Cardiovascular: Normal Physiology and Heart Failure

Comprehensive practice flashcards covering cardiovascular anatomy, histology, hemodynamic principles, necropsy sampling, and the distinguishing pathological lesions of right- and left-sided congestive heart failure.

What is the primary physiological function of the circulatory system?

To deliver nutrients and remove waste products from cells throughout the body.

How do arteries, veins, and lymphatic vessels differ in terms of pressure and direction of fluid transport?

Arteries operate under high pressure to transport blood away from the heart; veins operate under low pressure to carry blood back toward the heart; lymphatic vessels drain the extracellular space, course parallel to veins, and empty back into the venous system via the thoracic duct.

According to this circulatory pressure diagram, which systemic vessels carry blood under the highest pressure, and which experience the lowest pressure?

The aorta carries blood under the highest pressure, while the venae cavae experience the lowest pressure.

Based on this vascular diagram, what is the sequence of blood vessels transporting blood from the left side of the heart to the systemic venous return?

$$\text{Aorta} \rightarrow \text{Arteries} \rightarrow \text{Arterioles} \rightarrow \text{Capillaries} \rightarrow \text{Venules} \rightarrow \text{Veins} \rightarrow \text{Vena cava}$$

What types of autonomic innervation supply the heart, and how well-vascularized are the heart valves?

The heart receives autonomic innervation consisting of sympathetic, parasympathetic, and nonadrenergic, noncholinergic pathways; heart valves are poorly vascularized.

What is the pericardium and what is the role of its fluid?

It is a fibroelastic sac that encloses the heart and contains a very small quantity of serous fluid that provides lubrication during cardiac contractions.

Identify the three primary structural layers of the heart wall shown in this diagram, from outermost to innermost.

The epicardium (visceral layer of serous pericardium), the myocardium (middle muscular layer formed of cardiomyocytes), and the endocardium (innermost layer lining the chambers).

What factor determines the physiological thickness of the myocardium in each heart chamber?

The thickness of the myocardial wall is directly proportional to the amount of pressure present within each specific chamber.

Identify the gross anatomic structures labeled RAA, LAA, RV, and LV on this heart specimen.

RAA is the right auricular appendage, LAA is the left auricular appendage, RV is the right ventricle, and LV is the left ventricle.

What key histological features characteristic of cardiac muscle are identified in this tissue section?

Cardiomyocytes exhibiting centrally placed nuclei, transverse striations, branched cell architecture, and specialized intercellular junctions known as intercalated discs.

Following the conduction system diagram, what is the anatomical pathway of electrical impulse propagation through the heart?

$$\text{Sinoatrial (SA) node} \rightarrow \text{Atrioventricular (AV) node} \rightarrow \text{Atrioventricular bundle} \rightarrow \text{Left and right bundle branches} \rightarrow \text{Purkinje fibers (cardiac conduction fibers)}$$

What protocol must be followed when harvesting cardiac tissue samples for histopathology?

Samples must be full thickness (penetrating through the epicardium, myocardium, and endocardium) and must capture the junction between normal and abnormal tissue when a lesion is present.

In a normal heart cross section such as this, what is the expected thickness ratio of the left ventricular free wall and interventricular septum compared to the right ventricular free wall?

Both the left ventricular free wall and the interventricular septum are approximately $3$ times the thickness of the right ventricular free wall ($3:1$ ratio), measured without including the papillary muscles.

How should the normal luminal diameters of the aortic valve and the pulmonic valve compare at gross necropsy?

The diameters of the aortic valve and the pulmonic valve should be roughly similar.

Why does the complete absence of gross cardiac lesions on necropsy not rule out a primary cardiac failure as the cause of death?

The heart is a dynamic functional system and mechanical or electrical performance cannot be tested postmortem; a sudden arrhythmic or functional cardiac event often leaves no gross structural alterations.

What is heart failure, and how are low-output failure and congestive heart failure distinguished?

Heart failure is a progressive syndrome where impaired pumping decreases ventricular ejection and impedes venous return; low-output failure is the inability of cardiac pumping to maintain arterial pressure, whereas congestive heart failure is the inability to empty venous reservoirs.

What primary pulmonary lesion develops as a direct consequence of left-sided congestive heart failure?

Pulmonary edema, resulting from increased hydrostatic pressure backing up into the pulmonary veins and capillary beds.

What are the three principal systemic lesions associated with right-sided congestive heart failure?

Chronic passive hepatic congestion ('nutmeg liver'), ascites/hydroperitoneum (protein-rich modified transudate peritoneal effusion), and subcutaneous (SQ/dependent) edema.

What hepatic lesion of right-sided congestive heart failure is demonstrated in this gross cut surface, and what causes its appearance?

'Nutmeg liver' (chronic passive hepatic congestion), which displays a reticular pattern of red congested/necrotic centrilobular zones alternating with pale, uncongested or fatty periportal hepatocytes.

Does the extensive brisket/ventral subcutaneous edema evident on this bovine patient indicate right-sided or left-sided congestive heart failure?

Right-sided congestive heart failure, which leads to increased hydrostatic pressure throughout the systemic venous circulation and dependent edema.

Do these lung lesions (expanded interlobular septa and white foamy fluid in airways) represent left-sided or right-sided congestive heart failure?

Left-sided congestive heart failure, indicating severe pulmonary edema with alveolar transudate mixing with air to produce tracheobronchial foam.

Does the marked collection of peritoneal effusion (ascites/hydroperitoneum) seen in this opened abdominal cavity signify right-sided or left-sided congestive heart failure?

Right-sided congestive heart failure, caused by elevated hydrostatic pressure within the caudal vena cava, hepatic veins, and portal vasculature.