Podcast
Questions and Answers
What is the name of the structure that separates the right and left ventricles?
What is the name of the structure that separates the right and left ventricles?
What is the primary function of the left ventricle?
What is the primary function of the left ventricle?
What is the name of the valve that separates the right atrium and right ventricle?
What is the name of the valve that separates the right atrium and right ventricle?
Which of the following is NOT a characteristic of the left atrium?
Which of the following is NOT a characteristic of the left atrium?
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Which of the following statements is TRUE about the right ventricle?
Which of the following statements is TRUE about the right ventricle?
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What is the name of the valve that guards the opening between the left atrium and the left ventricle?
What is the name of the valve that guards the opening between the left atrium and the left ventricle?
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What is the normal filling pressure of the right atrium?
What is the normal filling pressure of the right atrium?
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Where is the mitral valve located in the heart?
Where is the mitral valve located in the heart?
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Which of the following is a potential complication of mitral valve insufficiency?
Which of the following is a potential complication of mitral valve insufficiency?
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The SA node is located in which chamber of the heart?
The SA node is located in which chamber of the heart?
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What is the function of the chordae tendineae?
What is the function of the chordae tendineae?
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The left ventricle is responsible for pumping blood into which vessel?
The left ventricle is responsible for pumping blood into which vessel?
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What is the difference between the mitral valve and the tricuspid valve?
What is the difference between the mitral valve and the tricuspid valve?
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What are the two portions of the left ventricle?
What are the two portions of the left ventricle?
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Which of the following structures is NOT part of the right ventricle?
Which of the following structures is NOT part of the right ventricle?
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Which of the following is a function of the ventricular septum?
Which of the following is a function of the ventricular septum?
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What is the name of the valve that guards the opening between the left ventricle and the aorta?
What is the name of the valve that guards the opening between the left ventricle and the aorta?
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Why is the pulmonary arterial pressure lower than the systemic pressure?
Why is the pulmonary arterial pressure lower than the systemic pressure?
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What is the name of the muscle bundles that compose the inner wall of the right atrium?
What is the name of the muscle bundles that compose the inner wall of the right atrium?
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Why is the left atrium wall slightly thicker than the right atrium wall?
Why is the left atrium wall slightly thicker than the right atrium wall?
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What is the patient's most likely underlying medical condition contributing to her irregular heart rate?
What is the patient's most likely underlying medical condition contributing to her irregular heart rate?
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What is the significance of the patient's history of smoking, even though she quit 20 years ago?
What is the significance of the patient's history of smoking, even though she quit 20 years ago?
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Based on the patient's vitals, what is the most concerning finding?
Based on the patient's vitals, what is the most concerning finding?
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What is the likely reason for the patient's poor endurance?
What is the likely reason for the patient's poor endurance?
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What is the purpose of the cardiac resynchronization defibrillator implanted in the patient?
What is the purpose of the cardiac resynchronization defibrillator implanted in the patient?
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What does the term 's/p' stand for in the patient's medical history?
What does the term 's/p' stand for in the patient's medical history?
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What is the primary concern regarding the patient's recent mechanical fall?
What is the primary concern regarding the patient's recent mechanical fall?
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What does the term 'RA' indicate in the context of the patient's oxygen saturation?
What does the term 'RA' indicate in the context of the patient's oxygen saturation?
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Which of the following is NOT a function of the cardiovascular system?
Which of the following is NOT a function of the cardiovascular system?
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Which of the following is NOT a type of artery?
Which of the following is NOT a type of artery?
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What type of vessel connects the arteriole to the venule?
What type of vessel connects the arteriole to the venule?
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Which of the following is a characteristic of veins?
Which of the following is a characteristic of veins?
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Which of the following structures is NOT located within the mediastinum?
Which of the following structures is NOT located within the mediastinum?
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Which of the following can cause volume changes in the mediastinum?
Which of the following can cause volume changes in the mediastinum?
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What is the name of the largest artery in the body?
What is the name of the largest artery in the body?
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What is the name given to the anatomical dilation of the ascending aorta?
What is the name given to the anatomical dilation of the ascending aorta?
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What is the function of the serous fluid found in the pericardial cavity?
What is the function of the serous fluid found in the pericardial cavity?
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Which layer of the heart is responsible for its pumping action?
Which layer of the heart is responsible for its pumping action?
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Which of the following is NOT a branch of the aortic arch?
Which of the following is NOT a branch of the aortic arch?
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What are the two main categories of myocardial cells?
What are the two main categories of myocardial cells?
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What is the name of the valve that separates the right atrium from the right ventricle?
What is the name of the valve that separates the right atrium from the right ventricle?
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Which heart chamber receives deoxygenated blood from the systemic circulation?
Which heart chamber receives deoxygenated blood from the systemic circulation?
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What is the function of intercalated disks in myocytes?
What is the function of intercalated disks in myocytes?
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Which of the following properties is NOT characteristic of myocardial cells?
Which of the following properties is NOT characteristic of myocardial cells?
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Which of the following correctly describes the flow of blood through the heart?
Which of the following correctly describes the flow of blood through the heart?
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What is the name of the main vein that drains the deoxygenated blood from the myocardium ?
What is the name of the main vein that drains the deoxygenated blood from the myocardium ?
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What is the significance of the coronary sinus?
What is the significance of the coronary sinus?
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Which of the following structures is NOT a part of the cardiac skeleton?
Which of the following structures is NOT a part of the cardiac skeleton?
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Which of the following is NOT a property of myocardial cells?
Which of the following is NOT a property of myocardial cells?
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The sympathetic nervous system ______ heart activity, while the parasympathetic nervous system ______ heart activity.
The sympathetic nervous system ______ heart activity, while the parasympathetic nervous system ______ heart activity.
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What is the primary function of platelets in the blood?
What is the primary function of platelets in the blood?
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Where is the apex of the heart located?
Where is the apex of the heart located?
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What is the name of the nerve tissue located anterior to the tracheal bifurcation that contains both sympathetic and parasympathetic nerves?
What is the name of the nerve tissue located anterior to the tracheal bifurcation that contains both sympathetic and parasympathetic nerves?
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Which of the following is a characteristic of a "vaso-vagal event"?
Which of the following is a characteristic of a "vaso-vagal event"?
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What is the function of the anulus fibrosus?
What is the function of the anulus fibrosus?
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Which of the following correctly describes the location of the heart?
Which of the following correctly describes the location of the heart?
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What are the two main branches of the Left coronary artery?
What are the two main branches of the Left coronary artery?
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The visceral pericardium is also known as:
The visceral pericardium is also known as:
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Which of the following statements is true regarding the SA node?
Which of the following statements is true regarding the SA node?
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What type of tissue makes up the anulus fibrosus?
What type of tissue makes up the anulus fibrosus?
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What is the name of the structure that transmits electrical impulses from the AV node to the ventricles?
What is the name of the structure that transmits electrical impulses from the AV node to the ventricles?
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The heart is situated obliquely in what anatomical space?
The heart is situated obliquely in what anatomical space?
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What is the patient's primary limitation in ambulation?
What is the patient's primary limitation in ambulation?
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What is the patient's highest recorded heart rate during the assessment?
What is the patient's highest recorded heart rate during the assessment?
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What level of assistance is the patient requiring for scooting to the edge of the bed?
What level of assistance is the patient requiring for scooting to the edge of the bed?
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What is the patient's oxygen saturation level at the end of the assessment?
What is the patient's oxygen saturation level at the end of the assessment?
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What is the patient's range of motion in the right shoulder?
What is the patient's range of motion in the right shoulder?
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What manual muscle test score is the patient achieving in most of their extremities?
What manual muscle test score is the patient achieving in most of their extremities?
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What is the patient's primary method of ambulation?
What is the patient's primary method of ambulation?
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Which of these options is a contributing factor to the patient's flexed posture while ambulating?
Which of these options is a contributing factor to the patient's flexed posture while ambulating?
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Flashcards
Mediastinum
Mediastinum
The central compartment in the thoracic cavity containing the heart, vessels, and more.
Cardiac Cycle
Cardiac Cycle
The sequence of events in one heartbeat: diastole and systole phases.
Blood Flow Pathway
Blood Flow Pathway
The route blood takes through the heart, lungs, and body.
Coronary Arteries
Coronary Arteries
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Conduction System of the Heart
Conduction System of the Heart
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Heart Rate (HR)
Heart Rate (HR)
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Systolic and Diastolic Blood Pressure
Systolic and Diastolic Blood Pressure
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Oxygen Saturation (O2Sat)
Oxygen Saturation (O2Sat)
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Standing Balance
Standing Balance
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Range of Motion (ROM)
Range of Motion (ROM)
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Manual Muscle Testing
Manual Muscle Testing
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Bed Mobility
Bed Mobility
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Transfers
Transfers
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Ambulation
Ambulation
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Posture
Posture
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Vital Signs
Vital Signs
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Heart Chambers
Heart Chambers
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Right Atrium
Right Atrium
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SA Node
SA Node
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Atrioventricular (AV) Valves
Atrioventricular (AV) Valves
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Tricuspid Valve
Tricuspid Valve
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Right Ventricle
Right Ventricle
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Pulmonary Valve
Pulmonary Valve
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Semilunar Valves
Semilunar Valves
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Left Atrium
Left Atrium
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Pulmonary Circulation
Pulmonary Circulation
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Artery
Artery
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Anastomoses
Anastomoses
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Capillary Beds
Capillary Beds
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Veins
Veins
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Left Coronary Artery (LCA)
Left Coronary Artery (LCA)
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Right Coronary Artery (RCA)
Right Coronary Artery (RCA)
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Sinoatrial (SA) Node
Sinoatrial (SA) Node
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Atrioventricular (AV) Node
Atrioventricular (AV) Node
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Bundle of His
Bundle of His
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Electrocardiogram (EKG)
Electrocardiogram (EKG)
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Coronary Sinus
Coronary Sinus
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Pacemaker
Pacemaker
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Electrical System of the Heart
Electrical System of the Heart
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Impairments
Impairments
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Tachycardia
Tachycardia
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Pericardium
Pericardium
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Pericardial Cavity
Pericardial Cavity
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Heart Layers
Heart Layers
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Myocardium
Myocardium
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Myocytes
Myocytes
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Automaticity
Automaticity
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Coronary Sulcus
Coronary Sulcus
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Blood Components
Blood Components
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Heart Apex
Heart Apex
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Cardiac Skeleton
Cardiac Skeleton
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Pericarditis
Pericarditis
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Mitral Valve
Mitral Valve
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Mitral Valve Prolapse
Mitral Valve Prolapse
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Left Ventricle
Left Ventricle
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Normal Systolic Blood Pressure
Normal Systolic Blood Pressure
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Interventricular Septum
Interventricular Septum
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Aortic Valve
Aortic Valve
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Pulmonary Veins
Pulmonary Veins
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Tunica Media
Tunica Media
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Mitral Valve Insufficiency
Mitral Valve Insufficiency
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Study Notes
Cardiac Anatomy and Physiology
- Presented by Golda Widawski, PT, DPT on January 27, 2025
- Objectives for the presentation included accurate identification of anatomy involved in circulation (mediastinum, heart, blood vessels), describing the path of blood flow, and identifying the blood supply to the heart.
- Objectives also include understanding the functions of the cardiovascular system, heart's electrical and mechanical systems and their related conduction system, inherent heart rates, the basic nerve supply to the heart, and the cardiac cycle.
Objectives
- Accurately identify anatomy involved in circulation: mediastinum, heart, blood vessels
- Accurately describe the path of blood flow
- Accurately identify blood supply to the heart
- Identify the functions of the cardiovascular system
- Explain clearly the parts of heart's electrical and mechanical systems and how they work
- Identify inherent heart rates of parts of the conduction system of the heart
- Identify the basic nerve supply to the heart
- Accurately describe the cardiac cycle and what occurs at each phase
Case Study
- Patient (Mrs. W): One week post-left lung upper lobe (UL) resection for lung cancer.
- Past medical history (PMH): Ovarian cancer (20 years prior), smoking history (quit 20 years prior), osteoarthritis.
- Initial evaluation vitals: Heart rate: 140 bpm (irregular), Blood pressure: 128/70 mm Hg, Respiratory rate: 12 breaths/min, Oxygen Saturation: 97% (room air).
- Course of action needed: Treatment or Not To Treat.
Mediastinum
- Space in the thorax between the right and left pleura
- Contains all structures in the thorax
- Surrounded by loose connective tissue, nerves, blood, and lymph vessels, lymph nodes and fat.
- Can accommodate changes in volume and movement due to the elasticity of the lungs and pleura
Pericardium
- Double-walled fibrous sac enclosing the heart and roots of great vessels
- Outer fibrous layer (fibrous pericardium): tough, thick, and attached to the outer layer of the great vessels and the central tendon of the diaphragm
- Inner double-layered sac (serous pericardium): parietal pericardium (outer layer) and visceral pericardium (aka epicardium-inner layer)
- Pericardial cavity: potential space between parietal and visceral layers, contains a thin layer of serous fluid, allowing frictionless heart movement.
- Phrenic nerve innervates parietal pericardium
- Visceral pericardium is insensitive to pain
Pericardial clinical notes
- Pericarditis: inflammation of the pericardium, presents as substernal pain, and can result in pericardial effusion.
- Pericardial rub: a sound heard during cardiac auscultation
Heart
- Muscular pump propelling blood via blood vessels to the body
- Pyramidal/cone-shaped
- Located obliquely in the thorax, with 2/3 to the left of the median plane, and contained within the pericardial sac
- Apex located at the 5th intercostal space, midclavicular line
- Base formed by the two atria
Layers of the Heart
- Epicardium (outermost): aka visceral pericardium
- Myocardium (middle): cardiac muscle
- Endocardium (innermost): innermost layer
Myocardium
- Consists of both mechanical cells (myocytes) and conductive cells for:
- Contraction of the heart, similar to skeletal muscle with actin/myosin
- Conduction system (SA & AV nodes, AV bundle, Purkinje fibers)
- Metabolic processes are almost exclusively aerobic.
Myocytes
- Tracts of striated muscle fibers
- Greater capacity for mechanical shortening
- Actin/myosin pattern similar to skeletal muscle
- Intercalated disks: join myocytes to create syncytium (atrial and ventricular) that support synchronized contraction
Myocardium (additional information)
- Cells have automaticity (intrinsic ability to contract without stimuli)
- Rhythmicity (intrinsic ability to contract in a rhythmic manner)
- Conductivity (intrinsic ability to transmit nerve impulses)
- Excitability (Ability to respond to electrical stimuli)
- Contractility (Ability to stretch as a single unit, then recoil actively)
- Myocardial cells cannot replace injured cells
Additional Anatomic Features of the Heart
- Coronary sulcus/groove (aka atrioventricular sulcus/groove): located where coronary sinus receives blood from heart veins to deliver to right atrium.
- Anterior interventricular sulcus
Cardiac Skeleton
- Made up of anulus fibrosus (fibrocartilaginous tissue)
- Separates atria from ventricles
- Insulates electrical impulses between atria and ventricles to only move through the AV node
- Supports valves
Blood (review)
- Composed of red blood cells (RBC = erythrocytes), white blood cells (WBC = leukocytes with 5 types: neutrophils, eosinophils, basophils, monocytes, lymphocytes), and platelets (aid in blood clotting)
- Plasma: liquid component of blood suspending RBCs, WBCs, and platelets. Made up of gases, salts, carbohydrates, proteins, and lipids.
Heart Anatomy
- Two sides divided into four chambers (two upper- receiving areas, two lower discharging chambers)
- Amount of blood in pulmonary circulation equals that in systemic circulation
- Pulmonary arterial pressure is 1/6th of systemic pressures
Right Atrium
- Thin muscular wall
- Receives venous blood from the superior and inferior vena cava and coronary sinus during diastole
- Contains the SA node
- Interatrial septum is the posteromedial wall
- Contains the fossa ovale
- Atrial septal defect (ASD).
Right Atrium (additional information)
- Normal filling pressure of RA = 0–8 mmHg
- Referred to as central venous pressure (CVP)
- Pectinate muscles: parallel muscle bundles, "comb like"
- Orthotopic heart transplant: the right atrium is excised and then the donor's heart is attached.
Atrioventricular (AV) Valves
- Separate atria and ventricles for one-way blood flow.
- Complex system of structures: valvular orifice surrounded by annulus, leaflets/cusps, chordae tendineae, papillary muscles, and trabeculae carneae (Rathke's bundles).
- AV Valves: Right = Tricuspid, Left = Mitral
Tricuspid Valve (Right AV Valve)
- Located between the right atrium and right ventricle (4th/5th intercostal space).
- Guards the right AV orifice.
- Composed of three cusps (anterior, posterior, septal).
- Thinner than the mitral valve cusps.
Right Ventricle
- Receives blood from the right atrium via tricuspid valve, pumps blood into pulmonary artery via the pulmonary valve.
- Most anterior part of the heart under the sternum
- Crescent-shaped with a thin myocardial wall
- Two portions: body of the right ventricle and infundibulum (conus arteriosus)
- Septo-marginal trabecula
Right Ventricle (additional information)
- Resistance of pulmonary circulation is about 1/10th that of systemic circulation
- Normal systolic pressure in the right ventricle = 15–30 mmHg.
- End diastolic pressure = 0–8 mmHg.
- Generates less than ¼ the stroke work of the left ventricle
Semilunar Valves
- Have three leaflets/cusps (anterior, right, left)
- Prevent backflow from the pulmonary artery and aorta during diastole
- Open and close due to pressure gradient changes in the cardiac cycle
- Pulmonary valve
- Aortic valve
Pulmonary (Pulmonic) Valve
- Located at the 2nd intercostal space to the left of the sternum
- Contraction of the right ventricle pushes blood through the pulmonary valve into the pulmonary trunk.
Left Atrium
- Slightly thicker walls than right atrium
- Collects oxygenated blood from the lungs via the four pulmonary veins
- Forms most of the posterior heart surface
- Auricular appendage ("dog ear"): represents original heart tube
- Blood flows via the left AV orifice (mitral valve) into the left ventricle
- Normal filling pressure = 4–12 mmHg
Left Atrium (Clinical Note)
- In certain cardiac conditions (such as atrial fibrillation), a thrombus can form on the left atrium. If it breaks off, it can travel and occlude peripheral arteries (brain) resulting in a stroke.
Mitral Valve (Left AV Valve)
- Guards the opening between the left atrium and left ventricle.
- Located between the left atrium and left ventricle, situated at the level of the 5th intercostal space (midclavicular line).
- Composed of two cusps (anterior, posterior)
- Also known as bicuspid valve
- Projects into the left ventricle.
Mitral Valve Insufficiency/Problems
- Can cause increased regurgitation of blood flow from the left ventricle through the leaky mitral valve into the left atrium.
- Mitral valve is frequently diseased—mitral valve prolapse, insufficiency or regurgitation, mitral stenosis
Left Ventricle
- Conical cavity forming the apex of the heart
- Receives blood from the left atrium via mitral valve.
- Pumps blood into the aorta via the aortic valve (systemic circulation).
- Makes up nearly the entire left border and inferior wall of the heart.
- Thick muscular wall, 2-3 times thicker than the right ventricular wall.
Left Ventricle (additional details)
- Two portions: inflow tract (funnel-shaped, directs blood toward the apex), outflow tract (sends blood from the apex superiorly and right toward the aortic valve).
- Superior and anterior portion forms the aortic vestibule
- Two large papillary muscles give rise to chordae tendinae, which attach to the cusps of the mitral valve.
- Normal systolic pressure: 80–120 mmHg
- Normal end-diastolic pressure: 4–12 mmHg
Ventricular Septum
- AKA: Interventricular septum
- Wall partitioning right and left ventricles (muscular and membranous portions)
- Contains electrical conduction tissue
- Provides stability during contraction.
- Margins correspond with anterior and posterior interventricular grooves.
Aortic Valve
- Guards the aortic orifice
- Contraction of the left ventricle pushes blood through the aortic valve into the aorta.
- Composed of three thick semilunar cusps attached to a fibrous ring.
- Located, roughly, at the 2nd intercostal space at the right sternal border.
General Anatomic Location of the Valves
- Shows the locations of the different heart valves on the anterior chest.
The Great Vessels
- Primary blood vessels
- Vena Cava: Superior and Inferior
- Pulmonary Veins: 4 veins (2 from the right and 2 from the left lung)
- Pulmonary Arteries: 2 (one to each lung)
- Aorta
Basic Design of Blood Vessels
- Three tunics: Tunica Intima (innermost layer), Tunica Media (mainly smooth muscle—bulk of arterial wall), and Tunica Externa/Adventitia (contains elastic and collagenous fibers).
- Thickest layer in Veins
Arteries
- Deliver oxygenated blood
- Arteries → arterioles → capillary beds
- More developed media than veins
- Anastomoses: connections between arterial branches to provide circulation to capillaries.
- Types: elastic, muscular, arteriole
Veins
- Return deoxygenated blood to the heart
- Lower pressure system relying on valves and muscle contraction
- Create anastamoses more easily than arteries
- Development of complete loops of blood from tissue
- Types: venule (small), medium-sized, larger
Capillaries
- Smallest blood vessels connecting arterioles to venules
- Thin walls of endothelium
- Exchange of oxygen, CO2, nutrients, and wastes through these walls
Lymphatics
- Similar to capillaries but begin blindly
- Lymph vessels' number varies regionally
- Form plexuses (small lymph vessels join to form larger vessels)
- Contain valves for one-way flow to the heart
- Pass through lymph nodes.
Aorta
- Largest artery in the body
- Coronary arteries arise from its root
- 3 branches: Brachiocephalic, left common carotid, left subclavian
- Made up of ascending, aortic arch, and descending aorta, which divides into thoracic and abdominal aorta.
Aortic Sinuses
- An anatomic dilation of the ascending aorta
- Typically with three aortic sinuses
- Right and left sinus areas give rise to the right and left coronary arteries.
- Prevents aortic valve cusps from sticking.
Route of Blood
- Diagram showing the flow of blood through the systemic and pulmonary circulation.
Circulation – Right Side of Heart
- Right atrium receives systemic blood.
- Right atrium contracts and pushes blood through tricuspid valve into the right ventricle.
- Right ventricle contracts and the tricuspid valve closes to prevent backflow into the right atrium.
- Blood is forced through the pulmonary valve into the pulmonary circulation.
Circulation – Left Side of the Heart
- Left atrium receives blood from lungs via the 4 pulmonary veins.
- Left atrium contracts and blood flows through the mitral valve into the left ventricle.
- Left ventricle contracts and mitral valve closes to prevent backflow into the left atrium.
- Blood is pumped through the aortic valve into the aorta for systemic circulation
Circulation to the Heart - Arterial Supply
- Coronary arteries arise from the aorta.
- Blood is supplied to the heart muscle via the right coronary artery (RCA) and the left coronary artery (LCA)
- Travel around the heart via two grooves (atrioventricular and interventricular grooves), which meet at the posterior heart aspect (crux).
- Right or left coronary dominance determined by which artery crosses the crux to supply the AV node.
Coronary Arteries
- Coronary arteries give rise to perforating arteries that travel deep into the myocardium
- Capillary network: about one capillary for each cardiac muscle cell.
Left Coronary Artery (LCA)
- Supplies blood to the left atria, most of the left ventricle, parts of the right ventricle, and the interventricular septum
- LCA divides into 2 main branches: Left anterior descending (LAD) and Left circumflex (LCX)
Left Anterior Descending (LAD)
- Runs in the anterior interventricular groove.
- Anastomoses with posterior branches of the RCA
- Supplies blood to the anterior two-thirds of the interventricular septum, the anterior, lateral, and apical wall of the left ventricle, and most of the bundle branches.
- Collateral circulation to the anterior right ventricle and posterior portion of the interventricular septum.
- Often occluded coronary artery ("widow maker").
Left Circumflex (LCX)
- Follows coronary groove around left border of the heart and ends in the posterior interventricular groove.
- Commonly anastomoses with the distal RCA
- Gives off marginal branches, with the terminal branch usually the largest.
- Supplies blood to the posterior and lateral walls of the left ventricle and most of the left atrium.
Right Coronary Artery (RCA)
- Travels from the aorta into the AV groove, curvng around to posterior surface of the heart that makes a bend at the crux.
- Then continues downward in the posterior interventricular sulcus (posterior coronary groove) to give off the posterior interventricular branch and terminal portion of the RCA descends towards the apex of the heart.
- Gives off variable branches to the right atrium and right ventricle.
- Right marginal branch: runs down the right margin of the heart and supplies the right ventricle
- Posterior descending artery (PDA): supplies the infererior wall of the left ventricle and the inferior portion of the interventricular septum
Right Coronary Artery (additional details)
- Supplies blood to the right atrium, right ventricle, interventricular septum, and inferior wall of the left ventricle
- Supplies the SA node and AV nodes
- SA Nodal Artery: branches off the RCA and goes across the crux of the heart. Occurs in ~55% of hearts, elsewhere it is a branch of the LCX.
- AV Nodal Artery: usually branches off the distal RCA; occurs in ~85-90% of hearts. The remaining 10–15% comes from the LCX.
Venous Drainage of the Heart
- Coronary veins follow coronary arteries.
- Collect deoxygenated blood from the myocardium, emptying into the right atrium through coronary sinus, located on posterior heart surface.
- Receipts drainage from great cardiac veins, middle cardiac vein, small cardiac veins, and smallest veins (Thebesian veins).
Function of the Heart and Cardiovascular System
- Deliver oxygen and nutrients to all tissues, removing CO2 and waste products via blood
- Transport heat and temperature to maintain body temp
- Transport white blood cells to fight infections
- Transport hormones
The Heart as a Pump
- Two systems: electrical and mechanical
- Electrical: impulses that trigger heart muscle
- Mechanical: cardiac muscle, chambers, and valves that contract to pump blood to lungs and body
- Conduction video: http://www.youtube.com/watch?v=fZT9vlbL2uA
Electrical System
- Resting myocardial cells are polarized (negatively charged)
- Depolarization: When myocytes become positive, leading to contraction and wave-like movements through the myocardium.
- Repolarization: Recovery phase after depolarization, myocardial cells return to resting negative charge; muscle relaxes
Electrocardiogram (EKG)
- Records the electrical activity of the heart.
- Provides information about heart function and structure, but does not measure heart function, recordings include P-wave, QRS complex, T-wave.
Conduction System of the Heart
- Sinoatrial (SA) Node
- Internodal Pathways
- Atrioventricular (AV) Node
- Bundle of His
- Bundle Branches
- Purkinje Fibers
Sinoatrial (SA) Node
- “Pacemaker” of the heart (normal 60–100 bpm, sinus rhythm)
- Located at the junction of superior vena cava and the right atrium.
- Initiate cardiac cycle when action potentials cause a wave of depolarization that spreads through the atria.
- Travels to AV node via internodal tracts.
Atrioventricular (AV) Node
- Located in the right atrial septal wall near the tricuspid valve.
- Receives impulses from SA node and conducts them to the Bundle of His.
- In a normal heart, the only way for impulses to spread from atria to ventricles is via the AV node.
- Two functions: slows depolarization allowing ventricles to fill from atria ("atrial kick") and controls the number of impulses going to ventricles
- Inherent rate of 40-60 bpm.
Bundle of His
- Cardiac impulse travels from AV node to Bundle of His
- Divides into right and left bundle branches.
- Inherent firing rate of 20-40 bpm.
- Terminates in Purkinje fibers, which are continuous with cardiac muscle to stimulate ventricular contractions.
Heart Rate (Pacemaker)
- SA Node: 60-100 bpm
- AV Node: 40-60 bpm
- Bundle of His/Purkinje Fibers = 20-40 bpm
- Clinical notes: abnormalities in conduction system show up as abnormal rate and/or ECG abnormalities, myocardial infarction in the interventricular septum.
Conduction System of the Heart (additional details)
- Chambers are electrically and physically isolated.
- Four properties of myocardial cells: automaticity (initiate own depolarization), rhythmicity (contract in a regular manner), conductivity (spread impulses quickly), and excitability (cells transmit nerve impulses).
Innervation of the Cardiovascular System
- Controlled by two opposing divisions of the autonomic nervous system (ANS).
- Usually balanced to create a steady state.
- Sympathetic Nervous System: dominant during stressful situations, leading to tachycardia, increased cardiac output (CO), and increased oxygen demand, and uses norepinephrine as a neurotransmitter, "adrenergic"
- Parasympathetic Nervous System: dominant during relaxed state, leading to resting HR, baseline CO, and decreased O2 demand; controls heart via vagus nerve (CN X) and releases acetylcholine, "cholinergic."
The Cardiac Plexus
- Nerve tissue of the heart located anterior to the tracheal bifurcation
- Consists of both sympathetic and parasympathetic nerves.
- Serves as conduit for neurotransmitters (norepinephrine and acetylcholine).
Nerve Supply (summary)
- Sympathetic (adrenergic): monitors SA and AV nodes, accelerates cardiac activity, increases HR, speed of contraction, and force of contraction ("fight or flight").
- Parasympathetic (cholinergic): monitors SA node, slows cardiac activity, increases vagal tone, slows HR during sleep, decreases vagal tone increases HR for walking, "vasovagal event" (fainting due to increased vagal tone)
Cardiac Reflexes
- Neural mechanisms that automatically increase/decrease heart rate.
- Stimulation of right heart stretch receptors: increased venous return increases heart rate ("Bainbridge reflex")
- Increased arterial pressure stimulates receptors, reducing heart rate.
- Baroreceptors sense changes in BP and “report” abnormal BP to CNS
- High BP: respond to high BP; quickly decrease rate and vessel resistance
- Low BP: regulate blood volume in the body
- Chemoreceptors sense chemical characteristics to help regulate function; ventilatory and cardiac responses; detect oxygen, pH, CO2 to determine someone needs to increase HR/RR
Mechanical System of the Heart
- Cardiac cycle: period from one heartbeat to the next, two phases: diastole (ventricular relaxation) and systole (ventricular contraction).
- Video: http://www.youtube.com/watch?v=jLTdgrhpDCg
Cardiac Cycle—5 Phases
- Mid Diastole: Ventricles receive blood from atria, AV valves open, semilunars are closed, pressure in atria > ventricles, 80% of blood to ventricles.
- Late Diastole: Remaining 20% of volume comes into ventricles, atrial contraction ("atrial kick"), SA node has fired.
- Early Systole: Impulse through AV node, ventricles contract, AV valves close, isovolumetric contraction, S1 = LUB.
- Late Systole: Aortic and Pulmonic valves are open, ventricular ejection, blood flows, only part is ejected = ejection fraction, end systolic volume = blood remaining after ejection
Cardiac Cycle Continued
- Early Diastole: S2 = DUB; pulmonic and aortic valves shut, AV valves open, repolarization occurs, isovolumetric relaxation.
- Timing of the cardiac cycle: each cycle lasts ~0.8 sec; atrial systole = ~0.1 sec, atrial diastole = ~0.7 sec, ventricle systole = ~0.3 sec, ventricle diastole = ~0.5 sec.
Blood Flow (Q)
- Q = CO = HR x SV
- Cardiac output (CO): Amount of blood ejected by left ventricle into the aorta/min
- Venous return: Amount of blood returned to the right atria/min
- Heart rate (HR) = beats/minute
- Stroke volume (SV) = amount of blood ejected / systolic period/minute
- Affected by three things: preload, contractility, afterload
Preload
- LVEDP (LV End Diastolic Pressure) and EDV (End Diastolic Volume)
- Pressure in LV before contraction
- Amount of muscle fiber stretch at the end of diastole
- Volume in ventricle at this phase
- Compliance: High volume creates a small change in pressure—normal
- Noncompliance: Small volume change creates a high change in pressure—diseased
Contractility
- Integrity of muscle fibers and effectiveness of force and rate of contraction.
- If muscle becomes hypertrophied or rate >120 bpm, heart effectiveness decreases (decreased ventricular filling times, less volume per beat, less efficient)
Afterload
- Resistance, impedance, pressure that the ventricle works against to eject blood (total peripheral resistance (TPR)).
- Dependent on: volume and mass of blood ejected, size and wall thickness of ventricle, and impedance of vasculature
- Inverse relationship to stroke volume— Resistance increases → SV decreases
Frank-Starling Mechanism
- Examines the relationship between ventricular filling pressure (EDV) and ventricular mechanical activity (stroke volume (SV) = CO/HR).
- SV is dependent on diastolic muscle fiber length and contractility.
- Found an optimal range of LV filling pressures, increasing pressure → increases stretch of muscle fibers; can decrease performance if too high or low.
- Frank-Starling Graph (Fig. 2): shows max activity relationship with diastolic volume.
Heart Cycle Summary Videos
- Links to videos summarizing the heart cycle, but the videos are not included.
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Test your knowledge on the structure and function of the human heart with this comprehensive quiz. Covering topics such as the ventricles, valves, and chambers, this quiz will challenge your understanding of cardiovascular anatomy. Perfect for students of anatomy or those interested in human biology!