Week 1 - General Principles of the Cardiovascular System Flashcards
What defines the superior boundary of the thoracic cavity?
The thoracic inlet is defined by the first thoracic vertebra, the first ribs, and the upper margin of the manubrium.
What forms the inferior boundary of the thoracic cavity?
The diaphragm forms a dome-shaped muscular partition between the thoracic and abdominal cavities.
What is the composition of the anterior chest wall?
The anterior chest wall comprises the sternum and costal cartilages.
What forms the lateral walls of the thoracic cavity?
The lateral walls are formed by the ribs and intercostal muscles.
What primarily constitutes the posterior wall of the thoracic cavity?
The posterior wall is primarily the vertebral column and associated musculature.
How many lobes does the right lung have?
The right lung is divided into three lobes: superior, middle, and inferior.
How many lobes does the left lung have?
The left lung is divided into two lobes: superior and inferior.
What is the function of alveolar sacs in the lungs?
Alveolar sacs are where gas exchange occurs.
What are the visceral and parietal pleura?
The visceral pleura closely adheres to the lung surface; the parietal pleura lines the inner chest wall, diaphragm, and mediastinum.
What is the role of pleural fluid?
Pleural fluid minimizes friction during respiratory movements.
Where is the heart located in the thoracic cavity?
The heart is centrally located in the mediastinum.
What encloses the heart?
The heart is enclosed by a double-layered pericardial sac.
What are the major components of the great vessels?
The great vessels include the aorta, pulmonary trunk and its branches, the superior and inferior vena cava, and the pulmonary veins.
What is the function of the esophagus?
The esophagus is a muscular tube for food passage.
What is the function of the trachea?
The trachea is a rigid cartilaginous tube for air conduction.
What is the role of the thymus in the thoracic cavity?
The thymus is involved in T-cell maturation and immune regulation.
What functions do the phrenic and vagus nerves serve?
The phrenic and vagus nerves provide motor, sensory, and autonomic input.
What is the thoracic duct’s role?
The thoracic duct plays key roles in immune surveillance and fluid balance.
What is the extent of the Superior Mediastinum?
From the thoracic inlet to the sternal angle (Angle of Louis).
What are the contents of the Superior Mediastinum?
- Thymus
- Trachea
- Esophagus
- Portions of the aortic arch
- Major branches (brachiocephalic vessels, left common carotid, left subclavian arteries)
- Important neural elements (vagus, phrenic, sympathetic chains)
What are the three regions of the Inferior Mediastinum?
- Anterior Mediastinum
- Middle Mediastinum
- Posterior Mediastinum
Where is the Anterior Mediastinum located and what does it contain?
Lies between the sternum and the pericardium; contains loose connective tissue, small lymph nodes, and residual thymic tissue.
What dominates the Middle Mediastinum?
The heart within its pericardial sac.
What does the Middle Mediastinum include aside from the heart?
Origins of the great vessels and proximal portions of the tracheobronchial tree.
What is located in the Posterior Mediastinum?
- Descending aorta
- Esophagus
- Thoracic duct
- Azygos system of veins
- Sympathetic chain
True or False: Detailed knowledge of mediastinal compartments is important for interpreting imaging studies.
True
Fill in the blank: The _______ Mediastinum lies between the sternum and the pericardium.
[Anterior Mediastinum]
What is the significance of understanding the mediastinal anatomy?
Vital for planning surgical interventions for mediastinal masses or infections.
What is the Fibrous Pericardium?
A dense, inelastic outer layer that anchors the heart to surrounding mediastinal structures and protects the heart from over-distension.
It connects to the diaphragm and sternum.
What are the two layers of the Serous Pericardium?
- Parietal Layer
- Visceral Layer (Epicardium)
The parietal layer lines the inner surface of the fibrous pericardium, while the visceral layer adheres directly to the heart surface.
What is the pericardial cavity?
The space between the parietal and visceral layers of the serous pericardium that contains a thin film of serous fluid.
This fluid facilitates frictionless movement during the cardiac cycle.
What primarily supplies blood to the pericardium?
Primarily from the pericardiacophrenic arteries and supplemented by small branches from the bronchial arteries.
The pericardiacophrenic arteries are branches of the internal thoracic arteries.
Which nerves provide sensory innervation to the pericardium?
The phrenic nerves, originating from C3–C5.
Irritation of these nerves may refer pain to the shoulder region.
What is one of the functions of the pericardium related to mechanical protection?
Minimizes friction and provides a stable mechanical environment for cardiac motion.
This function is crucial for the heart’s proper functioning during the cardiac cycle.
How does the pericardium provide structural support?
Limits excessive dilation of the heart, preserving optimal geometry for efficient contraction.
This helps maintain the heart’s shape during varying pressures.
What barrier role does the pericardium play?
Helps contain infections and inflammation within the pericardial space.
This is vital for protecting the heart from surrounding infections.
What are the functions of the atria?
Thin-walled chambers responsible for receiving blood
The right atrium collects systemic venous return; the left atrium receives oxygenated blood from the pulmonary veins.
What is the role of the ventricles?
Thick-walled chambers that generate the force required to propel blood
The right ventricle pumps blood into the low-pressure pulmonary circuit; the left ventricle ejects blood into the high-pressure systemic circulation.
What do the interatrial and interventricular septa do?
Maintain separation between oxygenated and deoxygenated blood
What is the function of the valvular apparatus?
Ensures unidirectional blood flow
Includes the atrioventricular (mitral and tricuspid) and semilunar (aortic and pulmonary) valves.
What is the function of the aorta?
Distributes oxygenated blood throughout the body
Emerges from the left ventricle.
What does the pulmonary trunk do?
Originates from the right ventricle and bifurcates into the pulmonary arteries
Delivers blood to the lungs.
What do the superior and inferior vena cavae do?
Return deoxygenated blood to the right atrium
What do the pulmonary veins do?
Return oxygenated blood to the left atrium
What does the Left Coronary Artery (LCA) typically divide into?
Left anterior descending (LAD) and circumflex (LCx) arteries
What areas does the Right Coronary Artery (RCA) supply?
Supplies the right atrium, right ventricle, and portions of the conduction system
Includes the SA and AV nodes in most individuals.
Describe the sequence of unidirectional blood flow.
Blood moves from systemic veins to the right atrium, to the right ventricle, through the pulmonary circulation, to the left atrium, to the left ventricle, and back into systemic circulation.
True or False: The right heart operates under higher pressure than the left heart.
False
The right heart operates under lower pressure with thinner walls.
What characterizes the myocardium of the left heart?
Thick myocardium to generate high pressures needed for systemic circulation
Where does the heart lie anatomically?
The heart lies within the middle mediastinum
What forms the right border of the heart?
The right atrium
What forms the left border of the heart?
The left ventricle
In which intercostal space is the apex of the heart typically found?
The left fifth intercostal space
What line is used to locate the apex of the heart?
The midclavicular line
Why is knowledge of the spatial arrangement of the heart’s chambers important?
It is crucial for interpreting imaging studies and physical examination findings
Fill in the blank: The heart is oriented _______.
obliquely
What is the origin of the Aorta?
Arises from the left ventricle
The aorta’s arch gives off branches that supply the head, neck, and upper limbs.
Where does the Pulmonary Trunk emanate from?
Right ventricle
The pulmonary trunk bifurcates into left and right pulmonary arteries that serve the lungs.
What does the superior vena cava (SVC) collect blood from?
Upper body
The inferior vena cava (IVC) traverses the diaphragm to empty into the right atrium.
How many pulmonary veins are typically present?
Four
Pulmonary veins return oxygenated blood from the lungs to the left atrium via a posterior approach.
Why is a detailed understanding of vascular landmarks essential?
During invasive procedures and in the interpretation of radiologic studies
Examples include catheterization and bypass surgery.
Fill in the blank: The _______ collects blood from the upper body.
superior vena cava
True or False: The pulmonary trunk bifurcates into three arteries.
False
The pulmonary trunk bifurcates into left and right pulmonary arteries.
What is the function of the aorta?
Supplies the head, neck, and upper limbs
It does this through branches that arise from its arch.
Fill in the blank: The inferior vena cava empties into the _______.
right atrium
Where is the apex beat typically palpated?
At the left fifth intercostal space
The location and strength of the apex beat can indicate left ventricular hypertrophy or dilation.
What areas are included in the precordial region?
Areas corresponding to the right ventricle and the left ventricle at the apex
The right ventricle is adjacent to the left lower sternal border.
Which peripheral pulses are assessed during examination?
Carotid, radial, and femoral pulses
Assessment provides information on systemic circulation and arterial compliance.
Why is careful palpation important in clinical integration?
It is essential for detecting abnormalities and assessing overall circulatory status
Abnormalities may include displaced or hyperdynamic apex beats.
Fill in the blank: The apex beat can indicate _______.
left ventricular hypertrophy or dilation
What is the location of the Aortic Area for auscultation?
The right second intercostal space at the sternal border
What does the Aortic Area evaluate?
Aortic valve function
Where is the Pulmonic Area located?
The left second intercostal space at the sternal border
What is assessed at the Pulmonic Area?
The pulmonary valve
Where can the Tricuspid Area be found?
The left lower sternal border (around the fourth intercostal space)
What is the purpose of auscultating the Tricuspid Area?
Listening to the tricuspid valve
What is the location of the Mitral Area (Apex)?
The left fifth intercostal space at the midclavicular line
What is the significance of the Mitral Area?
Key for mitral valve evaluation
What is the clinical significance of accurate auscultation?
Aids in diagnosing murmurs, extra heart sounds, and other pathologic findings
What is the first phase of the cardiac cycle?
Diastole
Diastole includes early diastole, mid-diastole, and late diastole (atrial systole).
What occurs during early diastole?
Rapid ventricular relaxation and steep decline in intraventricular pressure, allowing AV valves to open
This phase is crucial for initiating the filling of the ventricles.
What happens during mid-diastole?
Passive filling of the ventricles as blood flows from the atria
This phase continues to contribute to ventricular filling.
What is the role of atrial contraction in late diastole?
Tops off ventricular filling, contributing to end-diastolic volume
This phase ensures that the ventricles are adequately filled before systole.
What is isovolumetric contraction?
Ventricles contract with no change in volume until intraventricular pressure exceeds that in the aorta or pulmonary artery
This occurs after AV valve closure.
What occurs during the ejection phase of ventricular systole?
Blood is forcefully ejected into the arterial system
This phase begins once the semilunar valves open.
What is isovolumetric relaxation?
Ventricular relaxation begins with all valves closed, leading to a rapid fall in pressure
This sets the stage for the next cardiac cycle.
Why is understanding the phases of the cardiac cycle important in clinical practice?
Essential for interpreting pressure-volume loops and diagnosing dysfunction such as diastolic heart failure
Knowledge of these phases aids in patient assessment.
What determines preload in the cardiac cycle?
End-diastolic volume (EDV)
Preload stretches myocardial fibers according to the Frank-Starling law.
What is the Frank-Starling law?
The relationship between preload and stroke volume, indicating that increased preload leads to increased stroke volume
This principle is fundamental to cardiac function.
What do the opening and closing of the AV and semilunar valves ensure?
Efficient conversion of volume changes into pressure generation and unidirectional blood flow
This coordination is crucial for effective heart function.
What factors affect stroke volume?
Variations in venous return and end-diastolic volume (EDV)
Stroke volume directly influences cardiac output and systemic perfusion.
What are key parameters routinely assessed in clinical practice?
Stroke Volume (SV), End-Diastolic Volume (EDV), Ejection Fraction (EF)
These parameters are critical for evaluating heart function.
What is the definition of stroke volume (SV)?
The volume of blood ejected per heartbeat
SV is an important measure of cardiac efficiency.
What does ejection fraction (EF) represent?
The percentage of EDV expelled during systole
EF is a crucial measure of ventricular performance.
What components are illustrated in Wigger’s diagram?
Pressure curves, volume curves, ECG tracing, heart sounds (phonocardiogram)
These components correlate electrical activity with mechanical function.
What do the pressure curves in Wigger’s diagram show?
Temporal relationship between left ventricular pressure, aortic pressure, and atrial pressures
This helps in understanding cardiac dynamics.
What do the volume curves in Wigger’s diagram illustrate?
Changes in ventricular volume corresponding to phases of filling and ejection
This provides insight into the heart’s functional phases.
What is the significance of the ECG tracing in Wigger’s diagram?
Provides a temporal correlation of electrical activity with mechanical events
Correlates the heart’s electrical and mechanical functions.
What do heart sounds (phonocardiogram) visualize?
Timing of S1 and S2 in relation to electrical and hemodynamic events
This aids in diagnosing various cardiac conditions.
True or False: Systole is the relaxation phase of the cardiac cycle.
False
Systole is the contraction phase, while diastole is the relaxation phase.
What is the outer layer of the heart called?
Epicardium
The epicardium is continuous with the visceral pericardium and plays a role in protecting the heart and forming coronary vessels.
What is the main component of the myocardium proper?
Densely packed cardiac muscle fibers
These fibers are arranged in a complex spiral pattern that facilitates effective blood ejection.
What is the function of the endocardium?
Minimizes friction and modulates electrical activity
The endocardium is the smooth inner lining of the heart.
How does fiber orientation in the myocardium affect heart function?
Supports efficient contraction and relaxation
Disruption can impair both mechanical and electrical function, as seen in hypertrophic cardiomyopathy.
What morphological features characterize cardiomyocytes?
Long, striated cells with a central nucleus and organized sarcomeres
Sarcomeres contain A-bands, I-bands, and Z-discs, which are essential for contraction.
What are intercalated discs?
Specialized junctions enabling electrical coupling and mechanical adhesion
They contain gap junctions, desmosomes, and adherens junctions.
What is the metabolic profile of cardiomyocytes?
Rich in mitochondria with high oxidative capacity
This supports their continuous energy demand.
What can alterations in calcium handling or sarcomeric protein function cause?
Contractile dysfunction
This is observed in various cardiomyopathies.
What is cardiac output (CO)?
The product of heart rate (HR) and stroke volume (SV)
CO is critical for maintaining tissue perfusion.
What determines stroke volume?
Preload, afterload, and contractility
Preload is the initial stretch of myocardial fibers, afterload is the resistance against blood ejection, and contractility is the myocardium’s intrinsic ability to contract.
What is preload?
End-diastolic volume (EDV)
It determines the initial stretch of the myocardial fibers.
What is afterload?
The resistance against which the ventricles must eject blood
It impacts stroke volume.
What is contractility?
The intrinsic ability of the myocardium to contract
It is modulated by sympathetic stimulation.
What factors regulate preload?
Blood volume, venous tone, respiratory and skeletal muscle pumps, postural effects
These factors affect venous return and preload.
What effect does blood volume have on venous return?
Higher circulating volume increases venous pressure
This enhances venous return.
How does sympathetic-mediated vasoconstriction affect venous return?
Decreases venous capacitance
This augments venous return.
What role do respiratory and skeletal muscle pumps play?
Aid in propelling blood towards the heart
Negative intrathoracic pressure during inspiration and rhythmic muscle contraction contribute to this.
How does posture affect venous return?
Standing may reduce venous return compared to a supine position
Gravity influences venous pooling.
What can impairments in preload factors lead to?
Inadequate preload
This is critical in conditions such as hypovolemia and congestive heart failure.
What are the components of the Mitral Valve?
Anterior and posterior leaflet, tethered by chordae tendineae to papillary muscles
Papillary muscles are vital for preventing prolapse during ventricular contraction.
What are the components of the Tricuspid Valve?
Three leaflets: anterior, posterior, and septal, supported by chordae tendineae and papillary muscles
Similar to the Mitral Valve in structure and function.
What is the histological composition of Atrioventricular Valves?
A robust core of collagen and elastin, covered by an endocardial lining
This structure provides strength and flexibility while reducing friction.
What is the structure of Semilunar Valves?
Typically have three cusps, with a fibrous framework interlaced with elastic fibers and covered by a thin endothelial layer
Designed to withstand high-pressure environments.
What can structural defects in heart valves lead to?
Regurgitation or stenosis, impacting cardiac output
Such defects can be degenerative or congenital.
How do Atrioventricular Valves operate during the cardiac cycle?
Open during ventricular diastole and close rapidly during systole
This prevents retrograde flow of blood.
What is the function of Semilunar Valves during systole?
Open when ventricular pressure exceeds arterial pressure
They close promptly during diastole to maintain forward flow.
What heart sounds are generated by valve motion?
First (S1) and second (S2) heart sounds
Precise timing of valve motion is essential for efficient hemodynamics.
What produces the S1 heart sound?
Closure of the AV valves at the onset of ventricular systole
Its intensity and splitting provide diagnostic clues.
What produces the S2 heart sound?
Closure of the semilunar valves at the beginning of diastole
Variations in S2 can indicate abnormalities in ventricular conduction or valve pathology.
What does the S3 heart sound indicate?
May be present in normal young individuals or signify volume overload in pathologic states
It is not always pathological.
What does the S4 heart sound typically indicate?
A stiff, non-compliant ventricle, as seen in left ventricular hypertrophy
It suggests underlying cardiac conditions.
What are the consequences of regurgitation?
Inadequate closure of a valve leading to retrograde blood flow, volume overload, chamber dilation, and chronic heart failure
This condition can severely affect cardiac function.
What are the effects of stenosis on the heart?
Narrowing of the valve orifice increases the workload on the ventricle, leading to hypertrophy and potentially ischemia
This condition can lead to significant hemodynamic compromise.
Fill in the blank: Aberrant valve function can lead to significant clinical _______.
sequelae
This can occur due to conditions like rheumatic heart disease or calcific degeneration.
What is the clinical utility of auscultation of heart sounds?
A key non-invasive diagnostic tool in the evaluation of cardiac function
It helps in assessing valve function and overall heart health.
What is the primary pacemaker of the heart?
Sinoatrial (SA) Node
Located in the right atrial wall near the SVC junction, it generates spontaneous action potentials.
Where is the Atrioventricular (AV) Node located?
In the interatrial septum
It delays conduction to allow for complete ventricular filling.
What structure emerges from the AV node and bifurcates into right and left bundle branches?
Bundle of His
It rapidly conducts impulses down the interventricular septum.
What are Purkinje Fibers responsible for?
Distributing the electrical impulse throughout the ventricular myocardium
This ensures synchronous contraction.
What can disruptions in the cardiac conduction pathway lead to?
Arrhythmias or conduction blocks
Often necessitating clinical intervention such as pacemaker implantation.
How does the electrical impulse spread across the atria?
Rapidly via gap junctions
The impulse originates in the SA node.
What is the purpose of the AV Nodal Delay?
To ensure complete atrial contraction and optimize ventricular filling
This is critical for effective hemodynamics.
What leads to near-simultaneous ventricular activation?
Rapid conduction through bundle branches and Purkinje fibers
This follows the passage through the Bundle of His.
What does the timing of electrical activity events ensure?
Coordination between electrical and mechanical cardiac activity
Essential for maintaining effective hemodynamics.
What is the function of the SA Node?
Sets the intrinsic rate of the heart
It generates spontaneous action potentials.
What role does the AV Node play in cardiac function?
Acts as a critical delay junction
Ensures that ventricular filling is complete before contraction begins.
What is the role of Purkinje Fibers in the heart?
Ensures efficient propagation of the contraction wave throughout the ventricles
Their rapid conduction is crucial for effective heart function.
What abnormalities can occur in the SA Node, AV Node, or Purkinje Fibers?
Bradyarrhythmias, tachyarrhythmias, or conduction blocks
These influence overall cardiac performance.
What is the resting membrane potential in ventricular cells?
Approximately –90 mV
Maintained predominantly by potassium permeability.
What initiates the rapid depolarization phase (Phase 0) in cardiac myocytes?
Opening of voltage-gated sodium channels
Resulting in a swift influx of Na⁺.
What characterizes Phase 1 of the action potential?
Transient outward potassium currents (Ito)
Causes a brief, partial repolarization.
What occurs during the plateau phase (Phase 2) of the action potential?
Influx of Ca²⁺ via L-type calcium channels balanced by K⁺ efflux
Sustains a plateau essential for contraction.
What is the main event in Phase 3 of the action potential?
Enhanced K⁺ efflux restores the membrane potential
Returning it to its resting state.
What is the purpose of refractory periods in cardiac myocytes?
Prevent premature re-excitation
Ensures the rhythmicity of the heartbeat.
How do alterations in action potential phases affect cardiac health?
Central to many cardiac pathologies, including arrhythmias
Particularly in calcium dynamics.
What is the role of calcium in electromechanical coupling?
Triggers a larger release of calcium from the sarcoplasmic reticulum
Initiates actin–myosin cross-bridge formation.
What happens during repolarization in cardiac muscle?
Calcium is resequestered and muscle relaxes
Allowing the cycle to repeat.
What can disruptions in calcium handling lead to?
Contractile dysfunctions such as heart failure or ischemia
Clinical importance in cardiac health.
What initiates the calcium-induced calcium release?
Initial Ca²⁺ influx triggers ryanodine receptors
On the sarcoplasmic reticulum, releasing more calcium.
What is the sliding filament mechanism?
Interaction of elevated intracellular calcium with contractile proteins
Produces contraction.
What terminates muscle contraction?
Calcium removal via reuptake and extrusion
Leading to muscle relaxation.
What is a distinctive feature of the ventricular action potential?
Prolonged plateau phase
Ensures sufficient time for calcium influx.
How does ventricular contraction relate to calcium levels?
Highly sensitive to calcium levels
Making cells vulnerable to ion balance disturbances.
What prevents premature re-excitation in the heart?
The long action potential of the ventricular cells
Preserves coordinated contraction.
What characterizes the pacemaker action potential?
Spontaneous diastolic depolarization
Due to funny currents (If) and T-type calcium channels.
What is the state of the resting potential in pacemaker cells?
Absence of a stable resting potential
Continuously drifting towards threshold.
What underlies the heart’s inherent rhythmicity?
Unique combination of ionic currents in pacemaker cells
Setting the pace for the conduction system.
What is a clinical consequence of dysfunction in ionic channels of pacemaker cells?
Can lead to bradyarrhythmias or tachyarrhythmias
Targeted for pharmacologic intervention.
What is the source of sympathetic innervation in the heart?
Thoracic spinal segments
Sympathetic fibers release noradrenaline to impact cardiac function.
What neurotransmitter is released by the vagus nerve?
Acetylcholine
This neurotransmitter slows heart rate and prolongs AV nodal conduction.
What is the effect of sympathetic innervation on pacemaker cells?
Increases the rate of depolarization
This results in shorter conduction times and enhanced myocardial contractility.
What does the dynamic balance between sympathetic and parasympathetic innervation allow?
Rapid adaptation to changing physiological demands
Examples include adjustments during exercise versus rest.
What can alterations in autonomic tone lead to?
Arrhythmias
This is a key focus in pharmacologic and device-based therapy.
What receptor does noradrenaline bind to in order to enhance pacemaker activity?
β₁-adrenergic receptors
This increases the slope of the pacemaker potential.
What are the effects of sympathetic activation on conduction velocity?
Increased conduction velocity and contractility
Enhances calcium influx in both pacemaker and contractile cells.
What can excessive sympathetic stimulation lead to?
Tachyarrhythmias
It can also exacerbate myocardial ischemia.
What is the effect of acetylcholine on heart rate?
Decreases heart rate
This is due to negative chronotropic effects via M2 receptors.
What is the dromotropic effect of acetylcholine?
Slows conduction through the AV node
This results in a prolonged AV delay.
What factors influence the cardiac conduction pathway?
Autonomic tone, electrolyte balance, ischemia/infarction, pharmacologic agents
These factors can alter action potential duration and conduction velocity.
What electrolytes are critical in modulating cardiac conduction?
K⁺, Ca²⁺, Mg²⁺
Abnormalities in these ions can predispose to arrhythmias.
What can damage to the conduction system from ischemic events result in?
Blocks or ectopic pacemaker activity
This affects the normal rhythm of the heart.
What types of drugs modify conduction properties in the heart?
Beta-blockers, calcium channel blockers, antiarrhythmic medications
These are essential tools in managing arrhythmias.
Fill in the blank: The net effect on the conduction system is determined by the balance between _______ and _______.
sympathetic; parasympathetic activity
True or False: Acetylcholine has a positive chronotropic effect on the heart.
False
Acetylcholine decreases heart rate.
