Connective Tissue *The most abundant of the tissue types* I. Consists of: A. Cells B. Matrix ~ amorphus substance - ground substances (glycosaminoglycad ~ repeating units of hexose(6C) sugar with nitrogen; glycoproteins - fibers (3) - provide strength and support

3 types of fibers: 1. Collagen Fibers: 60% of protein in bone and cartilage; 50-90% of dry weight of skin, ligaments, tendons, and dentine (stain pink) tough fibers found in bone, cartilage, tendons, and ligaments 2. Elastic Fibers (stain purple) -can stretch -found in skin, blood vessels, lungs 3. Reticular Fibers (stain purple) -provide support -found in blood vessels, fat cells, nerve fibers, and muscle

II. Connective Tissue features - abundant matrix with few cells - usually does not occur on free surfaces - has a nerve supply (except cartilage) - vascular (except cartilage) - may be fluid, semifluid, gelatinous, fibrous, or calcified matrix. Cells of connective tissue secrete the matrix of the tissue.

III. Connective Tissue Cells - mature cells end in -cyte Ex. osteocyte, chondrocyte - immature cells end in -blast Ex. Fibroblast, chondroblast, osteoblast - destroying cells end in -clast Ex. osteoclast CT Cell Types: 1. fibroblasts – secrete fibers; most numerous 2. macrophages – phagocytic WBC - wanders through CT to fight infections 3. Plasma Cells – secrete antibodies to aid in immunity

Cell Types, cont. 4. Mast cells – produce histamine to dilate blood vessels in reaction to injury and infection; secrete heparin to prevent excessive blood clotting 5. Adipocytes – store energy in form of fat 6. Leukocytes – white blood cells - increase in number to fight infection

IV.Connective Tissue Types A. Loose Connective Tissue 1. Areolar Connective: 2. Adipose Connective 3. Reticular Connective B. Dense Connective Tissue 1. Dense Regular 2. Dense Irregular 3. Elastic Connective C. Cartilage 1. Hyaline cartilage 2. Fibrocartilage 3. Elastic cartilage D. Osseous (bone) E. Vascular (blood)

Areolar gel-like matrix with fibroblasts, macrophages, mast cells and collagen and elastic fibers; beneath epithelium, covering ventral organs; functions in diffusion of nutrients and gases; wraps and cushions organs

Adipose Closely packed adipocytes (fat cells) with nuclei pushed to one side within matrix Location=under skin and around kidneys and eyeballs, breasts Functions: energy store, insulation, protection

Reticular Network of reticular fibers within loose ground substance and reticulocytes Location = basement membranes and lymphatic organs (lymph nodes, thymus, spleen) Function = support

Dense Regular Primarily collagen fibers (pink) with few fibroblasts (you can only see nuclei) Location = tendons, ligaments Functions = attachment, tensile strength Poor blood supply=slow to no healing

Dense Irregular Primarily collagen fibers randomly arranged Location = dermis of skin, heart valves Function = primarily provides tensile strenth

Elastic Connective Primarily elastin fibers (purple) Location – lung tissue, wall of aorta, Funciton = durability with stretch

Hyaline Cartilage Amorphous (chondroitin and glucosamine) matrix that surround cells = chondrocytes (within lacunae) Locations = embryonic skeleton, costal cartilages, cartilage of the nose, trachea, and larynx Function = support Avascular = no healing

Fibrocartilage Less firm than elastic cartilage Locations = intervertebral discs, pubic symphysis Functions = tensile strength plus shock absorber

Elastic Cartilage Amorphous matrix that surrounds cells called chondrocytes; elastic fibers present Locations = external ear, epiglottis Functions = maintenance of shape plu flexibility

Osseus (bone) Hard, calcified matrix with collagen fibers and cells = osteocytes within lacunae Location = bones of skeleton Functions = protection, support, movement, calcium store, and hematopoiesis Highly vascular = fast healing

Vascular (blood) Red cells (erythrocytes), white cells (leukocytes), and platelets (thrombocytes) in a fluid matrix called plasma Location = within heart and blood vessels Function = transport of gases, nutrients, and wastes

Skeletal Muscle Tissue Structure: long thin cells (fibers) with many nuclei; alternating areas of light and dark (striations) Locations: attached to bones Function: move bones of skeleton Control: voluntary = conscious

Cardiac Muscle Tissue Structure: network of cells with one centrally located nucleus; intercalated discs (where 2 cells meet); striations Location: heart Function: to pump blood from heart to lungs and from lungs to heart Control: involuntary = unconscious

Smooth Muscle Tissue Structure: spindle-shaped cells with one centrally located nucleus; no striations Location: walls of hollow visceral organs; walls of blood vessels; attached to hair follicles in the dermis Function: movement of food through digestive tract; vasoconstriction Control: involuntary = unconscious

Nervous Tissue Structure: Primary cells = neurons which respond to changes in their surroundings (stimuli) Neurons are surrounded by neuroglia (supporting cells) Locations:Brain, Spinal Cord, Nerves Function: Coordination or integration of body parts (to transmit signals from body parts to brain and from brain back to body parts) No reproduction of neurons, only neuroglia can divide