This is a draft cheat sheet. It is a work in progress and is not finished yet.
General Definitions
Tissue |
A group of cells that have similar structure and function plus extracellular substance (matrix) |
Histology |
Study of the tissues of the body and how tissues are arranged to constitute organs |
Extracellular Matrix |
Glue that holds the cells together in tissues |
Basic types of tissues |
- Epithelial
- Connective
- Muscle
- Nervous |
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Epithelial Tissues
Location |
- Covers internal and external surfaces of the body |
- ex: Skin, linings of the digestive and respiratory tracts, blood vessels, body cavities... |
Characteristics |
- Cells close (packed) together (very little extracellular matrix) |
- Form most glands |
- Have a free (apical) surface |
- Have a Basal surface which attaches epithelial cells to underlying tissue |
Places Found |
Surface of skin |
Lining of digestive tract |
Lining of respiratory tract |
Lining of Secretory glands |
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Classifications of Epithelia
1. Simple Squamous - Single layer of flat cells |
eg. lining blood vessels, aveoli of the lungs, kidney tubules, serous membranes... |
Advantage: easier for substances to diffuse or be filtered across |
Good for gas exchange |
2. Stratified squamous, keratinized - several layers of cells |
eg. skin |
3. Stratified squamous, non-keratinized moist |
eg. lining esophagus |
4. Simple cuboidal |
eg. kidney tubule |
5. Simple columnar |
eg. intestine |
6. Pseudostratified |
eg. upper respiratory tract |
7. Stratified Cuboidal |
8. Stratified Columnar |
9. Transitional |
eg. urinary bladder |
Funtions of Epithelia
1. Permit the passage of substaces |
2. Protect underlying structures |
3. Barrier |
4. Absorption |
5. Secretion |
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