Connective Tissue Overview

Overview

This lecture covers the structure, types, and functions of connective tissue, highlighting its diversity and importance in the human body.

Humans are physically composed of muscle, nervous, epithelial, and connective tissue.
Connective tissue consists of fewer cells and more extracellular matrix with protein fibers.
Cooking meat breaks down connective tissue, making it edible by denaturing protein fibers.

Connective tissue proper is divided into loose and dense subclasses based on fiber content.
Loose connective tissue includes areolar, adipose, and reticular tissues; it has fewer fibers and more ground substance.
Areolar tissue is common, found under epithelial layers and around organs, and acts as a watery ground substance reservoir.
Adipose tissue (fat) stores energy, insulates, and cushions; made primarily of adipocytes.
Reticular tissue forms a supporting framework for spleen, lymph nodes, and bone marrow.
Dense connective tissue has more collagen fibers and is less flexible.
Dense regular tissue, found in tendons and ligaments, aligns collagen fibers in parallel for strong, one-direction tension resistance.
Dense irregular tissue has irregular collagen fibers, providing support where tension varies (e.g., skin dermis).
Dense elastic tissue gives flexibility to areas like spinal ligaments and large arteries.

Cartilage is avascular and anervous, providing resistance to tension and compression.
Hyaline cartilage appears glassy and gives pliable support (e.g., ribs to sternum, nose).
Elastic cartilage contains more elastic fibers, allowing stretchability (e.g., ear).
Fibrocartilage is packed with collagen, acting as a shock absorber in intervertebral discs and knee joints.

Bone (osseous tissue) is calcified connective tissue, providing support and protection.
Spongy bone is porous and stores marrow; compact bone is dense and stores calcium.
Blood is a connective tissue with cells in a plasma matrix, responsible for transporting nutrients, gases, and wastes.
Blood contains erythrocytes (red blood cells), leukocytes (white blood cells), and platelets for clotting.

Extracellular Matrix — Non-cellular material surrounding cells, rich in fibers like collagen.
Areolar Tissue — Loose connective tissue with open spaces for holding fluids.
Adipose Tissue — Fat-storing tissue made up of adipocytes.
Reticular Tissue — Loose connective tissue with reticular fibers providing organ frameworks.
Dense Regular Tissue — Collagen fibers aligned in parallel; found in tendons and ligaments.
Dense Irregular Tissue — Collagen fibers arranged non-parallel for flexible support in multiple directions.
Elastic Tissue — Connective tissue with lots of elastin fibers for stretchiness.
Hyaline Cartilage — Smooth cartilage providing pliable support.
Elastic Cartilage — Stretchy cartilage with many elastic fibers.
Fibrocartilage — Tough cartilage with dense collagen, acting as a shock absorber.
Osseous Tissue — Bone tissue, either compact (dense) or spongy (porous).
Erythrocytes — Red blood cells transporting oxygen and carbon dioxide.
Leukocytes — White blood cells for immune defense.
Platelets — Cell fragments essential for blood clotting.