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.