12 Key Concepts in Blood and Heart Function

This set of flashcards covers key concepts and terms related to blood cells, plasma, the cardiac cycle, and heart function, providing essential information for understanding human physiology.

What is the primary function of erythrocytes (RBCs)?

To transport O₂ and CO₂ via hemoglobin.

What role do leukocytes (WBCs) play in the body?

They defend the body against infections and injuries.

What is the role of platelets in the circulatory system?

They form a soft plug during bleeding and initiate clotting.

What makes up the composition of plasma?

Plasma is about 90% water and carries proteins, electrolytes, nutrients, hormones, and waste.

What stimulates erythropoiesis?

Erythropoiesis is stimulated by erythropoietin from the kidneys when oxygen levels drop.

What does pernicious anemia relate to in terms of dietary deficiency?

It requires supplementation with vitamin B₁₂ if the intrinsic factor is sufficient.

How do action potentials spread in the cardiac muscle?

They spread from cell to cell via gap junctions.

What is the sequence of the intrinsic conducting system of the heart?

SA node → Atrial internodal pathways → AV node → Bundle of His → Left and right bundle branches → Purkinje fibers.

What are the phases of the cardiac cycle at rest?

Atrial systole, isovolumetric ventricular contraction, ejection, isovolumetric relaxation, and ventricular filling.

What is cardiac output (CO) and how is it calculated?

CO is the volume pumped per minute, calculated as CO = HR × SV.

Explain the Frank–Starling Mechanism.

Greater venous return stretches cardiac fibers, leading to a stronger contraction and increased stroke volume.

What distinguishes veins from arteries?

Veins are thin-walled with valves and store volume, while arteries are thick-walled and designed to handle high pressure.

What does the QRS complex represent in an ECG?

It represents ventricular depolarization.

How does sympathetic stimulation affect heart rate?

It increases heart rate via β₁ receptors.

What does the Wiggers Diagram illustrate?

It synchronizes ECG waves with pressures, volumes, and valve events in the cardiac cycle.

What are the heart sounds associated with AV and semilunar closure?

S1 corresponds to AV closure (start of systole) and S2 corresponds to semilunar closure (start of diastole).