LECTURE ) :
TISSUES
● Cell junctions
○ Anchoring
■ Adherins-
■ Desmosomes - Spot welds
■ Hemidesmosomes - half-welds that join cells to a basement membrane.
○ Communication Junctions
■ Gap junctions - pores (connexons) that allow small substances to pass
between cells; Able to close off in danger
○ Occuling
■ Tight Junctions - leak-proof seal is needed between adjacent cells.
■ Ex. stomach - keep gastric juice in stomach
● 4 Basic Tissues
○ Epithelial tissue - Covers body surfaces, forms glands, and lines hollow
organs, body cavities, and ducts.
■ No direct blood supply so gets nutrients by diffusion
■ Regrenete
○ Connective Tissue - Functions in protection, support, and binding of organs.
○ Muscle Tissue- generates the physical force needed to make body structures,
or substances, move.
○ Nervous Tissues - Used for internal communication, to detect changes in the
body, and provide the means for quick response to stimuli.
● Tissues of the body develop from three primary germ layers:
○ Endoderm, Mesoderm, and Ectoderm
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, ● Epithelium -Line surfaces and form protective barriers.
○ The basal (bottom) layer of the epithelium secretes a basal lamina
○ Named according to the shape of their cells, and the thickness, or
arrangement, of their layers
■ If different shapes are present in layers of cells, the epithelium is
always named by the shape
■ Shape:
■
■ Arrangement:
■
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