NUR1112 Heart Anatomy & Physiology

Heart Anatomy and Physiology

• The heart is a double pump that simultaneously supplies both the pulmonary and systemic circuits.
• The cardiac structure facilitates function, enabling one-way blood flow through the heart.

Cardiac Cycle

• The cardiac cycle is a series of continually repeated mechanical (muscle contraction) events.
• The cardiac cycle is essential for understanding the anatomy and physiology of the heart.

Anatomy of the Heart

• The heart is a cone-shaped, muscular organ that is approximately 12-14 cm long, 9 cm wide, and weighs 250-350 grams.
• The heart is located in the mediastinum, which is the cavity between the two pleural cavities, and rests on the superior surface of the diaphragm.
• The heart sits posterior to the sternum and anterior to the vertebral column.

Coverings of the Heart

• The heart has three layers of coverings: the epicardium (or visceral pericardium), the myocardium, and the endocardium.
• The epicardium is the outermost layer of epithelial tissue, the myocardium is the middle layer of cardiac muscle cells, and the endocardium is the inner layer of endothelial cells.

Components of the Heart Wall

• The heart wall consists of three components: the epicardium, the myocardium, and the endocardium.
• The epicardium is the outermost layer, the myocardium is the middle layer, and the endocardium is the inner layer.

External Anatomy - Anterior View

• The anterior view of the heart shows the ascending aorta, superior vena cava, auricle of the left atrium, and the right and left ventricles.

External Anatomy - Posterior View

• The posterior view of the heart shows the aortic arch, left pulmonary artery, left pulmonary veins, and the right and left ventricles.

Internal Anatomy

• The internal anatomy of the heart shows the right and left atria, the right and left ventricles, and the atrioventricular valves.

Heart Valves

• The heart valves are responsible for ensuring one-way blood flow through the heart.
• There are two types of heart valves: atrioventricular (AV) valves and semilunar (SL) valves.

Atrioventricular (AV) Valves

• The atrioventricular valves are located between the atria and ventricles and ensure that blood flows from the atria to the ventricles.
• The AV valves are closed when the atrial pressure is less than the ventricular pressure.

Semilunar (SL) Valves

• The semilunar valves are located between the ventricles and the pulmonary artery and aorta, and ensure that blood flows from the ventricles to the pulmonary artery and aorta.
• The SL valves are closed when the arterial pressure is greater than the ventricular pressure.

Coronary Circulation

• The coronary circulation is responsible for supplying oxygenated blood to the myocardium.
• The coronary arteries arise from the base of the aorta and encircle the heart in the coronary sulcus.
• The coronary veins drain deoxygenated blood from the myocardium and empty into the right atrium.

Coronary Artery Disease (CAD)

• Coronary artery disease occurs when the coronary arteries become narrowed and hardened, reducing blood flow to the myocardium.
• CAD is often caused by atherosclerosis, which is the buildup of fatty plaques in the arteries.

Unidirectional Pathway of Blood Flow

• The unidirectional pathway of blood flow through the heart is essential for understanding the anatomy and physiology of the heart.

• The pathway of blood flow through the heart is from the superior and inferior vena cavae to the right atrium, then to the tricuspid valve, then to the right ventricle, then to the pulmonary valve, then to the pulmonary artery, then to the lungs, then to the pulmonary veins, then to the left atrium, then to the mitral valve, then to the left ventricle, and finally to the aortic valve and the aorta.### Cardiac Cycle

• The cardiac cycle involves alternating periods of contraction and relaxation, producing pressure and blood volume changes in the heart chambers.

• Systole is the period of contraction, increasing pressure and forcing blood out of the chambers, while diastole is the period of relaxation, allowing chambers to refill.

Cardiac Cycle Events

• The cardiac cycle consists of one complete heartbeat, involving atrial diastole and systole, and ventricular diastole and systole.
• The sequence of events includes: relaxation, atrial contraction, ventricular contraction, and relaxation.

Phases of the Cardiac Cycle

• The cardiac cycle can be divided into three phases: ventricular filling, ventricular systole, and ventricular diastole.

Phase 1: Ventricular Filling

• All four chambers are relaxed, and the AV valves are open, allowing blood to flow directly into the ventricles.
• Blood fills the ventricles to 70-80% capacity through passive filling.
• Atrial systole occurs, filling the ventricles with blood, and the atrial systole ends, beginning atrial diastole.

Phase 2a: Ventricular Systole – Isovolumetric Contraction

• Ventricular systole begins, and the ventricles contract, increasing pressure and closing the AV valves.
• The ventricular pressure is not yet great enough to open the SL valves, resulting in isovolumetric contraction.

Phase 2b: Ventricular Systole – Ventricular Ejection

• Increasing ventricular contraction increases pressure, opening the SL valves, and blood is ejected into the aorta and pulmonary trunk.
• The volume ejected is the stroke volume (SV), and the volume remaining is the end-systolic volume (ESV).

Phase 3: Ventricular Diastole (Early) – Isovolumetric Relaxation

• Ventricular diastole begins, and the ventricles relax, decreasing pressure, and the SL valves close.
• Isovolumetric relaxation occurs, and the AV valves remain closed, preventing blood from flowing into the ventricles.
• The ventricular pressure drops below arterial pressure, and the SL valves close, producing the heart sound S2.### Ventricular Diastole
• During mid-late ventricular diastole, ventricles continue to relax, and pressure drops below atrial pressure, causing AV valves to open and allow blood to flow from atria to ventricles.
• This phase is known as passive ventricular filling (Phase 1).
• The cardiac cycle consists of four phases: atrial systole, ventricular systole, ventricular diastole, and atrial diastole.

Heart Sounds

• Heartbeat is characterized by the "lubb-dubb" sound, corresponding to S1 and S2 heart sounds, which occur when AV valves and SL valves close, respectively.
• There are four heart sounds (S1-S4), with S1 and S2 being the most prominent.
• Heart murmurs occur when blood backflows through an incompetent valve, producing a swishing sound.

Phases of the Cardiac Cycle

• Phase 1: Atrial and ventricular diastole, during which AV valves open, allowing blood to flow from atria to ventricles.
• Phase 2a: Ventricular systole, during which ventricles contract, pushing blood up and closing AV valves (heart sound S1).
• Phase 2b: Ventricular systole, during which SL valves open, and blood is ejected into the aorta and pulmonary trunk.
• Phase 3: Ventricular diastole, during which ventricular pressure drops, and SL valves close (heart sound S2).

Innervation of the Heart

• The heart has two electrical systems: intrinsic conduction system (myocardium) and extrinsic innervation (autonomic nervous system).
• Intrinsic conduction system:
  • Sinoatrial node (SA node) acts as the pacemaker, setting the heart rate.
  • Atrioventricular node (AV node) delays depolarization for 0.1 seconds.
  • Atrioventricular bundle (Bundle of His) connects atria and ventricles.
  • Bundle branches and Purkinje fibers conduct depolarization to ventricular myocardium.
• Extrinsic innervation:
  • Autonomic nervous system modifies myocardial activity.
  • Cardioacceleratory center increases heart rate and force of contraction.
  • Cardioinhibitory center decreases heart rate.

Cardiac Output

• Cardiac output (CO) is the volume of blood pumped by the left ventricle in one minute.
• CO = stroke volume (SV) x heart rate (HR)
• Factors that determine SV and thus CO:
  • Heart rate
  • Stroke volume (EDV - ESV)
  • End-diastolic volume (EDV) and end-systolic volume (ESV)
  • Venous return
  • Passive filling time
  • Contractility
  • Plasma electrolytes
  • Sympathetic nervous system

Heart Anatomy and Physiology

• The heart is a double pump that simultaneously supplies both the pulmonary and systemic circuits.
• The cardiac structure facilitates function, enabling one-way blood flow through the heart.

Cardiac Cycle

• The cardiac cycle is a series of continually repeated mechanical (muscle contraction) events.
• The cardiac cycle is essential for understanding the anatomy and physiology of the heart.

Anatomy of the Heart

• The heart is a cone-shaped, muscular organ that is approximately 12-14 cm long, 9 cm wide, and weighs 250-350 grams.
• The heart is located in the mediastinum, which is the cavity between the two pleural cavities, and rests on the superior surface of the diaphragm.
• The heart sits posterior to the sternum and anterior to the vertebral column.

Coverings of the Heart

• The heart has three layers of coverings: the epicardium (or visceral pericardium), the myocardium, and the endocardium.
• The epicardium is the outermost layer of epithelial tissue, the myocardium is the middle layer of cardiac muscle cells, and the endocardium is the inner layer of endothelial cells.

Components of the Heart Wall

• The heart wall consists of three components: the epicardium, the myocardium, and the endocardium.
• The epicardium is the outermost layer, the myocardium is the middle layer, and the endocardium is the inner layer.

External Anatomy - Anterior View

• The anterior view of the heart shows the ascending aorta, superior vena cava, auricle of the left atrium, and the right and left ventricles.

External Anatomy - Posterior View

• The posterior view of the heart shows the aortic arch, left pulmonary artery, left pulmonary veins, and the right and left ventricles.

Internal Anatomy

• The internal anatomy of the heart shows the right and left atria, the right and left ventricles, and the atrioventricular valves.

Heart Valves

• The heart valves are responsible for ensuring one-way blood flow through the heart.
• There are two types of heart valves: atrioventricular (AV) valves and semilunar (SL) valves.

Atrioventricular (AV) Valves

• The atrioventricular valves are located between the atria and ventricles and ensure that blood flows from the atria to the ventricles.
• The AV valves are closed when the atrial pressure is less than the ventricular pressure.

Semilunar (SL) Valves

• The semilunar valves are located between the ventricles and the pulmonary artery and aorta, and ensure that blood flows from the ventricles to the pulmonary artery and aorta.
• The SL valves are closed when the arterial pressure is greater than the ventricular pressure.

Coronary Circulation

• The coronary circulation is responsible for supplying oxygenated blood to the myocardium.
• The coronary arteries arise from the base of the aorta and encircle the heart in the coronary sulcus.
• The coronary veins drain deoxygenated blood from the myocardium and empty into the right atrium.

Coronary Artery Disease (CAD)

• Coronary artery disease occurs when the coronary arteries become narrowed and hardened, reducing blood flow to the myocardium.
• CAD is often caused by atherosclerosis, which is the buildup of fatty plaques in the arteries.

Unidirectional Pathway of Blood Flow

• The unidirectional pathway of blood flow through the heart is essential for understanding the anatomy and physiology of the heart.

• The pathway of blood flow through the heart is from the superior and inferior vena cavae to the right atrium, then to the tricuspid valve, then to the right ventricle, then to the pulmonary valve, then to the pulmonary artery, then to the lungs, then to the pulmonary veins, then to the left atrium, then to the mitral valve, then to the left ventricle, and finally to the aortic valve and the aorta.### Cardiac Cycle

• The cardiac cycle involves alternating periods of contraction and relaxation, producing pressure and blood volume changes in the heart chambers.

• Systole is the period of contraction, increasing pressure and forcing blood out of the chambers, while diastole is the period of relaxation, allowing chambers to refill.

Cardiac Cycle Events

• The cardiac cycle consists of one complete heartbeat, involving atrial diastole and systole, and ventricular diastole and systole.
• The sequence of events includes: relaxation, atrial contraction, ventricular contraction, and relaxation.

Phases of the Cardiac Cycle

• The cardiac cycle can be divided into three phases: ventricular filling, ventricular systole, and ventricular diastole.

Phase 1: Ventricular Filling

• All four chambers are relaxed, and the AV valves are open, allowing blood to flow directly into the ventricles.
• Blood fills the ventricles to 70-80% capacity through passive filling.
• Atrial systole occurs, filling the ventricles with blood, and the atrial systole ends, beginning atrial diastole.

Phase 2a: Ventricular Systole – Isovolumetric Contraction

• Ventricular systole begins, and the ventricles contract, increasing pressure and closing the AV valves.
• The ventricular pressure is not yet great enough to open the SL valves, resulting in isovolumetric contraction.

Phase 2b: Ventricular Systole – Ventricular Ejection

• Increasing ventricular contraction increases pressure, opening the SL valves, and blood is ejected into the aorta and pulmonary trunk.
• The volume ejected is the stroke volume (SV), and the volume remaining is the end-systolic volume (ESV).

Phase 3: Ventricular Diastole (Early) – Isovolumetric Relaxation

• Ventricular diastole begins, and the ventricles relax, decreasing pressure, and the SL valves close.
• Isovolumetric relaxation occurs, and the AV valves remain closed, preventing blood from flowing into the ventricles.
• The ventricular pressure drops below arterial pressure, and the SL valves close, producing the heart sound S2.### Ventricular Diastole
• During mid-late ventricular diastole, ventricles continue to relax, and pressure drops below atrial pressure, causing AV valves to open and allow blood to flow from atria to ventricles.
• This phase is known as passive ventricular filling (Phase 1).
• The cardiac cycle consists of four phases: atrial systole, ventricular systole, ventricular diastole, and atrial diastole.

Heart Sounds

• Heartbeat is characterized by the "lubb-dubb" sound, corresponding to S1 and S2 heart sounds, which occur when AV valves and SL valves close, respectively.
• There are four heart sounds (S1-S4), with S1 and S2 being the most prominent.
• Heart murmurs occur when blood backflows through an incompetent valve, producing a swishing sound.

Phases of the Cardiac Cycle

• Phase 1: Atrial and ventricular diastole, during which AV valves open, allowing blood to flow from atria to ventricles.
• Phase 2a: Ventricular systole, during which ventricles contract, pushing blood up and closing AV valves (heart sound S1).
• Phase 2b: Ventricular systole, during which SL valves open, and blood is ejected into the aorta and pulmonary trunk.
• Phase 3: Ventricular diastole, during which ventricular pressure drops, and SL valves close (heart sound S2).

Innervation of the Heart

• The heart has two electrical systems: intrinsic conduction system (myocardium) and extrinsic innervation (autonomic nervous system).
• Intrinsic conduction system:
  • Sinoatrial node (SA node) acts as the pacemaker, setting the heart rate.
  • Atrioventricular node (AV node) delays depolarization for 0.1 seconds.
  • Atrioventricular bundle (Bundle of His) connects atria and ventricles.
  • Bundle branches and Purkinje fibers conduct depolarization to ventricular myocardium.
• Extrinsic innervation:
  • Autonomic nervous system modifies myocardial activity.
  • Cardioacceleratory center increases heart rate and force of contraction.
  • Cardioinhibitory center decreases heart rate.

Cardiac Output

• Cardiac output (CO) is the volume of blood pumped by the left ventricle in one minute.
• CO = stroke volume (SV) x heart rate (HR)
• Factors that determine SV and thus CO:
  • Heart rate
  • Stroke volume (EDV - ESV)
  • End-diastolic volume (EDV) and end-systolic volume (ESV)
  • Venous return
  • Passive filling time
  • Contractility
  • Plasma electrolytes
  • Sympathetic nervous system

Heart Anatomy and Physiology

• The heart is a double pump that simultaneously supplies both the pulmonary and systemic circuits.
• The cardiac structure facilitates function, enabling one-way blood flow through the heart.

Cardiac Cycle

• The cardiac cycle is a series of continually repeated mechanical (muscle contraction) events.
• The cardiac cycle is essential for understanding the anatomy and physiology of the heart.

Anatomy of the Heart

• The heart is a cone-shaped, muscular organ that is approximately 12-14 cm long, 9 cm wide, and weighs 250-350 grams.
• The heart is located in the mediastinum, which is the cavity between the two pleural cavities, and rests on the superior surface of the diaphragm.
• The heart sits posterior to the sternum and anterior to the vertebral column.

Coverings of the Heart

• The heart has three layers of coverings: the epicardium (or visceral pericardium), the myocardium, and the endocardium.
• The epicardium is the outermost layer of epithelial tissue, the myocardium is the middle layer of cardiac muscle cells, and the endocardium is the inner layer of endothelial cells.

Components of the Heart Wall

• The heart wall consists of three components: the epicardium, the myocardium, and the endocardium.
• The epicardium is the outermost layer, the myocardium is the middle layer, and the endocardium is the inner layer.

External Anatomy - Anterior View

• The anterior view of the heart shows the ascending aorta, superior vena cava, auricle of the left atrium, and the right and left ventricles.

External Anatomy - Posterior View

• The posterior view of the heart shows the aortic arch, left pulmonary artery, left pulmonary veins, and the right and left ventricles.

Internal Anatomy

• The internal anatomy of the heart shows the right and left atria, the right and left ventricles, and the atrioventricular valves.

Heart Valves

• The heart valves are responsible for ensuring one-way blood flow through the heart.
• There are two types of heart valves: atrioventricular (AV) valves and semilunar (SL) valves.

Atrioventricular (AV) Valves

• The atrioventricular valves are located between the atria and ventricles and ensure that blood flows from the atria to the ventricles.
• The AV valves are closed when the atrial pressure is less than the ventricular pressure.

Semilunar (SL) Valves

• The semilunar valves are located between the ventricles and the pulmonary artery and aorta, and ensure that blood flows from the ventricles to the pulmonary artery and aorta.
• The SL valves are closed when the arterial pressure is greater than the ventricular pressure.

Coronary Circulation

• The coronary circulation is responsible for supplying oxygenated blood to the myocardium.
• The coronary arteries arise from the base of the aorta and encircle the heart in the coronary sulcus.
• The coronary veins drain deoxygenated blood from the myocardium and empty into the right atrium.

Coronary Artery Disease (CAD)

• Coronary artery disease occurs when the coronary arteries become narrowed and hardened, reducing blood flow to the myocardium.
• CAD is often caused by atherosclerosis, which is the buildup of fatty plaques in the arteries.

Unidirectional Pathway of Blood Flow

• The unidirectional pathway of blood flow through the heart is essential for understanding the anatomy and physiology of the heart.

• The pathway of blood flow through the heart is from the superior and inferior vena cavae to the right atrium, then to the tricuspid valve, then to the right ventricle, then to the pulmonary valve, then to the pulmonary artery, then to the lungs, then to the pulmonary veins, then to the left atrium, then to the mitral valve, then to the left ventricle, and finally to the aortic valve and the aorta.### Cardiac Cycle

• The cardiac cycle involves alternating periods of contraction and relaxation, producing pressure and blood volume changes in the heart chambers.

• Systole is the period of contraction, increasing pressure and forcing blood out of the chambers, while diastole is the period of relaxation, allowing chambers to refill.

Cardiac Cycle Events

• The cardiac cycle consists of one complete heartbeat, involving atrial diastole and systole, and ventricular diastole and systole.
• The sequence of events includes: relaxation, atrial contraction, ventricular contraction, and relaxation.

Phases of the Cardiac Cycle

• The cardiac cycle can be divided into three phases: ventricular filling, ventricular systole, and ventricular diastole.

Phase 1: Ventricular Filling

• All four chambers are relaxed, and the AV valves are open, allowing blood to flow directly into the ventricles.
• Blood fills the ventricles to 70-80% capacity through passive filling.
• Atrial systole occurs, filling the ventricles with blood, and the atrial systole ends, beginning atrial diastole.

Phase 2a: Ventricular Systole – Isovolumetric Contraction

• Ventricular systole begins, and the ventricles contract, increasing pressure and closing the AV valves.
• The ventricular pressure is not yet great enough to open the SL valves, resulting in isovolumetric contraction.

Phase 2b: Ventricular Systole – Ventricular Ejection

• Increasing ventricular contraction increases pressure, opening the SL valves, and blood is ejected into the aorta and pulmonary trunk.
• The volume ejected is the stroke volume (SV), and the volume remaining is the end-systolic volume (ESV).

Phase 3: Ventricular Diastole (Early) – Isovolumetric Relaxation

• Ventricular diastole begins, and the ventricles relax, decreasing pressure, and the SL valves close.
• Isovolumetric relaxation occurs, and the AV valves remain closed, preventing blood from flowing into the ventricles.
• The ventricular pressure drops below arterial pressure, and the SL valves close, producing the heart sound S2.### Ventricular Diastole
• During mid-late ventricular diastole, ventricles continue to relax, and pressure drops below atrial pressure, causing AV valves to open and allow blood to flow from atria to ventricles.
• This phase is known as passive ventricular filling (Phase 1).
• The cardiac cycle consists of four phases: atrial systole, ventricular systole, ventricular diastole, and atrial diastole.

Heart Sounds

• Heartbeat is characterized by the "lubb-dubb" sound, corresponding to S1 and S2 heart sounds, which occur when AV valves and SL valves close, respectively.
• There are four heart sounds (S1-S4), with S1 and S2 being the most prominent.
• Heart murmurs occur when blood backflows through an incompetent valve, producing a swishing sound.

Phases of the Cardiac Cycle

• Phase 1: Atrial and ventricular diastole, during which AV valves open, allowing blood to flow from atria to ventricles.
• Phase 2a: Ventricular systole, during which ventricles contract, pushing blood up and closing AV valves (heart sound S1).
• Phase 2b: Ventricular systole, during which SL valves open, and blood is ejected into the aorta and pulmonary trunk.
• Phase 3: Ventricular diastole, during which ventricular pressure drops, and SL valves close (heart sound S2).

Innervation of the Heart

• The heart has two electrical systems: intrinsic conduction system (myocardium) and extrinsic innervation (autonomic nervous system).
• Intrinsic conduction system:
  • Sinoatrial node (SA node) acts as the pacemaker, setting the heart rate.
  • Atrioventricular node (AV node) delays depolarization for 0.1 seconds.
  • Atrioventricular bundle (Bundle of His) connects atria and ventricles.
  • Bundle branches and Purkinje fibers conduct depolarization to ventricular myocardium.
• Extrinsic innervation:
  • Autonomic nervous system modifies myocardial activity.
  • Cardioacceleratory center increases heart rate and force of contraction.
  • Cardioinhibitory center decreases heart rate.

Cardiac Output

• Cardiac output (CO) is the volume of blood pumped by the left ventricle in one minute.
• CO = stroke volume (SV) x heart rate (HR)
• Factors that determine SV and thus CO:
  • Heart rate
  • Stroke volume (EDV - ESV)
  • End-diastolic volume (EDV) and end-systolic volume (ESV)
  • Venous return
  • Passive filling time
  • Contractility
  • Plasma electrolytes
  • Sympathetic nervous system

This quiz is based on the lecture notes of NUR1112, covering the fundamental skills and knowledge of heart anatomy and physiology for nursing and midwifery practice.