Homeostasis and the Nervous System
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Questions and Answers

What physiological effect does an increase in contractility have on stroke volume?

  • It increases stroke volume by decreasing ESV. (correct)
  • It decreases stroke volume by increasing ESV.
  • It increases stroke volume by increasing EDV.
  • It decreases stroke volume by decreasing EDV.

    • What is the primary mechanism by which the heart rate is regulated by the autonomic nervous system?

  • The autonomic nervous system directly controls the contraction and relaxation of the heart muscle.
  • The autonomic nervous system regulates the duration of the cardiac cycle.
  • The autonomic nervous system adjusts spontaneous depolarization rates in pacemaker cells. (correct)
  • The autonomic nervous system regulates blood pressure.

    • What is the direct relationship between end diastolic volume (EDV) and stroke volume?

  • EDV and SV are directly related, meaning that an increase in EDV leads to an increase in SV. (correct)
  • EDV and SV are inversely related, meaning that an increase in EDV leads to a decrease in SV.
  • EDV and SV are independent of each other, meaning that changes in one do not affect the other.
  • EDV and SV are inversely related, meaning that a decrease in EDV leads to a decrease in SV.

    • Which of the following factors directly influences the ejection fraction?

    <p>Stroke volume and end diastolic volume. (D)</p> Signup and view all the answers

    What is the primary determinant of cardiac output?

    <p>Heart rate and stroke volume. (D)</p> Signup and view all the answers

    What happens to preload as the heart fills with blood?

    <p>Preload increases because the ventricle walls are stretched. (B)</p> Signup and view all the answers

    Which of the following is NOT a factor that directly affects stroke volume?

    <p>Blood vessel diameter. (D)</p> Signup and view all the answers

    Which of the following best describes what happens during vasoconstriction?

    <p>Blood vessel diameter decreases, decreasing blood flow. (D)</p> Signup and view all the answers

    What is the main function of the sympathetic nervous system in relation to the cardiovascular system?

    <p>To increase heart rate and contractility. (D)</p> Signup and view all the answers

    What is the relationship between sympathetic nervous system activity and blood flow?

    <p>Increased sympathetic activity leads to increased vasoconstriction and decreased blood flow. (C)</p> Signup and view all the answers

    In which chamber of the heart does oxygenated blood enter the heart from the lungs?

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

    Which valve prevents blood from flowing back into the left atrium from the left ventricle?

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

    Which coronary artery branches from the aorta and primarily supplies the right atrium and both ventricles?

    <p>Right coronary artery (D)</p> Signup and view all the answers

    What is the name of the fluid-filled space that surrounds the heart?

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

    Which layer of the heart wall is composed primarily of cardiac muscle tissue?

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

    Which of the following is NOT a function of the pericardium?

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

    What is the name of the fibrous cords that connect the papillary muscles to the cusps of the atrioventricular valves?

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

    Which of the following is responsible for the rhythmic depolarization of the heart, initiating the heartbeat?

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

    Which of the following correctly describes the sequence of electrical conduction through the heart?

    <p>SA node -&gt; AV node -&gt; AV bundle -&gt; bundle branches -&gt; Purkinje fibers (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a contractile myocardial cell?

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

    Which valve is responsible for regulating blood flow from the right ventricle to the pulmonary trunk?

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

    What is the primary function of the left anterior descending coronary artery?

    <p>Supply blood to the ventricles on the anterior side of the heart (A)</p> Signup and view all the answers

    Which chamber of the heart is responsible for pumping blood to the lungs?

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

    Which of the following is NOT a characteristic of the right ventricle?

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

    Which of the following accurately describes the first heart sound (S1, 'lub')?

    <p>Closure of the atrioventricular valves (A)</p> Signup and view all the answers

    What is the name of the condition where fluid builds up within the pericardial cavity, putting pressure on the heart?

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

    Which of the following is NOT a function of the blood?

    <p>Regulate body temperature (B)</p> Signup and view all the answers

    What is the primary function of the precapillary sphincters?

    <p>To regulate blood flow through the capillary bed (C)</p> Signup and view all the answers

    Which of the following correctly describes the flow of blood through the systemic circulation?

    <p>Heart - body tissues - lungs - heart (A)</p> Signup and view all the answers

    What is the primary function of the tunica media in an artery?

    <p>Contracting to regulate blood flow and pressure (A)</p> Signup and view all the answers

    Which of the following chambers of the heart receives deoxygenated blood from the body?

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

    What is the primary function of the venous valves?

    <p>To prevent backflow of blood in veins (A)</p> Signup and view all the answers

    Which of the following is a characteristic of elastic arteries?

    <p>They are found close to the heart and are highly elastic (A)</p> Signup and view all the answers

    Which of the following correctly describes the movement of blood in the pulmonary circulation?

    <p>Deoxygenated blood from the heart to the lungs, oxygenated blood from the lungs to the heart (B)</p> Signup and view all the answers

    Which of the following is a characteristic of sinusoidal capillaries?

    <p>They are highly permeable and allow for the passage of large molecules (A)</p> Signup and view all the answers

    Which of the following is NOT a consequence of venous valve failure?

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

    Which of the following accurately describes the role of hemoglobin in red blood cells?

    <p>Hemoglobin transports oxygen throughout the body (D)</p> Signup and view all the answers

    What is the primary function of the superior and inferior vena cava?

    <p>To carry deoxygenated blood from the body to the heart (C)</p> Signup and view all the answers

    Which of the following is the correct order of blood flow through the heart?

    <p>Right atrium - right ventricle - left atrium - left ventricle (B)</p> Signup and view all the answers

    Which of the following best describes the function of the pulmonary arteries?

    <p>They carry deoxygenated blood from the heart to the lungs (C)</p> Signup and view all the answers

    Flashcards

    Muscarine

    A compound in certain mushrooms that activates muscarinic receptors, causing difficulty breathing and slow heart rate.

    Adrenergic Receptors

    Receptors that respond to adrenaline; include Alpha 1, Beta 1, and Beta 2, each affecting different muscle types.

    Alpha 1 Receptors

    Adrenergic receptors that cause smooth muscle contraction.

    Beta 1 Receptors

    Adrenergic receptors that increase heart muscle contraction.

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    Beta 2 Receptors

    Adrenergic receptors that cause smooth muscle relaxation.

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    Functions of Blood

    Transport oxygen/nutrients, defend against toxins, clotting, regulate pH, and prevent fluid loss.

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    Plasma Composition

    Liquid part of blood, made up of water, proteins, electrolytes, gases, and hormones (43-63% of blood volume).

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    Hematopoiesis

    Process of blood cell formation from hematopoietic stem cells in bone marrow.

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    Red Blood Cell Structure

    Biconcave discs that carry oxygen, lack nucleus, allowing stacking and bending in vessels.

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    Hemoglobin

    Protein in RBCs that binds oxygen; consists of four heme molecules, each containing iron.

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    White Blood Cells Classes

    Includes Granulocytes (neutrophils, eosinophils, basophils) and Agranulocytes (lymphocytes, monocytes), each with distinct roles.

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    Jaundice

    Condition where bilirubin builds up in blood, causing yellow skin/eyes due to liver issues.

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    Anemia

    Condition characterized by decreased oxygen-carrying capacity of blood due to low RBC count or hemoglobin.

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    Platelets

    Fragments of megakaryocytes important for blood clotting, involved in the coagulation process.

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    Systemic vs. Pulmonary Circulation

    Systemic: blood flow to body, except lungs; Pulmonary: blood flow to lungs for oxygenation.

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    Cardiac Output

    Amount of blood pumped by the left ventricle in one minute.

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    Heart Rate

    Number of beats per minute; directly affects cardiac output.

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    End Diastolic Volume (EDV)

    Blood volume in the ventricle after filling, before contraction.

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    End Systolic Volume (ESV)

    Amount of blood left in the ventricle after contraction.

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    Stroke Volume

    Amount of blood pumped from the left ventricle during each contraction.

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    Preload

    Ventricular wall stretch due to filling with blood during diastole.

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    Afterload

    The pressure the ventricle must overcome to eject blood.

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    Contractility

    Force of contraction of the ventricle, affecting stroke volume.

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    Ejection Fraction

    Percentage of EDV pumped out with each beat; a measure of heart function.

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    Sympathetic Nervous System

    Increases vessel constriction, affecting blood flow.

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    Heart Wall Layers

    The heart wall consists of three layers: endocardium (inner), myocardium (middle), and epicardium (outer).

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    Pericardium

    A fibrous connective tissue sac that surrounds and protects the heart, consisting of two layers: fibrous and serous.

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    Pericardial Cavity

    A fluid-filled space between visceral and parietal pericardium that reduces friction during heartbeats.

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    Coronary Arteries

    Arteries that supply oxygenated blood to the heart; includes right coronary artery and left coronary artery.

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    Right Coronary Artery

    Branches from the aorta and supplies the right atrium, right ventricle, and part of the left ventricle.

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    Left Coronary Artery

    Branches from the aorta into two main arteries: left anterior descending and circumflex artery.

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    Cardiac Cycle Phases

    The heart's cycle consists of two main phases: systole (contraction) and diastole (relaxation).

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    AV Valves vs. Semilunar Valves

    AV valves (tricuspid and bicuspid) regulate blood flow from atria to ventricles; semilunar valves (pulmonary and aortic) regulate blood flow from ventricles into arteries.

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    Pacemaker Cells

    Specialized cardiac cells that generate action potentials to regulate heartbeats; primarily located in the SA and AV nodes.

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    Action Potential of Pacemaker Cells

    Pacemaker cells undergo depolarization (calcium influx) and repolarization (potassium efflux) to create an electrical signal.

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    Major ECG Waves

    An electrocardiogram (ECG) shows three key waves: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

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    Blood Pressure

    The force exerted by circulating blood on the walls of blood vessels; influenced by heart activity.

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    Common Conduction Disorders

    Conditions like bradycardia, tachycardia, and heart murmurs arise from abnormal heart rhythms and conduction issues.

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    Study Notes

    Homeostasis

    • Homeostasis is maintaining a stable internal environment, achieving balance.
    • Examples include temperature regulation and blood sugar levels.
    • Receptors detect stimuli, effectors respond, and the hypothalamus regulates set points.

    Endocrine System

    • Releases hormones into the bloodstream, affecting the entire body.
    • Hormones travel slowly (minutes to hours).
    • Targets all body tissues.

    Autonomic Nervous System (ANS)

    • Uses electrochemical impulses (neurotransmitters).
    • Affects specific organs locally (synapse).
    • Impulses are fast (milliseconds to seconds).
    • Targets neurons, muscles, and glands.

    Sympathetic Nervous System

    • Preganglionic neuron in the central nervous system (CNS)
    • One neuron chain (direct synapse)
    • Releases acetylcholine (ACh) at the synapse.
    • Postganglionic neuron releases norepinephrine (NE) onto target organs (adrenergic receptors).

    Parasympathetic Nervous System

    • Two neuron chain.
    • Preganglionic neuron in the CNS; postganglionic neuron in the autonomic ganglion.
    • Releases ACh at both pre and postganglionic synapses.
    • Postganglionic neuron releases ACh onto target organs (muscarinic receptors).

    Dual Innervation

    • Organs receive input from both sympathetic and parasympathetic systems.
    • These systems often have opposing effects to maintain homeostasis.

    Hypothalamus and Autonomic Centers

    • The hypothalamus acts as the master regulator of the body's internal conditions.
    • It receives input from hormones and the brain stem.
    • It coordinates sympathetic or parasympathetic responses to maintain internal balance.

    Neurotransmitters and Receptors

    • The parasympathetic nervous system uses acetylcholine (ACh) at both synapses which will bind to nicotinic receptors at the synapse and muscarinic receptors to the target organ. 
    • The sympathetic nervous system uses ACh at the first synapse (nicotinic) and norepinephrine (NE) at the second synapse (adrenergic) to the target organ.
    • Agonists mimic neurotransmitters.
    • Antagonists block neurotransmitter binding.

    Blood Functions and Composition

    • Transports oxygen and nutrients, defends against toxins, clottin, regulates pH, restricts fluid loss in case of injury.
    • Plasma (55%): mainly water, proteins, electrolytes, gases, and hormones
    • Formed elements (45-63%): red blood cells (erythrocytes).
    • Platelets (clotting).

    Hematopoiesis

    • Blood cell formation in red bone marrow.
    • Hematopoietic stem cells create all blood cell types.

    Red Blood Cells (RBCs)

    • Biconcave shape for maximizing surface area and flexibility.
    • Lack a nucleus (increases space for hemoglobin).
    • Carry oxygen to cells.
    • Hemoglobin (95% of RBC protein) carries oxygen, consists of 4 heme units with Iron.

    White Blood Cells (WBCs)

    • Different types with varying functions (e.g., immune defense, phagocytosis).

    Platelets and Blood Clotting

    • Fragments of megakaryocytes (cell fragments)
    • Important in blood clotting.

    Fibrin

    • Key protein in blood clot formation.

    tPA

    • Clotting-busting drug; used to dissolve clots in heart attacks & strokes.

    Thrombus vs. Embolus

    • Thrombus: blood clot formed within a blood vessel.
    • Embolus: a thrombus that dislodges and travels through blood vessels, blocking flow.

    Systemic and Pulmonary Circulation

    • Systemic: blood circulates through the body (high oxygen to organs -> low oxygen return)
    • Pulmonary: blood circulates to the lungs (low oxygen -> high oxygen return)

    Heart Anatomy

    • The heart is located in the mediastinum, behind the breastbone.
    • The heart consists of 4 chambers, two upper atria and two lower ventricles

    Heart Wall

    • Endocardium (innermost layer).
    • Myocardium (middle layer, cardiac muscle).
    • Epicardium (outer layer, connective tissue).

    Pericardium

    • Double-layered membrane around the heart.
    • Reduces friction.
    • Pericardial fluid within to reduce friction.

    Coronary Arteries

    • Supply oxygenated blood to the heart muscle.

    Cardiac Cycle

    • Systole: contraction phase (ventricles pump blood)
    • Diastole: relaxation phase (ventricles fill with blood)
    • Atrial systole (atria contract)
    • Ventricular systole (ventricles contract)
    • AV Valves (tricuspid & bicuspid): prevent backflow from ventricles to atria
    • Semilunar valves (pulmonary & aortic): prevent backflow from arteries to ventricles

    Cardiac Output & Factors Affecting It

    • Cardiac output (CO): volume of blood pumped per minute by each ventricle.
    • Determined by heart rate and stroke volume.
    • Factors affecting stroke volume: preload, contractility, afterload.

    Pacemaker Cells & Electrical Conduction

    • Pacemaker cells initiate and regulate heartbeat.
    • The sequence of electrical signals through the conduction system:
      1. Sino-atrial (SA) node (pacemaker) initiates.
      2. Atrioventricular (AV) node delays the signal.
      3. Bundle of His and Purkinje fibers conduct the signal through the ventricles for a coordinated contraction

    Heart Sounds

    • Heart sounds (lub-dub) result from the closing of valves.

    Ejection Fraction

    • Percentage of blood ejected from the ventricles with each contraction.

    Sympathetic and Parasympathetic Influence on Heart Rate

    • Sympathetic: increases heart rate by releasing norepinephrine
    • Parasympathetic: decreases heart rate by releasing acetylcholine

    ECG (Electrocardiogram)

    • A graphical recording of the electrical activity in the heart.

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    Description

    Explore the intricate systems of homeostasis, the endocrine system, and the autonomic nervous system in this quiz. Understand how these systems interact to maintain balance in the body and regulate responses to stimuli. Test your knowledge of the sympathetic and parasympathetic nervous systems as well.

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