tissues - edl · common characteristics extracellular matrix- many different types of cells plus...
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Tissues
Tissues
Group of cells that are similar in structure
and function
4 primary types
● Epithelium (covering)
● Connective (support)
● Nervous(control)
● muscle(movement)
Epithelial tissue (epithelium)
Lining, covering, and glandular tissue of the
body
Functions: protection, absorption,
filtration, and secretion
Special characteristics of epithelium - Cells fit closely together to form continuous
sheets
- Membranes have one free surface (apical surface)
which is exposed to body’s exterior or cavity
- Lower surface of epithelium rests on a basement
membrane (structureless material secreted by
cells)
- No blood supply of their own (avascular) and
depend on diffusion from capillaries in the
underlying connective tissue
- Regenerate easily if well nourished
Classification of epithelium
Simple epithelium- one layer of cells- most
concerned with absorption, secretion, and
filtration (not protection)
Stratified epithelium- more than one layer of
cells- function primarily to protect
shapes
Squamous cells- flattened cells like fish
scales
Cuboidal cells- cube-shaped like dice
Columnar cells- shaped like columns
Combine these with simple and stratified to
describe the epithelium fully
Simple epithelium Simple squamous epithelium-
single layer of thin
squamous cells resting on a
basement membrane- usually
forms membranes where
filtration or exchange
occurs by rapid diffusion-
also forms serous membranes
that line ventral body
cavity and cover the organs
in that cavity
Simple epithelium
Simple cuboidal
epithelium- 1 layer of
cuboidal cells resting
on a basement
membrane- common in
glands or ducts- forms
walls of kidney
tubules and surface of
ovaries
Simple epithelia Simple columnar epithelium-
single layer of tall cells that
fit closely together- lines
entire length of the digestive
tract
Goblet cells- produce lubricating
mucus are often seen here
Mucosae (mucous membranes)-
epithelial membrane that line
body cavities open to exterior
Simple epithelia
Pseudostratified
columnar epithelium- all
cells rest on basement
membrane but some are
shorter than others
giving it the false
appearance that it is
stratified- main
function is absorption
and secretion
Stratified epithelia Stratified squamous- most
common stratified in the
body- several layers of
cells- at the free edge are
squamous but at basement are
cuboidal or columnar - found
where abuse or friction
occurs (mouth, esophagus,
skin)
Stratified epithelia
Stratified cuboidal- usually has just
2 cell layers with at least the
surface cells being cuboidal in shape
Stratified columnar- columnar cells
but base cells vary in size or shape
Both are fairly rare in body being
found mainly in ducts of large glands
Stratified epithelia
Transitional epithelium- highly modified
squamous epithelium that forms the lining of
only a few organs (bladder, ureters, and part
of urethra due to considerable stretching)-
cells of the basal layer are cuboidal or
columnar; near free surface vary in
appearance- when organ is stretched the cells
become squamous like
Glandular epithelium
Gland- consists of one or more cells that
make and secrete particular products
Secretion- product secreted that typically
contain protein molecules in an aqueous
(water-based) fluid
2 major types of glands Both develop from epithelial sheets
Endocrine glands- lose their connection the surface
(duct)- secretions (hormones) diffuse directly into
the blood vessels that weave through the gland-
(thyroid, adrenals, pituitary)
Exocrine glands- retain ducts and secretions empty
through ducts into epithelial surface- (sweat and
oil, liver)
Connective tissue
● Connects body parts
● Found everywhere in the body
● Most abundant and widely distributed of the
tissue types
Common characteristics of connective tissue
● Variations in blood supply
○ Most are well vascularized
○ Exceptions: tendons and ligaments have
poor blood supply, cartilages are
avascular
■ Consequently takes longer to heal
Common characteristics
Extracellular matrix- many different types of cells
plus varying amounts of a nonliving substance found
outside the cells
Produced by the connective tissue cells then secreted
to their exterior
Can be liquid, semi-solid/gel-like, or solid
Because of this connective tissue is able to bear
weight to withstand stretching or other abuses
characteristics
Fibers- various types and amounts are
deposited in and form part of the matrix
material
Collagen (White) fibers
Elastic (yellow) fibers
Reticular (fine collagen) fibers
characteristics
Performs many functions:
● Protecting
● Supporting
● Binding together other body tissues
Types of connective tissue
Bone- (osseous) composed of bone cells siting
in cavities (lacunae) and surrounded by
layers of very hard matrix that contains
calcium salts in addition to large numbers of
collagen fibers
Exceptional ability to protect and support
cartilage
less hard and more flexible than bone
Found only a few places in the body
Hyaline- most widespread and has abundant
collagen fibers hidden in a matrix with a blue-
white appearance
● Forms supporting structures of the larynx,
attaches ribs to breast bone, covers ends of
bones where they form joints
cartilage
Elastic- found where structure with
elasticity is desired
Supports the external ear
Fibrocartilage- highly compressible- between
the vertebrae of the spinal column
Dense connective tissue (Dense fibrous tissue)
Collagen fibers are in matrix element- between collagen are
rows of fibroblasts
Forms strong, ropelike structures such as tendons and
ligaments; also lower layers of the skin
Tendons- attach skeletal muscles to bones
Ligaments- connect bones to bones at joints- more stretchy
and contain more elastic fibers
Loose connective tissue
Softer and have more cells/fewer fibers than
any other connective tissue except blood
Areolar tissue- wraps organs and protects
them
● edema= body region is inflamed areolar
tissue soaks up the excess fluid and swells
Loose connective tissue
Adipose tissue- commonly called fat- tissue
where cells predominate- cells filled with
oil
Forms subcutaneous tissue beneath the skin
to insulate the body- also surrounds some
organs
Reticular connective tissue
Consists of a delicate network of reticular
fibers with reticular cells
Limited at certain sites
Forms the stroma- internal supporting
framework which supports many free blood
cells in lymphoid organs
blood
Vascular tissue
Consists of blood cells surrounded by
nonliving, fluid matrix called blood plasma
Fibers are soluble protein molecules that are
visible only when blood clotting
Muscle tissue
Highly specialized to contract or shorten to
produce movement
Types:
● Skeletal- striated, voluntary, multinucleate
● Cardiac- only in heart, striated, uninucleate,
involuntary
● Smooth- no striations- uninucleate, stomach,
bladder, blood vessels, involuntary
Nervous tissue
Commonly called neurons- receive and conduct
impulses from one part to another
(irritability and conductivity are the 2
major functional characteristics)
Make up the nervous system (brain, spinal
cord, and nerves)
Name these structures!
A:
Fibroblas
ts
B:
Collagen
fibers
C:
Elastin
Fibers
Tendon
Stratified
Squamous
Adipose
tissue
Transitional
epithelium
Simple
columnar
Reticular
fibers
Bone tissue
osseous
Hyaline
cartilage
Simple
cuboidal
blood
Skeletal muscle
tissue
Elastic cartilage
Pseudostratified columnar epithelium
Nervous
tisse
Smoothe
muscle
tissue
Stratified
cuboidal
epithelium
Reticular tissue
fibrocartilage
ligament
Simple squamous
Cardiac
muscle
Stratified
columnar
Areolar
tissue