1. BIO 1110 1

2.  Tissues: A group of similar cells, having a similar origin, and functioning together to carry out specialized activities.  Tissues can be solid, semi-solid or liquid.  From conception until approximately day 14, all cells look and function the same (undifferentiated=stem cells).  Around day 15 post conception, cells start to differentiate or take on new characteristics.  This is the start of tissue formation. 2

3.  Histology is the study of tissues.  There are 4 main types of tissues in the human body:  Epithelial  Connective  Muscular  Nervous 3

4.  Tightly packed cells arranged in continuous single or multi-layered sheets.  Characteristics:  Avascular- without blood vessels. Epithelium gets nutrients from the adjacent connective tissue.  Bottom surface of epithelium is attached to the basement membrane (fibers that act like glue)  Has a nerve supply. 4

6.  This type of tissue is found on the outer covering of the skin and some internal organs as well as lining body cavities and some internal hollow organs.  There are 9 different types of lining/covering epithelium.  Epithelial tissue is classified based on the number of cell layers present and the shape of the cells of the tissue.

7.  Simple- - Single layer of tightly packed cells  Stratified- - 2 or more layers of tightly packed cells 7

8.  Pseudostratified Looks like many layers because not all cells reach the surface and the nuclei lie at different levels 8

9.  Squamous  Thin, flat and irregularly shaped  Cuboidal  Square/cube shaped  Columnar  taller than wide  Transitional  change shape due to stretching or movement of body parts 9

10.  A single layer of tightly packed thin, flat, irregularly shaped cells  Location:  Lines the blood vessels  Forms the peritoneum, pericardium and pleural linings  Found in the air sacs of lungs (alveoli)  Function:  Allows for easy diffusion of gases and blood components

11. Simple Squamous – Top View – found in the walls of capillaries and alveoli of lungs

13.  A single layer of tightly packed cube shaped cells.  Location:  Lines kidney tubules, ducts of glands, and secreting parts of glands  Function:  Secretion (force materials out of the cells) and absorption (pull materials into the cells)

14. Simple Cuboidal Epithelial Tissue – this is of ducts of the kidney

17.  A single layer of tightly packed rectangular cells  Can be non-ciliated or ciliated (tiny hairs)  Non-ciliated have microvilli (finger-like projections) on the free surface of the cells  Non-ciliated Location:  Lines the gastrointestinal tract (from stomach to anus)  Non-ciliated Function:  Secretion and absorption  Microvilli increase surface area 200-300 times for absorption

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19.  Ciliated Location:  Lines tubes of the respiratory tract, fallopian tubes, and ventricles of the brain  Ciliated Function:  The cilia beat in unison to move substances outside the cell like mucus and egg cells.

20. Simple Columnar Non-Ciliated Epithelial Tissue - This is a cross section through the small intestine – for absorption – microvilli on surface of cells

23. 23  A single layer of tightly packed columnar cells that appear to be multi-layered  Location:  Ciliated- Lines respiratory tract  Non-ciliated- Male urethra  Function:  Ciliated- moves materials across the apical surface of a tissue.  Non-ciliated- Absorb and protect

25.  Multiple layers of tightly packed squamous epithelial cells.  Location:  Areas that are subject to much “wear and tear”. ▪ Upper layers are designed to be shed and replaced.  Function:  Protection

27.  Two layers of cube shaped epithelial cells  Rare  Location:  Lining the ducts of glands found in the esophagus  Function:  Moderate protection from the stomach acid that refluxes

29.  Multiple layers of columnar epithelial cells  Rare  Only the layer closest to the lumen (opening in a duct) is columnar in shape. The outer layers are somewhat squashed.  Location:  Lining the ducts of glands lining the esophagus  Function:  Moderate protection from stomach acid that refluxes

31.  Epithelial tissue that has a variable shape  Can stretch and relax multiple times without being damaged  Location:  Lines the urinary bladder  Function:  Protection