Cardiovascular System Overview
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Questions and Answers

What effect do sympathetic impulses have on heart rate?

  • They only affect blood pressure.
  • They have no effect on heart rate.
  • They increase heart rate and force of contraction. (correct)
  • They slow down the heart rate.

Which neurotransmitter is released by the sympathetic nervous system to affect heart rate?

  • Serotonin
  • Acetylcholine
  • Dopamine
  • Norepinephrine (correct)

How does parasympathetic stimulation affect heart rate at rest?

  • It causes arrhythmias in the heart.
  • It predominates and slows the heart rate. (correct)
  • It has no significant effect on heart rate.
  • It increases heart rate significantly.

What impact does excess potassium (K+) have on heart rate?

<p>It decreases heart rate by blocking action potentials. (A)</p> Signup and view all the answers

Which hormone is NOT mentioned as affecting heart rate?

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

What initiates the opening of the semilunar valves?

<p>Blood pressure in the ventricles exceeds blood pressure in the arteries. (A)</p> Signup and view all the answers

Which condition is characterized by a narrowing of a heart valve opening?

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

In mitral valve prolapse, what happens to the cusps of the valve during contraction?

<p>They protrude into the left atrium. (B)</p> Signup and view all the answers

What can lead to valve damage, specifically in rheumatic fever?

<p>Bacterial infection from the throat. (D)</p> Signup and view all the answers

Which valve is most commonly replaced due to dysfunction?

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

What is the main function of the right side of the heart?

<p>To pump deoxygenated blood to the lungs for oxygenation. (D)</p> Signup and view all the answers

What occurs in systemic capillaries?

<p>Nutrient and gas exchange takes place. (C)</p> Signup and view all the answers

Which structure receives oxygenated blood from the pulmonary veins?

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

What is the purpose of creatine kinase in cardiac muscle cells?

<p>To produce ATP from creatine phosphate (C)</p> Signup and view all the answers

Which wave in an electrocardiogram represents ventricular repolarization?

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

What occurs immediately after the P wave appears in an electrocardiogram?

<p>Atrial contraction begins (A)</p> Signup and view all the answers

During which phase of the cardiac cycle do the ventricles contract?

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

What is the role of the AV node in the cardiac conduction system?

<p>To delay the impulse allowing atria to contract (D)</p> Signup and view all the answers

Which component of an ECG indicates the spread of impulse through the ventricles?

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

Which of the following describes the phase where both atria and ventricles are relaxed?

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

What is the primary effect of increased preload on cardiac muscle fibers?

<p>Increases the force of contraction (B)</p> Signup and view all the answers

What does the electrocardiogram help to determine with relation to heart function?

<p>Abnormal conduction pathways (B)</p> Signup and view all the answers

How does the Frank-Starling law contribute to heart function?

<p>It equalizes output between the right and left ventricles (B)</p> Signup and view all the answers

What effect does stimulation of the sympathetic nervous system have on cardiac muscle contraction?

<p>Increases calcium levels in the interstitial fluid (A)</p> Signup and view all the answers

What impact does increased afterload have on stroke volume?

<p>It decreases stroke volume by delaying valve opening (B)</p> Signup and view all the answers

Which of the following factors does NOT contribute to the regulation of heart rate?

<p>Direct contraction of cardiac muscle fibers (B)</p> Signup and view all the answers

What type of cells in the cardiac muscle act as a pacemaker?

<p>SA nodal cells (D)</p> Signup and view all the answers

What is primarily responsible for action potential propagation through the heart?

<p>Cardiac conduction system (B)</p> Signup and view all the answers

Which drug class decreases calcium inflow and subsequently reduces the strength of the heartbeat?

<p>Calcium channel blockers (C)</p> Signup and view all the answers

Which of the following structures has the longest refractory period in cardiac muscle?

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

What is the main mechanism by which the body regulates cardiac output in the short term?

<p>Adjustments in heart rate (A)</p> Signup and view all the answers

In terms of mitochondria, how does cardiac muscle tissue differ from skeletal muscle tissue?

<p>Cardiac muscle has more and larger mitochondria. (B)</p> Signup and view all the answers

Where does the nervous control of the cardiovascular system originate?

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

What characterizes the pacemaker potential of SA nodal cells?

<p>Repetitive depolarization to threshold spontaneously (A)</p> Signup and view all the answers

What is the primary form of ATP production in cardiac muscle?

<p>Aerobic cellular respiration (D)</p> Signup and view all the answers

Which option describes the function of intercalated discs in cardiac muscle?

<p>Facilitate the conduction of action potentials (A)</p> Signup and view all the answers

Which phase of the cardiac action potential involves the inflow of Ca2+?

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

What happens to the ductus arteriosus at birth?

<p>It closes and becomes the ligamentum arteriosum. (B)</p> Signup and view all the answers

What is the main reason for the thickness of the left ventricle's walls?

<p>It pumps blood through the body where resistance is higher. (D)</p> Signup and view all the answers

Which of the following statements accurately describes the function of atrioventricular (AV) valves?

<p>They prevent back flow of blood into the atria. (D)</p> Signup and view all the answers

What happens to the semilunar valves during ventricular contraction?

<p>They open to allow ejection of blood into the arteries. (C)</p> Signup and view all the answers

Why do the walls of the right ventricle have a thinner myocardium than the left?

<p>It pumps blood into the lungs, which have low resistance. (C)</p> Signup and view all the answers

What mechanism prevents back flow of blood in the atrioventricular valves?

<p>Action of chordae tendineae and papillary muscles. (B)</p> Signup and view all the answers

Which statement correctly defines how valves operate in the heart?

<p>Valves open and close in response to pressure changes. (D)</p> Signup and view all the answers

What is the primary function of the coronary arteries?

<p>To supply oxygen and nutrients to the heart muscle. (B)</p> Signup and view all the answers

Flashcards

Blood flow through the aorta

Blood from the aorta flows into coronary arteries and the rest flows through the arch and descending aorta.

Fetal ductus arteriosus function

In a fetus, the ductus arteriosus diverts blood from the pulmonary trunk to the aorta.

Ductus arteriosus closure

After birth, the ductus arteriosus closes and becomes the ligamentum arteriosum.

Myocardium thickness (atria)

Atrial walls are thin since they transfer blood to the ventricles.

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Myocardium thickness (ventricles)

Ventricular walls are thick because they pump blood far distances.

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Right ventricle vs. Left ventricle thickness

Right ventricle thinner, pumps near lungs; left ventricle thicker, pumps to entire body.

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Atrioventricular (AV) valve function

AV valves prevent backflow of blood from ventricles into atria.

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Semilunar valve function

Semilunar valves allow blood ejection into arteries while preventing backflow to ventricles.

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Semilunar valve opening

Semilunar valves open when ventricular pressure exceeds arterial pressure, pushing blood into the arteries.

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Semilunar valve closing

When the ventricles relax and blood flows back, it fills the cusps, causing the valves to close.

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Heart valve stenosis

Narrowing of a heart valve opening, restricting blood flow.

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Heart valve insufficiency

A valve failing to close completely, allowing backflow.

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Pulmonary circulation

The right side of the heart pumps blood to the lungs for oxygenation.

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Systemic circulation

The left side of the heart pumps oxygenated blood throughout the body.

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Mitral valve prolapse (MVP)

One or both mitral valve cusps protrude into the left atrium during contraction.

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Heart valve replacement

Replacing valves when they limit daily activities.

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Cardiac Muscle Fibers

Shorter, branching muscle fibers connected by intercalated discs containing desmosomes and gap junctions. They have larger mitochondria, smaller sarcoplasmic reticulum, and lower intracellular Ca2+ compared to skeletal muscle.

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Intercalated Discs

Specialized connections between cardiac muscle fibers, containing desmosomes (for structural integrity) and gap junctions (for electrical communication).

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Autorhythmic Cells

Heart muscle cells that spontaneously generate action potentials, acting as a pacemaker for the heart's contractions.

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Pacemaker Potential

The repeated depolarization to threshold in autorhythmic cells, triggering action potentials, and ultimately heart contractions.

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Cardiac Conduction System

Specialized pathway for propagating action potentials through the heart muscle, starting from the SA node and ending in the Purkinje fibers.

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SA Node

The sinoatrial node, the heart's primary pacemaker, initiating the heartbeat.

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Cardiac Action Potential

The electrical signal sequence for a heartbeat, involving depolarization(Na+), plateau(Ca2+), and repolarization(K+).

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ATP Production in Cardiac Muscle

Primarily generated by aerobic cellular respiration to provide energy for contractions in cardiac muscle cells.

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What increases heart rate?

Sympathetic impulses, released by cardiac accelerator nerves, increase heart rate through the release of norepinephrine, which speeds up spontaneous depolarization at the SA and AV nodes.

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How does norepinephrine affect heart contraction?

Norepinephrine enhances calcium ion (Ca2+) entrance through calcium channels, leading to increased contractility.

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What slows down heart rate?

Parasympathetic impulses, released by the vagus nerves, slow heart rate through the release of acetylcholine, which decreases the rate of spontaneous depolarization at the SA and AV nodes.

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How does potassium affect heart rate?

Excess potassium (K+) in the blood decreases heart rate by blocking the generation of action potentials.

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What is the effect of increased interstitial calcium levels?

A moderate increase in interstitial calcium levels increases heart rate and contractility.

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Cardiac Muscle Fuel Sources

Cardiac muscle cells use fatty acids, glucose, lactic acid, amino acids, ketone bodies, and creatine phosphate for energy.

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Creatine Kinase (CK)

An enzyme in cardiac muscle cells that helps produce ATP from creatine phosphate.

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Electrocardiogram (ECG)

A record of electrical activity during a heartbeat.

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P Wave (ECG)

ECG wave representing atrial depolarization (impulse spreading through atria).

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QRS Complex (ECG)

ECG complex representing ventricular depolarization (impulse through ventricles).

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T Wave (ECG)

ECG wave representing ventricular repolarization (reversal of electrical charge in ventricles).

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Cardiac Cycle

All events during one heartbeat, including contractions and relaxation phases.

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Atrial Systole

Atrial contraction; part of the cardiac cycle.

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Frank-Starling Law

The heart's ability to increase its force of contraction with increased blood volume, resulting in greater stroke volume.

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Cardiac Contractility

The inherent strength of the heart muscle's contraction at a given preload.

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Sympathetic Nervous System & Contractility

Stimulation of the sympathetic nervous system increases contractility by releasing epinephrine and norepinephrine, which boost calcium levels.

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Afterload

The pressure the heart must overcome to open the semilunar valves and eject blood into the aorta.

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How Afterload Affects Stroke Volume

Increased afterload reduces stroke volume because the valves open later, limiting the amount of blood ejected.

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Factors Increasing Afterload

Hypertension and atherosclerosis increase afterload, making it harder for the heart to pump blood effectively.

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Cardiac Output Regulation (Short-Term)

The body primarily regulates cardiac output by adjusting heart rate in the short term.

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Cardiovascular Center Role

The cardiovascular center in the medulla oblongata controls the autonomic regulation of the heart rate.

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Study Notes

Introduction

  • The cardiovascular system includes blood, heart, and blood vessels.
  • The heart pumps blood approximately 100,000 times daily, circulating it through 60,000 miles of blood vessels.

Heart Location and Structure

  • The heart is positioned in the mediastinum, with roughly two-thirds of its mass to the left of the body's midline.
  • The heart's apex is inferior, and its base is superior.
  • The heart is encased and held in place by the pericardium, composed of an outer fibrous pericardium and an inner serous pericardium (epicardium).
  • The serous pericardium consists of parietal and visceral layers, with a pericardial cavity in between containing pericardial fluid that reduces friction.
  • The heart wall is composed of three layers: epicardium, myocardium, and endocardium.

Heart Chambers

  • The heart has four chambers: two atria (upper) and two ventricles (lower).
  • The atria receive blood from veins, and the ventricles eject blood into arteries.
  • The auricles are small pouches on the atria's anterior surfaces, increasing their capacity.
  • The heart chambers are separated by grooves (sulci) containing blood vessels and fat. These include the coronary sulcus, anterior interventricular sulcus, and posterior interventricular sulcus.

Heart Valves

  • Atrioventricular (AV) valves prevent blood from flowing back into the atria from the ventricles.
  • Semilunar (SL) valves prevent backflow into the ventricles from the arteries.

Heart's Pumping Action

  • The heart pumps blood to the lungs for oxygenation and then pumps oxygen-rich blood throughout the body.
  • The right side of the heart pumps blood to the lungs for oxygenation.
  • The left side of the heart pumps oxygenated blood to the body.

Electrical Activity of the Heart

  • The heart's electrical activity is recorded as an electrocardiogram (ECG/EKG).
  • The ECG shows waves (P, QRS, T) that correspond to different phases of the heart's electrical activity.
  • The heart has specialized cells that generate and conduct electrical impulses (the conduction system) that coordinate the heart's contraction.
  • The sinoatrial node (SA node) is the heart's natural pacemaker, initiating electrical signals that cause heart contraction.

Cardiac Cycle

  • The cardiac cycle encompasses the systole (contraction) and diastole (relaxation) phases of both atria and ventricles.
  • Heart sounds (lub-dub) are produced by valve closure during the cardiac cycle.
  • Various factors, like the changing pressures within the heart and blood vessels, regulate the heart's pumping action.

Cardiac Output

  • Cardiac output (CO) refers to the blood volume pumped by a ventricle per minute.
  • Cardiac output is determined by heart rate (HR) and stroke volume (SV), the volume of blood pumped per heartbeat.
  • Factors such as preload, contractility, and afterload influence stroke volume.
  • The nervous and hormonal systems control the heart rate and ensure the efficient supply of oxygenated blood to body tissues.

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This quiz covers the key components and structure of the cardiovascular system, including the heart's anatomy and chambers. Test your knowledge on the heart's location, structure, and function within the circulatory system.

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