Podcast
Questions and Answers
What defines the cardiac output (CO)?
What defines the cardiac output (CO)?
Which of the following factors does NOT influence stroke volume?
Which of the following factors does NOT influence stroke volume?
Under which condition would stroke volume (SV) most likely increase?
Under which condition would stroke volume (SV) most likely increase?
What is the relationship between end diastolic volume (EDV) and end systolic volume (ESV) in determining stroke volume (SV)?
What is the relationship between end diastolic volume (EDV) and end systolic volume (ESV) in determining stroke volume (SV)?
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Which component is NOT included in the definition of blood pressure?
Which component is NOT included in the definition of blood pressure?
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Which of the following correctly describes the Frank-Starling Law of the Heart?
Which of the following correctly describes the Frank-Starling Law of the Heart?
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Which factor is likely to decrease contractility in cardiac muscles?
Which factor is likely to decrease contractility in cardiac muscles?
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What role does peripheral resistance play in the cardiovascular system?
What role does peripheral resistance play in the cardiovascular system?
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What effect does vasoconstriction have on systemic vascular resistance (SVR)?
What effect does vasoconstriction have on systemic vascular resistance (SVR)?
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Which hormone is primarily responsible for increasing heart rate during sympathetic nervous system activation?
Which hormone is primarily responsible for increasing heart rate during sympathetic nervous system activation?
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What is a common characteristic of hypovolemic shock?
What is a common characteristic of hypovolemic shock?
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Bradycardia is defined as a heart rate that is:
Bradycardia is defined as a heart rate that is:
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Which condition is associated with reduced ionic calcium levels in the body?
Which condition is associated with reduced ionic calcium levels in the body?
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What defines primary hypertension?
What defines primary hypertension?
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How does hyperkalemia affect heart function?
How does hyperkalemia affect heart function?
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What condition is characterized by inflammation of the pericardium?
What condition is characterized by inflammation of the pericardium?
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Which condition is described as a weakening of the arteries that can lead to bursting?
Which condition is described as a weakening of the arteries that can lead to bursting?
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What is the main role of the parasympathetic nervous system concerning heart rate?
What is the main role of the parasympathetic nervous system concerning heart rate?
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Study Notes
Cardiovascular System Lecture Notes
- Lecture topic: Cardiovascular System
- Instructor: Dr. P. Pugazhandi Bakthavatchalam, Assistant Professor of Anatomy and Physiology, AUACAS, AUA
Heart Physiology: Sequence of Excitation
- Starlings law of the heart: Defined
- Venous pressure and peripheral resistance: Described
- Blood pressure: Definition, components, determinants, effects, and management
Cardiac Output (CO) and Reserve
- CO: Amount of blood pumped by each ventricle in one minute
- CO = Heart rate (HR) x Stroke volume (SV)
- HR: Number of heartbeats per minute
- SV: Amount of blood pumped out by a ventricle with each beat
- Cardiac reserve: Difference between resting and maximal CO
Cardiac Output Example
- CO (ml/min) = 75 beats/min x 70 ml/beat = 5250 ml/min (5.25 L/min)
Regulation of Stroke Volume
- SV = End diastolic volume (EDV) - End systolic volume (ESV)
- EDV: Amount of blood collected in a ventricle during diastole
- ESV: Amount of blood remaining in a ventricle after contraction
Factors Affecting Stroke Volume
- Preload: Amount ventricles are stretched by contained blood
- Contractility: Cardiac cell contractile force due to factors other than EDV
- Afterload: Back pressure exerted by blood in the large arteries leaving the heart
Frank-Starling Law of the Heart
- Preload (stretch) is the critical factor controlling stroke volume
- Increased venous return (exercise/slow heartbeat) increases SV
- Blood loss/rapid heartbeat decreases SV
Preload and Afterload
- Diagrams showing preload and afterload on the heart
Extrinsic Factors Influencing Stroke Volume
- Contractility: Increased contractile strength, independent of stretch and EDV
- Increased contractility from: Increased sympathetic stimuli, Certain hormones, Ca2+ and some drugs
- Decreased contractility from: Acidosis, Increased extracellular potassium, Calcium channel blockers
Venous Pressure
- Average pressure within venous compartment of circulation
- Blood from systemic veins flows into the right atrium
- Central venous pressure: Pressure in the right atrium
- Jugular venous pulse (JVP): No valves between the right atrium and internal jugular vein, indicating right atrial pressure
- Increased JVP indicates hypertension, decreased heart sounds may indicate lower than normal pressure
Peripheral Resistance
- Systemic vascular resistance (SVR): Resistance in the circulatory system creating blood pressure and flow.
- Blood vessel constriction (vasoconstriction) increases SVR; vasodilation decreases SVR
- Pulmonary vascular resistance (PVR) refers to resistance within the pulmonary vasculature
Contractility and Norepinephrine
- Sympathetic stimulation releases norepinephrine to initiate a cyclic AMP second-messenger system, increasing contractility
Regulation of Heart Rate: Autonomic Nervous System
- Sympathetic nervous system (SNS): Activated by stress, anxiety, excitement, or exercise (fight or flight)
- Parasympathetic nervous system (PNS): Mediated by acetylcholine, opposing SNS (housekeeping)
- PNS slows heart rate and causes vagal tone
Extrinsic Innervation of the Heart
- Heart stimulated by sympathetic cardioacceleratory center
- Heart inhibited by parasympathetic cardioinhibitory center
Chemical Regulation of the Heart
- Hormones epinephrine and thyroxine increase heart rate
- Intra- and extracellular ion concentrations must be maintained
Homeostatic Imbalances
- Hypocalcemia: Reduced ionic calcium depresses the heart
- Hypercalcemia: Dramatically increases heart irritability, leading to spastic contractions
- Hypernatremia: Blocks heart contraction by inhibiting ionic calcium transport
- Hyperkalemia: Leads to heart block and cardiac arrest
- Tachycardia: Heart rate over 100 beats/min
- Bradycardia: Heart rate less than 60 beats/min
- Pericarditis: Inflammation of the pericardium, reducing cardiac output
- Circulatory Shock: Conditions where blood vessels are inadequately filled and blood cannot circulate normally
- Hypovolemic shock: Results from large-scale blood loss
- Vascular shock: Poor circulation from extreme vasodilation
- Cardiogenic shock: Heart cannot sustain adequate circulation
Alterations in Blood Pressure
- Hypotension: Low blood pressure (systolic pressure below 100 mm Hg)
- Transient elevations are normal (fever, exertion, upset)
- Chronic elevation causes heart failure, vascular disease, renal failure, stroke
- Orthostatic hypotension: Temporary low blood pressure and dizziness when rising.
- Chronic hypotension: Hint of poor nutrition and warning sign for Addison's disease
- Acute hypotension: Important sign of circulatory shock, a threat to patients needing intensive care
Hypertension
- Primary/essential hypertension: Risk factors include diet, obesity, age, race, heredity, stress, smoking
- Secondary hypertension: Due to identifiable disorders (excessive renin secretion, arteriosclerosis, endocrine disorders)
Aneurysm
- Weakening of arteries resulting in bursting.
- Due to hypertension or arteriosclerosis, mainly affecting cerebral arteries, aorta, and renal arteries.
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Description
Explore the fundamental concepts of the cardiovascular system, including heart physiology and the mechanics of cardiac output. This quiz covers essential topics such as Starling's law, stroke volume, and the regulation of blood pressure and cardiac reserve. Perfect for students studying anatomy and physiology.
