Cells: Cytology and Cell Physiology – Structure, Function, and Transport

Cells: Cytology and Cell Physiology

Introduction to Cells

Cells are the basic structural and functional units of all living organisms. The study of cells, known as cytology, and their physiological processes is fundamental to understanding anatomy and physiology.

Divisions of the Cell

Main Structural Components

• Plasma (Cell) Membrane: The outer boundary of the cell, controlling the movement of substances in and out.

• Cytoplasm: The region between the plasma membrane and the nucleus, containing cytosol and organelles.

  • Cytosol: The fluid portion of the cytoplasm, where many metabolic reactions occur.

  • Organelles: Specialized structures within the cytoplasm (excluding the nucleus) that perform specific cellular functions.

• Nucleus: The control center of the cell, containing genetic material (DNA).

Comparison of Cytoplasm and Cytosol

Definitions and Differences

• Cytoplasm: Includes both the cytosol and the organelles (except the nucleus).

• Cytosol: The semi-fluid, gel-like substance within the cytoplasm, excluding organelles.

Example: The cytoplasm is like a room filled with furniture (organelles) and air (cytosol); the cytosol is just the air.

	Cytoplasm	Cytosol
Includes	Cytosol + Organelles (except nucleus)	Fluid portion only
Main Function	Site of most cellular activities	Medium for chemical reactions