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.