) Inhibits renin secretion
D) Signals kidneys to increase sodium and fluid retention
D) Signals kidneys to increase sodium and fluid retention
True or False: Vasopressin stimulates the release of aldosterone from the adrenal cortex.
False
Describe: Action of Angiotensin II on Arterial Blood Vessels
Angiotensin II constricts resistance vessels, thereby increasing systemic vascular resistance and arterial pressure. This vasoconstrictive effect helps to elevate blood pressure.
True or False: Renin is released in response to increased sodium concentration in the distal tubule.
False
Define: Aortic Elasticity
Aortic elasticity refers to the ability of the aorta to expand and contract with each heartbeat, which is associated with increased compliance.
Describe: Compliance of Arteries
Compliance redirects heart energy to the arterial wall by storing energy during systole and releasing it during diastole, thereby pushing blood forward and facilitating circulation towards peripheral tissues.
Types of arteries include compliance arteries, impedance mismatch arteries, and those that facilitate smooth blood flow to the __________.
Capillaries
True or False: The cardiovascular system maintains smooth blood flow by solely relying on neurohumoral control mechanisms.
False
Which of the following are involved in neurohumoral control of blood pressure?
A) Compliance of arteries
B) Smooth blood flow to capillaries
C) Autonomic baroreflex
D) Impedance mismatch in arteries
C) Autonomic baroreflex
Describe: Risk of Pulse Pressure
Organs closer to the heart are more likely to be at risk of pulse pressure, which refers to the difference between systolic and diastolic blood pressure and reflects the pulsatile nature of blood flow in arteries.
Define: Compliance of Arteries
Compliance of arteries refers to their ability to expand and contract in response to changes in blood pressure, allowing them to accommodate changes in blood volume and maintain smooth blood flow.
Aortic elasticity is associated with increased ___________.
Compliance
True or False: Compliance arteries store energy during diastole and release it during systole, aiding in the redirection of heart energy to the arterial wall.
False
Which type of artery is associated with the reduction in pulse pressure from the heart to peripheral circulation?
A) Compliance arteries
B) Impedance mismatch arteries
C) Arteries facilitating smooth blood flow to capillaries
D) Elastic arteries
B) Impedance mismatch arteries
Describe: Smooth Blood Flow in Arteries
Arteries facilitate smooth blood flow to the capillaries by maintaining their elasticity and compliance, which allows them to dampen the pulsatile nature of blood pressure generated by the heart’s contractions.
True or False: Organs located farther away from the heart are more likely to be at risk of pulse pressure
False
Define: Baroreflex
The baroreflex is a physiological mechanism involving mechanoreceptors that relay information concerning blood pressure within the autonomic nervous system, primarily located in the aortic arch and carotid sinuses.
Describe: Mechanism of Baroreflex
Baroreceptors are stretch-sensitive mechanoreceptors primarily located in the aortic arch and carotid sinuses. They regulate blood pressure in response to short-term events, such as sudden changes like standing up quickly. The baroreflex is a quick reflex mechanism that operates through a negative feedback loop, completing its response in just a couple of heartbeats.
True or False: Baroreceptors are primarily located in the kidneys.
False
The main function of the baroreflex mechanism is to regulate blood pressure in response to:
A) Long-term events
B) Hormonal changes
C) Short-term events
D) Respiratory rate
C) Short-term events
The baroreflex regulates blood pressure through a __________ loop.
Negative feedback
Describe: Speed of Baroreflex Response
The baroreflex is a quick reflex mechanism that is complete in just a couple of heartbeats, allowing for rapid adjustments to changes in blood pressure.
Define: Renin-Angiotensin-Aldosterone System (RAAS)
The Renin-Angiotensin-Aldosterone System (RAAS) is a hormonal system that regulates blood volume and systemic vascular resistance, thereby influencing cardiac output and arterial pressure.
Describe: Mechanism of Action of RAAS
The RAAS regulates blood pressure by releasing renin, a proteolytic enzyme primarily from the kidneys. Renin acts on angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE). Angiotensin II functions to constrict resistance vessels, release aldosterone to increase sodium and fluid retention, and release vasopressin to increase fluid retention in the kidneys.
True or False: Renin release is stimulated by increased sodium delivery to the distal tubules of the kidney.
False
Which of the following are functions of angiotensin II?
A) Dilates resistance vessels
B) Reduces fluid retention in the kidneys
C) Increases sodium delivery to the distal tubules
D) Releases aldosterone
D) Releases aldosterone
Release of vasopressin increases fluid retention in the __________.
Kidneys
Describe: Negative Feedback Loop in RAAS
The release of natriuretic peptides (ANP/BNP) by the heart acts as a negative feedback mechanism in the RAAS, decreasing renin release and helping to regulate blood pressure.
Define: Renin
Renin is a proteolytic enzyme produced primarily by the kidneys, which plays a crucial role in the regulation of blood pressure by initiating the RAAS.
Renin acts on angiotensinogen to form the decapeptide ___________.
Angiotensin I
True or False: Angiotensin II functions to dilate resistance vessels, thereby reducing arterial pressure.
False
Renin release is stimulated by which of the following?
A) Increased sodium delivery to the distal tubules
B) Increased blood pressure in the renal arteries
C) Decreased sympathetic nerve activation
D) Increased angiotensin II levels
B) Increased blood pressure in the renal arteries
Describe: Role of Aldosterone
Aldosterone, released in response to angiotensin II, increases sodium and fluid retention in the kidneys, thereby contributing to an increase in blood volume and blood pressure.
True or False: The RAAS is essential only for chronic blood pressure adjustments, not for acute changes.
False
The release of natriuretic peptides by the heart acts as a negative feedback mechanism to decrease ___________ release.
Renin
Define: Anti-diuretic Hormone (ADH)
Anti-diuretic hormone (ADH), also known as arginine vasopressin (AVP), is a hormone involved in the regulation of blood pressure and the control of water reabsorption in the kidneys.
Describe: Synthesis of ADH
ADH is a nonapeptide synthesized in the hypothalamus, specifically in the supraoptic and paraventricular nuclei.
True or False: Osmoreceptors in the hypothalamus detect fluctuations in blood pressure and respond by shrinking, which increases nerve impulse frequency to the posterior pituitary gland.
True
ADH binds to which type of receptors on the basal lateral cell membranes of the principal cells in the nephron?
A) V1 receptors
B) V2 receptors
C) Alpha receptors
D) Beta receptors
B) V2 receptors
ADH increases the expression of aquaporins, specifically __________, in the apical membrane of principal cells in the nephron.
Aquaporin-2
Describe: Movement of Water in the Kidneys
After ADH increases the expression of aquaporins, water moves osmotically from the tubular fluid into the cell and then into the peritubular fluid. Finally, it moves into the surrounding interstitial fluid and into the blood, increasing blood volume and blood pressure.
True or False: Increased blood volume due to ADH secretion leads to a decrease in blood pressure.
False
Define: Osmoreceptors
Osmoreceptors are specialized cells located in the hypothalamus that detect changes in the concentration of solutes in the blood and play a role in regulating water balance and blood pressure.
ADH is synthesized in the __________ nuclei of the hypothalamus.
Supraoptic and paraventricular
True or False: ADH controls the movement of water from the tubular fluid into the renal tubular cells.
True
What stimulates the release of ADH from the posterior pituitary gland?
A) Increased blood pressure
B) Decreased extracellular fluid levels
C) Decreased osmolality of the blood
D) Increased sodium levels
B) Decreased extracellular fluid levels
Describe: Action of Aquaporins
ADH increases the expression of aquaporins, specifically aquaporin-2, in the apical membrane of principal cells in the nephron. These water channels facilitate the movement of water from the tubular fluid into the cell.
True or False: ADH secretion leads to a decrease in blood volume.
False
Water moves from the peritubular fluid into the surrounding __________ fluid and eventually into the bloodstream.
Interstitial
Define: Normal Adult Blood Pressure
Normal adult blood pressure is typically defined as systolic blood pressure less than 130 mm Hg and diastolic blood pressure less than 85 mm Hg.
Describe: Life Trajectory of Blood Pressure
Blood pressure tends to increase continuously from early adulthood until late life, with an initial increase in early adulthood, acceleration after the fourth decade, and a slower increase and possible decline later in life.
True or False: With aging, individuals lose the ability to maintain their blood pressure within a healthy level over time.
True
The prevalence of hypertension increases with age. What percentage of adults over the age of 65 are affected?
A) 32%
B) 50%
C) 70%
D) 90%
C) 70%
Describe: Impact of Hypertension
Hypertension is associated with various health issues such as dementia, physical disability, falls/fractures, and increased risk of developing other comorbidities.
Define: Essential Hypertension
Essential hypertension accounts for 95% of all cases and is characterized by high blood pressure without an identifiable cause.
Describe: Cardiovascular Vascular Aging
Cardiovascular vascular aging involves changes to the arterial wall, including increases in wall thickness and decreases in vessel elasticity, particularly in the aorta and systemic vasculature.
True or False: In essential hypertension, individuals typically have normal cardiac output but increased peripheral resistance.
True
Describe: Renal Hypertension
Renal hypertension is an exception to essential hypertension and occurs due to low blood flow to the kidneys, leading to activation of the Renin-Angiotensin-Aldosterone System (RAAS) and subsequent hypertension.
Define: Hypertension
Hypertension is defined as a condition where blood pressure measurements exceed 140/90 mmHg.
Describe: Prevalence of Hypertension with Age
The prevalence of hypertension increases with age, with 32% of adults aged 40-59 affected, and 70% of adults over the age of 65 affected.
True or False: Hypertension is associated with adverse health outcomes such as dementia, physical disability, and an increased risk of falls and fractures.
True
What are some factors contributing to hypertension?
A) Genetic factors
B) Environmental factors
C) Lifestyle factors
D) All of the above
D) All of the above
Describe: Study by Bert et al.
Bert et al. analyzed 8,636 patients over a 10-year period and found a rapid decline in kidney function associated with hypertension. In the 60-69 age group (n=4,128), they observed a significant decline in kidney function.
True or False: Essential hypertension accounts for 95% of all hypertension cases and has an identifiable cause.
False
In hypertension, changes to the arterial wall include an increase in wall thickness and a decrease in vessel __________.
Elasticity
Define: Renal Hypertension
Renal hypertension is characterized by low blood flow to the kidneys, leading to the activation of the Renin-Angiotensin-Aldosterone System (RAAS) and subsequent hypertension.
True or False: Blood pressure typically increases throughout life until around age 70 and then declines.
True
Describe: Mechanism of Blood Pressure Increase with Age
With aging, individuals typically experience an increase in blood pressure due to changes in arterial wall thickness and elasticity, as well as alterations in cardiac output and peripheral resistance.
Define: Aortic Stiffness
Aortic stiffness refers to a reduction in the ability of large arteries, particularly the aorta, to readily accommodate the increase in blood ejected from the heart during systole.
Describe: Characteristics of a Compliant Aorta
A compliant aorta exhibits slow pulse wave velocity (PWV), low-amplitude forward wave, and predominantly diastolic arrival of wave reflections to the aortic root, leading to augmentation of diastolic pressure with minimal augmentation of systolic pressure.
True or False: Elastin deposition in the arterial wall continues throughout adulthood.
False
What contributes to progressive elastin fragmentation/loss in aging arteries?
A) Increased elastin deposition
B) Mechanical fatigue
C) Reduced vascular smooth muscle tone
D) Collagen deposition
B) Mechanical fatigue over the lifetime (cyclic stress); Elastase-mediated proteolysis
Describe: Characteristics of a Stiff Aorta
A stiff aorta exhibits fast pulse wave velocity (PWV), high-amplitude forward wave, and systolic arrival of wave reflections to the central aorta. This leads to pronounced augmentation of mid-to-late systolic pressure with reduced augmentation of diastolic pressure.
True or False: Medial calcification in aging arteries is predominantly mediated by the osteochondrogenic differentiation of vascular smooth muscle cells (VSMCs).
True