Body Structure, Oncology, & Laboratory Tests: Organization of the Body

This page provides an overview of the human body's structural organization, from the cellular level to complex organ systems. It covers key components of cells, types of tissues, and the formation of organs and systems.

Definition: A cell is the basic unit of all living things. The human body is composed of trillions of cells, which vary in size and shape according to their function.

The cell structure is described in detail:

1. Cell membrane: Forms the boundary of the cell
2. Cytoplasm: Gel-like fluid inside the cell
3. Nucleus: Largest structure within the cell, usually spherical and centrally located
   • Contains chromosomes for cellular reproduction
   • Acts as the control center for cellular activity

Vocabulary: Chromosomes are located in the nucleus. There are 46 chromosomes in all normal human cells, except for mature sex cells, which have 23.

Genes, located within chromosomes, determine hereditary characteristics. DNA (deoxyribonucleic acid) comprises each gene and regulates cellular activities.

The page then explains different types of tissues:

1. Muscle Tissue: Composed of cells that can contract, usually producing movement
2. Nervous Tissue: Found in nerves, spinal cord, and brain; responsible for coordinating and controlling body activities
3. Connective Tissue: Connects, supports, penetrates, and encases various body structures (e.g., fat, bones, blood)
4. Epithelial Tissue: Forms membranes that line body cavities and organs; major tissue in glands

Example: The skin is an organ composed of epithelial, connective, muscle, and nervous tissue.

The document concludes by defining organs and systems:

• Organ: Two or more types of tissues that together perform special body functions
• Viscera: Large internal organs contained in body cavities, especially the abdominal cavity
• System: Group of organs that work together to perform complex body functions

Example: The cardiovascular system contains the heart, blood vessels, and blood.

This comprehensive overview of body structure provides essential knowledge for understanding human anatomy and physiology, which is crucial for medical professionals and students alike. It serves as an excellent foundation for more advanced medical terminology lecture notes PDF and basic medical terminology PDF resources.