LECTURE 2: HEART Flashcards by Ella Heithoff

Where does the heart sit?

In the middle of the mediastinum in the thoracic cavity.

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What is the first organ to form in fetal development?

The heart.

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What are the boundaries of the thoracic cavity?

Superior: root of neck; Anterior: sternum; Lateral: ribs & intercostal spaces; Posterior: vertebral column; Inferior: diaphragm.

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What are the subdivisions of the mediastinum?

Pulmonary cavities (pleurae and lungs) and mediastinum (pericardium & heart).

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What is the function of the pericardium?

Protects and confines the heart, accommodates diastole, restricts excessive dilation, anchors heart in mediastinum, protects from infections, and lubricates.

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What are the layers of the pericardium?

Fibrous pericardium (outer layer) and serous pericardium (inner layer, including parietal and visceral layers).

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What is the pericardial cavity?

The space between the parietal and visceral serous pericardium containing pericardial fluid.

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What supplies blood to the heart?

Pericardiacophrenic artery/vein.

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What is pericarditis?

Inflammation of the pericardium, which may be acute or chronic.

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What are the features of the heart?

Four chambers (2 atria and 2 ventricles), atrioventricular (AV) valves (tricuspid and bicuspid), and semilunar valves (pulmonary and aortic).

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What are the surfaces of the heart?

Anterior (sternocostal), pulmonary surfaces (right and left), base (left atrium), and diaphragmatic surface.

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What are the borders of the heart?

Superior border (adjacent to right atria), right border (right atrium), left border (left ventricle and left auricle), apex, and inferior border (ventricles).

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What is the coronary sulcus?

A groove between the atria and ventricles that contains the fibrous skeleton.

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What are the layers of the heart wall?

Outer layer (epicardium), middle layer (myocardium), and inner layer (endocardium).

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What is the myocardium composed of?

Cardiac muscle tissue, fibroblasts, with thinner atria and thicker ventricles.

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What is the function of intercalated discs?

Connect adjacent muscle cells and allow action potentials to pass through.

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What are the two loops of circulation?

Pulmonary loop (heart -> lungs -> heart) and systemic loop (heart -> body -> heart).

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What is the flow of blood through the heart?

Venae cavae drain deoxygenated blood into right atrium. 2. Flows from right AV valve to right ventricle. 3. Ventricular contraction squeezes blood into pulmonary trunk. 4. Blood goes to pulmonary arteries then out to lungs. 5. Travels through pulmonary veins to left atrium. 6. Left AV valve and contraction squeezes blood out of left ventricle. 7. To aorta. 8. Systemic circulation to body.

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What does the right atrium receive blood from?

Superior and inferior venae cavae and coronary sinus.

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What is the function of the pectinate muscles?

Muscular pouches in the atria that increase volume.

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What is the function of the right ventricle?

Pumps deoxygenated blood to the lungs through the pulmonary valve.

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What are the components of the left ventricle?

Left atrioventricular (AV) valve, chordae tendineae, papillary muscles, trabeculae carneae, and aortic valve.

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What are the two types of AV valves?

Right AV (tricuspid) valve and left AV (bicuspid, mitral) valve.

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What are the semilunar valves?

Pulmonary valve and aortic valve, each with three cusps.

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What happens during diastole?

AV valves open, all chambers fill, and semilunar valves close.

What happens during systole?

AV valves close and semilunar valves open as ventricles contract.

What is myocardial ischemia?

Reduced blood flow to myocardium, often causing angina pectoris.

What is myocardial infarction?

Death of myocardium due to lack of blood flow, commonly known as a heart attack.

What are the risk factors for coronary artery disease (CAD)?

Smoking, hypertension, diabetes, high cholesterol, obesity, and age.

What are the treatments for CAD?

Coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA) & stenting.

Which cardiac vein courses with the posterior interventricular artery?

Middle cardiac vein.

What is the fibrous skeleton of the heart?

A complex framework of dense collagen fibers.

What are the functions of the fibrous skeleton of the heart?

1. Separates atria from ventricles. 2. Provides structural support. 3. Acts as an anchor. 4. Prevents overstretching. 5. Acts as 'electrical' insulation.

What are specialized cardiomyocytes?

These cells are autorhythmic, meaning they can generate their own electrical impulses.

What is autorhythmicity?

Some groups of cells have a higher autorhythmic potential than others, determining the rate of heartbeat.

What does depolarization refer to?

The electrical excitation of the heart muscle, leading to contraction.

Where is the sinoatrial (SA) node located?

In the right atrium at the superior portion of the crista terminalis.

What is the function of the SA node?

It is the pacemaker of the heart, initiating the electrical impulse.

What is the rate of the SA node?

~100 bpm.

Where is the atrioventricular (AV) node located?

In the right atrium at the base of the interatrial septum.

What is the function of the AV node?

It delays the impulse from the SA node to ensure ventricles are filled before contraction.

What is the rate of the AV node?

~40-60 bpm.

Where is the AV bundle (of His) located?

In the interventricular septum.

What is the rate of the AV bundle (of His)?

~20-35 bpm.

What do the right and left bundle branches do?

They carry the impulse to the bundle branches.

What is the septomarginal trabecula (moderator band)?

A shortcut for part of the right bundle branch, ensuring synchronous depolarization of the ventricles.

What are Purkinje fibers?

Fibers that distribute the electrical impulse to the muscle cells of the ventricles, causing them to contract.

What can disruptions in the conduction system lead to?

Cardiac arrest.

What is the normal heart rate (HR) in adults?

60-100 bpm (normal resting rate).

What does extrinsic control of the heart modulate?

It modulates heart rate by affecting the SA node.

What is the role of parasympathetic input in heart rate?

It decreases HR via the cardiac branches of the vagus nerve (CN X).

What is the role of sympathetic input in heart rate?

It increases HR via the cardiac branches of the sympathetic trunk.

Where are presynaptic fibers for sympathetic input located?

From T1-T4/5 spinal cord levels, synapsing at inferior cervical to T4 ganglia.

What is the superficial cardiac plexus?

Located in the concavity of the aortic arch.

What is the deep cardiac plexus?

Located at the tracheal bifurcation, continuous with pulmonary plexuses.

What is the sympathetic response in the cardiac plexus?

Increases heart rate and dilates coronary arteries.

What is the parasympathetic response in the cardiac plexus?

Slows heart rate and narrows coronary arteries.

What is a normal sinus rhythm?

A heart rhythm ranging from 60-100 bpm with a typical ECG pattern.

What is bradycardia?

A heart rate of less than 60 bpm.

What is tachycardia?

A heart rate of more than 100 bpm.

What is atrial fibrillation (A-fib)?

An irregular heart rhythm originating in the atria.

What is ventricular fibrillation (V-fib)?

An emergency condition leading to the lack of coordinated ventricular contractions.

What is cardiac arrest?

A serious consequence of arrhythmias like v-fib.

What is S1 ('Lub')?

The sound that occurs when AV valves close, marking the beginning of systole.

What is S2 ('Dub')?

The sound that occurs when semilunar valves close, marking the beginning of diastole.

What causes S3 heart sound?

Blood turbulence during ventricular filling; common in children.

What is the sound associated with S3?

S1, S2, S3 (KEN-TUCK-y gallop).

What causes S4 heart sound?

Blood turbulence during atrial systole; rare and usually occurs with ventricular non-compliance or hypertrophy.

What is the sound associated with S4?

S4, S1, S2 (tenn-ES-SEE).

What are murmurs?

Abnormal heart sounds characterized by clicking, gurgling, or rushing sounds.

Where is the aortic valve located?

In the right 2nd intercostal space (IC).

Where is the pulmonary valve located?

In the left 2nd-3rd intercostal space (IC).

Where is the tricuspid valve located?

In the left 4th-5th intercostal space (IC).

Where is the bicuspid (mitral) valve located?

In the left 5th intercostal space (IC), midclavicular line.

Which structure conducts the right bundle branches to the anterior papillary muscle and wall of the right ventricle?

C. Septomarginal trabecula (moderator band)

What event during the cardiac cycle produces the second (S2) heart sound, 'dub'?

D. Semilunar valve closure