Lab 1: Epithelium Reading Flashcards
Which germ layers are epithelium derived from?
All three: endoderm, mesoderm, ectoderm
What is epithelium composed of?
Very closely packed, contiguous cells, with very little or no extracellular material in the extracellular spaces
What can epithelia form?
Membranes and glands
Epithelia and their derivates are separated from underlying or surrounding connective tissue by the _______ ________.
Basement membrane
What is the basement membrane is composed of?
Epithelially derived basal lamina (lamina lucida and lamina densa) & connective tissue derived lamina reticularis
Describe epithelial membranes
Avascular, deriving their nutrients by diffusion from blood vessels in the adjacent connective tissues
What can epithelial membranes do? (General)
- Cover a surface
- Line a cavity
- Line a tube
Membranes that line serous body cavities are referred to as _______.
Mesothelia
Membranes lining blood and lymph vessels and the chambers of the heart are known as _________.
Endothelia
How are epithelial membranes classified according to shape?
-Squamous (flat)
-Cuboidal
Columnar
How are epithelial membranes classified according to number of layers?
- Simple (one layer)
- Stratified (more than one layer)
Characteristics of pseudostratified columnar epithelium
All the cells contact the basal lamina, although some cells are much shorter than others and do not reach the free surface
Classes of stratified squamous epithelium
- Keratinized
- Nonkeratinized
- Parakeratinized
Characteristics of transitional epithelium
The stratified epithelium lining much of the urinary tract; large, dome-shaped cells
Functions of epithelial membranes (9)
- Protection
- Reduction of friction
- Absorption of nutrients
- Secretion
- Excretion
- Synthesis of various substances
- Receiving sensory signals
- Forming glands
- Movement of materials
