Date post: | 18-Jan-2016 |
Category: |
Documents |
Upload: | marshall-hood |
View: | 237 times |
Download: | 0 times |
EPITHELIAL TISSUE
2 Types: Membranous (covering or lining) Glandular
Functions: Protection Sensory functions Secretion Absorption Excretion
HISTOLOGY
Epithelial Tissue
EPITHELIAL TISSUE (cont)
CharacteristicsLittle matrixPresent in surface layers (free surface)Basement membrane - “glue” layer that
holds epithelial tissue to connective tissue below it
Avascular; gets nutrients via diffusion through basement membrane
CLASSIFICATION
Cell Type:Squamous - Flat; scalelike (view from top;
looks like an egg)Cuboidal - Square shapeColumnar - More tall than wide; Nuclei tend
all be in the same placePseudostratified columnar - Columnar cells
are odd shapes; all touch BM; Some nuclei at top and some at bottom
CLASSIFICATION (cont)
Cell Layers:Simple – one layer of cellsStratified – more than one layer of
cells of the same shapeTransitional – more than one layer of
varying shapes
Simple Squamous Function: diffusion & filtration Location: alveoli, lining blood &
lymph vessels (endothelium), pleura, pericardium, and peritoneum (mesothelium)
Simple Cuboidal
Function: secretion, excretion , & absorption Location: glands and their ducts & ducts and
tubules of organs such as the kidney
Simple Columnar
Function: protection,
secretion & absorption Location: lining most
of the digestive tract Structure: goblet cells,
cilia, and microvilli
can be present
Pseudostratified Columnar
Function: protection (trap and move "pollutants" to the mouth where they are swallowed)
Location: respiratory tract
and part of male repro Structure: Cilia & goblet
cells present
Stratified squamous
Function: protection 2 types:
Keratinized Dry No nuclei in top layer Location: skin
Nonkeratinized Moist Nuclei in top layer Location: lining of vagina, mouth,
esophagus, & anus
Keratinized vs. Nonkeratinized
Keratinized or Nonkeratinized?
Stratified Cuboidal
Function: protection Location: pharynx, ducts of sweat glands, &
epiglottis
Stratified Columnar
Top layer (superficial) is the only one that appears columnar in shape
Function: protection Location: male urethra
& mucous layer near
anus
Stratified Transitional
Cell shape varies Function: allows for stretching Location: urinary bladder
Glandular Epithelium
Function – secretion (requires energy; therefore a form of active transport)
Structure Unicellular gland – cell working alone Multicellular gland – cells working in cluster,
cords, or follicles Location – make up the 2 types of glands
present in the body1. Exocrine – use ducts to distribute products2. Endocrine – do NOT use ducts to distribute
products; instead release products directly into bloodstream or interstitial fluid
Classification of Exocrine Glands
Two Methods:1. Structural
Based on duct shape & # of ducts Shapes
1. Tubular
2. Alveolar # of ducts
1. Simple
2. Compound
Classification cont’d.
2. Functional Based on discharge method 3 types:
1. Apocrine Secretory product collects at tip of cell causing
distention; eventually distended end pinches off; some damage to cell
Ex – mammary glands2. Holocrine
Secretory product collects in cell & eventually causes it to rupture; cell destroyed
Ex – sebaceous glands3. Merocrine
Majority are this Secretory product leaves cell through cell membrane;
cell not damaged Ex - salivary glands
Quiz time!!!!
Epithelium Practical Practice