Chapter 4: Tissues The Living Fabric

Tissues: A grp of cells that perform the same function Differ in: Size & shape Amt & kind of matrix (stuff btw the cells) Functions they perform

Tissues are held together by intercellular junctions Gap junctions Desmosomes Tight junctions

Embryonic Dvlpt: The 4 major tissues of the body appear in the 1st 2 months after conception of the embryonic period After fertilization, the zygote will begin cont. cell divisions to form a blastocyst (hollow ball of cells)

The blastocyst implants in the uterus, where in 2 wks the cells will move & regroup into the 3 primary germ layers – gastrulation – the layers are: a.) endoderm – becomes the inner organs b.) mesoderm – becomes the muscles c.) ectoderm – becomes the skin & nervous system

4 Types of Tissues Epithelial – covers the body & lines body cavities Packed close together w/ little matrix Divided into membranous & glandular Functions are: Protection d.) Absorption Sensory e.) Excretion Secretion

Types: Membranous – classified according to: shape a.) squamous – squiggly shaped cells b.) cuboidal – cube shaped cells c.) columnar – column shaped cells d.) pseudostratified columnar – 1 layer of odd shaped cells

Arrangement a.) simple – 1 layer of the same shape b.) stratified – many layers of the same shape c.) transitional – several layers of diff shaped cells

Types of Epithelial Tissue: Simple Squamous Epithelium Simple Cuboidal Epithelium Simple Columnar Epithelium Pseudostratified Columnar Epithelium Stratified Squamous Epithelium Stratified Cuboidal Epithelium Stratified Columnar Epithelium Transitional Epithelium Glandular Epithelium

Glands!!! Consists of 1 or more cells that make & secrete a particular product Classified as: Endocrine – internally secreting – ex.) hormones Exocrine – externally secreting – more numerous – diverse in their product – ex.) mucus, milk, sweat, oil

Exocrine contains: Apocrine – milk producing mammary glands Holocrine – oil glands Merocrine – salivary glands

4 Types continued… 2. Connective Tissue – most abundant & widely distrib - many types, appearances & functions - few matrix cells – contains 1 or more A.) collagenous fibers – tough B.) reticular fibers – delicate C.) elastic fibers - extensible

Functions are: Connects Supports Transports Defends

- Types of connective tissue: A.) Loose, ordinary (areolar) – contains: 1.) areolar – “glue” that holds organs together – area btw other tissues & organs 2.) adipose – “fat” – under the skin – used for padding & insulation 3.) reticular – 3-D web – filters harmful substances out of the blood & lymph 4.)dense fibrous – tendons, scars, ligaments, fascia, & dermis

B. )Bone – calcified matrix – support & protection C B.)Bone – calcified matrix – support & protection C.) Cartilage – matrix has the consistency of firm plastic or gristle-like gel – nasal septum, trachea rings D.) Blood – fluid matrix - transportation

4 Types continued…. 3. Muscle Tissue – 3 types a.) Skeletal Muscle – - attached to bones - striated voluntary - striations are visible b.) Cardiac Muscle – - striated involuntary - compose heart wall

C.) Smooth Muscle – - nonstriated (visceral) or involuntary - no cross striations - found in blood vessels & other tube shaped organs

4 Types cont…. 4.) Nervous Tissue – rapid communication btw body structures & control of body functions - 2 cell types a.) Neurons – conducting cells - composed of: 1.) cell body 2.) one axon – carries impulses away from cell body 3.) 1 or more dendrites – carries nerve impulses toward the cell body b.) Neuroglia – supports & connects neurons

Tissue Repair: usually accomplished by means of regeneration of tissue epithelial tissues readily regenerate collagen fibers to fill gaps connective tissue also regenerates muscle & nerve tissues have very limited abilities to repair themselves spinal cord damage results in permanent disability

Inflammatory Response: Redness Swelling Pain Heat ***Can determine if tissue will regenerate

Tissue Regeneration

See Handout!!!! Tumors

Tumors of the Tissues:

Cancers of the Tissues: