Hematology

Definition and Scope

Hematology is the study of the formed elements of the blood (cells) and blood-forming tissues. It is a foundational topic in general biology and clinical medicine, focusing on the structure, function, and pathology of blood components.

• Formed elements: Includes red blood cells (RBC), white blood cells (WBC), and platelets (PLT).

• Quantitative analysis: Measures the number of each type of cell.

• Qualitative analysis: Examines the appearance and morphology of each cell type.

Laboratory tests in hematology are essential for:

• Assessing general well-being

• Diagnosing anemias and leukemias

• Detecting inherited blood disorders

• Monitoring cancer treatments

The Circulatory System

Functions of the Circulatory System

The circulatory system is responsible for the transport of substances throughout the body, regulation of physiological processes, and protection against disease.

• Transport: Delivers oxygen (O2), nutrients, water, and hormones to tissues and cells.

• Removal: Removes carbon dioxide (CO2) and waste products from tissues and cells.

• Regulation: Maintains body temperature.

• Protection: Defends against infections.

Types of Circulation

• Cardiopulmonary Circulation: Blood circulates from the heart to the lungs and back. In the lungs, blood picks up O2 and releases CO2.

• Systemic Circulation: Blood is carried from the heart to the tissues and back. O2 is delivered to tissues in exchange for CO2 waste.

Example: The heart pumps oxygen-poor blood to the lungs, where it becomes oxygen-rich, then sends it to the rest of the body.

The Circulatory System: Blood Vessels

Types of Blood Vessels

Blood vessels are specialized structures that transport blood throughout the body. They are classified based on their structure and function.

• Arteries: Thick-walled, elastic, and muscular vessels that carry oxygenated blood away from the heart.

• Capillaries: The smallest blood vessels, connecting arterioles and venules. Their thin walls allow for the exchange of fluids, nutrients, and waste products. This is where O2 and CO2 are exchanged between blood and tissues.

• Veins: Vessels that carry deoxygenated blood from capillaries back to the heart. They are less thick, elastic, or muscular than arteries and contain valves to ensure one-way blood flow.

Key Fact: The average human body contains approximately 60,000 miles of blood vessels.

Additional info:

• Red Blood Cells (RBCs): Specialized for oxygen transport via hemoglobin.

• White Blood Cells (WBCs): Involved in immune defense.

• Platelets (PLT): Essential for blood clotting.