Circulatory System: Cardiac Structure, Conduction, Hemodynamics, and Pathology (copy)

Comprehensive practice flashcards covering cardiac anatomy, heart wall layers, valve structure and mechanics, electrical conduction, the cardiac cycle, coronary and systemic circuits, microvasculature, and cardiovascular pathologies.

Where is the heart anatomically located within the body?

The heart is located in the thoracic cavity within the mediastinum, resting on the diaphragm between the lungs, and lying obliquely behind the sternum with its apex pointing to the left.

What is the structural role of the fibrous pericardium?

It is a tough outer layer that prevents overdistension of the heart.

What are the two layers of the serous pericardium, and what is the function of pericardial fluid?

The serous pericardium consists of parietal and visceral (epicardium) layers; pericardial fluid is situated between these layers to reduce friction during contractions.

What are the three layers of the heart wall and their primary characteristics?

The epicardium (thin outer visceral layer adhering closely to the cardiac surface), myocardium (thick middle layer of specialized cardiac muscle fibers responsible for involuntary contractions), and endocardium (smooth inner epithelial lining covering chambers and valves to prevent blood clots).

Which major vessels deliver deoxygenated blood into the right atrium?

The Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus.

How does the left atrium receive oxygenated blood?

It receives oxygenated blood from the lungs via four Pulmonary Veins.

How do the right and left ventricles differ in terms of myocardial thickness and pressure generation?

The right ventricle is a thinner-walled pump that sends blood under low pressure into the Pulmonary Artery, while the left ventricle is a thick-walled pump (three times thicker than the right) that sends oxygenated blood under high pressure into the Aorta.

What are the anatomical location, structural features, and functional role of the tricuspid valve?

It is located between the Right Atrium & Ventricle, features $3$ Cusps anchored by Chordae Tendineae, and prevents backflow into the Right Atrium.

What are the anatomical location, structural features, and functional role of the bicuspid (mitral) valve?

It is located between the Left Atrium & Ventricle, features $2$ Strong Cusps with Papillary Muscle ties, and prevents backflow into the Left Atrium.

What are the anatomical location, structural features, and functional role of the pulmonary semilunar valve?

It is located at the Orifice of Pulmonary Trunk, contains $3$ Half-moon shaped Pocket Cusps, and prevents regurgitation into the Right Ventricle.

What are the anatomical location, structural features, and functional role of the aortic semilunar valve?

It is located at the Orifice of Ascending Aorta, possesses $3$ Heavy Cusps with Coronary Artery ostia, and prevents regurgitation into the Left Ventricle.

What is the location, pacemaker role, and firing rate of the Sino-Atrial (SA) Node?

It is located in the right atrial wall, serves as the heart's natural pacemaker, and fires at $60\text{--}80\,\text{bpm}$.

What role does the Atrio-Ventricular (AV) Node play in the cardiac conduction system?

It sits in the interatrial septum and delays the electrical impulse, allowing the atria to empty completely.

What is the function of the AV Bundle of His?

It transmits electrical impulses down the interventricular septum.

What is the function of the Purkinje Fibers?

They distribute action potentials rapidly through the ventricular myocardium.

What is the duration of each phase in a single $0.8\,\text{second}$ cardiac cycle at an average resting rate of $75\,\text{beats per minute}$?

Atrial Systole lasts $0.1\,\text{sec}$, Ventricular Systole lasts $0.3\,\text{sec}$, and Complete Diastole lasts $0.4\,\text{sec}$.

What cardiac events generate the 'Lubb' and 'Dupp' heart sounds?

'Lubb' occurs during ventricular systole when the AV valves snap shut; 'Dupp' occurs during complete diastole when the semilunar valves close.

Which cardiac regions are perfused by the Right Coronary Artery?

The right atrium, right ventricle, SA node, and inferior ventricular wall.

Into which branches does the Left Coronary Artery divide, and what region do they supply?

It branches into the Anterior Interventricular (LAD) and Circumflex arteries to nourish the left myocardium.

What are the three structural tunics of blood vessel walls and their key characteristics?

Tunica Adventitia (protective outer layer of fibrous connective tissue), Tunica Media (middle layer of smooth muscle and elastic fibers; thickest layer in arteries), and Tunica Intima (smooth inner endothelial lining that minimizes blood friction).

What is the structural characteristic of capillaries that facilitates nutrient and gas exchange?

Capillaries consist solely of a single endothelial layer.

What is the exact pathway of blood flow through the Pulmonary Circuit?

Right Ventricle $\rightarrow$ Pulmonary Trunk $\rightarrow$ Pulmonary Arteries $\rightarrow$ Lungs (Gas Exchange) $\rightarrow$ Pulmonary Veins $\rightarrow$ Left Atrium.

What is the exact pathway of blood flow through the Systemic Circuit?

Left Ventricle $\rightarrow$ Aorta $\rightarrow$ Systemic Arteries $\rightarrow$ Tissues Capillaries $\rightarrow$ Venae Cavae $\rightarrow$ Right Atrium.

What is the circulatory route and physiological role of the Hepatic Portal System?

It drains venous blood from the stomach, intestines, pancreas, and spleen through the Portal Vein into the liver before entering systemic circulation via hepatic veins, enabling the liver to process nutrients, store glycogen, and detoxify byproducts.

What are the standard baseline values for Stroke Volume (SV), Heart Rate (HR), and Resting Cardiac Output?

Stroke Volume is approximately $70\,\text{mL}$ per contraction, resting Heart Rate averages $70\text{--}75\,\text{beats per minute}$, and Resting Output is approximately $5.0\,\text{L/min}$.

What is atherosclerosis, and what pathological consequence does it cause?

It is lipid accumulation in the tunica intima of arteries that reduces lumen size and causes tissue ischemia.

What causes valvular incompetence, and what are its clinical consequences?

Damaged valve cusps allow blood regurgitation, producing heart murmurs and leading to cardiac enlargement.

How does hypertension affect the left ventricle?

Persistent high systemic vascular resistance places an excessive workload on the left ventricle.

What is the clinical definition and mechanism of a myocardial infarction?

Complete occlusion of coronary arteries causing ischemic necrosis of cardiac tissue.