VET 223 Exam 2

How is cardiac muscle different from skeletal muscle?

Cardiac muscle contracts longer, has intercalated discs for synchronized contraction, and has an intrinsic electrical conduction system.

What is the main function of the SA node?

It acts as the heart’s natural pacemaker, generating electrical impulses to start the heartbeat.

What is the order of the heart’s electrical conduction system?

SA Node → AV Node → Bundle of His → Right & Left Bundle Branches → Purkinje Fibers.

What happens during the plateau phase of a cardiac action potential?

Calcium (Ca2+) enters the cell, prolonging depolarization and ensuring sustained contraction.

What ion is responsible for repolarization in cardiac muscle?

Potassium (K+) leaving the cell restores the resting membrane potential.

What is the main function of the AV node?

It delays the electrical signal to allow the atria to contract before the ventricles.

What are the two main phases of the cardiac cycle?

Systole (contraction) and Diastole (relaxation).

What causes the "LUB" heart sound?

The closing of the AV valves (tricuspid & bicuspid/mitral) at the beginning of ventricular systole.

What causes the "DUB" heart sound?

The closing of the semilunar valves (aortic & pulmonary) at the beginning of ventricular diastole.

Why is the Purkinje fiber system important?

It spreads the electrical signal quickly, ensuring the ventricles contract efficiently from the apex upward.

What are the two main circulatory routes in the body?

Systemic circulation (carries oxygenated blood from the heart to the body) and pulmonary circulation (carries deoxygenated blood from the heart to the lungs).

What is the function of arteries?

Carry oxygen-rich blood away from the heart under high pressure.

What is the function of veins?

Carry oxygen-poor blood back to the heart and serve as blood reservoirs.

What do capillaries do?

Exchange oxygen, nutrients, and waste between blood and tissues.

What is edema, and what causes it?

Excess fluid in tissues due to high blood pressure, low plasma protein levels, or lymphatic blockage.

What are the three main components of blood?

Red blood cells (RBCs), white blood cells (WBCs), and platelets.

What is the main function of red blood cells (RBCs)?

Transport oxygen (O2) using hemoglobin and assist in CO2 transport.

What is the main function of white blood cells (WBCs)?

Defend against infections by attacking pathogens and producing antibodies.

What do platelets do?

Help with blood clotting (hemostasis) to prevent excessive bleeding.

What is the function of hemoglobin?

Binds to oxygen in the lungs and releases it in tissues; also carries some carbon dioxide.

What are the two types of immunity?

Innate immunity (non-specific, fast) and adaptive immunity (specific, memory-based, slower but stronger over time).

What are the main types of WBCs?

Neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

What do B-cells and T-cells do?

B-cells produce antibodies; T-cells directly attack infected or abnormal cells.

What is the role of the lymphatic system?

Returns excess interstitial fluid to circulation and plays a key role in immune defense.

What is an antigen?

A foreign substance that triggers an immune response by stimulating the production of antibodies.

What are the three types of capillary exchange mechanisms?

Diffusion, transcytosis, and bulk flow (filtration & reabsorption).

What is the function of the Starling Hypothesis?

Explains how fluid movement across capillary walls is governed by hydrostatic and osmotic pressures.

What is cardiac output, and how is it calculated?

The amount of blood pumped by the heart per minute; calculated as CO = Stroke Volume × Heart Rate.

What is the difference between preload and afterload?

Preload = The stretch of the heart before contraction; Afterload = The resistance the heart must pump against.

How does the autonomic nervous system affect heart rate?

Sympathetic (fight/flight): Increases heart rate and force of contraction. Parasympathetic (rest/digest): Slows heart rate.

What is the function of baroreceptors?

Detect changes in blood pressure and signal the brain to adjust heart rate and vessel diameter.