Physiology Quiz on Cardiovascular System

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Questions and Answers

What primarily causes the condition of ascites in malnourished children?

Increased smooth muscle contraction in the abdominal area

Decrease in plasma protein concentration disrupting osmotic balance (correct)

Increase in interstitial fluid pressure due to dehydration

Increased vascular tone leading to vessel constriction

What neurotransmitter is responsible for the vasodilation mediated by the endothelium as observed by Furchgott?

Norepinephrine

Serotonin

Acetylcholine (correct)

Dopamine

What characterizes vascular tone in blood vessels?

It indicates the maximum dilation capacity of a vessel only

It is entirely dependent on intrinsic factors alone

It refers solely to the constriction of the blood vessels

It is the balance between contraction and dilation of vessels (correct)

What is the role of ATII in relation to sodium and water?

It increases sodium reabsorption in the proximal tubule. Signup and view all the answers

Which factors influence smooth muscle contraction in blood vessels?

Calcium levels inside the muscle cells and various signal transduction mechanisms Signup and view all the answers

Which hormone is released from the adrenal cortex and plays a significant role in sodium balance?

Aldosterone Signup and view all the answers

In the event of left ventricle failure, where would you expect edema to primarily occur?

In the lungs from pulmonary congestion Signup and view all the answers

Which mechanism is NOT typically involved in the control of vascular tone?

Only hormonal responses from the endocrine system Signup and view all the answers

How does the renin-angiotensin system primarily affect the sympathetic nervous system (SNS)?

By increasing sympathetic neurotransmission centrally and peripherally. Signup and view all the answers

What is the primary mediator released by the vascular endothelium that acts similarly to EDRF as identified in the 1980s?

Nitric Oxide Signup and view all the answers

What is the primary stimulus for the production of Nitric Oxide?

Acetylcholine Signup and view all the answers

Which isoform of Endothelin is primarily responsible for cardiovascular effects?

ET-1 Signup and view all the answers

What is the effect of Prostaglandin I2 (PGI2) on platelet aggregation?

Inhibits platelet aggregation Signup and view all the answers

What triggers the release of A-Type Natriuretic Peptide (ANP)?

Atrial stretch Signup and view all the answers

Which receptor primarily mediates vasoconstriction in response to Endothelin?

ETA Signup and view all the answers

What is the primary function of B-Type Natriuretic Peptide (BNP)?

Increase sodium excretion in urine Signup and view all the answers

Which enzyme is responsible for synthesizing Endothelin?

Endothelin converting enzyme Signup and view all the answers

What effect does Nitric Oxide (NO) have on blood vessels?

Vasodilation Signup and view all the answers

Which receptor is primarily responsible for vasoconstriction in blood vessels?

Alpha 1 receptor Signup and view all the answers

What effect do beta 1 receptors have on heart function?

Increase inotropy Signup and view all the answers

What is the overall function of muscarinic receptors like M2 in the cardiovascular system?

Have no effect on heart contractility Signup and view all the answers

Which neurotransmitter is associated with both alpha 1 and beta 2 receptor activation?

Norepinephrine Signup and view all the answers

What is the role of chromaffin cells in the sympathetic nervous system?

Secrete hormones like adrenaline into the bloodstream Signup and view all the answers

Which of the following is NOT a function of beta 2 receptors?

Increased heart rate Signup and view all the answers

Which effect is expected when both alpha 1 and beta 2 receptors are activated simultaneously?

Balanced vasoconstriction and vasodilation Signup and view all the answers

Which of the following effects primarily results from parasympathetic activation?

Decreased heart rate Signup and view all the answers

What role do baroreceptors play in blood pressure regulation?

They are sensitive to changes in the stretch of vessel walls caused by blood pressure variations. Signup and view all the answers

Which neurotransmitter is primarily associated with the sympathetic nervous system's effects on the heart?

Norepinephrine Signup and view all the answers

What is the effect of the sympathetic nervous system on heart function?

Increases heart rate and force of contraction, leading to tachycardia. Signup and view all the answers

Which receptors are activated by acetylcholine in the parasympathetic nervous system?

Muscarinic receptors Signup and view all the answers

How does the autonomic nervous system maintain homeostasis in heart function?

They work antagonistically to modulate heart rate and force of contraction. Signup and view all the answers

Which of the following is NOT a function associated with the sympathetic nervous system?

Vasodilation of blood vessels Signup and view all the answers

Where are the highest concentrations of baroreceptors located?

In the aortic arch and carotid sinus Signup and view all the answers

What outcome results from the increased stretch of vessel walls detected by baroreceptors?

Increased parasympathetic activity Signup and view all the answers

What percentage of adrenaline is released compared to noradrenaline?

80% Signup and view all the answers

What is the effect of low concentrations of adrenaline on β2 receptors?

Vasodilation Signup and view all the answers

Which of the following stimuli triggers the release of renin from juxtaglomerular cells?

Decreased blood pressure Signup and view all the answers

What is formed by angiotensin-converting enzyme (ACE) from angiotensin I?

Angiotensin II Signup and view all the answers

What is an effect of angiotensin II acting through AT1 receptors?

Vasoconstriction Signup and view all the answers

Which of the following is a primary action of angiotensin II?

Release of aldosterone Signup and view all the answers

How does increased sympathetic nervous system activity affect blood pressure?

Increases blood pressure Signup and view all the answers

What is the main role of renin in the Renin-Angiotensin-Aldosterone System (RAAS)?

Convert angiotensinogen to angiotensin I Signup and view all the answers

Study Notes

Blood Pressure and Control Mechanisms

Pressure in the cardiovascular (CV) system is a vital factor
Factors influencing blood pressure include peripheral resistance and cardiac output
Volume control is crucial for blood pressure homeostasis
Homeostatic control of cardiovascular functions is managed by the autonomic nervous system and the renin-angiotensin-aldosterone system (RAAS)
Endothelial factors, nitric oxide (NO), and prostacyclin (PGI2) are also involved
Natriuretic peptides play a role in blood pressure regulation

Blood Pressure

Blood pressure is generated by ventricular contraction, causing pulsatile surges in arteries
Systolic and diastolic pressures are measured, for example, 120mm Hg/80 mm Hg (120/80)
Elastic rebound in arteries maintains pressure

Pulse and Mean Arterial Pressures

Systolic pressure is the peak pressure during ventricular contraction
Diastolic pressure is the minimum pressure during ventricular relaxation
Pulse pressure is the difference between systolic and diastolic pressures
Mean arterial pressure (MAP) is the average pressure throughout the cardiac cycle

Role of Arteries

During ventricular contraction, the semilunar valve opens, allowing blood to enter the aorta and arteries
Arteries expand and store pressure in their elastic walls
During ventricular relaxation, the semilunar valve closes, and elastic recoil of the arteries propels blood forward through the circulatory system.

Factors Affecting Blood Pressure

Cardiac output is a key factor
Peripheral vascular resistance is another key factor
Blood volume is also a factor influencing blood pressure

Mean Arterial Pressure (MAP)

MAP is the average arterial pressure during a cardiac cycle
The formula for MAP is: Diastolic pressure + (1/3)Pulse Pressure

Mean Arterial Pressure (Important Equations)

Mean arterial pressure (MAP) is calculated as cardiac output (CO) multiplied by peripheral vascular resistance (PVR)
Cardiac output (CO) is determined by stroke volume (SV) and heart rate (HR)

Factors Affecting Cardiac Output

Heart rate (HR) is influenced by autonomic innervation, hormones, fitness levels, and age
Stroke volume (SV) depends on heart size, fitness levels, gender, contractility, preload (end-diastolic volume), and afterload (resistance)

Factors Affecting Stroke Volume

Contractility, preload (stretch during diastole), and afterload (pressure against ejection) are key factors determining stroke volume
An increase in any of these factors generally results in a higher stroke volume

Factors Affecting Contractility

Starling's Law of the Heart describes the relationship between preload and contractility.
Increased contractility is often seen with adrenergic agonists
Decreased contractility can be a sign of heart failure

Pressure, Flow, and Resistance

Fluid flows from high to low pressure
Resistance depends on vessel length, vessel radius, and blood viscosity.
A smaller radius leads to a much larger increase in resistance.

Resistance to Blood Flow (Poiseuille equation)

The Poiseuille equation describes the relationship between resistance (R), viscosity (η), length (L), and radius (r) of a blood vessel
R=(8nL)/(πr^4)

Effect of Blood Volume on Blood Pressure

Blood volume is approximately 5 liters
Arteries contain a smaller percentage of the total blood volume compared to veins.
Increased blood volume (hypervolemia) results in increased blood pressure.
Decreased blood volume (hypovolemia) results in decreased blood pressure

Factors Affecting Blood Volume

Oedema is the accumulation of fluid in interstitial space due to disruptions in fluid exchange
Increased hydrostatic pressure, decreased plasma protein concentration, and increased interstitial proteins can disrupt fluid balance.

Questions

Edema in the case of left ventricular failure is most likely to occur in the lower extremities or abdomen due to fluid buildup from inadequate pumping.
Malnutrition can lead to ascites—or fluid buildup in the abdomen—because malnutrition can lead to decreased plasma protein concentration, causing lower osmotic pressure.
Lower osmotic pressure causes fluid leakage from blood vessels to tissue compartments.

Vascular Tone

Vascular tone refers to a blood vessel's constriction relative to its maximum dilation—the widest the vessel can be.
All arterial and venous vessels under basal conditions exhibit some smooth muscle contraction
Vascular tone is influenced by the composition of the vessels and control by intrinsic and extrinsic factors.

Smooth Muscle Contraction

Extrinsic and intrinsic mechanisms influencing vasoconstriction and vasodilation involve signal transduction pathways
Calcium changes in smooth muscle cells are linked to contraction or relaxation

Cardiovascular Physiology (Control Mechanisms)

Nervous, cytokine, and autoregulatory mechanisms influence the cardiovascular system
Autonomic nervous system (ANS) and renin-angiotensin-aldosterone system (RAAS) are key components
Nitric oxide (NO) and prostaglandins (PGs) are also significant factors

Baroreceptors

Baroreceptors are stretch-sensitive mechanoreceptors located in the aortic arch and carotid sinus.
Increased or decreased blood pressure leads to baroreceptor firing rate changes
Firing rate changes alter sympathetic and parasympathetic activity to regulate blood pressure.

Autonomic Nervous System

The sympathetic nervous system (SNS) is associated with "fight or flight" responses, often increasing HR
The parasympathetic nervous system (PNS) promotes "rest and digest," typically decreasing HR.

What effect will the sympathetic nervous system have on?

Heart rate: increase
Force of contraction of the heart: increase
Blood pressure: increase

Systems work to oppose each other

Sympathetic (SNS) nerves increase heart rate through chronotropy and inotropy (force of contraction) and also increase dromotropy (impulse conduction), while excitability increases
Parasympathetic (PNS) nerves decrease heart rate, whereas dromotropy, inotropy, and lusitropy decrease.

Innervation of the Heart

The sympathetic nervous system innervates the atria, sinoatrial (SA) node, and ventricles.
The vagus nerve (X) innervates the heart, but sometimes overlaps in function with sympathetic nerves

Adrenergic receptors

Alpha1 receptors are primarily involved in vasoconstriction
Beta1 receptors are primarily involved in increasing heart rate and contractility
Beta2 receptors are primarily involved in vasodilation

Muscarinic receptors

M2 receptors primarily affect heart rate, including decreasing heart rate and contractility.

Blood Vessels

Alpha1 receptors are primarily involved in vasoconstriction; Beta2 receptors are primarily involved in vasodilation.

Renin-Angiotensin-Aldosterone System (RAAS)

RAAS is a hormonal system that regulates blood pressure.
Renin is released in response to decreased blood pressure and initiates a cascade of events, ultimately contributing to blood pressure regulation
ACE converts angiotensin I to angiotensin II, which is a potent vasoconstrictor and stimulates the release of aldosterone

Angiotensin-Converting Enzyme (ACE)

ACE converts angiotensin I to angiotensin II
ACE is inhibited by medications like captopril
ACE2 is involved in COVID-19 pathogenesis

Angiotensin II

Angiotensin II acts via AT1 and AT2 receptors
Angiotensin II causes vasoconstriction, ADH release, increased sympathetic activity, and increases sodium/water reabsorption.
AT1 receptors are primary for vasoconstriction and for stimulating ADH release

Aldosterone

Aldosterone is a mineralocorticoid hormone
Primary actions include increasing sodium reabsorption and secretion of potassium.
Aldosterone release is stimulated by angiotensin II

Natriuretic Peptides

Natriuretic peptides (ANP and BNP) are released by the heart in response to stretch
ANP and BNP act to oppose the effects of Angiotensin II; they increase natriuresis and diuresis (increasing sodium and water excretion)
BNP is a biomarker for heart failure.

Nitric Oxide (NO)

NO is a vasodilator
NO is produced in response to stimulation by acetylcholine, histamine, bradykinin, serotonin, shear stress and other stimuli.
NO acts through increasing cyclic GMP, leading to smooth muscle relaxation

Endothelin

Endothelin is a potent vasoconstrictor
Endothelin-1 is primarily responsible for cardiovascular effects.
Endothelin effects are largely opposite to those of NO.

Prostaglandin 12 (PGI2)

PGI2 is produced from arachidonic acid
PGI2 is a vasodilator and inhibits platelet aggregation

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Description

Test your knowledge on various aspects of cardiovascular physiology with this quiz. Questions cover key concepts like vascular tone, neurotransmitters involved in vasodilation, and the role of hormones in blood pressure regulation. Perfect for students studying advanced physiology or related subjects.