Human Circulatory System Quiz
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Questions and Answers

What is the relationship between blood flow, pressure, and resistance expressed in an equation?

  • Blood Flow = Pressure - Resistance
  • Blood Flow = Pressure / Resistance (correct)
  • Blood Flow = Pressure x Resistance
  • Blood Flow = Pressure + Resistance

    • Which factor does NOT affect peripheral resistance?

  • Vessel diameter
  • Heart rate (correct)
  • Vascular length
  • Blood viscosity

    • During the baroreceptor reflex, which physiological parameter is adjusted to maintain blood pressure?

  • Only heart rate
  • Only blood viscosity
  • Only peripheral resistance
  • Both cardiac output and peripheral resistance (correct)

    • Which of the following is NOT a component of mean arterial pressure (MAP)?

    <p>Pulse pressure</p> Signup and view all the answers

    What does an increase in vessel diameter generally do to peripheral resistance?

    <p>Decreases peripheral resistance</p> Signup and view all the answers

    What is one role of the sympathetic nervous system in blood pressure regulation?

    <p>Increases cardiac output</p> Signup and view all the answers

    In terms of homeostasis, how does the cardiovascular system respond to a drop in blood pressure?

    <p>By increasing cardiac output and vascular resistance</p> Signup and view all the answers

    Which of the following factors is part of the chemoreceptor reflex coordination?

    <p>Increasing respiratory rate to improve oxygen supply</p> Signup and view all the answers

    What effect do sympathetic impulses have on the heart?

    <p>They increase heart rate, contractility, and cardiac output</p> Signup and view all the answers

    Where are the baroreceptors that respond to blood pressure changes located?

    <p>In the carotid sinuses and aortic arch</p> Signup and view all the answers

    What initiates the homeostatic response to rising blood pressure?

    <p>Stimulus from baroreceptors</p> Signup and view all the answers

    What is the role of vasomotor impulses in blood pressure regulation?

    <p>They facilitate vasodilation, aiding in blood pressure return to normal</p> Signup and view all the answers

    Which of the following processes is primarily involved when blood pressure rises above the normal range?

    <p>Stimulus for homeostatic response is activated</p> Signup and view all the answers

    What is the consequence of baroreceptors detecting elevated blood pressure?

    <p>They trigger vasodilation and reduced heart rate</p> Signup and view all the answers

    How does the body respond to a drop in blood pressure?

    <p>By increasing sympathetic impulses to the heart</p> Signup and view all the answers

    What is a primary function of the sympathetic nervous system regarding cardiovascular function?

    <p>Increasing heart rate and contractility during stress</p> Signup and view all the answers

    What happens to cardiac output when sympathetic stimulation is activated?

    <p>Cardiac output increases</p> Signup and view all the answers

    What physiological change occurs to maintain blood pressure homeostasis?

    <p>Vasodilation response from blood vessels</p> Signup and view all the answers

    What physiological response is primarily triggered by crisis stressors such as exercise or trauma?

    <p>Activation of vasomotor and cardio-acceleratory centers</p> Signup and view all the answers

    How is diastolic pressure defined during blood pressure measurement?

    <p>Pressure when arterial sounds disappear and blood flows freely</p> Signup and view all the answers

    What is the primary role of baroreceptors in the cardiovascular system?

    <p>Monitoring blood volume and pressure</p> Signup and view all the answers

    Which factor does NOT directly influence cardiac output?

    <p>Body temperature</p> Signup and view all the answers

    What typically occurs to blood pressure during physical exertion?

    <p>Transient elevations may occur</p> Signup and view all the answers

    What happens when arterial blood pressure falls below the normal range?

    <p>Blood pressure returns to homeostatic range.</p> Signup and view all the answers

    Which centers are affected by impulses from baroreceptors when blood pressure is low?

    <p>The cardioacceleratory and vasomotor centers.</p> Signup and view all the answers

    What role do vasomotor fibers play in regulating blood pressure?

    <p>They stimulate vasoconstriction, raising blood pressure.</p> Signup and view all the answers

    What is the effect of sympathetic impulses on heart function when blood pressure drops?

    <p>They increase heart rate, contractility, and cardiac output.</p> Signup and view all the answers

    Which part of the body contains baroreceptors that respond to blood pressure changes?

    <p>Carotid sinuses and aortic arch</p> Signup and view all the answers

    What happens to the cardioinhibitory center when blood pressure decreases?

    <p>It is inhibited by impulses from baroreceptors.</p> Signup and view all the answers

    Which factor primarily stimulates the vasomotor center when blood pressure falls?

    <p>Impulses from baroreceptors</p> Signup and view all the answers

    What would most likely occur if baroreceptors become inhibited?

    <p>Compromised cardiovascular homeostasis.</p> Signup and view all the answers

    What is the primary response of the body to increased sympathetic activity due to low blood pressure?

    <p>Increased heart rate and vasoconstriction.</p> Signup and view all the answers

    What aspect of blood pressure is primarily monitored by baroreceptors?

    <p>Mechanical stretch of arterial walls</p> Signup and view all the answers

    Which factor does NOT influence blood pressure?

    <p>Skin temperature</p> Signup and view all the answers

    What is the relationship between blood pressure and cardiac output?

    <p>Blood pressure is directly proportional to cardiac output</p> Signup and view all the answers

    What role does the brain play in maintaining blood pressure?

    <p>It supervises the heart and kidneys</p> Signup and view all the answers

    If MAP (Mean Arterial Pressure) increases, which of the following must also increase?

    <p>Stroke volume or heart rate</p> Signup and view all the answers

    Which pressure range is considered normal for capillary blood pressure?

    <p>17 to 35 mm Hg</p> Signup and view all the answers

    What happens if blood pressure is too high in capillaries?

    <p>Rupture of fragile, thin-walled capillaries</p> Signup and view all the answers

    Which formula represents the relationship among mean arterial pressure (MAP), stroke volume (SV), and heart rate (HR)?

    <p>MAP = SV × HR × R</p> Signup and view all the answers

    Which mechanism assists in increasing venous return to the heart?

    <p>Contraction of skeletal muscles</p> Signup and view all the answers

    What is the primary factor affecting peripheral resistance?

    <p>Vessel diameter</p> Signup and view all the answers

    If a person's blood volume decreases significantly, what effect would this likely have?

    <p>Decrease in systemic blood pressure</p> Signup and view all the answers

    What is the term for the resistance to blood flow in the vessels?

    <p>Peripheral resistance</p> Signup and view all the answers

    Peripheral resistance only depends on blood viscosity.

    <p>False</p> Signup and view all the answers

    What is the equation used to express the relationship between blood flow, pressure, and resistance?

    <p>Blood Flow = Blood Pressure / Peripheral Resistance</p> Signup and view all the answers

    The __________ reflex helps to regulate blood pressure by adjusting cardiac output and peripheral resistance.

    <p>baroreceptor</p> Signup and view all the answers

    Which of the following factors does NOT affect peripheral resistance?

    <p>Heart rate</p> Signup and view all the answers

    Match the following components with their associated roles in the cardiovascular system:

    <p>Systolic Pressure = Pressure during heart contraction Diastolic Pressure = Pressure during heart relaxation Pulse Pressure = Difference between systolic and diastolic pressure Mean Arterial Pressure = Average pressure in the arteries during one cardiac cycle</p> Signup and view all the answers

    An increase in vessel diameter results in increased peripheral resistance.

    <p>False</p> Signup and view all the answers

    Give an example of how the cardiovascular system responds to maintain homeostasis during exercise.

    <p>Increased heart rate and blood flow to the muscles.</p> Signup and view all the answers

    What happens to blood pressure during physical exertion?

    <p>Blood pressure increases</p> Signup and view all the answers

    Systolic pressure is the pressure when sounds disappear during blood pressure measurement.

    <p>False</p> Signup and view all the answers

    What is the primary function of chemoreceptors in the cardiovascular system?

    <p>To monitor blood chemistry such as oxygen and carbon dioxide levels.</p> Signup and view all the answers

    The pressure at which sounds first occur during blood flow is called __________ pressure.

    <p>systolic</p> Signup and view all the answers

    Match the following elements with their physiological responses:

    <p>Exercise = Increased blood pressure Dehydration = Decreased blood volume Angiotensin II = Increased vasoconstriction Baroreceptors = Monitoring blood pressure</p> Signup and view all the answers

    Which factor does NOT directly influence blood pressure?

    <p>Lymphatic flow</p> Signup and view all the answers

    High capillary blood pressure is desirable for effective filtration.

    <p>False</p> Signup and view all the answers

    What is the normal range for capillary blood pressure?

    <p>17 to 35 mm Hg</p> Signup and view all the answers

    Blood pressure is calculated as CO multiplied by _____.

    <p>Peripheral resistance</p> Signup and view all the answers

    Match the following factors with their effect on blood pressure:

    <p>Increased cardiac output = Raises blood pressure Increased peripheral resistance = Raises blood pressure Decreased blood volume = Lowers blood pressure Vasodilation = Lowers blood pressure</p> Signup and view all the answers

    The formula for mean arterial pressure (MAP) is derived from which relationship?

    <p>MAP = CO × R</p> Signup and view all the answers

    What primarily regulates long-term blood pressure by altering blood volume?

    <p>Hormonal Regulation</p> Signup and view all the answers

    Baroreceptors are found only in the carotid sinuses and the aortic arch.

    <p>False</p> Signup and view all the answers

    Name one physiological response that occurs to increase cardiac output.

    <p>Increased heart rate or increased stroke volume</p> Signup and view all the answers

    Control of blood pressure is solely managed by the heart.

    <p>False</p> Signup and view all the answers

    What effect does increased blood pressure have on the baroreceptor reflex?

    <p>Increases input to the vasomotor center, inhibits the vasomotor and cardioacceleratory centers.</p> Signup and view all the answers

    The __________ center oversees changes in cardiac output and blood vessel diameter.

    <p>Cardiovascular</p> Signup and view all the answers

    The primary structure that regulates heart rate in response to blood pressure is located in the _____.

    <p>medulla</p> Signup and view all the answers

    Which of the following factors can increase mean arterial pressure (MAP)?

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

    Match the following reflexes with their functions:

    <p>Baroreceptor Reflex = Modulates blood pressure based on stretch Chemoreceptor Reflex = Regulates blood flow in response to chemical changes Vasomotor Center = Controls vessel diameter Cardioinhibitory Center = Reduces heart rate</p> Signup and view all the answers

    Which of the following hormones is primarily involved in short-term neural control?

    <p>Water-soluble hormones</p> Signup and view all the answers

    The vasomotor center sends impulses that lead to moderate vessel dilation known as vasomotor tone.

    <p>False</p> Signup and view all the answers

    Identify a primary factor that increases mean arterial pressure (MAP).

    <p>Increased cardiac output or increased peripheral resistance.</p> Signup and view all the answers

    The vasomotor center receives inputs from __________ and chemoreceptors.

    <p>baroreceptors</p> Signup and view all the answers

    Which part of the brain is responsible for overseeing cardiovascular responses?

    <p>Medulla</p> Signup and view all the answers

    What happens when blood pressure falls below the normal range?

    <p>Vasomotor fibers stimulate vasoconstriction</p> Signup and view all the answers

    The cardioacceleratory center is inhibited when blood pressure drops.

    <p>False</p> Signup and view all the answers

    What role do baroreceptors play in blood pressure regulation?

    <p>They detect changes in blood pressure and send impulses for cardiovascular adjustments.</p> Signup and view all the answers

    The ______ of blood pressure is primarily adjusted by the sympathetic nervous system.

    <p>heart rate</p> Signup and view all the answers

    Match the following components with their associated function:

    <p>Baroreceptors = Detect changes in blood pressure Vasomotor center = Stimulates vasoconstriction Sympathetic impulses = Increase heart rate and cardiac output Cardioinhibitory center = Slows down heart rate</p> Signup and view all the answers

    Which physiological change occurs due to a drop in blood pressure?

    <p>Increased heart rate and contractility</p> Signup and view all the answers

    The location of baroreceptors includes the carotid sinuses and aortic arch.

    <p>True</p> Signup and view all the answers

    What is the primary consequence of inhibiting baroreceptors?

    <p>Increased blood pressure due to unregulated sympathetic activity.</p> Signup and view all the answers

    The ______ center is stimulated to increase cardiac output during low blood pressure.

    <p>cardioacceleratory</p> Signup and view all the answers

    Which of the following describes the body's response to low blood pressure?

    <p>Increased heart rate and vasoconstriction</p> Signup and view all the answers

    What is primarily monitored to assess circulatory efficiency?

    <p>Vital signs including pulse, blood pressure, and respiratory rate</p> Signup and view all the answers

    Which of the following accurately describes systolic pressure during blood pressure measurement?

    <p>The highest pressure in the arteries during heart contraction</p> Signup and view all the answers

    What physiological mechanism is primarily activated to respond to crisis stressors like trauma?

    <p>Activation of vasomotor and acceleratory centers in the brain stem</p> Signup and view all the answers

    What direct effect does dehydration cause in relation to blood parameters?

    <p>Increased hematocrit and higher blood viscosity</p> Signup and view all the answers

    Which component is involved in the physiological response to maintain blood volume during hemorrhage?

    <p>Release of hormones such as ANP and ADH</p> Signup and view all the answers

    Which statement correctly describes blood flow in the circulatory system?

    <p>Blood flow is inversely related to the pressure gradient.</p> Signup and view all the answers

    What is the primary determinant of peripheral resistance?

    <p>Blood vessel diameter</p> Signup and view all the answers

    How does blood viscosity affect resistance in the circulatory system?

    <p>Higher viscosity results in increased resistance.</p> Signup and view all the answers

    Which factor most significantly affects the resistance encountered in systemic circulation?

    <p>Blood vessel diameter changes.</p> Signup and view all the answers

    What is the effect of vasoconstriction on peripheral resistance?

    <p>It increases peripheral resistance.</p> Signup and view all the answers

    How does an increase in the length of blood vessels influence resistance?

    <p>Increases resistance due to longer travel distance.</p> Signup and view all the answers

    Which method provides the driving force for blood to move through the circulatory system?

    <p>Pressure gradient.</p> Signup and view all the answers

    What is the relationship between blood flow and peripheral resistance in the circulatory formula F = ΔP/R?

    <p>Blood flow decreases when peripheral resistance increases.</p> Signup and view all the answers

    What type of blood flow is primarily disrupted by sudden changes in vessel diameter?

    <p>Turbulent flow.</p> Signup and view all the answers

    Which condition would most likely increase resistance in the peripheral circulation?

    <p>Long-term increase in blood viscosity.</p> Signup and view all the answers

    What primarily determines the systolic pressure in the aorta during cardiac function?

    <p>Pressure generated during ventricular contraction</p> Signup and view all the answers

    What happens to mean arterial pressure (MAP) as one moves further away from the heart?

    <p>It declines due to increased resistance and decreased blood flow</p> Signup and view all the answers

    Which of the following best describes pulse pressure?

    <p>Difference between systolic and diastolic pressure</p> Signup and view all the answers

    What contributes to the decline of blood pressure from the aorta to the right atrium?

    <p>Increased vascular resistance and reduced cross-sectional area</p> Signup and view all the answers

    How is diastolic pressure characterized in terms of arterial function?

    <p>The lowest pressure within the arteries during the cardiac cycle</p> Signup and view all the answers

    Which factor directly influences the compliance of arteries and affects blood pressure?

    <p>Age and conditioning of the vascular system</p> Signup and view all the answers

    What equation represents the calculation for mean arterial pressure (MAP)?

    <p>MAP = diastolic pressure + 1/3 pulse pressure</p> Signup and view all the answers

    What characteristic of arterial blood pressure is described as 'pulsatile' near the heart?

    <p>It fluctuates in response to ventricular ejection</p> Signup and view all the answers

    Which of the following best defines blood flow in the context of cardiovascular physiology?

    <p>The volume of blood that travels through a vessel in a given period</p> Signup and view all the answers

    What does an increase in peripheral resistance generally result in?

    <p>Increased blood pressure</p> Signup and view all the answers

    Which of the following is a local factor that can affect peripheral resistance?

    <p>Vessel diameter changes due to metabolic demands</p> Signup and view all the answers

    What is the primary purpose of baroreceptors in the cardiovascular system?

    <p>To monitor changes in blood pressure</p> Signup and view all the answers

    From which of the following does the chemoreceptor reflex primarily rely on input?

    <p>Blood oxygen and carbon dioxide levels</p> Signup and view all the answers

    Mean arterial pressure (MAP) is influenced predominantly by which of the following factors?

    <p>Systolic and diastolic blood pressure readings</p> Signup and view all the answers

    In the event of a sudden drop in blood pressure, what role does the sympathetic nervous system play?

    <p>Stimulates increased heart rate and vasoconstriction</p> Signup and view all the answers

    What is the primary effect of vasomotor impulses during a blood pressure increase?

    <p>Increased sympathetic activity to constrict blood vessels</p> Signup and view all the answers

    Which equation is most closely associated with calculating pulse pressure?

    <p>$PP = SBP - DBP$</p> Signup and view all the answers

    What physiological change occurs in response to increased blood flow demand in tissues?

    <p>Dilation of local blood vessels to increase flow</p> Signup and view all the answers

    What is the primary stimulus that triggers the autonomic response in blood pressure regulation?

    <p>Blood pressure exceeding the normal range</p> Signup and view all the answers

    Which of the following physiological changes occurs as a result of sympathetic impulses during a blood pressure increase?

    <p>Vasoconstriction of peripheral blood vessels</p> Signup and view all the answers

    What is the role of baroreceptors located in the carotid sinuses and aortic arch?

    <p>Monitoring changes in arterial blood pressure</p> Signup and view all the answers

    What effect do increased vasomotor impulses have on blood vessels?

    <p>Vasoconstriction of blood vessels</p> Signup and view all the answers

    When blood pressure rises above the homeostatic range, what is the primary physiological response?

    <p>Activation of baroreceptor reflexes</p> Signup and view all the answers

    Which mechanism contributes to returning blood pressure to the normal range when elevated?

    <p>Stimulating parasympathetic activity</p> Signup and view all the answers

    What happens to cardiac output during sympathetic stimulation in response to low blood pressure?

    <p>It increases significantly</p> Signup and view all the answers

    How do baroreceptors respond when blood pressure decreases below normal levels?

    <p>They trigger an increase in vasomotor impulses</p> Signup and view all the answers

    What is the consequence of a significant decrease in a person's blood volume?

    <p>Potential for dangerously low blood pressure</p> Signup and view all the answers

    Which response is associated with the body's regulatory mechanism for maintaining homeostasis during increased blood pressure?

    <p>Reduced peripheral resistance and heart rate</p> Signup and view all the answers

    Study Notes

    Blood Flow and Pressure

    • Blood flow: is the volume of blood that moves through a vessel in a given time
    • Blood pressure: is the force per unit area that blood exerts against the inside walls of a blood vessel
    • Peripheral resistance: is the opposition to blood flow caused by blood vessels
    • Blood flow is directly proportional to blood pressure, meaning it increases as blood pressure increases
    • Blood flow is inversely proportional to peripheral resistance, meaning it decreases as peripheral resistance increases

    Capillary Blood Pressure

    • The range of capillary blood pressure is generally between 17 and 35 mm Hg

    Maintaining Blood Pressure

    • Blood pressure maintenance requires cooperation of the heart, blood vessels, and kidneys.
    • The brain also supervises blood pressure
    • Main factors influencing blood pressure are:
      • Cardiac output (CO)
      • Peripheral resistance (PR)
      • Blood volume
    • The formula relating blood pressure to CO, PR, and blood volume is:
      • Blood pressure = CO × PR
    • CO is dependent on blood volume
    • Blood pressure varies directly with CO, PR, and blood volume
    • Changes in one variable are quickly compensated for by changes in other variables

    Factors Affecting Cardiac Output

    • Factors that influence cardiac output include:
      • Venous return to the heart, which is affected by:
        • Activity of the muscular pumps (skeletal muscles)
        • Activity of the respiratory pump (ventral body cavity pressure)
        • Sympathetic venoconstriction
      • Contractility of cardiac muscle
      • Heart rate (HR)
      • Stroke volume (SV)

    Regulation of Blood Pressure

    • Mean arterial pressure (MAP) is a function of cardiac output and peripheral resistance: MAP = SV × HR × R
    • Increases in SV, HR, or R will increase MAP
    • SV is affected by venous return (EDV)
    • HR is maintained by medullary centers
    • R is mostly affected by vessel diameter

    Baroreceptor Reflex

    • Baroreceptors in carotid sinuses and aortic arch monitor blood pressure
    • When blood pressure rises above normal:
      • Baroreceptors are stimulated
      • Sympathetic impulses to the heart are decreased which lowers HR, contractility, and CO
      • Vasomotor impulses allow vasodilation, which lowers peripheral resistance (R)
      • CO and R return blood pressure to the normal range, restoring homeostasis
    • When blood pressure falls below normal:
      • Baroreceptors are inhibited
      • Sympathetic impulses to the heart increase, increasing HR, contractility, and CO
      • Vasomotor fibers stimulate vasoconstriction, increasing peripheral resistance (R)
      • CO and R return blood pressure to the normal range, restoring homeostasis

    Chemoreceptor Reflex

    • Chemoreceptors are sensory receptors located in the carotid arteries and aorta that monitor blood chemistry, especially oxygen, carbon dioxide, and pH levels
    • When blood oxygen levels drop, carbon dioxide levels rise, or pH becomes more acidic:
      • Chemoreceptors are stimulated
      • Signals are sent to the brainstem, resulting in increased activity of the sympathetic nervous system
      • This increases heart rate and vasoconstriction, ensuring adequate tissue oxygenation and removal of CO2

    Factors Influencing Peripheral Resistance

    • Factors that influence peripheral resistance:
      • Blood vessel diameter
      • Blood viscosity
      • Blood vessel length
      • Vasomotor tone, which is regulated by:
        • Bloodborne chemicals (epinephrine, norepinephrine (NE), ADH, angiotensin II)
        • Sympathetic nervous system
        • Dehydration
        • High hematocrit
        • Body size

    Monitoring Circulatory Efficiency

    • Vital signs, including pulse and blood pressure, respiratory rate, and body temperature, are used to monitor circulatory efficiency
    • Pulse is the pressure wave created by the expansion and recoil of arteries
    • The radial pulse, taken at the wrist, is commonly used
    • Pressure points are areas where arteries are close to the body surface and can be compressed to stop blood flow

    Measuring Blood Pressure

    • Systolic blood pressure is the pressure when sounds first occur as blood begins to flow through an artery, usually less than 120 mm Hg
    • Diastolic blood pressure is the pressure when sounds disappear, indicating unrestricted blood flow through the artery, usually less than 80 mm Hg

    Variations in Blood Pressure

    • Transient elevations in blood pressure can occur due to changes in posture, physical exertion, emotional upset, or fever.

    Blood Flow, Pressure, and Resistance

    • Blood flow is the volume of blood flowing through a vessel in a given time (mL/min)
    • Blood pressure is the force exerted by the blood against any unit area of the vessel wall (mm Hg)
    • Peripheral resistance is the opposition to blood flow, caused by friction between blood and vessel walls
    • The relationship between these factors is represented by the equation: Blood flow = Change in pressure / Resistance

    Factors Influencing Peripheral Resistance

    • Local factors: Diameter of blood vessels, blood viscosity (thickness), and vessel length
    • Hormonal factors: Epinephrine and norepinephrine cause vasoconstriction, while hormones like ANP cause vasodilation
    • Neuronal factors: Sympathetic nervous system causes vasoconstriction, while parasympathetic nervous system promotes vasodilation

    Capillary Blood Pressure

    • Ranges from 17 to 35 mm Hg, which is lower than arterial pressure
    • This low pressure is desirable to prevent capillary rupture and facilitates fluid movement into interstitial spaces

    Maintaining Blood Pressure

    • Requires cooperation of heart, blood vessels, and kidneys, and supervision of the brain
    • Main factors influencing blood pressure: Cardiac output (CO), Peripheral resistance (PR), and Blood volume

    Blood Pressure Maintenance Equation

    • Blood pressure = CO × PR
    • Changes in one variable are compensated for by changes in other variables

    Factors Increasing Cardiac Output and Blood Pressure

    • Exercise: Activates cardiac centers in the medulla, increases respiratory and muscular pump activity, and leads to increased venous return
    • Sympathetic activity: Increases contractility of cardiac muscle and heart rate
    • Epinephrine in blood: Increases heart rate and contractility
    • Sympathetic venoconstriction: Increases venous return

    Regulation of Blood Pressure

    • Short-term neural and hormonal controls: Counteract short-term fluctuations in blood pressure by altering peripheral resistance and CO
    • Long-term renal regulation: Counteracts long-term fluctuations in blood pressure by altering blood volume

    Cardiovascular Center

    • Located in the medulla and oversees changes in CO and blood vessel diameter
    • Consists of cardiac centers and vasomotor center
    • Vasomotor center maintains vasomotor tone (moderate constriction)
    • Receives input from baroreceptors, chemoreceptors, and higher brain centers

    Baroreceptor Reflexes

    • Baroreceptors are located in carotid sinuses, aortic arch, and walls of large arteries
    • Monitors blood pressure changes, sending signals to the vasomotor center
    • Increase in blood pressure stimulates baroreceptors, leading to inhibition of vasomotor and cardioacceleratory centers, causing arteriolar dilation and venodilation, and stimulation of the cardioinhibitory center, resulting in decreased blood pressure

    Chemoreceptor Reflexes

    • Respond to changes in blood oxygen, carbon dioxide, and pH
    • Stimulate cardiovascular and respiratory centers, coordinating flow and oxygen delivery to tissues

    Factors Affecting Mean Arterial Pressure

    • Blood volume: Dehydration, hemorrhage, high hematocrit, body size, and excessive sweating affect blood volume and ultimately MAP
    • Blood pH, O2, CO2: These factors trigger chemoreceptor reflexes affecting MAP
    • Blood viscosity: Increased viscosity leads to increased resistance and higher MAP
    • Blood vessel length: Longer vessels create more resistance and higher MAP
    • Venous return: Increased venous return increases stroke volume and ultimately MAP
    • Heart rate: Increased heart rate leads to increased CO and ultimately MAP
    • Stroke volume: Increased stroke volume increases CO and ultimately MAP
    • Diameter of blood vessels: Vasoconstriction increases resistance and MAP, while vasodilation decreases resistance and MAP

    Monitoring Circulatory Efficiency

    • Vital signs: Pulse and blood pressure (along with respiratory rate and body temperature) are used to gauge circulatory efficiency
    • Pulse: Pressure wave caused by expansion and recoil of arteries
    • Pressure points: Areas where arteries are close to the body surface and can be compressed to stop blood flow

    Measuring Blood Pressure

    • Systolic pressure: Pressure when sounds first occur as blood starts to flow through the artery (normally less than 120 mm Hg)
    • Diastolic pressure: Pressure when sounds disappear because blood flows freely through the artery (normally less than 80 mm Hg)

    Transient Elevations in Blood Pressure

    • May occur during changes in posture, physical exertion, emotional upset, or fever

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