Tissues
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Four primary tissue types
epithelial: covering, connective:support, muscular:movement, nervous:control
Histology
study of tissues
study of tissues
a sheet of cells that covers a body surface or lines a body cavity
location of epithelial tissues
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function of epithelial tissue
protection, absorption, filtration, excretion, secretion, sensory reception
epithelial tissue
all cells in the layer usually have the same shape
stratified epithelial
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stratified epithelia
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simple epithelia
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pseudostratified columnar epithelium
function: secretion mucus propulsion of mucus by ciliary
actionlocation: trachea
simple cuboidal epithelium
Function: secretion and absorption Location: Kidney
tubules; ducts and secretory portions of small glands, ovary surface.
simple columnar epithelium
Function: Absorption; secretion of mucus, enzymes, and other
substancesLocation: nonciliated type lines most of the digestive
tract (stomach to anal canal).
stratified squamous epithelium
Function: protects underlying tissues in areas subject to abrasion
Location: nonkeratinized type forms the moist lining of the
esophagus, mouth, and vagina
stratified cuboidal epithelium
Function: protection
Location: Largest ducts of sweat glands, mammary glands, and
salivary glands.rare
stratified columnar epithelium
found in limited distributiononly its apical later of cells is columnar
transitional epithelium
function: stretches readily and permits distension of urinary organ
by contained urine
Location: lines the ureters, urinary bladder, and part of the urethra
glandular epithelia
A gland is one or more cells that makes and secretes an aqueous
fluid-endocrine:internally secreting-exocrine: externally secreting
endocrine glands
produce hormones: regulatory chemicals that they secrete by
exocytosis directly into the extracellular spaceductless glands
exocrine glands
secrete their products onto body surfaces (Skin) or into body
cavitiesunicellular glands directly multi cellular glands
via duct that transports the secretion to epithelial surface
unicellular exocrine glands
unicellular gland is the goblet cellshaped like a goblet
pseudostratified columnar epithelium unicellular exocrine glands
function: secretion particulary of mucus location nonciliated
type in males sperm carrying ducts of large glands
multicellular exocrine glands
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multicellular exocrine glands
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connective tissue
Found everywhere in the body Four functions: connective tissue
propercartilagebone tissue blood
connective tissue functions
binding and support protectioninsulation transportation
common characteristics of connective tissue
1. common origin2. degrees of vascularity3. extracellular matrix
embryonic connective tissue
function: gives rise to all other connective typeslocation: embryo
Structural Elements of Connective Tissue
unstructured material that fills the space between the cells and
contains the fiberscomposed: interstitial (tissue) fluid
ground substance
holds large amounts of fluid and functions as a molecular sieve, or medium
collagen fibers
strongest and most abundant, bundles of protein-
fibrocartlidgecollagen fibers are extremely strong and provide
high tensile strength
elastic fibers
long, thin fibers that form branching networks in the extracellular
matrixcontain a rubber like protein elstin that allows them to
stretch and recoil like rubber bands found where elasticity is
needed; skin, lungs, blood vessel walls
reticular fibers
fine, collagenous fibers whose networks surround and support the soft
tissue of organs, and stabilize the positions of functional cells
cartilage
tough but flexiblelacks nerve fibers and is avascular
contains firmly bound collagen fibers and in some cases elastic
fibers and in some cases elastic fibers matrix contains an
exceptional amount of tissue fluid 80% water
cartilage
avascular and aging cartilage cells lose their ability to divide,
cartilages heal slowly when injuredcartilages tend to calcify or
even ossify (bony)
types of bone tissues
osteoblasts;immature bone cellsosteocytes; mature bone cellsvascularized
type of blood tissues
blood is classified as a connective tissues because it developed from
mesenchyme consists of blood cells and plasma proteins
surrounded by blood plasma
nervous tissue
Nervous tissue is the main component of the nervous
systemscomposed of two types of cells neurons are
specialized cells that generate and conduct electrical impulses
supporting cells are non conductive cells that support, insulate
and protect neurons
ground substance
unstructured material that fills the space between the cells and
contains the fiberscomposed: interstitial (tissue) fluid