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Cardiovascular Physiology

Blood Pressure and Vascular Resistance Practice Questions

20 free Blood Pressure and Vascular Resistance practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

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Question 1 of 20 Medium

According to Poiseuille's Law, if the radius of a blood vessel is reduced by half, the resistance to blood flow will increase by a factor of:

  1. A 2-fold
  2. B 4-fold
  3. C 8-fold
  4. D 16-fold

Correct answer: 16-fold

Resistance is inversely proportional to the fourth power of the radius. Halving the radius therefore multiplies resistance by 2 to the fourth power, that is 16 times. This steep relationship is why small changes in arteriolar calibre have such a large effect on blood flow.

Question 2 of 20 Medium

Which of the following vessels are considered the 'resistance vessels' of the systemic circulation and are the primary site of blood pressure regulation?

  1. A Aorta
  2. B Large arteries
  3. C Arterioles
  4. D Capillaries

Correct answer: Arterioles

Arterioles have thick layers of smooth muscle and the smallest individual diameters among pre-capillary vessels. By altering their diameter, they provide the greatest contribution to Total Peripheral Resistance (TPR).

Question 3 of 20 Medium

Mean Arterial Pressure (MAP) is most accurately estimated using which of the following formulas?

  1. A Systolic Pressure + Diastolic Pressure / 2
  2. B Diastolic Pressure + 1/3 Pulse Pressure
  3. C Systolic Pressure - Diastolic Pressure
  4. D 2 x Systolic Pressure + Diastolic Pressure / 3

Correct answer: Diastolic Pressure + 1/3 Pulse Pressure

Since the heart spends more time in diastole than in systole at resting heart rates, MAP is weighted toward diastolic pressure. It is calculated as Diastolic BP + 1/3 (Systolic BP - Diastolic BP).

Question 4 of 20 Medium

The 'Baroreceptor Reflex' initiates a rapid response to a decrease in blood pressure. Where are the primary high-pressure baroreceptors located?

  1. A Right atrium and Superior Vena Cava
  2. B Carotid sinus and Aortic arch
  3. C Renal afferent arterioles
  4. D Hypothalamus and Medulla

Correct answer: Carotid sinus and Aortic arch

The carotid sinus (via the Glossopharyngeal nerve) and the aortic arch (via the Vagus nerve) contain stretch-sensitive mechanoreceptors. They monitor arterial blood pressure and send signals to the cardiovascular center in the medulla.

Question 5 of 20 Medium

Which of the following describes the relationship between 'Compliance' and 'Vascular Resistance' in the venous system?

  1. A Low compliance and high resistance
  2. B High compliance and low resistance
  3. C Low compliance and low resistance
  4. D High compliance and high resistance

Correct answer: High compliance and low resistance

Veins are thin-walled and highly distensible, allowing them to hold large volumes of blood with little change in pressure (high compliance). Because they are wide, they also offer very low resistance to flow.

Question 6 of 20 Medium

Total Peripheral Resistance (TPR) would be DECREASED by which of the following factors?

  1. A Increased blood viscosity (polycythemia)
  2. B Systemic vasoconstriction via Alpha-1 receptors
  3. C Release of Atrial Natriuretic Peptide (ANP)
  4. D Increased sympathetic nerve activity to the skin

Correct answer: Release of Atrial Natriuretic Peptide (ANP)

ANP is released in response to atrial stretch and promotes vasodilation and sodium excretion. Vasodilation decreases the resistance of the systemic vasculature, thereby lowering TPR.

Question 7 of 20 Medium

The Renin-Angiotensin-Aldosterone System (RAAS) regulates blood pressure over the long term. What is the direct effect of Angiotensin II on blood vessels?

  1. A Potent vasoconstriction
  2. B Potent vasodilation
  3. C Increased capillary permeability
  4. D Inhibition of the sympathetic nervous system

Correct answer: Potent vasoconstriction

Angiotensin II is one of the most powerful vasoconstrictors in the body. It acts directly on AT1 receptors on vascular smooth muscle to increase TPR and blood pressure.

Question 8 of 20 Medium

Pulse pressure is defined as the difference between systolic and diastolic pressure. Which factor primarily determines pulse pressure?

  1. A Heart rate and blood viscosity
  2. B Blood viscosity and vessel length
  3. C Stroke volume and arterial compliance
  4. D Total blood volume and hydration status

Correct answer: Stroke volume and arterial compliance

Pulse pressure increases if stroke volume increases (more blood pumped into the arteries) or if arterial compliance decreases (arteries become stiffer, as seen in aging or atherosclerosis).

Question 9 of 20 Medium

What happens to the firing rate of the carotid sinus nerve when blood pressure increases?

  1. A It decreases, signaling the medulla to increase heart rate and cardiac output
  2. B It increases to signal the medulla to decrease sympathetic outflow
  3. C It remains constant while aortic arch firing decreases proportionally
  4. D It stops completely once mean arterial pressure exceeds 100 mmHg

Correct answer: It increases to signal the medulla to decrease sympathetic outflow

Increased blood pressure stretches the baroreceptors, increasing their firing rate. This inhibits the vasomotor center and stimulates the cardioinhibitory center to lower heart rate and induce vasodilation.

Question 10 of 20 Medium

Which of the following local metabolic factors causes 'Active Hyperemia' (vasodilation) in skeletal muscle during exercise?

  1. A Increased Oxygen (O2) concentration
  2. B Decreased Carbon Dioxide (CO2)
  3. C Increased Potassium (K+) and Adenosine
  4. D Increased pH (decreased tissue acidity)

Correct answer: Increased Potassium (K+) and Adenosine

During exercise, active muscles produce metabolites like K+, Adenosine, H+, and CO2. These substances act directly on local arteriolar smooth muscle to cause vasodilation, increasing blood flow to meet metabolic demands.

Question 11 of 20 Medium

Laminar flow in a blood vessel is characterized by:

  1. A Fluid moving in all directions with high resistance
  2. B A parabolic velocity profile with the highest velocity in the center
  3. C The random formation of eddies and turbulent whorls throughout the vessel
  4. D A Reynolds number exceeding 2000, producing turbulent flow patterns

Correct answer: A parabolic velocity profile with the highest velocity in the center

In laminar flow, blood moves in concentric layers. Friction with the vessel wall slows the outer layers, while the central layer moves fastest, resulting in a smooth, quiet, and efficient flow.

Question 12 of 20 Medium

Which of the following hormones is a potent vasoconstrictor released by the posterior pituitary in response to low blood pressure or high plasma osmolarity?

  1. A Oxytocin
  2. B Aldosterone
  3. C Vasopressin
  4. D Epinephrine

Correct answer: Vasopressin

Vasopressin (ADH) has dual roles: it increases water reabsorption in the kidneys and, at higher concentrations, causes systemic vasoconstriction via V1 receptors to support blood pressure.

Question 13 of 20 Medium

The 'Critical Closing Pressure' of a blood vessel refers to:

  1. A The maximum pressure at which a healthy vessel wall will rupture or burst
  2. B The minimum pressure required to open and re-expand a collapsed capillary
  3. C The pressure in the vena cava just before it enters the heart
  4. D The internal pressure at which a small vessel collapses and flow stops

Correct answer: The internal pressure at which a small vessel collapses and flow stops

Small vessels require a minimum internal pressure to counteract the active tension of the smooth muscle in their walls. If blood pressure falls below this critical level, the vessel collapses and blood flow ceases.

Question 14 of 20 Medium

According to the Law of Laplace, the wall tension required to withstand a given internal pressure is proportional to the vessel's:

  1. A Length
  2. B Viscosity
  3. C Compliance
  4. D Radius

Correct answer: Radius

The Law of Laplace ($T = P imes r$) states that wall tension (T) is the product of transmural pressure (P) and radius (r). This explains why larger vessels, like the aorta, require much thicker walls than capillaries to withstand the same pressure.

Question 15 of 20 Medium

What is the effect of 'Turbulent Flow' on the pressure-flow relationship?

  1. A It makes the flow much more efficient than smooth laminar flow
  2. B It significantly reduces the overall resistance of the vessel
  3. C It occurs primarily within the smallest capillary beds of tissue
  4. D It requires a larger pressure gradient to maintain the same flow rate

Correct answer: It requires a larger pressure gradient to maintain the same flow rate

Turbulence increases the resistance to flow because energy is lost in the form of eddies and vibrations (which can be heard as bruits). Therefore, higher pressure is needed to drive the same volume of blood compared to laminar flow.

Question 16 of 20 Medium

Which of the following describes 'Autoregulation' of blood flow?

  1. A The ability of an organ to maintain constant blood flow despite changes in arterial pressure
  2. B The regulation of heart rate and contractile rhythm by the SA node's intrinsic pacemaker activity
  3. C The redistribution of blood flow from the skin and gut to the core during cold exposure
  4. D The increase in systemic blood pressure and heart rate during the fight-or-flight stress response

Correct answer: The ability of an organ to maintain constant blood flow despite changes in arterial pressure

Organs like the brain and kidneys can maintain steady blood flow over a wide range of Mean Arterial Pressures (approx. 60–160 mmHg) through intrinsic myogenic and metabolic mechanisms.

Question 17 of 20 Medium

How does an increase in hematocrit (e.g., in polycythemia) affect blood pressure?

  1. A It increases BP by increasing blood viscosity and vascular resistance
  2. B It decreases BP by thinning the blood
  3. C It has no effect because capillaries expand to accommodate the cells
  4. D It decreases BP by increasing the oxygen-carrying capacity

Correct answer: It increases BP by increasing blood viscosity and vascular resistance

Hematocrit is the primary determinant of blood viscosity. Higher viscosity increases the resistance to flow (as per Poiseuille's Law), requiring a higher arterial pressure to maintain cardiac output.

Question 18 of 20 Medium

The 'Bayliss Effect' (myogenic mechanism) refers to vascular smooth muscle contracting in response to:

  1. A Increased carbon dioxide levels
  2. B Decreased pH (increased tissue acidity)
  3. C Sympathetic nerve stimulation
  4. D Increased transmural pressure (stretch)

Correct answer: Increased transmural pressure (stretch)

The myogenic response is an intrinsic property where vascular smooth muscle contracts when stretched by increased intravascular pressure. This helps protect downstream capillaries and maintain constant flow during pressure fluctuations.

Question 19 of 20 Medium

Which of the following receptors mediates vasodilation in skeletal muscle and coronary arteries in response to low doses of Epinephrine?

  1. A Alpha-1 receptors
  2. B Alpha-2 receptors
  3. C Beta-1 receptors
  4. D Beta-2 receptors

Correct answer: Beta-2 receptors

Epinephrine has a high affinity for Beta-2 receptors at low concentrations. Stimulation of Beta-2 receptors leads to smooth muscle relaxation and vasodilation, which is essential for increasing blood flow to muscles during stress.

Question 20 of 20 Medium

If Cardiac Output is 5 L/min and Mean Arterial Pressure is 100 mmHg (with Right Atrial Pressure of 0 mmHg), what is the Total Peripheral Resistance in mmHg/L/min?

  1. A 20
  2. B 0.05
  3. C 2
  4. D 200

Correct answer: 20

TPR is calculated using the formula $TPR = (MAP - RAP) / CO$. In this case, $(100 - 0) / 5 = 20$ mmHg/L/min.

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