Histology: Cell Types and Modifications

Study Notes

Cells in multicellular organisms grow, mature, and differentiate into specialized types.
Over 200 differentiated cell types exist in the human body, forming tissues.
Tissues consist of groups of similar cells serving a common function.
Histology is the study of animal and plant tissues, involving thin section preparation and microscopic examination.

Capable of division and differentiation into various cell types (e.g., bone, epithelial).

Essential for bone production and repair.
Types include:
- Osteoclasts: dissolve bone tissue.
- Osteoblasts: create new bone.
- Osteocytes: communicate with other bone cells.

Red Blood Cells (RBC): transport oxygen.
White Blood Cells (WBC): divided into:
- Granulocytes
- Monocytes
- Lymphocytes (subtypes include neutrophils, phagocytic, and basophils, involved in pathogen defense).
Platelets: aid in blood clotting.

Also called Myocytes; long, tubular cells supporting organ function and peristalsis.

Responsible for reproduction through:
- Oogenesis: formation of egg cells.
- Spermatogenesis: formation of sperm cells.

Neurons: transmit and relay signals throughout the body, facilitating communication.

Line surfaces and cavities, playing pivotal roles in communication and protection.
Types include:
- Epithelium
- Endothelium
- Mesothelium

Chondrocytes are the primary cells responsible for forming cartilage, residing within lacunae.

Four primary types in animals:
- Epithelial
- Connective
- Muscular
- Nervous
Organs consist of multiple tissue types, working together for specific functions, like the stomach which contains:
- Columnar epithelial cells for absorption.
- Smooth muscle tissues for peristalsis.
- Nervous tissues for signaling.
- Blood as connective tissue for nutrient transport.

Composed of specialized cells organized in one or more layers.
Categories include:
- Simple Epithelium: single layer.
- Stratified Epithelium: multiple layers.
Shapes of epithelial cells:
- Squamous: flattened (found in alveoli and capillaries for gas exchange).
- Cuboidal: cube-shaped with larger cytoplasm, facilitating absorption and secretion.
- Pseudostratified: appears stratified but consists of varying cell heights, often found in respiratory pathways.

Characterized by dispersed cells and extensive extracellular matrix (ECM).
ECM components include:
- Protein fibers (collagen, elastic, reticular).
- Ground substances, predominantly secreted by connective tissue cells.
Types of ECM:
- Solid (bone)
- Soft (connective tissues)
- Liquid (blood)
Functions include:
- Protection
- Cushioning
- Fat storage
- Nutrient and waste transport
- Maintenance of structure.