tissues Flashcards
groups of specialized cells and the extracellular
substances surrounding them.
tissues
the microscopic study of tissue structure
histology
four primary tissue types
(1) epithelial tissue, (2) connective tissue, (3) muscle tissue, and (4)
nervous tissue
found
virtually everywhere, both inside and outside the body.
Epithelium
especially important in hollow organs with openings
to the outside environment, because it protects against foreign materials
entering the body
epithelium
one surface of their cells is in direct contact with either the outside environment
or the contents of our hollow organs. The surface that is exposed is called the ________
surface.
free surface, or apical (A-pi-kal)
surface
The surface of the cells that is anchored in place is
called the
basal surface
attaches the epithelial cells to
underlying tissues.
basement membrane
Found throughout the body where it covers internal
and external surfaces. It also forms most of the glands.
EPITHELIAL TISSUE
EPITHELIAL TISSUE: FUNCTIONS
- Protecting underlying structures
- Acting as barriers
- Permitting the passage of substances
- Secreting substances
- Absorbing substance
consists of a single layer of cells, with each cell extending
from the basement membrane to the free surface
simple epithelium
consists of more than one layer of cells, but only the
deepest layer of cells attaches to the basement membrane.
Stratified epithelium
is a special type of simple epithelium.
The prefix pseudo- means false, so this type of epithelium appears to be
stratified but is not. It consists of one layer of cells, with all the cells attached to
the basement membrane. There appear to be two or more layers of cells because
some of the cells are tall and extend to the free surface, whereas others are
shorter and do not extend to the free surface
Pseudostratified columnar epithelium
cells are flat or scalelike.
Squamous
cells are cube-shaped—about as wide as they are tall.
cuboidal
cells tend to be taller than they
are wide
columnar
Diffusion, filtration, some
secretion, and some
protection against friction
Simple Squamous Epithelium
Single layer of flat, often
hexagonal cells; the nuclei
appear as bumps when
viewed in cross section
because the cells are so flat
Simple Squamous Epithelium
Secretion and absorption
by cells of the kidney
tubules; secretion by cells
of glands and choroid
plexuses; movement of
particles embedded in
mucus out of the terminal
bronchioles by ciliated cells
Simple Cuboidal Epithelium
Structure:
Single layer of cube-
shaped cells; some cells
have microvilli (kidney
tubules) or cilia (terminal
bronchioles of the lungs)
Simple Cuboidal Epithelium
Single layer of tall, narrow
cells; some cells have cilia
(bronchioles of lungs,
auditory tubes, uterine
tubes, and uterus) or
microvilli (intestines)
Simple Columnar Epithelium
Movement of particles out
of the bronchioles of the
lungs by ciliated cells;
partially responsible for
the movement of oocytes
through the uterine tubes
by ciliated cells; secretion
by cells of the glands, the
stomach, and the
intestines; absorption by
cells of the intestines
Simple Columnar Epithelium
Structure:
Single layer of cells; some
cells are tall and thin and
reach the free surface, and
others do not; the nuclei of
these cells are at different
levels and appear
stratified; the cells are
almost always ciliated and
are associated with goblet
cells that secrete mucus
onto the free surface
Pseudostratified Columnar Epithelium
Synthesize and secrete
mucus onto the free
surface and move mucus
(or fluid) that contains
foreign particles over the
surface of the free surface
and from passages
Pseudostratified Columnar Epithelium
Structure:
Several layers of
cells that are
cuboidal in the
basal layer and
progressively
flattened toward
the surface; the
epithelium can
be
nonkeratinized
(moist) or
keratinized; in
nonkeratinized
stratified
squamous
epithelium, the
surface cells
retain a nucleus
and cytoplasm;
in keratinized
stratified
epithelium, the
cytoplasm of cells
at the surface is
replaced by a
protein called
keratin, and the
cells are dead
Stratified Squamous Epithelium
the surface cells
retain a nucleus
and cytoplasm
nonkeratinized
stratified
squamous
epithelium
the
cytoplasm of cells
at the surface is
replaced by a
protein called
keratin, and the
cells are dead
keratinized
stratified
epithelium
Function:
Protects against
abrasion, forms a
barrier against
infection, and
reduces loss of
water from the
body
Stratified Squamous Epithelium
outer layer of the
skin;
Keratinized
mouth, throat,
larynx,
esophagus, anus,
vagina, inferior
urethra, and
corneas
nonkeratinized
Stratified cells
that appear
cuboidal when
the organ or tube
is not stretched
and squamous
when the organ
or tube is stretched by fluid
transitional epithelium
Function:
Accommodates
fluctuations in
the volume of
fluid in an organ
or a tube;
protects against
the caustic
effects of urine
transitional epithelium
a single layer of thin, flat cells. Some substances easily pass through this thin layer of cells, but other
substances do not.
Simple squamous epithelium
a single layer of cubelike cells that carry out active transport, facilitated diffusion, or secretion.
simple cuboidal epithelium
single layer of tall, thin cells. The large size of these cells enables them to perform complex
functions.
Simple columnar epithelium
actually a single layer of
cells, but the cells appear to be layered due to the differing heights of adjacent
cells and positions of their nuclei. This epithelium provides protection for the
body
Pseudostratified columnar epithelium
forms a thick epithelium because it
consists of several layers of cells. The deepest cells are cuboidal or
columnar and are capable of dividing and producing new cells. As these newly
formed cells are pushed to the surface, they become flat and thin
Stratified squamous epithelium
a special type of stratified epithelium that
can stretch
Transitional epithelium
best adapted for areas of
the body where filtration and diffusion are common
simple squamous epithelium
due to the larger
volume of these cells, has a greater secretory capacity
Simple cuboidal epithelium
Smooth free surfaces reduce friction. This kind of tissue is a specialized type of simple
squamous epithelium called
endothelium
Cell connection structures that mechanically bind epithelial cells together
are called
desmosomes
those that bind cells to the basement membrane are called
hemidesmosomes
the anchors of epithelial tissues to the underlying basement membrane,
preventing the movement of the tissue.
hemidesmosomes
cell connection structures that (1) form barriers and
(2) anchor cells to each other. form a barrier to movement of
molecules or ions between epithelial cells. In addition, anchor
cells together.
tight junction
are found just below the
tight junctions, and help the tight junctions anchor the epithelial cells to each
other
adhesion belt
consist of groups of channels that allow small molecules and ions to pass from one epithelial cell to an adjacent
one.
gap junction
specialized secretory organs, called
glands
are
composed of epithelium supported by a network of connective tissue.
glands
two major types of glands in the body
) endocrine glands, and (2)
exocrine glands