Epithelial Tissue Flashcards
What is epithelial tissue?
A sheet of cells that covers a body surface or lines a body cavity.
They form the surface of the skin and line the digestive, respiratory, reproductive, and urinary tracts
What are functions of the epithelial tissue?
- Provide physical protection
- Control permeability - meaning that any substance to enter or leave must cross the epithelium. ( Physical stress can alter the structure and properties of the epithelia like calluses form on your hands when you do manual labor for some time)
- Provide sensation ( neuroepithiluim) contains sensory cells that why we know where to hit when a mosquito lands on us
- Epithelial cells produce secretions = gland cells
What are characteristics of the epithelia tissue that make it unique?
It has polarity
- Apical surface
- Basal Surface
It has specialized contacts
- The cells fit close together to form membranes or sheet of cells and bound together by junctions
It is supported by the C.T
- The cells are attached to the basement membrane
They are avascular
- Meaning no blood supply they depend on diffusion from the C.T
They Regenerate, They can easily divide to regenerate tissue.
What classifications do I need to know about the epithelia tissue?
They are based on number of cell layers and cell shape.
What does simple epithelia mean
It consists of 1 layer of cells attached to the basement membrane
What does Stratified mean ?
It consists of 2 or more layers of cells
What 3 cell shapes is there to classify the epithelia?
- Squamous ( scalelike)
-Cuboidal( Cubelike)
-Columnar(Column - Shaped)
What is the simple squamous epithelium
It is a single layer of small flat cells arranged in a large empty space.
It has nuclei the dark spots
It is found in the lungs the lining of the air sacs, lining of heart and blood vessels.
It allows materials to pass by diffusion.
Simple cuboidal epithelium
It is a single layer of cubelike cell with large round nuclei, usually arranged in a circle.
Found in kidney tubules, ovary surface
Simple columnar epithelium
Single layer of tall, column-like cells and the nuclei looks oval, The goblet cells is the white circle, has microvilli
Found in the lines of digestive tract, gallbladder,
It absorbs, secretion of mucus enzymes
Pseudostratified columnar epithilium
Single layer of cells of different heights, the nuclei is in irregular rows, there is CILIA on outer surface of cell
GOBLET CELLS are under the cilia
Found in trachea inner lining
Stratified Squamous epithelium
It is thick and has several cell layers,
It has connective tissue at the bottom,
it has the pink squiggly line at the top lining of mouth.
Protects from abrasion and infection
Nuclei
Stratified cuboidal epithelium
2 layers of cubelike cells
-protection
- ducts of sweat glands, mammary glands, salivary glands
Stratified columnar epithelium
Several cell layers mainly cuboidal but in layers
protection and secretion
Transitional epithelium
