Cell Structure, Function, and Tissue Classification in Human Anatomy & Physiology

Cell Structure and Function

Overview of Cell Anatomy

Cells are the basic structural and functional units of all living organisms. Understanding the components of a cell and their respective functions is fundamental in anatomy and physiology.

• Centrosomes (Centrioles): Organize microtubules and are essential for cell division.

• Chromatin: Complex of DNA and proteins; stores genetic information.

• Cytoplasm: Gel-like substance where cellular processes occur.

• Cytosol: Fluid portion of cytoplasm containing dissolved substances.

• DNA: Molecule carrying genetic instructions for development and function.

• Golgi Apparatus/Body: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

• Lysosomes: Contain digestive enzymes to break down waste materials and cellular debris.

• Mitochondria: Powerhouse of the cell; site of ATP (energy) production.

• Nuclear Membrane: Encloses the nucleus, controlling passage of materials.

• Nucleolus: Produces ribosomal RNA and assembles ribosomes.

• Nucleus: Contains genetic material; controls cell activities.

• Organelles: Specialized structures within the cell performing distinct functions.

• Peroxisomes: Break down fatty acids and detoxify harmful substances.

• Plasma (Cell) Membrane: Semi-permeable barrier controlling entry and exit of substances.

• Ribosomes: Synthesize proteins from amino acids.

• Rough Endoplasmic Reticulum: Studded with ribosomes; involved in protein synthesis and processing.

• Smooth Endoplasmic Reticulum: Synthesizes lipids and detoxifies chemicals.

• Vesicles: Small membrane-bound sacs for transport and storage of substances.

Example: The mitochondria generate ATP through cellular respiration, providing energy for cellular activities.

Classification of Tissues

Introduction to Tissue Types

Tissues are groups of similar cells that perform a specific function. The four primary tissue types in the human body are epithelial, connective, muscle, and nervous tissues. Each type has unique structures, locations, and functions.

• Epithelial Tissue: Covers body surfaces, lines cavities, and forms glands.

• Connective Tissue: Supports, binds, and protects organs.

• Muscle Tissue: Responsible for movement.

• Nervous Tissue: Transmits electrical impulses for communication.

Example: Simple squamous epithelium lines blood vessels and facilitates diffusion of gases.

Functions and Locations of Major Tissue Types

Each tissue type can be further classified based on cell shape, arrangement, and function. The following table summarizes the main types, their locations, and one key function for each.

Tissue (Full) Name	Suggested Slide / Location(s)
Epithelial
Simple Squamous	Lung, capillaries, blood vessels endothelium
Simple Cuboidal	Kidney (e.g., glandular epithelium)
Simple Columnar	Simple columnar (e.g., small/large intestines)
Pseudostratified Columnar	Pseudostratified columnar (e.g., Nasopharynx, Larynx, Trachea)
Stratified Squamous	Skin
Transitional	Bladder, Ureters
Connective Tissues
Loose Areolar	Areolar tissue, skin
Loose Adipose	Adipose tissue, skin, other organs
Loose Reticular	Reticular tissue
Dense Irregular	Skin
Dense Regular	Tendon
Cartilage (Hyaline)	Hyaline cartilage
Cartilage (Fibrocartilage)	Fibrocartilage (e.g., intervertebral discs)
Cartilage (Elastic)	Elastic cartilage
Bone (Osseous)	Bone tissues
Blood	Blood smear
Muscles
Skeletal	Skeletal muscle
Cardiac	Cardiac muscle
Smooth	Smooth muscle
Nervous System
Neuron	Neuron smear
Nerve	Nerve tissues
Spinal Cord	Spinal cord
Cerebrum	Cerebrum
Cerebellum	Cerebellum

Key Definitions

• Histology: The study of tissues at the microscopic level.

• Epithelium: Tissue forming the outer layer of body surfaces and lining internal organs.

• Connective Tissue: Tissue that supports, connects, or separates different types of tissues and organs.

• Muscle Tissue: Tissue capable of contraction, enabling movement.

• Nervous Tissue: Tissue composed of neurons and supporting cells, responsible for transmitting signals.

Additional info:

• For each tissue type, students should learn the full name, one location, and one function. For example, stratified squamous epithelium is found in the skin and provides protection against abrasion.

• Histological slides are used to identify tissue types based on cell shape, arrangement, and staining characteristics.