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AP Biology Cell Journal
Part 1
Brandon Fleres
Simple Squamous Epithelium

Simple squamous cells are thin and flat.
They are one layer thick and are bound
together by tight junctions, which form a
permeable barrier. They serve as
mediators of diffusion and filtration, and
are commonly found in places like the
kidney that utilize these processes.
Simple Cuboidal Epithelium

The simple cuboidal epithelium is a single
layer of cube like cells that are equally wide
as they are tall. They provide protection by
lining the ducts of different glands and
organs. In kidney tubules, the cells help with
absorption and transport of filtered
substances.
Simple Columnar Epithelium

Simple columnar epithelial cells are
have a greater length than width. They
are connected by tight junctions, and
have their nuclei at the base of the cell.
Because of their unique shape, these
cells can serve many different functions
and can be found in places the
digestive, respiratory, and reproductive
systems.
Stratified Squamous Epithelium

The stratified squamous epithelium consists
of multiple layers of epithelial cells. Basal
layers are more cuboidal or columnar, and
the top layer are more larger and squamous.
The epithelium is specialized to resist
against abrasion, with the top layers
protecting the deeper layers. The top apical
cells are replaced by the deeper basal cells.
They can be found in places where wear and
tear can occur, like the linings of the
esophagus, vagina, and oral cavity
Pseudostratified Epithelium

Consists of a single layer of cells,
although not all the cells are the
same length, giving it a stratified
appearance. All cells rest on the
basement membrane, but not all
of them reach the top (apical)
surface. Each cell as a different
cell and a different function.

Two types: Ciliated columnar
(lining the upper respiratory
tract) and nonciliated columnar
(lining the epididymus)
Heart Muscle

Cardiac muscle cells are what
make up the heart muscle. They
have a long rectangular shape to
help the heart pump blood to
other areas of the body.
Intercalated disks in the heart
muscles hold adjacent cells
together and allow impulses to
move through cells quickly.
Skeletal Muscle

Skeletal muscle cells are cylindrical,
long, and have multiple nuclei.
Individual cells are often referred to
as muscle fibers. Skeletal muscle is
attached to bones, so can be found
wherever there is bone in the body.
These cells are able to shorten or
contract in order to do different
tasks.
Smooth Muscle

Smooth muscle cells have a
spindle like shape. Like skeletal
muscle, smooth muscle is able to
tense and relax, although with
greater elasticity. Smooth cells
can stretch while still maintaining
contractility, which is important
in organs like the intestines and
the bladder. Other places the
smooth muscle cells can be found
are in the walls of blood vessels
and arteries, veins, and the iris of
the eye.
Loose Connective Tissue

The loose connective tissue is
the most common of the
connective tissues in
vertebrates. They hold organs in
place and attach epithelial
tissue to other tissues. The loose
connective cells tend to be
spread apart and separated by a
substance made up of
collagenous and elastic fibers.
Dense Connective Tissue

Dense connective tissue is made up
primarily of collagen. Between
collagen fibers are fibroblasts that
create the fibers. The tissue forms
tendons that attach skeletal muscles
to bones and ligaments that connects
bones to other bones at joints. Dense
connective tissue also makes up the
lower layer of the skin.
Elastic Connective Tissue

Elastic connective tissue contains
bundle of proteins called elastic
fibers. The fibers can stretch to
greater lengths and return to
their original length when
relaxed. The elastic fibers are
created from fibroblasts and
muscle cells in the arteries.
Reticular Connective Tissue

Reticular connective tissue contains a
network of reticular fibers, which are
made out of type III collagen. The
fibers are used as a soft skeleton that
supports lymphoid organs. Reticular
connective tissue is found in areas by
the liver, kidney, spleen, bone marrow,
and lymph nodes.