A group of cells that usually have a common function and are similar in structure.
Four Major Families of Tissues
- 1. Epithelial Tissue
- 2. Connective Tissue
- 3. Muscle Tissue
- 4. Nervous Tissue
- Covers body surfaces; lines hollow organs, body cavities, and ducts; forms glands
- Allows body to interact with internal and external environments
Protects and supports the body and its organs; binds organs together; stores energy reserves as fat; provides immunity
- Provides movement and generation of force
- Generates heat that warms the body
Initiates and transmits nerve impulses (signals) that help control and coordinate body activities.
All tissues develop from what?
Three (embryonic) primary germ layers.
Primary germ layers
Ectoderm, Endoderm, and Mesoderm
Three main functions of Epithelial Tissue or Epithelium
- 1. Selective Barriers
- 2. Secretory surfaces (to release products)
- 3. Protective Surfaces
Two Major types of epithelium
- 1. Covering and lining epithelium
- 2. Glandular epithelium
Covering and lining Epithelium
- Outer covering of skin and some internal organs or vessels, ducts and cavities.
- Interior of respiratory, digestive, urinary, and reproductive systems.
Secreting portion of glands (Ex: Thyroid, adrenal, sweat glands)
- Single layer of cells
- functions in diffusion, osmosis, filtration, secretion, absorption
- Several layers of cells
- protect underlying tissues in locations where there is considerable wear and tear
single layer that appears stratified (because nuclei lay @ different layers)
cells that undergo changes in shape and therefore is located in areas subject to stretching (urinary bladder)
- Thin like floor tiles (rapid passage of substances)
- microvilli @ their apical surface and function in sercretion or absorption
- tall and cylindrical or rectangular
- Protect underlying cells
able to undergo changes in shape caused by distentsion
- ductless (thyroid, adrenal)
- secrete horomones which diffuse through the extracellular fluid into the blood
- Secrete substances into ducts or onto the surface of the body
- structually classified into unicellular and multicellular glands
- Goblet cell
- secrete their products into body tubes such as the respiratory tract (secrete mucus directly on apical surface)