CONNECTIVE TISSUE p.110

Connective Tissue Most widespread tissue Fat, cartilage, rigid bones, fluid Found in nearly every organ of the body Made up mostly of matrix with relatively few cells Qualities of the matrix and fibers largely determine the structural characteristics of each type of connective tissue

Classification of connective tissue Fibrous Bone Cartilage Blood

Fibrous connective tissue Have extracellular fibers as their predominant feature Strengthen and support CT Arrangement of the fibers is what makes each type different

Fibrous connective tissue 3 Fiber types: collagenous, elastic, and reticular Collagen=very strong, but flexible Most abundant (bone, cartilage, and tendons) Elastic=property of elasticity Can stretch 150% from original shape without damage Reticular=support tissues & organs Frame soft organs (fat)

Fibrous connective tissue Loose (areolar) It forms the subcutaneous layer Layer under the skin that connects skin to tissues and organs Made of collagen, elastic, and reticular fibers Fibroblasts: produce a gel-like substance Creates the extracellular matrix Macrophages: carry out phagocytosis

Loose CT Elastic fiber (black) Collagen fiber (Pink) Fibroblast cells (purple)

Fibrous connective tissue Adipose (fat) Storage for excess food Specialized for storage of triglyceride Insulating material Reduces heat loss through skin Support and protection fatty tissue layer over internal organs in anterior abdominal region

Fat storage area Nucleus of adipocyte Blood vessel

Fibrous connective tissue Reticular (Loose CT) Forms the framework of the liver, spleen, and lymph nodes Help defend against invaders Fibers in spleen filter and remove blood cells Fibers in lymph filter and remove bacteria

Nucleus of reticular cell Lymph Node Reticular fiber

Fibrous connective tissue Dense Made mostly of fibers packed densely in the matrix Regular: fibers are in parallel rows Flexible, but great strength Examples: tendons, ligaments Irregular: the bundles are NOT parallel Intertwine and form a thick material Can withstand stress from any direction Example: dermis and pericardium

Nucleus of fibroblast Tendons Collagen fiber Periosteum – membrane surrounding bone fibroblast Collagen fiber

Bone connective tissue One of the most highly specialized CTs Osteocytes: mature bone cells Contain Osseous Tissue: Spongy Bone or Compact Bone

Bone connective tissue Function Provide protection and support Point of attachment for muscles Helps move muscles Serves as a mineral reservoir Yellow marrow stores triglycerides Blood production Red marrow creates RBCs

Calcified extracellular matrix Humerus Lacuna (outer space of osteocyte)

Cartilage connective tissue Chondrocyte (cartilage cells) – found in lacunaes Avascular, so they receive nutrients through diffusion No blood vessels = no blood supply Perichondrium – membrane that allows for diffusion Covers the surface of most cartilage Heals very slowly if at all due to method of nutrient delivery

Cartilage connective tissue 3 types: 1. Hyaline: most abundant and weakest very flexible and supportive, also reduces friction 2. Fibrocartilage: strongest Serve as shock absorbers (ball & socket joints) 3. Elastic: contain very fine elastic fibers to add strength and flexibility (nose, ears, epiglottis, larynx)

trachea, nose, bronchi, etc Hyaline: trachea, nose, bronchi, etc Elastic: Ear & Epiglottis Fibro: Discs between vertebrate, menisci of knee, etc

Blood connective tissue Most unusual connective tissue contains neither ground substance nor fibers Moves O2 and CO2 (RBCs) Maintains body temp and regulates pH Helps defend body (WBC) Liquid part 55% (plasma) Cells 45% (erythrocytes, leukocytes, thrombocytes)

Platelet WBC RBC Plasma