Morfoología y Tejido Epitelial

Morphology

• Morphology refers to the study of the form and structure of biological organisms, including their tissues, organs, and systems.
• It's a fundamental aspect of biology, crucial for understanding the function and evolution of organisms.
• Morphology can be descriptive, focusing on detailed documentation of anatomical features, or comparative, examining structural similarities and differences across species.
• It's often intertwined with other fields of biology, like physiology, genetics, and evolution.

Epithelial Tissue

• Epithelial tissue is one of the four basic types of animal tissues.
• It's composed of cells tightly packed together, forming continuous sheets that cover body surfaces (internal and external) and line body cavities.
• Epithelial cells are characterized by their high cellularity, specialized cell junctions (e.g., tight junctions, desmosomes), and a basement membrane.
• Functions of epithelial tissue vary but commonly include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.

Types of Epithelia

• Epithelial tissues are classified based on the shape of the cells forming the layers and the number of layers present.
  • Shape:
• Squamous: Cells are flattened and scale-like.
• Cuboidal: Cells are cube-shaped.
• Columnar: Cells are tall and column-shaped.
  • Layers:
• Simple: A single layer of cells.
• Stratified: Multiple layers of cells.
• Pseudostratified: A single layer of cells but appears stratified due to varying cell heights.

Characteristics of Epithelial Tissues

• Cellularity: Epithelia are composed predominantly of cells, with minimal extracellular matrix.
• Specialized Contacts: Cells are connected by various junctions, like tight junctions, desmosomes, and gap junctions.
• Polarity: Epithelia exhibit apical and basal surfaces, with distinct features and functions.
• Support by Connective Tissue: Epithelia rest on a basal lamina (basement membrane), a specialized layer of connective tissue.
• Avascularity: Epithelial tissues do not contain blood vessels, relying on diffusion from underlying connective tissue for nutrients and waste removal.
• Regeneration: Epithelial tissues have a high capacity for renewal and repair.

Functions of Epithelial Tissues

• Protection: Forms barriers against mechanical injury, pathogens, and dehydration.
• Secretion: Some types produce specialized substances like hormones, enzymes, or mucus.
• Absorption: Specialised epithelium line the digestive tract, facilitating nutrient uptake.
• Excretion: Involved in the removal of waste products.
• Filtration: Involved in the separation of substances from the environment in organs like the kidneys.
• Diffusion: Allows the passage of substances through the epithelium.
• Sensory Reception: Some sensory receptors are found on specialized epithelial surfaces.

Locations of Epithelial Tissues

• Covering and lining surfaces of the body (skin, lining of the digestive tract, respiratory system, etc.)
• Forming glands (endocrine and exocrine).

Connective Tissue

• Connective tissue is another primary tissue type.
• It connects, supports, and separates different tissues and organs.
• It's characterized by relatively fewer cells and a substantial extracellular matrix composed of ground substance and fibers.
• The matrix composition varies greatly depending on the specific type of connective tissue, influencing its properties (e.g., flexibility, strength).

Generalized Structure of Connective Tissue

• Specialized cells: such as fibroblasts, chondrocytes, and osteocytes
• Extracellular matrix: composed of ground substance and fibers