[2] Cardiovascular System: Heart

Vocabulary practice flashcards for Pharm 121 covering cardiovascular system anatomy, layers, conduction system, ECG waveforms, cardiac cycle metrics, and heart failure pathophysiology.

Mediastinum

The anatomical space within the thoracic cavity between the sternum and vertebral column, extending from the first rib to the diaphragm and between the lungs, which houses the heart.

Apex of the Heart

The inferior, pointed tip of the left ventricle that rests on the diaphragm and is directed anteriorly, inferiorly, and to the left.

Base of the Heart

The posterior aspect of the heart opposite the apex, formed mainly by the atria (predominantly the left atrium).

Fibrous Pericardium

The superficial layer of the pericardium composed of dense, irregular connective tissue that anchors the heart in the mediastinum and prevents overstretching.

Serous Pericardium

The deeper, double-layered membrane surrounding the heart composed of mesothelium overlying fibroelastic tissue and adipose, divided into parietal and visceral layers.

Pericardial Cavity

The fluid-filled space between the parietal and visceral layers of the serous pericardium containing pericardial fluid to reduce friction during heart contractions.

What is Epicardium?

It is the outermost layer of the heart wall, also known as the visceral layer of serous pericardium, composed of mesothelium and connective tissue containing blood vessels, lymphatics, and nerves.

How many tissue layers make up the epicardium?

2 tissue

What are the 2 tissue layers of the epicardium?

1. Mesothelium (outermost)
2. Fibroelastic and adipose tissue (underneath)

What is the mesothelium of the epicardium part of?

The visceral serous pericardium

What is Myocardium?

It is comprises approximately $95\%$ of the heart wall mass

Cardiac muscle tissue

What is Endocardium?

It is the innermost layer of the heart.

What type of tissue lines the endocardium?

Endothelium

What lies beneath the endothelium?

Connective tissue

Is the endocardium vascular or avascular?

avascular

What is the function of Endocardium?

It lines chambers, covers valves, reduces friction from blood flow

What is Carditis?

The general medical term for inflammation of the heart tissue.

What is Myocarditis?

Inflammation of the myocardium that reduces pumping efficiency and can trigger dysrhythmias (fast or abnormal heart rhythms), caused by infections or drug hypersensitivity.

What is Infective Endocarditis?

A serious infection involving the endocardium and heart valves, most commonly caused by staphylococci or streptococci.

What are the risk factors of Infective Endocarditis?

• Presence of a prosthetic valve

• Previous endocarditis

• Congenital heart disease

• Mitral valve prolapse with regurgitation

Why does the bacteria adhere specifically to the endocardium?

Endocardium is avascular, allowing bacteria to adhere which leads to biofilm formation → vegetation

What is Cardiac Vegetation?

An infectious bacterial biofilm mass adhering to the avascular endocardium that can detach and embolize, causing vessel blockage and myocardial death.

What are the 2 heart chambers?

Atria - superior

Ventricles - inferior

What are Atria?

Heart chamber that has thinner walls

• The right atrium receives de-O₂ blood from veins (venae cavae & coronary sinus)

What are Ventricles?

Heart chamber that has thicker walls

Which ventricle is thicker than the other?

Left ventricle because it pumps blood throughout the entire body

What is the function of the right ventricle?

Pumps blood to the lungs for pulmonary circulation

What is the left atrioventricular valve?

Bicuspid/mitral valve

What is the right atrioventricular valve?

Tricuspid valve

What is semilunar valves?

Pulmonary valve, aortic valve

What is Stenosis?

An abnormal narrowing or constriction of a heart valve orifice that obstructs blood flow.

What is Regurgitation?

A condition in which a heart valve fails to close completely, allowing blood to flow backward.

What is Chordae Tendineae?

Tendon-like fibrous cords connecting the leaflets of atrioventricular valves to papillary muscles in the ventricles.

valves → chordae tendinae → papillary muscles

What are papillary muscles?

cone-shaped trabeculae carnae

What is Mitral Regurgitation?

Mitral valve does not fully close which causes blood to flow backward from left ventricle into left atrium that promotes blood clot formation in the heart.

If the clot becomes lodged in a blood vessel it can cause a blockage (embolism)

What is S1 Heart Sound?

The first normal heart sound ("lub") created by blood turbulence associated with the closure of the atrioventricular (tricuspid and mitral) valves at the start of systole.

What is S2 Heart Sound?

The second normal heart sound ("dub") created by blood turbulence associated with the closure of the semilunar (aortic and pulmonary) valves at the start of diastole.

What is S3 Heart Sound?

An extra heart sound ("lub dub dub") caused by rapid ventricular filling during diastole, often heard in conditions like mitral regurgitation.

What is associated with 5-HT2B receptor activation

Cardiac valvulopathy

What can 5-HT2B activation cause in heart valves?

It can cause fibrosis and thickening of valve leaflets which makes them stiff and impairs proper closure that leads to regurgitation

What are drugs that has serotonergic activity that can activate 5-HT2B

• Methysergide

• Ergotamine

• Fenfluramine

• MDMA

• Benfluorex

• Pergolide

• Cabergoline

• Serotonin

What are some causes of valvular heart disease?

1. Drugs

2. endocarditis

3. Rheumatic fever

4. other heart diseases

What happens when 5-HT2B receptor is present and treated with Bleomycin?

Significant valve fibrosis

What is Ductus Arteriosus?

A fetal blood vessel connecting the pulmonary trunk directly to the aorta to bypass non-functional lungs, kept patent (open) by prostaglandin E2.

Why is the ductus arterioussu needd before birth?

It allows blood to bypass the non-functioning fetal lungs.

What keeps the ductus arteriosus open before birth?

Prostaglandin E₂ (PGE₂)

What happens to the ductus arteriosus after birth?

It normally closes.

What is it called when the ductus arteriosus fails to close?

Patent ductus arteriosus (PDA)

What drugs can be used to close a PDA?

NSAIDs, especially ibuprofen and indomethacin

What does the ductus arteriosus become after complete closure?

Ligamentum arteriosum

What is “broken heart syndrome”?

Takotsubo cardiomyopathy

What is a characteristic feature of Takotsubo cardiomyopathy?

Apical ballooning

What can trigger Takotsubo cardiomyopathy?

Severe emotional or physical stress and a cathecolamine surge that can cause temporary weakening of the heart muscle and ballooning of the heart

What is Pulmonary Circulation?

The circulatory pathway carrying deoxygenated blood from the right ventricle to the lungs for gas exchange and returning oxygenated blood to the left atrium.

What is Systemic Circulation?

The circulatory pathway pumping oxygenated blood from the left ventricle through the aorta to body tissues and returning deoxygenated blood to the right atrium.

What is Coronary Circulation?

The intrinsic blood supply system of the heart wall originating from the ascending aorta via coronary arteries and draining into the coronary sinus.

What do the coronary arteries supply?

Oxygen-rich blood to the myocardium → blood then reaches the capillaries, where O₂ and nutrients are delivered → CO₂ and wastes are removed

What is the function of coronary veins?

Carries deoxygenated blood from myocardial capillaries back to coronary sinus.

What is the function of Coronary Sinus?

Collects deoxygenated blood from the myocardium and drains it into the right atrium.

What is Angina?

Chest pain or discomfort resulting from myocardial ischemia due to insufficient coronary blood flow.

What is Ischemic Heart Disease/Coronary Artery Disease (CAD)

Narrowing or blockage of the coronary arteries

What is Chronic Coronary Syndrome?

A chronic, progressive condition caused by reduced blood flow to the heart.

What term did chronic coronary syndrome replace?

Stable angina

When does angina typically occur in CCS?

During exertion or physical activity

What are some modifiable risk factors for CAD?

1. Smoking

2. Unhealthy diet

3. Physical inactivity

What happens in Acute Coronary Syndrome (ACS)?

A medical emergency arising when myocardial oxygen demand exceeds supply.

What can ACS lead to?

Myocardial infarction (MI)

What is Myocardial Infarction (MI)?

Irreversible necrosis of myocardial cells resulting from severe and prolonged myocardial ischemia.

What cardiac biomarker increases with myocardial injury?

Cardiac troponin

What tests can show evidence of myocardial injury?

Troponin, ECG, and cardiac imaging

What are the two major types of ACS?

NSTE-ACS and STEMI

What does NSTE-ACS stand for?

Non-ST-Elevation Acute Coronary Syndrome

What conditions are included under NSTE-ACS?

Unstable angina and NSTEMI (non-ST-elevation myocardial infarction)

What does STEMI stand for?

ST-Elevation Myocardial Infarction

What are the 4 main parts of the cardiac conduction system?

1. SA node

2. AV node

3. AV bundle

4. Purkinje fibers

What is Sinoatrial (SA) Node?

The main pacemaker of the heart

What does the SA node generate?

An electrical impulse spontaneously

What does the SA node initiate?

Atrial depolarization and contraction

What is the function of Atrioventricular (AV) Node?

Delays the electrical impulse

Why does the AV node delay the impulse?

To give the atria enough time to contract and push blood into the ventricles

What is another name for the AV bundle?

Bundle of His

What is the function of AV Bundle?

Carries the electrical impulse from the atria toward the ventricles

What are the two branches of the AV bundle?

Right bundle branch (right ventricle) and left bundle branch (left ventricle)

What does Purkinje Fibers do?

Distribute/spread the electrical impulse throughout the ventricular myocardium

What does Purkinje fiber activation cause?

Ventricular depolarization and contraction

What is an action potential?

A rapid, temporary reversal of a cardiac cell's membrane potential.

What connects cardiac muscle cells to each other?

Intercalated discs

What are the two important structures found in intercalated discs?

Desmosomes and gap junctions

What is the function of desmosomes and gap junctions?

allows faster flow of electrons from one cell to another

What specialized fibers can generate their own action potentials?

Autorhythmic fibers

What is the conduction cycle?

The sequence by which electrical impulses are generated and conducted through the heart, leading to contraction.

What is a pacemaker?

A specialized cluster of autorhythmic fibers that establishes the heart's rhythm.

What is a P Wave in ECG?

Atrial depolarization

What is a PQ Segment in ECG?

Time traveled of signals traveled from SA to AV nodes

What is a QRS Complex in ECG?

Ventricular depolarization

What is a ST Segment in ECG?

Plateau in the myocardial action potential where the ventricles contract and pump blood

What is a T Wave in ECG?

Ventricular repolarization

What are the properties of Sinoatrial and Atrioventricular Nodes?

Slow activation and higher threshold voltage and resting membrane potential

What is Phase 4 of Sinoatrial and Atrioventricular Nodes?

Spontaneous depolarization - inward leak of Na⁺ ions

What is Phase 0 of Sinoatrial and Atrioventricular Nodes?

Depolarization - driven by Ca⁺ ions