Tissues

Four types of tissues

Organs generally have multiple tissue types

Epithelial Tissue – General Characteristics - Divides and organizes the body - Covers all body surfaces both inside and out (In between you and the outside world) -Also composes glands (structures that secrete substances like hormones, saliva, and many others) Like a balloon

Epithelial Tissue - General Characteristics - Attached to underlying connective tissue by non-cellular non-living basement membrane - No vascular tissue (blood supply) - Cells reproduce rapidly (rapid healing) - Cells tightly packed together

Epithelial Tissue - Functions Protection from physical & chemical injury Protection from microbial invasion Contains receptors which respond to stimuli Filters, secretes and reabsorbs materials Secretes fluids to lubricate structures

Epithelial Tissue Remember – form follows function! Categorized by: Number of layers: Simple = one layer Stratified = 2 or more layers Shape: Squamous = tile shaped Cuboidal = cube shaped Columnar = column shaped Remember – form follows function!

Epithelial Tissue SIMPLE SQUAMOUS single layer of very thin, flattened cells Function: diffusion and filtration Found in air sacs of lungs, walls of capillaries

Epithelial Tissue SIMPLE CUBOIDAL Single layer, cube-shaped cells Function: Secretion and absorption Found in ducts of glands

Epithelial Tissue SIMPLE COLUMNAR single layer, elongated cells Function in protection, secretion, absorption Found in the lining of digestive tract. - some columnar cells (involved in absorption) have tiny finger-like processes from their free surface called microvilli (increases surface area)

Epithelial Tissue STRATIFIED SQUAMOUS multi-layered, squamous cells Functions in protection. Found lining body cavities like the mouth and outer layer of skin

Epithelial Tissue PSEUDOSTRATIFIED – appear "stratified" but really a single layer with nuclei at various levels giving the appearance of layered cells Function is secretion and cilia-aided movement Found lining air passages like the trachea and tubes of the reproductive system Usually ciliated (tiny, hair-like projections for sweeping materials along a surface).

Epithelial Tissue TRANSITIONAL EPITHELIUM thick, layered cuboidal cells Function: "Stretchable" tissue, also forms barrier to block diffusion Found: lining of urinary bladder.

Connective Tissue General Characteristics: -Most abundant tissue in your body, found throughout -Binds structures together -Provides support, protection, insulation, framework, fills space, stores fat, produces blood cells, fights infection, and helps repair tissue. -Composed of scattered cells with abundant intercellular non-living material (matrix) -Most has a good blood supply -Cells can reproduce

Connective Tissue Types Bone Cartilage Dense Loose Blood

Connective Tissue Bone Support, protection, movement Mineral and fat storage Blood cell production

Connective Tissue Cartilage Firm but flexible 3 Types Hyaline – rubbery matrix, absorbs compression 2. Fibrocartilage – discs between vertebrae 3. Elastic – very flexible (ex. ear)

Connective Tissue Dense Connective Tissue – abundance of collagen fibers Tendons – connect muscle to bone Ligaments – connect bone to bone Fibroblasts – connective tissue cells that produce collagen

Connective Tissue Loose Connective Tissue – softer, less fibrous Areolar – holds organs in place Adipose – fat Reticular – forms scaffolding for lymph nodes

Connective Tissue Blood – transport substances Matrix = plasma

Muscle Tissue General Characteristics - Elongated cells that can shorten to cause movement

Muscle Tissue 3 Types Skeletal – muscles attached to bones, voluntary movement Smooth – muscle that surround organs, involuntary Cardiac – heart muscle, involuntary

Nervous Tissue General Characteristics - Composed of neurons which transmit signals and neuroglial cells which support neurons