Epithelial Tissue
Tuesday, 15th February 2022
Epithelial Tissue - common:
Out of the trillions of cells in the human body, because of differentiation only 200
types are present. Tissues allow for efficient function and coordination of cellular
activity.
💡 Histology is the study of tissues which are groups of cells in similar
structure and all perform a common function. They include the epithelial
(protective), connective (support), muscle (movement) and nervous
(control) tissue.
Epithelial tissue covers and protects internal and external surfaces.
Common epithelia covers surfaces (skin, organ coverings, ducts etc) while
glandular epithelia forms exocrine and endocrine glands that produce fluid
secretions (sweat glands, mucous cells etc).
Cells in epithelia are closely packed together and joined with little space
between. They also have a structural polarity.
The apical portion is exposed to the lumen or outside and can have cilia,
microvilli or stereo-cilia. The basal portion is involved with the basement
membrane and connective tissue.
Cells are attached to the basal membrane with only one free surface exposed to
the outside and their lateral surfaces in contact with cells along their sides.
Epithelial Tissue 1
, They are avascular and receive nourishment from the underlying connective
tissue.
Blood vessels would lead to a ‘gap’.
It is highly regenerative and are constantly replaced by mitosis.
There are junctions between the cells and the basal membrane.
Epithelial tissue is derived from the ectoderm (epidermis), endoderm (lining of
digestive and respiratory tracts) and mesoderm (lining of the cardiovascular and
lymphatic tracts) from the embryonic stage.
Specialisations:
Epithelial tissue aid in the movement of fluids over the apical surface and through
themselves, as well as the production of these secretory fluids themselves.
The apical surface has microvilli
that increase absorption and found
in the intestines and the kidneys.
Cilia on the tissue help with
movement of fluids.
Stereocilia are non-motile
microvilli that just increase
surface area and are found in
specific places in the body like
the epididymis and ductus
deferens.
Epithelial tissue is an effective barrier with aid of its
intercellular connections via their plasma membranes, the
cells are attached to the basal lamina and are fast to
regenerate.
Intercellular connections allow cell to cell / cell to
matrix attachment and thus forms a longer singular
layer.
It allows for cellular communication and thus
have many transmembrane proteins to allow for
easy movement of signalling molecules.
Epithelial Tissue 2
Tuesday, 15th February 2022
Epithelial Tissue - common:
Out of the trillions of cells in the human body, because of differentiation only 200
types are present. Tissues allow for efficient function and coordination of cellular
activity.
💡 Histology is the study of tissues which are groups of cells in similar
structure and all perform a common function. They include the epithelial
(protective), connective (support), muscle (movement) and nervous
(control) tissue.
Epithelial tissue covers and protects internal and external surfaces.
Common epithelia covers surfaces (skin, organ coverings, ducts etc) while
glandular epithelia forms exocrine and endocrine glands that produce fluid
secretions (sweat glands, mucous cells etc).
Cells in epithelia are closely packed together and joined with little space
between. They also have a structural polarity.
The apical portion is exposed to the lumen or outside and can have cilia,
microvilli or stereo-cilia. The basal portion is involved with the basement
membrane and connective tissue.
Cells are attached to the basal membrane with only one free surface exposed to
the outside and their lateral surfaces in contact with cells along their sides.
Epithelial Tissue 1
, They are avascular and receive nourishment from the underlying connective
tissue.
Blood vessels would lead to a ‘gap’.
It is highly regenerative and are constantly replaced by mitosis.
There are junctions between the cells and the basal membrane.
Epithelial tissue is derived from the ectoderm (epidermis), endoderm (lining of
digestive and respiratory tracts) and mesoderm (lining of the cardiovascular and
lymphatic tracts) from the embryonic stage.
Specialisations:
Epithelial tissue aid in the movement of fluids over the apical surface and through
themselves, as well as the production of these secretory fluids themselves.
The apical surface has microvilli
that increase absorption and found
in the intestines and the kidneys.
Cilia on the tissue help with
movement of fluids.
Stereocilia are non-motile
microvilli that just increase
surface area and are found in
specific places in the body like
the epididymis and ductus
deferens.
Epithelial tissue is an effective barrier with aid of its
intercellular connections via their plasma membranes, the
cells are attached to the basal lamina and are fast to
regenerate.
Intercellular connections allow cell to cell / cell to
matrix attachment and thus forms a longer singular
layer.
It allows for cellular communication and thus
have many transmembrane proteins to allow for
easy movement of signalling molecules.
Epithelial Tissue 2
