Chapter 4 The Tissue Level of Organization

adipose tissue

(fat) similar to areolar tissue but contains adipocytes (fat cells) which store fat. 2 types are : white fat and brown fat brown fat is more vascularized

Classification of Connective Tissues

1. Connective tissue proper 2. Fluid Connective Tissues 3. Supporting Connective Tissues

3 types of dense connective tissue

1. Dense Regular Connective Tissue: tendons, ligaments, aponeurosis 2. Dense Irregular Connective Tissues 3. Elastic Tissue

4 major tissues of the body

1. Epithelial 2. Connective 3. Muscle 4. Neural

4 Functions of Epithelial Tissue

1. Provide Physical Protection 2. Control Permeability 3. Provide Sensation 4. Produce Specialized Secretions

exocrine glands by secretion

1. Serous glands: secrete watery solution that contains enzymes. 2. Mucous glands 3. mixed exocrine glands

3 Modes of Secretion by glandular epithelial cells

1. merocrine secretion 2. apocrine secretion 3. holocrine secretion

Three Basic Components of Connective Tissue

1. specialized cells 2. Extracellular Protein Fibers 3. a fluid, extracellular, known as ground substance

The Four Tissue Types

Epithelial, connective, muscle, and neural

Three Epithelial Shapes

Squamous, Cuboidal, and Columnar

functions of epithelia

provide physical protection, control permeability, provide sensation, and produce specialized secretions.

simple cuboidal epithelium

provides limited protection and occurs where secretion or absorption takes place. cube-shaped cells line portions of the kidney tubules

stratified columnar epithelium

relatively rare, providing protection along portions of the pharynx, epiglottis, anus and urethra, as well as along a few large excretory ducts. has two layers or multiple layers, if it has multiple layers, only the superficial cells are columnar

stratified cuboidal epithelia

relatively rare, they are located along the ducts of sweat glands and in larger ducts of mammary glands

exocrine glands

release their secretions into passageways called ducts that open onto an epithelial surface, classified by their mode of transportation

endocrine glands

release their secretions into the interstitial fluid, release endocrine (or hormones). examples: thyroid, pituitary glands

histamine

released after injury stimulates local inflammation.

merocrine secretion

releases product from secretory vesicles by exocytosis, this is the most common mode of secretion. Mucin is one type of secretion.

Hemidesmosomes

resemble half of a spot desmosome. Rather than attaching one cell to another, these attach a cell to extracellular filaments in the basement membrane. Helps stabilize the position of the epithelial cell and anchors it to underlying tissues

Holocrine secretions

secretion that destroys the gland cell. during this secretion the entire cell becomes packed with secretory products and then bursts, releasing the secretion, but killing the cell. sebaceous glands, associated with hair follicles, produce an oily hair coating by means of this secretion

cell junctions

specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials. There are 3 types: 1. tight 2. gap 3. desmosomes

muscle tissue

specialized for contraction, includes the skeletal muscles of the body, the muscle of the heart, and the muscular walls of hollow organs

lymphocytes

specialized immune cells carried by the lymphatic system-including plasma cells which produce antibodies

Mesenchymal cells

stem cells that are present in many connective tissues. these cells respond to local injury or infection by dividing to produce daughter cells that differentiate into fibroblasts, macrophages, or other connective tissue cells

glands

structures that produce fluid secretions, they are attached to or derived from epithelia

malanocytes

synthesize and store brown pigment melanin

basement membrane

the base of an epithelium are bound to this, also known as a basal lamina

ciliated epithelium

the coordinated beating of the cilia on a __________ _______ moves materials across the epithelial surface

tight junction

type of junction where the two lipid portions of two plasma membranes are tightly bound together by interlocking membrane proteins. prevents passage of water and solutes between the cells

simple columnar epithelium

typically found where absorption or secretion occurs, such as in the small intestine. protect against chemical stresses in stomach and large intestines

mucous connective tissue

wharton's jelly; a loose connective tissue found in many parts of the embryo including the umbilical cord

apical surface

where the cell is exposed to an internal or external environment (the top of the cell)

cuboidal epithelium

Type of epithelial tissue with cube-shaped cells.

columnar epithelia cells

appear rectangular. densely packed cells are hexagonal, but are taller and more slender than cells in cuboidal epithelium.

Tendons

are cords of dense regular tissue that attach skeletal muscles to bones

Macrophages

are large amoeboid cells scattered throughout the matrix. these scavengers engulf damaged cells or pathogens that enter the tissue. name means "big eater"

Microphages

are phagocytic blod cells that normally move through connective tissues in small numbers. when an infection or injury occurs, chemicals released by macrophages and mast cells attract numerous microphages to the site

glands

are secretory structures derived from epithelia

basement membrane (basal lamina)

attaches epithelia to underlying connective tissues

dense connective tissues

collagenous tissues- are the second type of connective tissue proper. they are dense because of their high collagen fiber content.

glands

collections of epithelial cells that produce secretions

tissues

collections of specialized cells and cell products that perform limited number of functions

Ligaments

connect one bone to another

Fibroblasts

connective tissue cells that produce fibrous components of extracellular matrix like collagen and elastin

cell junctions

epithelia are composed of cells bound closely together by these interconnections

Connective Tissue

fills internal spaces, provides structural support for other tissues, transports materials within the body, and stores energy reserves

Ground Substance

fills the spaces between cells and surrounds connective tissue fibers. in connective tissue proper, it is clear, colorless and viscous

dense irregular connective tissue

forms an interwoven meshwork in no consistent pattern. these tissues strengthen and support areas subjected to stresses from many directions.

hyaluronan (hyaluronic acid)

membranes of adjacent cells may be bonded by a thin layer of proteoglycans that contain polysaccharide derivatives known as glycosaminoglycans, most notably these___________

embryonic connective tissues

mesenchyme or embryonic stem cells, the first connective tissue to appear in embryos

glandular epithelium

most or all of the epithelial cells produce secretion, which are either discharged onto the surface of the epithelium

ciliated epithelium

cilia are characteristic of surfaces covered by this. these cilia beat in a coordinated manner

simple epithelium

An epithelium consisting of a single layer of cells that all touch the basal lamina. very fragile. cant provide much mechanical protection, so they are only located in protected areas of the body, they line compartments and passageways, including the ventral body cavities, the heart chambers and blood vessels. also characteristic of regions in which secretion or absorption occurs, such as the lining of the intestines and gas exchange surfaces of lungs

desmosome

At a __________CAMs and proteoglycans link opposing plasma membranes. These are very strong and can resist stretching and twisting.

fibrocytes

Second most abundant fixed cell in connective tissue proper Differentiate from fibroblasts Maintain connective tissue fibers made by fibroblasts

pseudostratified columnar epithelium

a columnar epithelium that includes several types of cells with varying shapes and functions. appears to be layered or stratified. it is not truly stratified though because every epithelial cell contacts the basement membrane. these typically possess cilia. these line the nasal cavity, the trachea, the bronchi, and portions of the the male reproductive tract

elastic tissue

a dense regular connective tissue dominated by elastic fibers.

multicellular exocrine gland

a secretory sheet, in which gland cells form an epithelium that releases secretions into an inner compartment. protects the stomach from its own acids

lumen

a space inside a tube, example; intestinal tract

capsule

a thick fibrous layer which surrounds internal organs such as the liver, kidneys and spleen and encloses cavities of joints

Adipocytes

also known as fat cells. contains a single enormous lipid droplet. squeezes the nucleic content to one side of the cell

polarity

an epithelium has an exposed surface, which faces exterior of the body or an internal space, and a base, which is attached to underlying tissues. this term refers to the presence of structural and functional differences between the exposed and attached surfaces.

transitional epithelia

an unusual stratified epithelium because, unlike most epithelia, it tolerates repeated cycles of stretching and recoiling without damage. called this because it changes in appearance as it stretches. located in urinary system, such as the bladder, where large changes in volume occur

fluid connective tissue

blood and lymph are examples of this.

basophils

blood cells that enter damaged tissues and enhance the inflammation process, also contain heparin and histamine

heparin

blood thinner

simple squamous epithelium

body's most delicate type of epithelium.

neural tissue

carries information from one part of the body to another in the form of electrical impulses

Cell Adhesion Molecules, Cell Junctions

cells can attach to other cells or to extracellular protein fibers by means of ________ or__________

connective tissue

connects the epithelium to the rest of the body. other connective tissues provide structure (bone), store energy (fat), and transport materials throughout the body (blood)

Elastic Fibers

contain the protein elastin, branched and wavy; return to original length after stretching: example: elastic ligaments of vertebrae

epithelial tissue

covers exposed surfaces, lines internal passageways and chambers and forms glands

polarity

epithelial cells may show this- an uneven distribution of cytoplasmic components

stratified squamous epithelium

generally located where mechanical stresses are severe. the cells form a series of layers, like the layers in a sheet of plywood. located on the surface skin, lining of the mouth, esophagus, and anus

reticular tissue

has a complex 3 dimensional network of supportive fibers (stroma). The stroma support functional cells (parenchyma) organs include: spleen, liver, lymph nodes and bone marrow

gap junction

in this junction, two cells are held together by two interlocking transmembrane proteins called connexons. Because these are channel proteins, they form a narrow passageway that lets small molecules and ions pass from cell to cell. these are crucial to the coordination of muscle cell contractions

multicellular glands

include glandular epithelia and aggregations of gland cells that produce exocrine or endocrine secretions

basolateral surfaces

includes both the base, where the cell attaches to the underlying epithelial cells or deeper tissues, and the sides, where the cell contacts its neighbors

Epithelial tissue

includes epithelia and glands

unicellular glands

individual secretory cells

Apocrine Secretion

involves the loss of cytoplasm as well as the secretory product. the apical part of the cytoplasm becomes packed with secretory vesicles and is then shed. Milk production in the mammary glands involves a combo of merocrine and apocrine secretions.

aponeurosis

is a tendinous sheet that attaches a broad flat muscle to another muscle or several bones of the skeleton

epithelium

is an avascular layer of cells that forms a barrier that provides protection and regulates permeability

neuroepithelia

is an epithelium that is specialized to perform a particular sensory function; contain sensory cells that provide sensations of smell, taste, sight, equilibrium, and hearing

avascularity

lacking blood vessels.

CAMs

large areas of opposing plasma membranes are interconnected by transmembrane proteins calledcell adhesion molecules, bind to each other and to extracellular materials.

collagen fibers

long, straight and unbranched. most common fibers in the connective tissue proper. tendons and ligaments are made of collagen fibers. strong and flexible they resist force in one direction.

reticular fibers

similar to collagen fibers but shaped differently. network of branching, interwoven fibers (stroma); strong and flexible; resists forces in many directions; stablilizes the positions of functional cells (parenchyma) and structures

Spot Desmosome

small discs connected to bands of intermediate filaments. These filaments function to stabilize the shape of the cell

mast cells

small, mobile connective tissue cells that are common near blood vesels. the cytoplasm of this cell is filled with granules containing histamine and heparin

dense layer

the deeper portion of the basement membrane, contains bundles of coarse protein fibers produced by connective tissue cells. gives the basement membrane its strength. also acts as a filter that determines what substances can diffuse between the adjacent tissues and the epithelium

matrix

the extracellular fibers and ground substance together, constitute this

clear layer

the layer closer to the epithelium. contains glycoproteins and a network of fine protein filaments. acts as a barrier that restricts the movement of proteins and other large molecules from the underlying connective tissue into the epithelium

areolar tissue

the least specialized connective tissue in adults. it may contain all the cells and fibers of any connective tissue proper in a very loosely organized array. viscous ground substance absorbs shock. elastic fibers return to original shape holds blood vessels and capillary beds

mucous (goblet) cells

the only unicellular exocrine glands in the body, secrete mucins. these cells are scattered among other epithelium cells

endothelium

the simple squamous epithelium lining the inner surface of the heart and all blood vessels

mesothelium

the simple squamous epithelium that lines the ventral body cavities

histology

the study of tissues

stem cells

these help epithelium cells maintain its structure over time by continually dividing. also often called germinative cells. these are located near the basement membrane

Squamous Epithelium

thin, flat and somewhat irregular in shape, like pieces of jigsaw puzzle. from the surface they resemble fried eggs laid on one side.