Overview
This lecture reviews the structure, function, and subtypes of connective tissue, including loose and dense connective tissue, cartilage, bone, and blood.
Connective Tissue Overview
- Connective tissues originate from the same embryonic cells and are dominated by an extracellular matrix full of fibers.
- The main reason humans cook meat is to break down tough connective tissue for easier consumption.
Types of Connective Tissue Proper
- Connective tissue proper comes in loose and dense forms, based on fiber quantity in the ground substance.
- Loose connective tissue (e.g., areolar, adipose, reticular) has fewer fibers, more cells, and more ground substance.
- Dense connective tissue (e.g., tendons, ligaments) has more collagen fibers and provides strong resistance to tension.
Loose Connective Tissue Subtypes
- Areolar tissue: Most common, found under epithelial tissue and around organs; holds ground substance for tissues.
- Adipose tissue: Fat tissue, mainly adipocyte cells; stores lipids, insulates, and provides energy reserves.
- Reticular tissue: Contains reticular fibers; forms the soft framework (stroma) of spleen, lymph nodes, and bone marrow.
Dense Connective Tissue Subtypes
- Dense regular tissue: Parallel collagen fibers; found in tendons (muscle to bone) and ligaments (bone to bone).
- Dense irregular tissue: Thick, erratic fiber arrangement; found in the dermis where tension comes from multiple directions.
- Dense elastic tissue: High elasticity; found in artery walls and between vertebrae for flexibility.
Cartilage Types
- Hyaline cartilage: Most common, glassy appearance; connects ribs to sternum, found in nose tips.
- Elastic cartilage: More elastic fibers; found in ears, allows stretch and strength.
- Fibrocartilage: Thick collagen fibers; forms intervertebral discs and knee joint cushions.
Bone (Osseous) Tissue
- Bone is living, calcified connective tissue that supports and protects body structures.
- Spongy bone: Porous, found in heads of long bones, contains bone marrow.
- Compact bone: Dense, forms bone exterior, stores calcium.
Blood as Connective Tissue
- Blood connects body parts, develops from mesenchyme, and consists of cells in plasma (extracellular matrix).
- Contains erythrocytes (red cells), leukocytes (white cells), and platelets for clotting.
- Protein in plasma forms fibers during blood clotting.
Key Terms & Definitions
- Connective tissue — tissue with cells in an extracellular matrix, supports, binds, or separates other tissues.
- Extracellular matrix — nonliving material outside cells, mainly fibers and ground substance.
- Collagen — strong, fibrous protein in connective tissue.
- Areolar tissue — loose connective tissue under skin and around organs.
- Adipose tissue — fat-storage tissue with adipocyte cells.
- Reticular tissue — loose tissue with reticular fibers, forms organ stroma.
- Dense regular tissue — connective tissue with parallel collagen fibers.
- Cartilage — flexible connective tissue without blood vessels or nerves.
- Hyaline cartilage — glassy, pliable cartilage.
- Fibrocartilage — cartilage with thick collagen, resists compression.
- Spongy bone — porous bone with marrow.
- Compact bone — dense, external bone layer.
- Blood plasma — fluid matrix of blood.
Action Items / Next Steps
- Review the four primary types of connective tissue and their subtypes.
- Study the functions and locations of each connective tissue type.
- Prepare for questions on connective tissue structure and function for upcoming assessments.