Cardiovascular System Module
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Questions and Answers

What is the primary mechanism responsible for autoregulation in coronary blood flow?

  • Increased sympathetic stimulation
  • Adenosine release
  • Parasympathetic stimulation
  • O2 demand and local hypoxia (correct)

    • Which factor leads to reduced coronary blood flow during a faster heart rate?

  • Increased oxygen demand
  • Nervous sympathetic stimulation
  • Shortened diastolic period (correct)
  • Increased diastolic duration

    • What reflex is triggered by distension of the stomach during a heavy meal, affecting coronary blood flow?

  • Anerp's reflex
  • Gastrocoronary reflex (correct)
  • Vasodilator reflex
  • Baroreflex

    • What effect does nitroglycerin have on coronary blood flow?

    <p>Rapid coronary dilation</p> Signup and view all the answers

    Which statement is true regarding the effect of sympathetic stimulation on coronary blood flow?

    <p>Both vasoconstriction and vasodilation can occur</p> Signup and view all the answers

    How does active hyperemia typically manifest in response to exercise?

    <p>Marked increase in coronary blood flow</p> Signup and view all the answers

    What impact does a decrease in diastolic blood pressure have on coronary blood flow in aortic regurgitation?

    <p>Decreases coronary flow</p> Signup and view all the answers

    How do beta-blockers influence myocardial oxygen requirements?

    <p>Decrease myocardial oxygen requirements</p> Signup and view all the answers

    What is the normal range for intracranial pressure (ICP)?

    <p>0-10 mm Hg</p> Signup and view all the answers

    How is cerebral perfusion pressure (CPP) calculated?

    <p>CPP = MAP - ICP</p> Signup and view all the answers

    What occurs when intracranial pressure exceeds 33 mm Hg?

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

    Which statement regarding the role of sympathetic nervous stimulation in cerebral circulation is true?

    <p>It is protective during marked increases in arterial blood pressure.</p> Signup and view all the answers

    What is the primary function of autoregulation in pulmonary blood flow?

    <p>To redistribute blood flow to better ventilated regions</p> Signup and view all the answers

    What happens to pulmonary blood vessels when oxygen concentration decreases in the alveoli?

    <p>Vasoconstriction occurs to reduce blood flow</p> Signup and view all the answers

    Which of the following enhances pulmonary blood flow?

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

    Which chemical factors influence the extrinsic regulation of pulmonary blood flow?

    <p>Carbon dioxide, oxygen, and hydrogen ions</p> Signup and view all the answers

    What is the primary effect of increased arterial blood pressure (ABP) on cerebral blood flow (CBF) during autoregulation?

    <p>It causes increased blood flow due to coronary VC</p> Signup and view all the answers

    Which of the following statements about the regulation of cerebral blood flow is true?

    <p>Regulation includes both intrinsic and extrinsic mechanisms.</p> Signup and view all the answers

    How does a decrease in partial pressure of oxygen (PO2) below 30 mm Hg affect cerebral blood vessels?

    <p>It stimulates vasodilation of cerebral blood vessels.</p> Signup and view all the answers

    What is the significance of cerebral blood flow being sensitive to hypoxia and hypoglycemia?

    <p>It ensures quick responses to changes in blood flow demands.</p> Signup and view all the answers

    Which factor is primarily responsible for the vasodilation of cerebral blood vessels in response to increased levels of carbon dioxide (PCO2)?

    <p>The direct effect of H+ ions generated from increased PCO2.</p> Signup and view all the answers

    What occurs in the brain's grey matter compared to the white matter in terms of blood flow?

    <p>Blood flow in grey matter is approximately six times that of white matter.</p> Signup and view all the answers

    In which range does cerebral blood flow (CBF) largely remain constant despite fluctuations in arterial blood pressure (ABP)?

    <p>60-150 mm Hg</p> Signup and view all the answers

    What is one of the primary theories behind autoregulation of cerebral blood flow?

    <p>The myogenic response of vascular smooth muscle.</p> Signup and view all the answers

    Study Notes

    Cardiovascular System Module

    • The module covers functional characteristics of different special circulations including coronary, pulmonary, cerebral, skeletal muscle, and cutaneous.

    Functional Characteristics of Special Circulations

    • The lecture contents include details on coronary, pulmonary, cerebral, skeletal muscle, and cutaneous circulations.

    Coronary Circulation

    • Functional characteristics of coronary vessels are discussed.
    • O2 consumption in heart tissues is explained.
    • Coronary blood flow is detailed.
    • Regulation of CBF (Intrinsic and extrinsic) is examined.

    Coronary Circulation: Blood Vessels

    • Two coronary arteries (right and left) arise from the aorta.
    • Little anastomoses (connections) exist between the two coronary arteries.
    • Coronary capillaries run parallel to cardiac muscle fibers.
    • Venous drainage occurs via the coronary sinus and anterior cardiac veins.

    Coronary Blood Flow and O2 Consumption

    • At rest, coronary arteries receive about 70% of O2 in the blood.
    • Other tissues receive about 25% of O2.
    • Coronary venous blood has a low O2 reserve.
    • During rest, coronary blood flow is approximately 250 ml/minute.
    • During severe exercise, coronary blood flow can increase to 3-4 times the resting rate (reaching 1 L/min).

    Phasic Changes in Coronary Blood Flow

    • During ventricular systole, coronary blood flow (CBF) decreases.
    • During diastole, CBF increases, peaking during isometric relaxation.
    • Ischemic necrosis (myocardial infarction), which is often due to poor blood flow, can impact mainly the left ventricle (and not as severely on the right ventricle).

    Regulation of Coronary Blood Flow

    • Intrinsic Regulation (autoregulation): The ability of the heart to maintain constant blood flow in response to changing O2 demand.
    • Extrinsic Regulation: Including nervous, mechanical, and chemical factors.

    A) Intrinsic or Autoregulation of CBF

    • O2 demand is the main factor for local blood flow regulation.
    • Mechanism involves direct relaxing effects on smooth muscle and the release of substances like adenosine, K+, H., CO2, bradykinin and PGI2 inducing vasodilation.

    B) Extrinsic Regulation of CBF

    • Nervous system: Sympathetic stimulation increases coronary blood flow, while parasympathetic stimulation has the opposite effect.
    • Mechanical factors: Heart rate, blood pressure (ABP), and cardiac output (COP) affect CBF.
    • Chemical factors: substances like nitroglycerin and nitrates cause coronary dilation.

    Cerebral Circulation

    • Functional characteristics of cerebral vessels are covered.
    • Cerebral blood flow and its measurement are described.
    • Regulation of CBF (Intrinsic and extrinsic) is reviewed.
    • The cerebral circulation is characterized by numerous blood vessels, a circular arrangement (Circle of Willis) and very sensitive to oxygen and glucose levels.

    Cerebral Circulation; Blood Supply

    • The cerebral circulation receives approximately 15% of the cardiac output (COP).
    • The brain's blood flow is highly sensitive to oxygen levels (hypoxia).
    • Blood flow through the grey matter is usually higher than the white matter.
    • The autoregulation range of blood pressure is from 60 to 150 mmHg.
    • Important factors involved in the regulation are chemical and mechanical, such as changes in the blood flow in response to the concentration of CO2, O2 & H+ ; intracranial pressure (ICP).

    Pulmonary Circulation

    • Functional characteristics of pulmonary vessels are provided.
    • Pulmonary blood flow and its measurement are detailed.
    • Regulation of pulmonary blood flow (PBF) (Intrinsic and extrinsic) is assessed.

    Pulmonary Circulation; Blood Vessels

    • Pulmonary circulation is the passage of blood from the right ventricle through the lungs and to the left atrium.
    • The process takes about 7 seconds.
    • Lungs receive blood from pulmonary and bronchial arteries.
    • Pulmonary blood flow is regulated by intrinsic (local O₂ and chemical signaling) and extrinsic factors (nervous, chemical etc.).

    Regulation of Pulmonary Blood Flow

    • Intrinsic regulation of pulmonary blood flow is discussed.
    • Extrinsic regulation includes chemical, nervous, and mechanical factors. This part details the impact of cardiac output, peripheral resistance and various nervous factors involved in pulmonary blood flow regulation.

    Skeletal Muscle Circulation

    • Functional characteristics of skeletal muscle blood vessels.
    • Regulation of skeletal muscle blood flow in resting and exercising conditions.

    Skeletal ms blood vessels and blood flow

    • The skeletal muscle's primary function is contraction.
    • This high activity leads to the need for a large blood flow to supply it with oxygen and nutrients.
    • Skeletal muscle receives roughly 20% of cardiac output at rest. This increases significantly during exercise (by over 20 times).

    Regulation of skeletal ms Blood Flow

    • There are 2 main regulatory factors for skeletal muscle blood flow: Nervous and Local control.

    Skin or Cutaneous Circulation

    • Functional characteristics and regulation of cutaneous blood flow.
    • Temperature regulation is a primary role to cutaneous circulation.

    Cutaneous Circulation

    • The major function of the skin's blood flow is to maintain the body temperature.
    • The blood vessels in the skin are classified in nutritive and non-nutritive vessels.

    Regulation of Cutaneous Blood Flow

    • Mechanism of nervous and local metabolite regulation on cutaneous blood flow are covered.

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    L28 Functional Characteristics of Special Circulation PDF

    Description

    Explore the functional characteristics of special circulations, including coronary, pulmonary, cerebral, skeletal muscle, and cutaneous systems. This quiz delves into the nuances of coronary circulation, blood flow, and oxygen consumption in heart tissues. Understand the intricate details of how blood vessels and flows are regulated in various contexts.

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