Biological Terminology: Blood Components, Pathology, and System Functions

Essential Biological Definitions: Blood, Systems, and Pathology

Blood Components and Characteristics

Chordae Tendineae: "Heart Strings"

These are fibrous cords that connect the papillary muscles to the cusps of the atrioventricular valves (mitral and tricuspid valves) in the heart.

Erythrocytes (Red Blood Cells)

The primary function of erythrocytes is oxygen transport.

Leukocytes (White Blood Cells)

Leukocytes are crucial components of the immune system, defending the body against infection and disease.

Granulocytes

Their cytoskeleton contains visible granules.

Agranulocytes

The cytoskeleton lacks granules. There are two main kinds:

• Lymphocytes: Possess large spherical nuclei.
  • T Lymphocytes: Found primarily in the lymph; they attack tumor cells.
  • B Lymphocytes: Found in the blood; responsible for the production of antibodies.
• Monocytes: Characterized by U or kidney-shaped nuclei; they are phagocytic.

Platelets (Thrombocytes)

Platelets constitute approximately 1% of whole blood volume. They are small cell fragments derived from megakaryocytes. Their functional role is essential in blood clotting. They typically last 5–9 days.

Hematocrit

Hematocrit measures the percentage of total blood volume occupied by Red Blood Cells (RBCs).

• Females: Approximately 42%.
• Males: Approximately 47% (due to testosterone stimulating RBC production).

Pathology, Virology, and Immunity

Endemic Disease

Transmission occurs, but the number of cases remains relatively constant within a population or region.

Pathogenicity and Virulence

Pathogenicity: The ability of a microbe to cause disease.

Virulence: The degree or extent of the ability to cause a disease.

Viral Structures and Mechanisms

• Viral Envelope: A membrane that surrounds the capsid of some viruses.
• Provirus: The genome of an animal virus that becomes integrated into the host cell's genome.

Vaccine

Vaccines utilize harmless variants of pathogenic microbes to stimulate the immune system to mount defenses against the actual pathogen.

Oncogenes

Viral genes directly involved in triggering cancerous characteristics in cells. The transition to a cancerous state probably involves combinations of events.

Prion

A prion is a misfolded form of a protein normally present in brain cells. When introduced into a brain, it converts the normal protein into the prion version. Prions may repeatedly trigger chain reactions that increase their numbers.

Functions of Major Body Systems

What is the general function of the Respiratory, Digestive, Lymphatic, and Circulatory systems?

Respiratory System

The respiratory system facilitates gas exchange between the blood and the environment. The primary site of exchange is the alveoli. It also functions to purify, humidify, and warm inhaled air.

Digestive System Functions

1. Mechanical Processing and Movement: Includes ingestion and propulsion of food.
2. Digestion: Secretion of enzymes chemically breaks down large molecules.
3. Absorption: End products are absorbed into the blood or lymph.
4. Elimination: Defecation of indigestible substances.

Lymphatic System

The lymphatic system transports escaped fluid back to the blood and plays a vital role in defense and resistance to disease.

Elaborated Functions:

• Maintenance of blood volume in the cardiovascular system.
• Transport of fats and fat-soluble vitamins from the digestive system to the cardiovascular system.
• Filtration of foreign material to defend against infection.

Circulatory System

The circulatory system is essential to life, supplying the body with blood and maintaining homeostasis. It acts as a pump and highway, ensuring blood travels to body tissues to exchange gases and nutrients.