Connective Tissue *The most abundant of the tissue types* I. Consists of: A. Cells B. Matrix ~ amorphus substance - ground substances (glycosaminoglycad.

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. osteoclastCT Cell Types:1. fibroblasts – secrete fibers; most numerous2. macrophages – phagocytic WBC

- wanders through CT to fight infections3. 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 TypesA. Loose Connective Tissue

1. Areolar Connective: 2. Adipose Connective3. Reticular Connective

B. Dense Connective Tissue1. Dense Regular2. Dense Irregular3. Elastic Connective

C. Cartilage1. Hyaline cartilage2. Fibrocartilage3. 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