Detailed summary of the lectures from the course histology. It includes images and good overviews of the histology of epithelia, glands etc. I completed this course with a 7,5.
, Histology
Despite its complexity, the organs of the human body are composed of only four basic tissue types:
epithelial, connective, muscular and nerve tissue. The basic tissues each containing ECM as well as
cells, associate with one another in the variable proportions and morphologies characteristic of each
organ. Most organs can be divided into the parenchyma, which is composed of the cells responsible
for the organ’s specialized function and the stroma, the cells of which have a supporting role in the
organ.
Tissue Cells ECM Main functions
Epithelial Aggregated polyhedral cells Small amount Lining of surface or body cavities;
glandular secretion
Connective Several types of fixed and Abundant amount Support and protection of
wandering cells tissues/organs
Muscle Elongated contractile cells Moderate amount Strong contraction; body
movements
nervous Elongated cells with Very small amount Transmission of nerve impulses
extremely fine processes
Epithelia
Epithelial tissues are composed of closely aggregated polyhedral cells adhering strongly to one
another and to a thin layer of ECM, forming cellular sheets that line the cavities of organs and cover
the body surface. Epithelia line all external and internal surfaces of the body and all substances that
enter or leave the organ must cross the epithelia.
The principle functions of epithelial tissues include the following: 1) covering, lining and protecting
surfaces; 2) absorption; 3) secretion.
The basement membranes
All epithelia are bordered by a basement membrane, a semi permeable filter for substances reaching
the epithelia from below. Below the basal membrane is connective tissue containing blood vessels
from which the epithelia cells receive the nutrients and oxygen. The basement membrane consist of
two parts the basal lamina (thin sheet like layer) and the reticular lamina (fibrous layer).
The basal lamina is a thin meshwork of type IV collagen
(lamina densa) and laminin (lamina lucida) produced by
the epithelial cells.
The reticular lamina contain type III collagen, collagen
IV and anchoring fibrils of VII collagen, all secreted by
cells of the immediately adjacent connective tissue.
Together these components attach epithelia to
connective tissue, regulate (filter) substances passing
through, provide a scaffold for regeneration and
compartmentalize epithelial cells from other tissues.
Including: collagen III, collagen IV, collagen
VII, laminin, hemidesmosomes, epithelial
cells, lamina lucida + lamina densa (basal
lamina, reticular lamina
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