Human Biology: Lymphatic and Cardiovascular Systems
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What is the primary function of the lymphatic system?

  • To circulate waste products to the kidneys
  • To transport oxygen to body tissues
  • To deliver nutrients to every organ system
  • To pick up lipids and transport them to the bloodstream (correct)

    • Which of the following structures is part of the lymphatic system?

  • Heart
  • Aorta
  • Pulmonary trunk
  • Spleen (correct)

    • What role do valves in lymphatic capillaries play?

  • They allow gas exchange
  • They prevent backflow of lymph (correct)
  • They increase lymph production
  • They facilitate nutrient absorption

    • In which circuit does gas exchange occur primarily in the lungs?

    <p>Pulmonary circuit</p> Signup and view all the answers

    Where does oxygen-rich blood go after it leaves the lungs?

    <p>To the systemic capillaries</p> Signup and view all the answers

    What is the first structure to receive blood from the lungs?

    <p>Pulmonary veins</p> Signup and view all the answers

    Which side of the heart receives oxygen-poor blood from systemic circulation?

    <p>Right side</p> Signup and view all the answers

    What is the function of systemic arteries?

    <p>To transport nutrient-rich blood from the heart to tissues</p> Signup and view all the answers

    What is the primary sound of the heartbeat attributed to?

    <p>Blood turbulence caused by closing of heart valves</p> Signup and view all the answers

    Which phase of the cardiac cycle occurs when atria are relaxed?

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

    How is cardiac output (CO) calculated?

    <p>Stroke volume (SV) x heart rate (HR)</p> Signup and view all the answers

    What does the QRS complex on an ECG represent?

    <p>Ventricular depolarization</p> Signup and view all the answers

    Which heartbeat sound occurs when the AV valves close?

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

    What does the T wave in an ECG signify?

    <p>Ventricular repolarization</p> Signup and view all the answers

    Which of the following describes ventricular tachycardia?

    <p>Rapid heart rate with abnormal rhythm</p> Signup and view all the answers

    What is the typical stroke volume for a resting male?

    <p>70 mL/beat</p> Signup and view all the answers

    What is the primary function of the coronary circulation?

    <p>To provide alternate routes for blood flow to the heart muscle</p> Signup and view all the answers

    What unique characteristic distinguishes cardiac muscle fibers from skeletal muscle fibers?

    <p>They have intercalated discs that connect ends of fibers</p> Signup and view all the answers

    Which structure acts as the primary pacemaker of the heart?

    <p>Sinoatrial (SA) node</p> Signup and view all the answers

    What process occurs after the depolarization phase in cardiac action potentials?

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

    How do autorhythmic fibers contribute to heart function?

    <p>They create action potentials that trigger contractions</p> Signup and view all the answers

    What causes the plateau phase during the action potential in a ventricular contractile fiber?

    <p>Ca2+ inflow through slow Ca channels</p> Signup and view all the answers

    Which of the following events occurs first during the action potential in a ventricular contractile fiber?

    <p>Na+ inflow via fast Na+ channels</p> Signup and view all the answers

    What type of blood does the pulmonary circuit carry?

    <p>Deoxygenated blood from the heart to the lungs</p> Signup and view all the answers

    What does the P wave in an electrocardiogram (ECG) represent?

    <p>Atrial depolarization</p> Signup and view all the answers

    What is the primary role of the intercalated discs in cardiac muscle?

    <p>To facilitate rapid electrical conduction between cells</p> Signup and view all the answers

    Which component of the cardiac conduction system is responsible for transmitting impulses from the AV node to the ventricles?

    <p>Bundle of His</p> Signup and view all the answers

    The QRS complex represents which of the following in the ECG?

    <p>Rapid depolarization of the ventricles</p> Signup and view all the answers

    What does the P-R interval indicate in an ECG?

    <p>Time taken for the action potential to travel from SA to AV node</p> Signup and view all the answers

    During repolarization in a ventricular contractile fiber, what primarily causes the membrane potential to return to a more negative value?

    <p>K+ outflow when more K+ channels open</p> Signup and view all the answers

    Which segment of the ECG represents the conduction time from the AV node to the bundle of His and Purkinje fibers?

    <p>P-R segment</p> Signup and view all the answers

    What does the T wave in an electrocardiogram (ECG) indicate?

    <p>Ventricular repolarization</p> Signup and view all the answers

    What is the effect of greater preload on stroke volume?

    <p>It increases the force of contraction.</p> Signup and view all the answers

    Which of the following determines end-diastolic volume (EDV)?

    <p>Duration of ventricular diastole</p> Signup and view all the answers

    What role do positive inotropic agents play in cardiac function?

    <p>They enhance the force of contraction.</p> Signup and view all the answers

    How does an increase in afterload affect stroke volume?

    <p>It reduces stroke volume.</p> Signup and view all the answers

    Which condition would likely increase afterload?

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

    What effect does increased sympathetic stimulation have on heart rate?

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

    Which neurotransmitters are the most important in autonomic regulation of the heart?

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

    In what situation would the heart experience insufficient filling time for the ventricles?

    <p>During high heart rates</p> Signup and view all the answers

    Which hormone is known to increase heart rate and contractility?

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

    What effect does potassium ion (K+) imbalance have on the heart?

    <p>Compromises pumping effectiveness</p> Signup and view all the answers

    According to the Frank-Starling law, cardiac muscle fibers will contract more forcefully with what condition?

    <p>Increased preload</p> Signup and view all the answers

    Which factors can increase cardiac output?

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

    What is the result of increased afterload on heart function?

    <p>Decreased stroke volume</p> Signup and view all the answers

    Which of the following substances is considered a positive inotropic agent?

    <p>Thyroid hormones</p> Signup and view all the answers

    What role do catecholamines play in heart regulation?

    <p>Increase sympathetic stimulation</p> Signup and view all the answers

    What mechanism results in semilunar valves opening sooner?

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

    Study Notes

    Physiology of the Cardiovascular System (Part I)

    • The cardiovascular system's function is to transport nutrients, heat, oxygen, and hormones, and regulate pH and coordination. It also provides protection.

    Blood Composition

    • Blood is a connective tissue.
    • Plasma (55% of blood): Mostly water, proteins (albumins, globulins, fibrinogen), nutrients, amino acids, glucose, nucleotides, lipids, gases, electrolytes, and waste products.
    • Formed elements (45% of blood): Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.

    Red Blood Cells (RBCs)

    • Transport oxygen throughout the body.
    • Biconcave-shaped and small enough to pass through capillaries.
    • Contain hemoglobin, a pigment that carries oxygen (oxyhemoglobin - bright red) and lacks oxygen (deoxyhemoglobin - dark red).

    White Blood Cells (WBCs)

    • Granulocytes:
      • Neutrophils (55%): Destroy bacteria, viruses, and toxins.
      • Eosinophils (3%): Fight parasitic infections (allergic).
      • Basophils (1%): Control inflammation and allergic reactions.
    • Agranulocytes:
      • Monocytes (8%): Destroy bacteria, viruses, and toxins.
      • Lymphocytes (33%): Provide immunity.

    Platelets

    • Fragments of cells found in the blood stream.

    • Crucial for blood clotting (thrombocytes).

    • 130,000 to 360,000 platelets per cubic millimeter of blood.

    • Blood clotting (Hemostasis): Three processes of hemostasis: Blood vessel spasm: Platelet plug formation: Blood coagulation:

    Blood Vessels

    • Arteries and arterioles: The strongest blood vessels, carry blood away from the heart under high pressure, and have thick walls.
    • Veins and venules: Blood flow is of low pressure in these and valves prevent backflow.
    • Capillaries: Connect arterioles to venules. Oxygen and nutrients pass out into body cells; carbon dioxide and waste products pass into capillaries from body cells.

    Lymphatic System

    • A network of vessels collecting fluid between cells and returning it to the bloodstream.
    • Picks up lipids from digestive organs and transports them to the bloodstream.
    • Protects the body from disease-causing agents (pathogens).
    • Lymph nodes, thymus gland, and spleen are important components.
    • Lymphatic fluid, or lymph, contains lymph nodes and capillaries. Lymphatic capillaries contain valves to prevent backflow.

    Circulation of Blood

    • Blood circulation is the process of blood being pumped from the heart to the lungs to pick up oxygen, then to the digestive system to pick up nutrients, and then to all the organ systems in the body to deliver oxygen and nutrients.
    • This system also circulates waste products to certain organ systems so those products can be removed from the blood.

    Systemic Circuit

    • Circulation of blood from the heart to the body's tissues and then back to the heart.
    • The left side of the heart receives oxygenated blood from the lungs, pumps it to the body through the aorta, and then the blood returns to the right side of the heart.

    Pulmonary Circuit

    • Circulation of blood from the heart to the lungs.
    • The right side of the heart receives deoxygenated blood from the body, pumps it to the lungs through the pulmonary arteries where it releases carbon dioxide and picks up O2, then the blood returns to the left side of the heart through pulmonary veins.

    Coronary Circulation

    • Coronary arteries branch from the aorta, supplying the heart muscle with oxygen and nutrients.
    • Coronary capillaries deliver oxygen and nutrients to heart muscle cells, and coronary veins collect waste.
    • Anastomoses (connections) provide multiple routes for blood flow, even if one vessel is blocked.

    Heart

    • The heart muscle is a specialized muscle composed of specialized cells that contract rhythmically to pump blood.

    Cardiac Muscle Characteristics

    • Shorter and less circular than skeletal fibers, branching giving a "stair step" appearance; usually have one centrally located nucleus.
    • Intercalated discs connect fibers through desmosomes and gap junctions.
    • Contains many mitochondria.
    • Actin and myosin are arranged similarly to skeletal muscles.

    Autorhythmic Fibers (Specialized Cardiac Muscle Fibers)

    • Self-excitable cardiac muscle fibers, repeatedly generating action potentials triggering heart contractions.
    • Act as pacemakers creating a self-contained conduction system for the heart.

    Cardiac Conduction System

    • Consists of specialized cells; SA node, AV node, Bundle of His, right and left bundle branches, and Purkinje fibers.
    • The conduction system regulates the heartbeat by initiating and transmitting electrical signals in a coordinated manner.

    Action Potentials and Contractions

    • Action potential initiated by the SA node excites working fibers called contractile fibers.
    • Depolarization stage, a plateau stage, and a repolarization stage occur in cardiac contractile fibers.

    ECG (Electrocardiogram)

    • A composite record of action potentials from all heart muscle fibers.
    • Used to compare different leads and normal records.
    • P, QRS, and T waves represent different phases of the cardiac cycle.
    • Abnormal tracings can indicate various heart disorders/problems.

    Cardiac Cycle

    • The sequence of events as blood enters the atria and exits the ventricles, starting the cycle over.
    • Atrial systole (atrial contraction): Ventricles are relaxed
    • Ventricular systole (ventricular contraction): Atria are relaxed.

    Cardiac Output (CO)

    • Volume of blood ejected from the left ventricle into the aorta per minute.
    • Determined by stroke volume (SV) multiplied by heart rate (HR).
    • In a typical resting male, CO = 5.25 L/min = (70mL/beat) × (75 beats/min).
    • Entire blood volume flows through pulmonary and systemic circuits every minute.

    Stroke Volume (SV)

    • The amount of blood ejected from the ventricles with each contraction.
    • Factors impacting SV Preload: Degree of stretch before contraction; proportional to end-diastole volume (EDV). Contractility: Strength of ventricle's contraction. Afterload: Pressure the ventricles overcome to eject blood.

    Factors Affecting Stroke Volume (SV):

    • Preload: The more blood stretching the heart, the greater the force of contraction.
    • Contractility: Determines the heart's strength, and this is influenced by chemicals (positive—e.g., epinephrine and norepinephrine; negative—anoxia, acidosis, some anesthetics, and increased K+ in interstitial fluid).
    • Afterload: Pressure the ventricles must overcome to open semilunar valves; increased afterload = decreased stroke volume and vice-versa.

    Regulation of Heart Beat

    • Cardiac output depends on heart rate (normal range 60-100 beats/min) and stroke volume.
    • Autonomic nervous system and hormones (epinephrine/norepinephrine and thyroid hormones) influence heart rate.
    • Filling time for ventricles is insufficient when heart rate is high.

    Autonomic Regulation

    • Originates in the cardiovascular center of the medulla oblongata.
    • Sympathetic nervous system = fight-or-flight response
    • Parasympathetic nervous system = rest-and-digest response
    • Both systems adjust heart rate as needed.

    Exercise and the Heart

    • Exercise increases blood volume, venous return, cardiac output, heart rate, and stroke volume.

    Chemical Regulation of Heart Rate

    • Epinephrine and norepinephrine increase heart rate and contractility.
    • Thyroid hormones also influence heart rate and contractility.
    • Imbalances in K+, Ca2+ and Na+ can impact pumping effectiveness.

    Other Factors

    • Infants/senior citizens, females, fitness levels, temperature, and disease can influence the heart rate as well.

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    Description

    Test your knowledge on the human lymphatic and cardiovascular systems with this quiz. Explore various components, functions, and characteristics of these essential systems in the body. Perfect for students studying biology or related fields.

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