49 Questions
What is the main purpose of the pulmonary circuit?
To pump deoxygenated blood from the right side of the heart to the lungs
What is the primary function of the intercalated discs in cardiac muscle cells?
To allow for the rapid transmission of electrical signals between adjacent cardiac muscle cells
Which of the following is a key hemodynamic concept that describes the resistance to blood flow in blood vessels?
Resistance
How do the properties of cardiac muscle cells differ from those of skeletal muscle cells?
Cardiac muscle cells have a higher metabolic rate and require a constant supply of oxygen and nutrients
What is the primary function of the conduction system in the heart?
To generate the electrical impulses that coordinate the contraction of the heart
What is the main purpose of the systemic circuit?
To distribute oxygenated blood from the left side of the heart to the body
Which type of muscle cells are responsible for generating and rapidly spreading action potentials over the entire myocardium?
Conducting cells
What is the primary function of pacemaker cells in the heart?
Generating automatic rhythmical electrical discharge
Which aspect is included in cardiac electrophysiology?
Excitability and refractory periods
Where are conducting cells located in the heart?
SA node, AV node, AV Bundle, Purkinje Fibers
What initiates the action potentials in the heart's myocardium?
SA node
What is the primary function of cardiac muscle cells?
To contract and generate force/pressure
What is the significance of the term 'functional syncytium' in relation to cardiac muscle?
It describes the electrical connection between individual cardiac muscle cells
Which structures in the intercalated disk facilitate the rapid spread of action potentials between cardiac muscle cells?
Gap junctions
What is the primary function of desmosomes in the intercalated disk?
To provide mechanical strength and anchor cardiac muscle fibers
Which of the following statements about cardiac muscle cells is NOT true?
They fuse into multinucleated fibers during embryonic development
What are the two different cell types present in cardiac muscle?
Contractile cells and conductive cells
Which statement about systole is correct?
It is the contraction and emptying of the heart.
What is the primary function of the cardiovascular system?
To transport oxygen, nutrients, and wastes
Which blood vessels have the highest resistance to blood flow?
Arterioles
What is hemodynamics?
The principles that control blood flow in the cardiovascular system
Which blood vessels are the sites of exchange of nutrients, gases, water, and solutes between blood and tissues?
Capillaries
What is the primary pacemaker of the heart responsible for initiating the action potential?
SA node
Where is the SA node located within the heart?
Right atrium
What is the function of the AV node in the heart's conduction system?
Delays impulse conduction from atria to ventricles
Which specialized conducting system in the heart ensures rapid distribution of action potential to the ventricles?
Purkinje fibers
Why must ventricles contract from apex to base for efficient ejection of blood?
To allow for efficient contraction and ejection of blood
What happens if impulses are generated in the SA node but are blocked?
Decreased stroke volume
What is the role of the AV bundle (Bundle of His) in cardiac conduction?
Delays impulse conduction between atria and ventricles
What can increased conduction velocity through the AV node lead to?
Decreased stroke volume and cardiac output
What is the function of the Bachmann's bundle in the heart's electrical conduction system?
Transmits action potential from SA node to AV node
What anatomical structure separates atrial muscle from ventricular muscle to prevent abnormal conduction routes?
Fibrous skeleton
What is the main difference in development between cardiac muscle cells and skeletal muscle cells?
Skeletal muscle cells remain as separate cells with distinct sarcolemma structures.
What is the primary function of contractile cells in cardiac muscle?
Generation of force and pressure
Which term describes a group of cells that function as a single unit while maintaining their individual cellular roles?
Functional syncytium
Where are conducting cells not located in the heart's conduction system?
Intercalated disks
What is the role of the AV bundle (Bundle of His) in the heart's conduction system?
Conducting action potentials to the ventricles
Which aspect is included in cardiac electrophysiology?
Cardiac action potentials
How do pacemaker cells differ from conducting cells in the heart?
Pacemaker cells generate force while conducting cells respond to nerves
What is the primary function of cardiac muscle cells?
To generate and rapidly spread action potentials over the entire myocardium
What is the role of the Bachmann's bundle in the heart's electrical conduction system?
Allowing rapid conduction of impulses between the atria
Why is the conduction of action potentials through the AV node slower compared to other cardiac conduction pathways?
The AV node has a smaller quantity of gap junctions between cells
What is the primary function of the Purkinje fiber system?
To rapidly distribute the action potential throughout the ventricles
Which of the following statements about the sinoatrial (SA) node is correct?
It initiates the action potential that spreads throughout the heart
What is the role of the Bundle of His (AV bundle) in cardiac conduction?
To allow only forward electrical conduction from the atria to the ventricles
What is the significance of the term 'functional syncytium' in relation to cardiac muscle?
It refers to the presence of gap junctions between cardiac muscle cells
What would happen if the impulses generated in the SA node were blocked?
The AV node would take over as the primary pacemaker
Which of the following statements about the Purkinje fibers is correct?
They penetrate the ventricular muscle mass and become continuous with cardiac fibers
What is the primary function of the atrial internodal tracts?
To conduct the action potential from the SA node to the atrial walls
Study Notes
Cardiovascular Physiology Overview
- Cardiovascular physiology is the study of the heart, blood vessels, and blood.
- The primary function of the cardiovascular system is to transport oxygen and nutrients to tissues and remove waste products.
Cardiovascular Terminology
- Systole: Contraction and emptying of the heart.
- Tachycardia: Increase in heart rate.
- Diastole: Relaxation and filling of the heart.
- Bradycardia: Decrease in heart rate.
- Cardiac output: The total volume of blood pumped by the heart per unit time (mL/min).
- Heart rate: Number of heartbeats per minute.
Hemodynamics
- Hemodynamics describes the principles that control blood flow in the cardiovascular system.
- Depends on the characteristics of different blood vessels, such as diameter (related to resistance) and elasticity (related to compliance).
- Blood vessels actively participate in regulating blood flow to organs.
Blood Vessels
- Arteries: deliver oxygenated blood to organs; thick-walled with elastic tissue, smooth muscle, and connective tissue; under high blood pressure.
- Arterioles: smallest branches of arteries; extensive smooth muscle; highest resistance to blood flow; highly innervated.
- Capillaries: thin-walled with single layer of endothelial cells; sites of exchange of nutrients, gases, water, and solutes between blood and tissues.
Cardiac Muscle
- Cardiac muscle is a functional syncytium, consisting of cells that function together while maintaining individual cellular roles.
- Cardiac muscle cells do not fuse into a single multinucleated fiber during embryonic development.
- Cardiac myocytes branch and bind to other myocytes, remaining separated as distinct cells with sarcolemma, connected by intercalated disks (desmosomes + GAP junctions).
Intercalated Disk
- A dark, dense cross-band found at the end of each myocardial cell.
- Part of the sarcolemma (plasma membrane).
- Contains two important cell-cell junctions: GAP junctions (allow rapid ion transport) and desmosomes (provide mechanical strength).
Cardiac Cells
- Contractile cells (cardiomyocytes/myocardium): constitute most of atrial and ventricular tissues; responsible for contraction and generation of force/pressure.
- Conducting cells: specialized muscle cells that do not contribute significantly to generation of force; function to generate and rapidly spread action potentials over the entire myocardium.
Conduction System of the Heart
- The action potential initiated in the SA node is conducted to the entire myocardium in a specific, timed sequence.
- SA node: the normal/natural/primary pacemaker of the heart; starts the action potential; located in the right atrium.
- AV node: delays impulse conduction from the atria to the ventricles; located in the posterior wall of the right atrium.
- Bundle of His or AV bundle: allows only forward electrical conduction from the atria to the ventricles; passes downward in the ventricular septum and divides into left and right bundle branches.
- Purkinje fibers system: conduction is extremely fast, rapidly distributing the action potential to the ventricles; essential for efficient contraction and ejection of blood.
This study guide covers cardiovascular terminology, parts and functions of the cardiovascular system, hemodynamics, blood vessels and their characteristics, as well as hemodynamic concepts like blood flow, blood pressure, resistance, and compliance. It also correlates blood vessel types with hemodynamic concepts along with explanations on different types of cardiac...
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