Compared to a "junk drawer" – contains various elements.
Made up of a matrix with collagen and elastin fibers.
Primarily about the matrix, unlike epithelial tissues which focus on cells.
Key Fibers in Connective Tissue
Collagen Fibers:
Thick, pink ropes visible under a microscope.
Made of collagen protein and provide strength.
Analogous to a non-stretchable rope.
Elastin Fibers:
Darker purple, thinner fibers.
Provide elasticity – likened to a bungee cord.
Found in lungs, skin, and blood vessels for quick recoil.
Reticular Fibers:
Made of collagen but in a different arrangement.
Surround blood vessels and some organs.
Major Cells in Connective Tissue
Fibroblasts: Most common, build collagen and elastin.
Macrophages: Large phagocytic cells, act as garbage collectors.
Mast Cells: Release heparin (prevents blood clotting) and histamine (related to allergies and inflammation).
Characteristics of Connective Tissue
Vascularity varies: can be avascular, poorly vascularized, or rich in blood supply.
Forms structural frameworks, transports nutrients, provides protection, support and interconnection, stores energy, and aids in body defenses.
Types of Connective Tissue
Areolar Connective Tissue:
Also called loose connective tissue.
Looks like a stringy mess, providing cushion and binding muscles.
Adipose Tissue:
Fat tissue, appears like marshmallows under a microscope.
Cushions, stores energy, insulates.
Reticular Tissue:
Specialized collagen, supports other tissues.
Dense Connective Tissue:
Includes tendons (muscle to bone) and ligaments (bone to bone).
Strong in one direction, like ropes.
Special Types of Connective Tissue
Cartilage:
Avascular, lacks nerves.
Types: Hyaline (most abundant, like gristle), Elastic (flexible), Fibrocartilage (strongest).
Provides cushioning and structural support.
Bone (Osseous Tissue):
Supports and protects, highly vascularized.
Composed of osteons, collagen fibers, and mineral salts.
Blood:
Liquid tissue, consists of plasma, erythrocytes (red blood cells), leukocytes (white blood cells), and platelets.
Conclusion
Connective tissues have diverse functions and structures, acting as the body's framework, protective layers, and facilitating various physiological processes.