Chapter 3: Cell Structure and Function

Introduction

The study of cells is fundamental to understanding human physiology. Cells are the basic structural and functional units of all living organisms, and their properties underpin the function of tissues, organs, and entire systems within the body.

An Introduction to Cells

Cell Theory

• Cells are the building blocks of all plants and animals.

• All cells arise from the division of preexisting cells, ensuring continuity of life.

• Cells are the smallest units that perform all vital physiological functions, such as metabolism, growth, and response to stimuli.

• Each cell maintains homeostasis at the cellular level, regulating its internal environment to sustain life.

Homeostasis refers to the maintenance of a stable internal environment within the cell, which is essential for proper function and survival.

The Study of Cells (Cytology)

• Cytology is the study of the structure and function of cells.

• Understanding cell biology requires the ability to observe cells and their components, which is achieved through various forms of microscopy.

Microscopy in Cell Biology

• Light Microscopy (LM): Uses visible light to observe cells and tissues. Suitable for viewing living cells and general cell structure.

• Electron Microscopy (EM): Uses beams of electrons for much higher resolution imaging. Two main types:

  • Scanning Electron Microscopy (SEM): Provides detailed three-dimensional images of cell surfaces.

  • Transmission Electron Microscopy (TEM): Allows visualization of internal cell structures at very high magnification and resolution.

Example: Red blood cells can be observed using light microscopy to study their shape, while electron microscopy reveals detailed surface and internal features.

Additional info: The ability to visualize cells and their organelles has been crucial in advancing our understanding of cell function, disease mechanisms, and the development of medical treatments.