Animal Tissues
QUILONA, KLARISSE JANE A.
BSP-1B
Animal Tissues
1. Epithelial
Epithelial tissue is made of closely-packed cells arranged in flat sheets. Epithelia form the surface of the skin, line the various cavities and tubes of the body, and cover the internal organs.
Subsets of Epithelia
Epithelia that form the interface between the internal and external environments.
Skin as well as the lining of the mouth and nasal cavity. These are derived from ectoderm.
Inner lining of the GI tract, lungs, urinary bladder, exocrine glands, vagina and more. These are derived from endoderm.
The apical surface of these epithelial cells is exposed to the "external environment", the lumen of the organ or the air. [View example]
Mesothelia. These are derived from mesoderm. pleura — the outer covering of the lungs and the inner lining of the thoracic (chest) cavity. peritoneum — the outer covering of all the abdominal organs and the inner lining of the abdominal cavity. pericardium — the outer lining of the heart.
Endothelia. The inner lining of the heart, all blood and lymphatic vessels — derived from mesoderm.
The basolateral surface of all epithelia is exposed to the internal environment (ECF). The entire sheet of epithelial cells is attached to a layer of extracellular matrix that is called the basement membrane or, better (because it is not a membrane in the biological sense), the basal lamina. [View example]
View showing relationship between the apical and basolateral surfaces of epithelial cells and how they maintain their distinction.
The function of epithelia always reflects the fact that they are boundaries between masses of cells and a cavity or space. Some examples:
The epithelium of the skin protects the underlying tissues from mechanical damage ultraviolet light dehydration invasion by bacteria
The columnar epithelium of the intestine secretes digestive enzymes into the intestine; absorbs the products of digestion from it.
An epithelium also lines
BSP-1B
Animal Tissues
1. Epithelial
Epithelial tissue is made of closely-packed cells arranged in flat sheets. Epithelia form the surface of the skin, line the various cavities and tubes of the body, and cover the internal organs.
Subsets of Epithelia
Epithelia that form the interface between the internal and external environments.
Skin as well as the lining of the mouth and nasal cavity. These are derived from ectoderm.
Inner lining of the GI tract, lungs, urinary bladder, exocrine glands, vagina and more. These are derived from endoderm.
The apical surface of these epithelial cells is exposed to the "external environment", the lumen of the organ or the air. [View example]
Mesothelia. These are derived from mesoderm. pleura — the outer covering of the lungs and the inner lining of the thoracic (chest) cavity. peritoneum — the outer covering of all the abdominal organs and the inner lining of the abdominal cavity. pericardium — the outer lining of the heart.
Endothelia. The inner lining of the heart, all blood and lymphatic vessels — derived from mesoderm.
The basolateral surface of all epithelia is exposed to the internal environment (ECF). The entire sheet of epithelial cells is attached to a layer of extracellular matrix that is called the basement membrane or, better (because it is not a membrane in the biological sense), the basal lamina. [View example]
View showing relationship between the apical and basolateral surfaces of epithelial cells and how they maintain their distinction.
The function of epithelia always reflects the fact that they are boundaries between masses of cells and a cavity or space. Some examples:
The epithelium of the skin protects the underlying tissues from mechanical damage ultraviolet light dehydration invasion by bacteria
The columnar epithelium of the intestine secretes digestive enzymes into the intestine; absorbs the products of digestion from it.
An epithelium also lines