ant & phys: HISTOLOGY

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After fixation, most tissue get spliced into sections

sectioning necessary to allow light of a microscope to pass through and so the image is not confused by too many overlapping layers of cells

sections are mounted onto slides and stained to enhance detail. (different stains bind to different components of tissue)

longitudinal section-tissue cut on its long axis

cross section-tissue cut perpendicular to long axis

oblique section-section cut on a slant between longitudinal and cross section.

4 primary tissues are : muscular, connective, nervous and epithelial

the first tissue appears during human development when cells stat to organize themselves into layers (primary germ layers) which give rise to all of the body's mature tissues

5.2

Epithelial tissue consist of a sheet of closely adhering cells with upper surface usually exposed to the envionment or to an internal space in body.

--covers body surface, lines body cavities, forms external and internal linings of many organs and constitutes most gland tissue.

Functions:

1. Protection: protect deeper tissues from invasion and injury. (ex: epidermis in barrier for infection & inner lining of stomach protects deeper tissues from stomach acid and enzymes

2. secretion: produces mucus, sweat, enzymes, hormones and most of the body's other secretions. glans made up of largely of epithelial tissue

3. Excretion: (e) void wastes from tissues such as, co2 across pulmonary epithelium and bile from the epithelium of liver

4. Absorption: (e) absorbs chemicals from the adjacent medium (ex: nutrients are absorbed through epithelium of small intestine)

5. filtration: all substances leaving blood are selectively filtered through epithelium that lines blood vessels-- all urinary waste is filtered through epithelia of kidneys.

6. Sensation: (e) are provided with nerve endings that sense stimulation ranging from touch on skin to irritation of stomach.

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Basement Membrane- Layer between epithelium and underlying connective tissue

--contains collagen, glycoproteins and other protein-carbohydrate complexes and blends into other proteins of connective t.

--serves to anchor an epithelium to the connective tissue & controls exchange of materials bt/ epithelium and underlying tissues

--also binds growth factors from below that regulate epithelial development.

Basal surface- surface of an epithelial cell that faces the basement membrane

apical surface- surface that faces away from it toward the internal cavity (lumen)

Simple Epithelium- only one layer of cells, but debatable in the psuedostratified columnar type

-- 3 types:

1.smple squamous (thin scaly cells)

2. simple cuboidal (squarish or round cells)

3. simple columnar (tall narrow cells)

4. psuedostratified columnar ( not all cells reach the surface -- shorter cells covered by taller ones)

goblet cells- produce protective mucous coatings over the mucous membranes.

-have expanded apical end filled with secretory vesicles

-product becomes mucus when secreted and absorbs water and the basal part of the cell is a narrow stem that reaches to the basement membrane.

-Microscopic appearance: single layer of thin cells