Epithelial Tissue

classify epithelial, specializations, junctions & functions, sturcture/function differences between exocrine and endocrine

What are the 3 layers of epithelial derived from (3)

1. ectoderm

2. endoderm

3. mesoderm

T/F all epithelial tissue shares structural features

true

Epithelial cells exhibit ____

polarity

What are epithelial cells capable of

rapidly replacing damaged and dead cells

T/F epithelial cells are not highly cellular

Flase, they are highly cellular with little to no extracellular material between cells

What are cell juntions

adjoining cells that form intercellular connections

Describe avascular

nutrients enter by diffusion or absorption from underlying tissues or surface

What does the epithelial tissue provide protection from (3)

1. physical

2. chemical

3. biological

What are epithelial cells capable of secreting

mucous and other specific compound into apical surfaces

How are epithelial cells typically characterized (4)

1. unequal distribution of organelles between apical and basal surfaces

2. Have cilia, microvilli, and stereocilia

3. Secretes glycoproteins and collagen from the basal surface forming the basal lamina

4. Has a basement membrane that anchors the reticular lamina and underlying connective tissue

What 3 connections may be present in epithelial cells

1. tight junction

2. anchoring junction

3. gap junction

What are tight junctions

restrict movement of fluids between adjacent cells using integral proteins that fuse together to form a firm seal

What are anchoring juctions

desmosomes, hemidesmosomes, and adherens

What are gap junctions

form intercellular passageway between the membranes of adjacent cells to facilitate movement between small molecules and ions

What can epithelial tissue be classified as (5)

1. squamous

2. cuboidal

3. columnar

4. simple

5. stratified

What does simple squamous epithelium make

makes the mesothelium that secretes serous fluid to lubricate internal body cavities

What is simple cuboidal invovled in

secretion and absorption using active transport

what is simple columnar involved in

absorption and secretion using active transport

what is pseudostratified columnar involved in

secretion and mucous production

What is a goblet cell

mucous secreting unicellular gland interspersed between the columnar epithelial cells of a mucous membraneWh

What does a goblet cell protect against because of the gel-like layer

bacterial invasion

What is stratified squamous involved in

protecting underlying tissues from abrasion

What is stratified transitional epithelium involved in

stretching and expanding

What is the endocrine gland

ductless gland that releases secretions directly into surrounding tissues and fluids

What is the exocrine gland

secretions leave through a duct that opnes to the external environment

What are the 2 exocrine glands classified as

1. unicellular

   1. multicellular

what is a unicellular exocrine gland

individual cells scattered throughout an epithelial lining

What is a multicellular exocrine gland

composed of 2 or more cells which either secrete or release contents into an inner body cavity or duct

Types of multicellular glands (5)

1. Simple

2. Compound

3. Tubular

4. Alveolar

5. Tubuloaveolar

What is simple mult. exocrine glands

single duct carrying contents to the external environment

What is tubular mult. exocrine glands

enlongated secretory regions

What is compound mult. exocrine glands

multiple ducts divided into one or more branches

What is alveolar mult. exocrine glands

spherical secretory regions

What is tubuloalverolar mult. exocrine glands

combine alveolar and tubular secretory

what other 3 classifications can exocrine glands be put into

1. merocrine secretion

2. apocrine secretion

3. holocrine secretion

What is merocrine secretions

its the most common, the secretions enclosed in vesicles that move to apical surface of cell where contents are released by exocytosis

What is apocrine secretions

secretions accumulate near apical portion of secretory cell, that portion of the cell and its secretory contents pinch off from the cell and are released

What is holocrine secretions

The complete rupture and destruction of a gland cell occur as it accumulates secretory products and releases them only upon bursting. New gland cells then differentiate from surrounding tissue to replace those lost during secretion.