Connective Tissue Functions and Characteristics

Study Notes

Connective tissue provides structure to tissues and organs (e.g., bones, ligaments).
It protects organs by providing immune defence, wound healing, and cushioning.
It facilitates transport of nutrients, water, and waste products (e.g., blood).
It insulates and stores energy (e.g. fat tissue).
Connective tissue is composed of cells, fibers, and an extracellular matrix (ECM).

The ECM is a gel-like substance surrounding and supporting cells.
It's composed of water, proteins, glycoproteins, and glycosaminoglycans.
The ECM provides structural integrity and facilitates transport of nutrients and waste.
Its properties differ depending on the tissue type (e.g., calcified in bone, flexible in cartilage).

Fixed cells:
- Fibroblasts: produce and maintain fibers (collagen, elastic) and ECM.
- Adipocytes: store fat for energy, insulation, and cushioning.
- Macrophages: engulf pathogens and dead cells (immune defense).
- Mast cells: release histamine during allergic reactions, contributing to inflammation.
Transient cells:
- Plasma cells: produce antibodies to combat infections.
- Eosinophils: combat parasites and participate in allergic responses.

Collagen fibers: thick fibers providing tensile strength, resisting stretching; abundant in tendons and ligaments.
Elastic fibers: thin fibers allowing tissues to stretch and recoil; found in skin, lungs, and arteries.
Reticular fibers: thin, branching fibers forming a mesh-like structure supporting soft tissues like spleen and lymph nodes.

Connective Tissue Proper:
- Loose connective tissue (Areolar): binds skin to underlying structures, supports blood vessels.
- Loose connective tissue (Adipose): stores fat, insulates the body, cushions organs.
- Loose connective tissue (Reticular): supports lymphoid organs (e.g., spleen, lymph nodes).
- Dense Regular Connective Tissue: parallel collagen fibers for strength (tendons, ligaments).
- Dense Irregular Connective Tissue: densely packed fibers in random directions for strength (dermis).
- Elastic Connective Tissue: contains mostly elastic fibers for stretch and recoil (arteries, lungs).
Specialized Connective Tissue:
- Cartilage (hyaline, fibrocartilage, elastic).
- Bone (compact and spongy bone).
- Blood: transports oxygen, nutrients, waste; involved in immune defense and clotting.