TISSUES

Tissues Cells are organized into sheets or groups called tissues. There are four major tissue types found in the body: – epithelial tissue (ET) – connective tissue (CT) – muscle tissue – nervous tissue

Epithelial Tissue (ET) Epithelia are sheets of cells that function in protection, secretion, absorption, and excretion. Epithelium is composed of tightly packed cells anchored to a basement membrane. It lacks blood vessels and rapidly divides. ET are classified by cell shape and number of cell layers.

Structure Location Function thin, single cell diffusion, cushion air sacs, blood vessels

Structure Location Function boxy, single cell absorption, secretion kidneys, ducts of glands

Structure Location Function tall, single cell protection, secretion, absorption digestive tract

Structure Location Function tall, un- uniform single layers protection, secretion trachea fallopian tubes

Structure Location Function flat, multi- layered protection, keep out anything “unwanted” keratinized – epidermis non- keratinized – mouth, anus

Structure Location Function shape changing, single layer shape changing, stretching urinary bladder

Connective Tissues (CT) Connective tissue is the most abundant tissue in the body. Extracellular material, a matrix, makes up the bulk of the tissue. Matrix is composed of fibers and ground substance. Connective tissue cells usually can divide.

NAMEDESCRIPTIONLOCATIONFUNCTION MESENCHYMEprecursor matrixEmbryogives rise to all other CT’s AREOLARgel-like matrix with fibroblasts, collagen and elastic fibers beneath ET (serous membranes around organs & lining cavities) cushions, diffusion, inflammation ADIPOSEclosely packed adipocytes with nuclei pushed to side beneath skin, breasts, around kidneys & eyeballs insulation, energy store, protection RETICULARreticular net of fibers in loose matrix; lymphocytes and reticulocytes basement membrane, lymph organs support DENSE REGULAR dense matrix of collagen fibers tendons, ligamentsattachment (high tensile strength) DENSE IRREGULAR loose matrix of collagen fibers dermis of skintensile strength ELASTIC CTmatrix of elastic fiberslung tissue, wall of aortadurability with stretch HYALINE CARTILAGE chondrocytes in lacunae in amorphous matrix embryo skeleton, costal cartilage, tip of nose, trachea, larynx support FIBRO- CARTILAGE less firm than aboveintervertebral discs, pubic symphysis tensile strength, shock absorber ELASTIC CARTILAGE above plus elastic fibersexternal ear, epiglottisshape maintenance plus flexibility BONEconcentric circles of calcified matrix bonessupport, protection, movement, Ca ++ store, hematopoiesis BLOODred and white cells; platelets in plasma in heart, and blood vesselstransport of nutrients, wastes & gases

CT Cell Types Three types of CT cells… – Fibroblasts – Macrophages – Mast Cells

Loose Connective Tissue Loose CT or areolar tissue binds organs together and holds tissue fluids. It forms thin membranes found beneath the skin, between muscles, and beneath epithelial tissue.

Reticular Connective Tissue Reticular connective tissue supports organs.

Dense Connective Tissue Dense connective tissue binds organs together. It is found in tendons, ligaments, and the dermis of the skin. *CONTAINS COLLAGEN

Elastic Connective Tissue Elastic connective tissue supports, protects, and provides a flexible framework. It connects vertebrae and is found in the walls of arteries and airways.

Adipose Tissue Adipose tissue protects, insulates, and stores fat in droplets inside the cells. It is found beneath the skin, around the kidneys, behind the eyes, and on the heart.

Cartilage (CT) Cartilage is a rigid connective tissue. Cartilage lacks blood vessels. Thee types of Cartilage… – Hyaline cartliage – Elastic cartliage – Fibrocartliage

Bone Bone supports, protects, provides a framework for muscle attachment.

Blood Blood transports gases, nutrients, and wastes, defends against disease, and acts in clotting.

Muscle Tissue (MT) There are three types of muscle tissue: skeletal, smooth, and cardiac. Properties: It is contractile (muscle fibers can shorten and thicken). It is excitable.

Structure Location Function found in bundles, contracts movement on the skeleton – whole body

Structure Location Function thin, smooth, tapered peristalsis digestive tract

Structure Location Function thick, with striated bands keep heart beating – does not tire easy heart

Nervous Tissues Nervous tissue is excitable like muscle tissue. It is found in the brain, spinal cord, and peripheral neurons. Nerve cells or neurons sense changes and transmit signals.