tissues

tissues (location is important !!!)

  • group of cells that are similar in structure and function

epithelial tissue

  • lining, covering, glandular tissue of body functions: protection, absorption, filtration, secretion,

hallmarks:

  • special contacts | fits closely together to form continuous sheets (except for gland epi)

  • polarity | membranes have one free surface

  • apical surface | exposed to body’s exterior or cavity of internal organ; either smooth, or has microvilli or cilia (look into basal surface)

  • supported by connective tissue

  • basement membrane | under epithelium; acts as glue

  • avascular, but innervated | epithelial tissue has no blood supply; gains nutrients through diffusion (other tissues)

  • regeneration | more nourished, more regeneration

classification (naming) (note: naming is based of top layer):

  1. cell arrangement

  • simple (one layer of cells)

  • stratified (more than one layer)

  1. by shape of cell

  • squamous cell (flat like fish scale)

  • cubodial (?)

  • …

classification of epithelia:

simple epithelia

  • concerned with absorption, secretion, filtration; very thin not for protection

  1. simple squamous epithelium | forms membrane where filtration/exhange happens through rapid diffusion

  • air sacs of lungs (alveoli), walls of capillaries, serous membranes

  1. simple cuboidal epithelium | common in glands and their associated small tubes (ducts)

  2. simple columnar epithelium | lines digestive tract of stomach to anus; absorption and secretion

  • goblet cells - produces lubricating mucus

  1. puesdostratified columnar epithelium | all cells in class rest in basement membrane variation: ciliated columnar epithelium - important for respiratory tract; works with goblet cells by propelling mucus forward to expel

stratified epithelia

  • more than one layer; protection

  1. stratified squamous epithelium | most common in body; at the free edge (apical)

  • found in sites that get friction or abuse (skin, mouth, esophagus)

  1. stratified cubodial and columnar epithelium | works in secretion/absorption; rare and only two cell layers

  • found in sweat glands, esophogal glands, uretheal glands note: lumen = empty space

  1. transitional epithelium | changes from one shape to another

  • found in urinary bladder, ureters, part of urethra (storing piss) (from cubodial to squamous [stretching])

  1. glandular epithelium | consists of one or more cells that make/secrete particular product (enzymes, hormones, oil, sweat); contains protein molecules in aqueous fluid

secretion

  • active process where glandular cells obtain materials from blood to make their products, discharged by exocytosis

glandular tissue

  1. endocrine gland | ductless, secretion (all hormones) diffuse directly into blood vessels ex. thyroid gland, adrenals, pituitary gland

  2. exocrine gland | retains ducts, secretions exit through ducts to epithelial surface; functions both externally and internally ex. sweat and oil glands

connective tissue

  • most abudant tissue; widely distributed around body

  • connects body parts, protecting supporting and binding other body tissues ex. blood (delivering nutrients to other parts of body)

hallmarks of connective tissue:

  • common origin | all are embryonic tissue, (mesenchyme)

  • variation in blood supply | MOST connective tissue are well vascularized exceptions: tendons and ligaments (poor blood supply), and cartilage (avascular)

  • extracellular matrix | connective tissue made up of different amounts of nonliving substances found OUTSIDE of cel ground substance - compoased of water + cell adhesion

  • cell adhesion proteion - allows ctissue to attch to matrix fibers

  • charged polusaccharide - trap water as they intertwine fibers - various types and amounts of fibers contribute to the matrix collagen (white) fibers elastic (yellow) …

types of connective tissue:

  • bone (osseous tissue)

  • major cell type osteocytes/fibers (bone cells) in lacunae (pits) function: support, …

  • cartiliage

  • less hard more flexible than bone; major cell type: chondrocytes (cartilage cells)

    types of cartilage

    1. hyaline cartilage - most seen type; has abundat collage fibers with rubbery matrix

    2. fibrocartilage - highly compressible (flexible); forms cushion-like discs

    3. elastic cartilage - structure with elasticty; examples are external ear (auricle), eustachian tube, epiglottis

  • dense connective tissue

  1. dense regular fibrous tissue

  • majority is collagen fibers, rows of fibroblast that withstands tension in one direction tendions | attch skeletal muscle to bones ligaments | connects bones to bones at joints aponeuroses | attach muscle to muscle or muscle to bone; sheet-like tendons

  1. dense irregular connective tissue

  • located in fasciae (tissue beneath skin and around muscle and other organs), reticular region, periosteum of bone, pericondriom of cartilage, … can go many directions

  • loose connective tissue

  • more cells than fibers compared to other connective tissues except blood types of loose connective tissue

  1. areolar (small, open spaces) connective tissue

  • soft, pliable, ‘cobwebby’ tissue that cushions and protects body organs

  • universal packing and connective tissue ‘glue’

  • underlies all mucous membrane

  • …

  • resoviour of water and salts of surrounding tisue; obtains and release nutrients/waste into this tissue

  • many phagocytes

  • edema; when body is inflamed, areolar tissue soaks up fluid and become puffy

  1. adipose connective tissue (fat)

  • insulates the body and protects it from bumps and extremes of both heat and cold contains oil

  • fule or energy in fat depots (hips, and breats, belly)

  1. reticular connective tissue

  • internal framework; ‘cellular bleachers’ where cells go to rest

  • blood (vascular tissue)

  • consists of blood cells surrounded by nonliving, fluid matrix (blood plasma); fibers are soluble proteins; atypical - not typical, uncommon function: transport vehicle

muscle tissue

  • highly specialized to contract, or shorten; generates force to produce movement

  • muscle must be irritable to respond to stimuli

types of muscle tissue:

  1. skeletal muscle tissue/fiber

  • voluntarly, consciously controlled

  • forms the flesh of the body; muscular system

  • contract = pull on bobnes or skin cell characteristics: long, cylindrical, multinucleate, have obvious striations (stripes)

  1. cardiac muscle

  • found only in heart wall

  • pumps blood

  • involuntary cell characteristics: striated, only having SINGLE nucleus, relatively shorter, branching intercalacted discs - passageway for charged ions

  1. smooth (visceral) muscle

  • no striations seen, single nucleus, tapered (point edge)

  • found in walls of hollow organs (stomach, uterus, blood vessels)

nervous tissue

  • composed of neurons and neuroglia

  1. neurons

  • receives and sends electrochemical impulses form one part of body to another function: irribitability (respond to stimuli) and conductivity (receive stimuli)

  • cytoplasm has long processes/extensions reaching 3 feet or more in leg for SINGLE NEURON to conduct inpulse to distant body location

  • neurons DONT regenerate

  1. neuroglia

  • special group of supporting cells helping neurons

  • insulate, support, protect the delicate neurons