Cardiovascular System Week 6
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Questions and Answers

What is the primary effect of binding to alpha adrenergic receptors in the vasculature?

  • Decreased total peripheral resistance
  • Increase in cardiac contractility
  • Vasodilation of coronary arteries
  • Vasoconstriction of arteries and arterioles (correct)

Which adrenergic receptors are responsible for contractility increases in the heart?

  • Delta adrenergic receptors
  • Gamma adrenergic receptors
  • Alpha adrenergic receptors
  • Beta adrenergic receptors (correct)

What physiological change occurs due to sympathetic activation?

  • Increased heart rate and stroke volume (correct)
  • Decreased heart rate and stroke volume
  • Decreased venous return
  • Arteriolar vasodilation

What is an effect of parasympathetic inhibition on heart rate?

<p>Increased heart rate (C)</p> Signup and view all the answers

Where are beta adrenergic receptors primarily found?

<p>In coronary arteries (D)</p> Signup and view all the answers

Which of the following accurately describes vasoconstriction?

<p>Increases resistance in blood vessels (B)</p> Signup and view all the answers

Which best explains the role of norepinephrine during exercise?

<p>It promotes vasoconstriction in certain blood vessels. (A)</p> Signup and view all the answers

What occurs during the baroreceptor reflex?

<p>Sympathetic activation helps to increase blood pressure (C)</p> Signup and view all the answers

What are baroreceptors primarily sensitive to in relation to blood pressure?

<p>Changes in pressure (A)</p> Signup and view all the answers

Where are the two main anatomical sites that contain the majority of baroreceptors?

<p>Internal carotid arteries and aortic arch (D)</p> Signup and view all the answers

Which of the following statements best describes low-pressure receptors?

<p>They detect minute changes in low pressure areas. (C)</p> Signup and view all the answers

What is the primary function of the vasomotor center in the brain?

<p>To maintain vasomotor tone and blood vessel diameter (B)</p> Signup and view all the answers

What does vasomotor tone refer to?

<p>Continual sympathetic nervous system activity inducing slight vasoconstriction (B)</p> Signup and view all the answers

Which neurotransmitters primarily influence blood vessel tone?

<p>Epinephrine and norepinephrine (C)</p> Signup and view all the answers

In which brain areas can the vasomotor center be located?

<p>Reticular substance of medulla and lower third of pons (C)</p> Signup and view all the answers

What factor influences the activity of the vasomotor center?

<p>Other parts of the brain (A)</p> Signup and view all the answers

What is the function of the afferent component in a reflex arc?

<p>It sends an input signal from a specialized receptor to the CNS. (C)</p> Signup and view all the answers

Which statement best describes the role of higher brain centers in reflex actions?

<p>They can override reflex actions if desired. (B)</p> Signup and view all the answers

In the knee jerk reflex, what triggers the afferent component?

<p>The stretching of the patellar tendon. (C)</p> Signup and view all the answers

What is a key characteristic of reflex actions?

<p>They happen automatically without intentional input. (B)</p> Signup and view all the answers

Which of the following is an example of a reflex that can be overridden?

<p>Attempting to hold back a cough or sneeze. (C)</p> Signup and view all the answers

What is the central component of a reflex arc responsible for?

<p>Interpreting afferent information and coordinating a response. (C)</p> Signup and view all the answers

What is primarily responsible for detecting changes in blood pressure?

<p>Baroreceptors. (A)</p> Signup and view all the answers

Which component of the reflex arc is responsible for the output signal to a target site?

<p>Efferent component. (C)</p> Signup and view all the answers

Flashcards

Reflex Arc Anatomy

A reflex arc is a pathway that controls a reflex action. It has three components: afferent (input) signal from receptor; CNS (central nervous system) processing the input; and efferent (output) signal which produces an action.

Afferent Component

The input signal in a reflex arc, typically from a specialized receptor.

CNS Component

The central nervous system (brain and/or spinal cord) interprets the afferent (input) information.

Efferent Component

The output signal from the CNS to a target site, initiating an action/response.

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Reflex Override

Higher brain centers can consciously override automatic reflex actions.

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Baroreceptor

A specialized receptor that detects changes in blood pressure.

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Knee-jerk Reflex

A reflex action where the quadriceps muscle contracts when the patellar tendon is tapped.

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Reflex

An automatic, involuntary response to a stimulus.

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Low-Pressure Receptors

Baroreceptors located in the atria and pulmonary arteries, sensitive to small changes in blood pressure due to blood volume fluctuations.

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Vasomotor Center

The area in the brain stem (medulla and lower pons) controlling blood vessel tone, with three main regions: vasoconstrictor, vasodilator, and sensory.

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Vasomotor Tone

The constant, slight vasoconstriction caused by the continuous firing of sympathetic nerves, contributing to overall blood pressure regulation.

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Epinephrine and Norepinephrine

Hormones released by the adrenal glands that bind to adrenergic receptors on blood vessels, typically causing vasoconstriction (except in skeletal muscles).

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Adrenergic Receptors

Receptors on blood vessels and other tissues that respond to epinephrine and norepinephrine, influencing blood vessel tone and other physiological functions.

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How do baroreceptors maintain blood pressure?

Baroreceptors detect changes in blood pressure and send signals to the brain's vasomotor center, which adjusts sympathetic nerve activity to regulate vessel diameter and blood pressure.

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Why is vasomotor tone important for blood pressure?

Vasomotor tone provides a baseline constriction of blood vessels, ensuring a certain level of pressure even when the body is at rest.

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Alpha Adrenergic Receptors

These receptors are located on blood vessels and generally cause vasoconstriction. Different blood vessels have varying types of alpha receptors, leading to diverse responses.

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Beta Adrenergic Receptors

Located primarily in coronary arteries, these receptors trigger vasodilation. This promotes increased blood flow to the heart during activity.

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Epinephrine's Vasoconstriction

Epinephrine, when binding to alpha receptors, constricts vessels in the kidneys and digestive tract, raising overall peripheral resistance.

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Epinephrine's Vasodilation

Epinephrine also activates beta receptors in coronary arteries, causing vasodilation. This allows more blood to reach the heart muscle.

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Sympathetic Activation

This involves activating the sympathetic nervous system, leading to vasoconstriction in arteries and veins, and increasing heart rate and stroke volume.

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Parasympathetic Inhibition

This involves reducing parasympathetic activity, leading to an increased heart rate.

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Vasoconstriction vs. Contractility

Vasoconstriction refers to the narrowing of blood vessels. Cardiac contractility refers to the force of the heart's contractions. The two are separate actions.

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Baroreceptor Reflex

This is a feedback mechanism regulating blood pressure. Baroreceptors in blood vessels detect pressure changes and send signals to the brain, which adjusts heart rate and blood vessel diameter to maintain proper pressure.

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Study Notes

Cardiovascular System (Week 6)

  • Neural Control of Blood Pressure
    • Reflexes
      • A reflex arc involves an afferent component (input signal from a receptor), a CNS component (interpretation), and an efferent component (output signal to a target).
      • Reflexes are automatic responses, but higher brain centers can override them.
      • Examples:
        • Knee-jerk reflex: Tapping the patellar tendon stretches it, triggering a signal for the quadriceps muscle to contract. Conscious override is possible.
        • Cough/sneeze reflex (discussed separately): Can be consciously overridden.
    • Baroreceptor Basics (Basic Info): Baroreceptors detect changes in blood pressure. Play a crucial role in maintaining short-term blood pressure homeostasis. Respond rapidly – within a second or less.

Baroreceptors (More Detail)

  • Location: Most abundant in internal carotid arteries and aortic arch. Lower pressure receptors found in atria and pulmonary arteries, for sensing changes in pressure related to blood volume.
  • Role: Respond to subtle changes in blood pressure, like variations in blood volume, not just the absolute pressure. This is different from their high-pressure counterparts.
  • Central Nervous System: The vasomotor center in the brainstem's reticular substance and lower pons regulates vasoconstriction and vasodilation. Contains vasoconstrictor, vasodilator, and sensory areas.

Adrenergic Receptors

  • Effect on Blood Vessels: Norepinephrine and epinephrine impact blood vessel tone by binding to alpha and beta adrenergic receptors.
    • Alpha Receptors: Primarily cause vasoconstriction.
    • Beta Receptors: Typically cause vasodilation, particularly in the coronary arteries.

Baroreceptor Reflex

  • Afferent Signal: Rapidly increasing blood pressure triggers a higher rate of action potentials.
  • CNS Response:
    • Inhibition of the vasoconstrictor center.
    • Excitation of the vagal parasympathetic center.
  • Efferent Response:
    • Causes vasodilation (or reduced vasoconstriction)
    • Decreases heart rate
    • Decreases stroke volume

Venous Return

  • Influence: Blood pressure gradients drive blood flow (high to low).
  • Factors Increasing Venous Return:
    • Increased venous blood pressure
    • Venous vasoconstriction
    • External compression of veins, like during exercise (muscle pump).
    • Increased blood volume in veins.
  • Factors Affecting Venous Return: Right atrial pressure and right ventricle contractility and pulmonary resistance.

Cardiovascular Response to Exercise

  • Systolic Blood Pressure: Increases during aerobic exercise, related to the amount of active muscle mass.
  • Diastolic Blood Pressure: Remains unchanged or slightly decreases during aerobic exercise.
  • Blood Flow Control: Active skeletal muscles send signals leading to vasodilation in those muscles and vasoconstriction in inactive areas (e.g., digestive system), redirecting blood flow.
  • Total Peripheral Resistance (TPR): Increases during exercise, but the increase isn't as severe if more muscle groups are involved.

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Cardiovascular System (Week 6) Study Guide PDF

Description

Explore the neural control of blood pressure through reflexes and baroreceptors in the cardiovascular system. This quiz covers the mechanisms of how these reflexes operate and their significance in maintaining blood pressure homeostasis. Test your understanding of these critical processes that regulate cardiovascular health.

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