Page 29 - Demo 1

Figure 11. Types of epithelial ssue based on arrangement of layers and cell shape
Source:
http://higheredbcs.wiley.com/legacy/college/tortora/0470565101/hearthis_ill/pap13e_ch04_illustr_audio_mp3_am
/simulations/figures/cell_shape.jpg

On the basis of cell shape, epithelial cells may be categorized into
squamous epithelium, cuboidal epithelium, or columnar epithelium.
Squamous epithelium consists of thin, flaened cells, like the cells that line
blood vessels and air sacs of the lungs. Cuboidal epithelium consists of cube-
shaped cells that are approximately of the same height and width. This
epithelium lines kidney tubules and glands. Columnar epithelium is composed
of cells that resemble rectangular pillars or columns, with nuclei commonly
located at or near the base of each cell. Columnar epithelium forms the lining
of most digesve organs.

Connecve Tissue

Connecve ssue binds and supports body parts. The many types of
connecve ssue funcon in binding organs together and providing support and
protecon. As a rule, connecve ssue cells are widely separated by a matrix, a
non-cellular substance that ranges from solid to semifluid to fluid. The matrix
is usually made up of collagen fibers, the most common protein in the human
body.
Connecve ssue cells have three funconal categories: (1) the cells of the
immune system that funcons for defense; (2) the cells of the skeletal system
that provides structural support; and (3) the blood and fat cells which store
and transport substances throughout the body.
Tissue cells of the immune system include the white blood cells which
roam the body as part of the bloodstream. The two principal kinds of immune
system cells are macrophages, which engulf and digest infecous pathogens,
and lymphocytes, which produce anbodies – molecules that combine with
foreign substances to inacvate them. Immune cells are transported throughout
the body in a fluid matrix called plasma.

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