Heart Physiology Quiz - Cardiac Cycle and Regulation

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Questions and Answers

What type of ion channel is primarily responsible for the initial depolarization of the pacemaker potential?

  • IRK channels
  • T-type Ca++ channels
  • Funny channels (HCN) (correct)
  • L-type Ca++ channels

Which of the following statements accurately describes the role of the sympathetic nervous system in heart rate regulation?

  • It slows down heart rate by decreasing Na+ and Ca++ influx into autorhythmic cells.
  • It speeds up heart rate by increasing Na+ and Ca++ influx into autorhythmic cells. (correct)
  • It has no effect on heart rate.
  • It slows down heart rate by increasing K+ permeability.

Which phase of the cardiac cycle is characterized by the relaxation of the heart chambers?

  • Systole
  • Diastole (correct)
  • Plateau phase
  • Repolarization

Which of the following best describes the pressure changes in the ventricles during a heartbeat?

<p>Pressure increases during systole and decreases during diastole. (D)</p> Signup and view all the answers

What is the primary mechanism that governs the opening and closing of heart valves?

<p>Pressure differences between chambers. (B)</p> Signup and view all the answers

During which phase of the cardiac cycle are the semilunar valves open?

<p>Ventricular systole (D)</p> Signup and view all the answers

Which type of ion channel is responsible for the 'spike' or rapid depolarization during an action potential in autorhythmic cells?

<p>L-type Ca++ channels (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the pacemaker potential?

<p>It is triggered by external stimuli. (D)</p> Signup and view all the answers

During isovolumetric contraction, which of the following statements is TRUE?

<p>The ventricles are contracting and the semilunar valves are closed. (A)</p> Signup and view all the answers

What is the role of albumin in plasma?

<p>Maintains osmotic pressure (A)</p> Signup and view all the answers

Which of the following is NOT directly involved in the increase of heart rate and contraction strength by the sympathetic nervous system?

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

Which valve closure causes the 'Lub' sound of the heartbeat?

<p>Atrioventricular valves closing (D)</p> Signup and view all the answers

What is the relationship between preload and stroke volume?

<p>Preload is directly proportional to stroke volume, meaning an increase in preload leads to an increase in stroke volume. (A)</p> Signup and view all the answers

What is the typical range for the stroke volume of a healthy heart?

<p>50-70 mL (A)</p> Signup and view all the answers

What is the primary role of baroreceptors in regulating heart rate?

<p>Detecting blood pressure changes (C)</p> Signup and view all the answers

Which of the following accurately describes the relationship between stroke volume (SV) and cardiac output (CO)?

<p>CO is directly proportional to SV. (D)</p> Signup and view all the answers

What is the primary function of the parasympathetic nervous system in heart regulation?

<p>Decrease heart rate and contraction strength (D)</p> Signup and view all the answers

Which of the following statements correctly describes passive filling of the ventricles?

<p>Blood flows passively into the relaxing ventricles due to pressure difference. (C)</p> Signup and view all the answers

What is the main component of plasma?

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

How is the ejection fraction (EF) calculated?

<p>EF = (SV / EDV) × 100 (C)</p> Signup and view all the answers

Which of the following is a significant protein in plasma that is involved in maintaining osmotic pressure?

<p>Albumin (B)</p> Signup and view all the answers

What is the primary purpose of an Electrocardiogram (EKG)?

<p>To record the electrical activity of the heart. (C)</p> Signup and view all the answers

Which of the following correctly describes a 'dipole' in the context of an EKG?

<p>A pair of opposite electrical charges within the heart. (A)</p> Signup and view all the answers

What is serum?

<p>Plasma without clotting factors (B)</p> Signup and view all the answers

What is the primary function of red blood cells?

<p>Carrying oxygen (C)</p> Signup and view all the answers

Which of the following contributes to a higher hematocrit percentage?

<p>High altitude living (A)</p> Signup and view all the answers

What is the role of erythropoietin (EPO) in red blood cell production?

<p>Stimulates red blood cell production when oxygen levels are low (A)</p> Signup and view all the answers

What is the primary component of blood responsible for maintaining the blood's pH balance?

<p>Plasma (D)</p> Signup and view all the answers

Which of the following is NOT a function of blood?

<p>Producing antibodies (C)</p> Signup and view all the answers

What is the term for the process of blood clotting?

<p>Hemostasis (B)</p> Signup and view all the answers

Which of the following is NOT a primary function of platelets?

<p>Carrying oxygen to the tissues (A)</p> Signup and view all the answers

Which of the following is a chemical released by platelets that contributes to platelet aggregation?

<p>ADP (D)</p> Signup and view all the answers

Which of the following clotting factors is NOT directly involved in the intrinsic pathway?

<p>Factor VII (C)</p> Signup and view all the answers

Which of the following is a direct consequence of plasminogen activation?

<p>Degradation of fibrin (C)</p> Signup and view all the answers

In the ABO blood group system, an individual with blood type A possesses which antigen(s)?

<p>Only antigen A (A)</p> Signup and view all the answers

Hemolytic Disease of the Newborn (HDN) primarily occurs when a(n):

<p>Rh-negative mother carries an Rh-positive fetus (B)</p> Signup and view all the answers

Which layer of a blood vessel is responsible for vasoconstriction and vasodilation?

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

Which type of blood vessel is primarily responsible for maintaining diastolic blood pressure?

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

Which of the following accurately describes the relationship between blood pressure, vessel diameter, and resistance?

<p>Decreased diameter leads to increased resistance and decreased blood pressure (C)</p> Signup and view all the answers

At the venule end of a capillary bed, which force is primarily responsible for pulling fluids back into the capillary?

<p>Blood colloid osmotic pressure (BCOP) (C)</p> Signup and view all the answers

What is the main difference between an autorhythmic cell and a contractile myocyte?

<p>Autorhythmic cells are responsible for generating electrical impulses, while contractile myocytes are responsible for contraction. (B)</p> Signup and view all the answers

Which of the following statements accurately describes the difference between the SA node and the AV node?

<p>The AV node has a smaller size and fewer gap junctions, leading to slower conduction compared to the SA node. (D)</p> Signup and view all the answers

What structural feature enables cardiac muscle cells to be more flexible compared to skeletal muscle cells?

<p>Less extensive sarcoplasmic reticulum (B)</p> Signup and view all the answers

Which of these statements is correct about the T-tubules in cardiac muscle cells compared to skeletal muscle cells?

<p>Cardiac muscle T-tubules are larger and more branched. (C)</p> Signup and view all the answers

What is the function of the Bachmann's bundle in the conduction system of the heart?

<p>It delivers the electrical signal from the SA node to the left atrium. (D)</p> Signup and view all the answers

What is the difference between the arrangement of sarcomeres in cardiac muscle cells and skeletal muscle cells?

<p>Sarcomeres are arranged more randomly in cardiac muscle cells than in skeletal muscle cells. (B)</p> Signup and view all the answers

Which of the following characteristics is shared between contractile myocytes and neurons?

<p>Both cells are capable of generating electrical impulses. (D)</p> Signup and view all the answers

Why do cardiac muscle cells have more mitochondria than skeletal muscle cells?

<p>Cardiac muscle cells require more energy to sustain continuous contractions. (C)</p> Signup and view all the answers

Flashcards

Pulmonary Circulation

The pathway of blood from the heart to the lungs and back.

Systemic Circulation

The journey of oxygen-rich blood from the heart to the body and back.

Cardiac Muscle

Muscle tissue of the heart that contracts to pump blood.

Autorhythmic Cells

Special heart cells that generate electrical signals to regulate heart rate.

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Contractile Myocytes

Heart muscle cells that contract to pump blood.

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Comparing Muscle Cells

Cardiac muscle cells are smaller and branched compared to skeletal muscle cells.

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SA Node

The heart's pacemaker that initiates contraction by generating action potentials.

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Bundle of HIS

Part of the conduction system in the heart that helps transmit signals to the ventricles.

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Funny Channels (HCN)

Channels that allow Na+ to leak into cells, increasing positivity.

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Pacemaker Potential

The ability of autorhythmic cells to generate action potentials without brain signals.

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Systole

The phase of heart contraction when blood is pumped out of the chambers.

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Diastole

The phase of heart relaxation allowing chambers to fill with blood.

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L-type Ca++ Channels

Channels that allow a large influx of Ca++ during cardiac action potentials.

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T-type Ca++ Channels

Channels that briefly open and help push the cell towards the threshold.

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Valve Function

Heart valves open or close based on pressure differences between chambers.

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Sympathetic vs Parasympathetic

Sympathetic speeds up heart rate; parasympathetic slows it down.

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Preload

The degree of stretch of the heart muscle at the end of diastole, influencing stroke volume.

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Stroke Volume

The amount of blood pumped by the heart with each beat, influenced by preload and contractility.

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Sympathetic Nervous System

Part of the autonomic nervous system that increases heart rate and contraction strength during stress.

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Parasympathetic Nervous System

Part of the autonomic nervous system that slows down heart rate and promotes relaxation.

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Baroreceptors

Sensors that detect changes in blood pressure and help regulate heart rate accordingly.

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Chemoreceptors

Sensors that monitor levels of oxygen and carbon dioxide, influencing heart rate during changes.

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Albumin

A key plasma protein that maintains osmotic pressure and transports substances in blood.

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Fibrinogen

A plasma protein involved in blood clotting, essential for healing.

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Red Blood Cells (RBCs)

Cells that carry oxygen and define hematocrit percentage.

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Hematocrit

The percentage of blood volume made up of red blood cells.

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Erythropoiesis

Process by which red blood cells are produced in the bone marrow.

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Erythropoietin (EPO)

Hormone from kidneys that stimulates RBC production when oxygen is low.

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Hemoglobin

Protein in red blood cells made of globin and heme that carries oxygen.

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Bilirubin

A waste product formed from the degradation of heme, excreted in bile.

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Vascular Spasm

Initial response of blood vessels, temporary contraction to reduce blood flow.

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Platelet Plug Formation

Process where platelets adhere and aggregate at injury sites to form a plug.

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Closed valves

Valves close to prevent backflow of blood when ventricles relax.

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Atrioventricular (AV) valves

Valves that open when ventricles relax, allowing blood flow from atria.

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Isovolumetric contraction

Phase where ventricles contract but no blood leaves.

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Heart sounds (Lub-Dub)

Sounds produced by valve closures during heart cycles.

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Stroke Volume (SV)

Amount of blood pumped out of one ventricle per heartbeat (~70mL).

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End-Diastolic Volume (EDV)

Amount of blood in the ventricle before contraction (~120mL).

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Cardiac Output (CO)

Total amount of blood pumped per minute; CO = SV × Heart Rate.

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Ejection Fraction (EF)

Percentage of blood pumped out of ventricle per beat; EF = (SV/EDV) × 100.

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Fibrin Activation

Fibrin is activated by thrombin during coagulation.

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Plasminogen Activation

Plasminogen is converted to plasmin by tPA, facilitating clot dissolution.

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Intrinsic Pathway

The clotting pathway that starts with factor XII and leads to factor X.

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Extrinsic Pathway

The clotting pathway initiated by thromboplastin leading to factor X.

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Common Pathway

The coagulation pathway where factors X and V convert prothrombin to thrombin.

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Role of Vitamin K

Vitamin K is essential for the synthesis of certain clotting factors.

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Blood Vessel Layers

Blood vessels comprise three layers: adventitia, media, and intima.

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Capillary Exchange

Exchange of nutrients occurs via hydrostatic pressure at arteriole end and BCOP at venule end.

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Study Notes

Unit 1: The Heart - Anatomy

  • Pulmonary vs. Systemic Circulation:

    • Systemic circulation: oxygen-poor blood received by the right side of the heart.
    • Pulmonary circulation: blood travels to the lungs.

  • Chambers and Valves:

    • Oxygenated vs. Unoxygenated blood flow.
    • Cardiac muscle vs. skeletal muscle (cell size, branching, nuclei). Cardiac muscle cells are smaller, branched, and have a single nucleus.
    • T-tubules: Larger and more branched in cardiac muscle compared to skeletal muscle.
    • Sarcomeres: Not as ordered in cardiac muscle as in skeletal muscle; striations less distinct.
    • Sarcoplasmic Reticulum: Less extensive in cardiac muscle allowing for more flexibility and repeated contractions.
    • Mitochondria: More numerous than in skeletal muscle, providing aerobic respiration.

  • Conduction System:

    • SA node: Pacemaker, generates action potentials initiating contraction.
    • AV node: Slows down signal conductance.
    • Bachmann's bundle: Delivers SA signal to left atrium.
    • Bundle of HIS, bundle branches, Purkinje fibers: Fast conduction system for ventricles.

Unit 1: The Heart - Function

  • Action Potentials: Compare and contrast contractile myocytes, autorhythmic cells, and neurons.

  • Pacemaker Potential:

    • How autorhythmic cells generate their own action potentials without brain signals.
    • The role of funny channels.
    • How the sympathetic and parasympathetic nervous systems speed up or slow down the heart rate.

  • Cardiac Cycle:

    • Systole vs. Diastole: Contraction and relaxation of heart chambers.
    • Pressure changes in ventricles and atria during a heartbeat.
    • Valve activation (semi-lunar and atrioventricular valves). Opening and closing based on pressure differences.
    • Isovolumetric contraction: Squeezing the ventricles without blood leaving yet.

  • Cardiac sounds: Lub-dub sound from valve closure.

Unit 1: The Heart - Additional

  • EKG: Represents electrical currents flowing through extracellular fluids.
    • Reading EKG deflections and dipoles.
  • Regulation of Cardiac Function: Intrinsic (end-diastolic volume & stroke volume) and extrinsic mechanisms (sympathetic, parasympathetic nervous systems).

Unit 2: Blood

  • Blood Composition: Plasma (55%) and Formed Elements(45%).

    • Plasma proteins (albumin, globulins, fibrinogen) and their functions.
    • Formed Elements (red blood cells, white blood cells, platelets) their function and role in blood composition. -Hemoglobin function in oxygen transport.

  • Hemostasis: Blood clotting process:

    • Vascular spasm, platelet plug formation, blood clot formation and role of fibrin, clot dissolution -Role of vitamin K. -Blood typing (ABO and Rh systems).

  • Regulation of Blood Pressure: Short term vs. long term mechanisms: baroreceptors, chemoreceptors, adrenal medullary reflex, CNS ischemic response, renin-angiotensin-aldosterone system, anti-diuretic hormone, and atrial naturetic hormone mechanisms.

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