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Bio 102 Animal tissues lab
Microscopy basics:
* Clean slides with Kimwipes and lenses on scope with lens paper.
* How to use the microscope
Four major tissue types: 1. Epithelial
2. Connective 3. Muscle 4. Nervous
1. Epithelial: Found on coverings of surfaces, linings of tubes and cavities (and glands).
What is the advantage / disadvantage of relative thickness?
How does thickness relate to function or location of tissue?
*Squamous: These are flat cells in a single layer. Used wherever: a) rapid highly efficient
transport is needed AND b) virtually no surface contact occurs – no friction. Simple squamous
lines the lungs (alveoli), the entire cardiovascular system and much of the renal system including
kidneys and bladder.
*Stratified squamous: These are epithelial cells arranged in layers, with the uppermost layer
being squamous, and successive layers becoming progressively thicker. Used at high contact,
high turnover areas such as skin, tongue, esophagus and anus. This is the epithelial type least
involved in transport.
*Cuboidal: These cells are more or less square / cube-shaped. They may exist as a single layer
of cells or in comination with other epithelial types. Used to line tubes that see minimal fluid
contact with a bit more friction than simple squamous, and moderately lower need for rapid
transport. Cuboidal cells are found lining most of the kidney tubules and other parts of kidneys,
bladder, glands (thyroid) and their ducts, in the epithelium layer of the retina, and the germinal
layer of the ovary.
*Columnar: These are elongated cells, longer than they are wide, often with terminal
nuclei. They usually exist as a single layer of epidermis, not in combination with other
types. Used to line tubes that experience high contact, high friction, but slower transport
needs. They are found lining the stomach and intestines, the gall bladder, the uterus, and the
bronchioles of the lung.
2. Connective: Most diverse of the 4 major tissue types.
What does the name suggest? This can mean a lot of things.
* Areolar (loose connective) tissue is the most widespread of the connective tissues. Think of it
as weak glue that fastens down skin and other epithelia, surrounds blood vessels and nerves, and
binds together muscles and their components. It appears as a variety of cells trapped in a loose
meshwork of collagen fibers. Its appearance has been described as hair in a drain.
* Cartilage tissue cells appear as dispersed cells on a pale purple or blue transparent
background. It looks like cells imbedded in plastic (like a milk jug).
* Bone contains spider-shaped cells called “osteocytes― embedded in a calcium salt
matrix. Osteocytes are arranged in concentric rings around the central Haversion canal.
* Adipose tissue is fat cells. The cells are large, roughly spherical and contain a single fat
droplet which fills about 90% of the cell, so they will look like large, round, empty cells.
* Blood cells are also connective tissue.
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