What are the four types of tissue and their main function
Epithelial - Provides covering
Connective - Provides support
Muscle - Provides movement
Nervous - Provides control
What are the four main characteristics of epithelial tissue?
Polarity, specialized contacts, support by connective tissue, avascular but innervated, high regeneration rate
What does polarity mean in epithelial tissue?
Cells have apical, lateral, and basal surfaces
What is the basement membrane made of?
Basal lamina and reticular lamina
What are the two layers of the basal lamina?
Lamina lucida and lamina densa
What is the function of the basement membrane?
Anchors epithelium, acts as filter, guides regeneration
Why are epithelial tissues avascular?
They lack blood vessels and get nutrients by diffusion
What are tight junctions?
Junctions that seal cells to prevent leakage
What are desmosomes?
Anchoring junctions that resist mechanical stress
What are hemidesmosomes?
Junctions that anchor cells to the basement membrane
What are gap junctions?
Junctions that allow cell-to-cell communication
How are epithelial tissues classified?
By number of layers and cell shape
What are the three epithelial cell shapes?
Squamous, cuboidal, columnar
What is simple epithelium?
One layer of cells
What is stratified epithelium?
Two or more layers of cells
What is pseudostratified epithelium?
Appears layered but all cells touch basement membrane
What is the function of simple squamous epithelium?
Rapid diffusion and filtration
Where is simple squamous epithelium found?
Alveoli, endothelium, serous membranes
What is the function of simple cuboidal epithelium?
Secretion and absorption
Where is simple cuboidal epithelium found?
Kidney tubules and glands
What is the function of simple columnar epithelium?
Absorption and secretion
What specializations may simple columnar cells have?
Microvilli or cilia
What is the function of pseudostratified ciliated columnar epithelium?
Secretes and moves mucus