Histology Epithelial Tissue & Glands

epithelium

one of the basic tissues, which covers all body surfaces; avascular (no vasculature); renewed continuously; rests on basement membrane

cilia, microvilli, stereocilia

3 specializations of the apical surface of epithelium

cilia

relatively large epithelial surface specialization (0.2 micrometer diameter) that are motile; associated with dynein and nexin; each cilium extends from a basal body; found on respiaroty epithelium and lining of the fallopian tubes

respiratory epithelium and lining fallopian tubes

Where are cilia found in the body?

dynein; nexin

There are 2 proteins associated with cilia: ___________ (motor protein) and ________ (elastic protein).

left: basal body

right: cilia

What structure is each arrow (left and right) pointing to? (slide 12)

basal body

structure that anchors the cilium, with 9 triplets of microtubules inside

9 peripheral doublets with 2 central singlets (9+2)

describe the arrangement of microtubules within each cilium

Kartagener/immotile cilia syndrome

an inherited syndrome in which the outer dynein arms are absent, microtubules are abnormal, and cilia are unable to beat effectively; respiratory infections are recurrent and women's fertility is reduced (fallopian tubes)

microvilli

relatively small epithelial surface specialization (0.08 micrometer diameter) with actin filaments and a terminal web; nonmotile; increases surface area and functions in absorption

terminal web

layer inside plasma membrane in cells forming a layer or lining, at the bottom of microvilli

intestinal epithelium (simple columnar) and proximal tubules (simple cuboidal)

Where are microvilli found in the body?

microvilli

Which epithelial surface specialization forms a brush border?

junctional complex

The point at which epithelial cells join to one another in very close proximity

glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication

stereocilia

nonmotile epithelial surface specialization less than 0.1 micrometers in diameter but 10 micrometers or more in length, which largely increase surface area and function in absorption; made up of actin filaments (slide 19)

epididymis and vas deferens

Where are stereocilia found in the body?

tight junctions (zonula occludens)

lateral surface specialization that completely surround the apical cell borders to form a seal between the plasma membranes of 2 cells, preventing movement of material from the lumen into the ECM

adherens junctions (zonula adherens)

lateral surface specialization that are found just beneath the tight junction, also forming a band-like junction surrounding the entire cell and serving to attach adjacent cells

E-cadherins

Adherens junctions contain the transmembrane protein _______________.

desmosomes (macula adherens)

lateral surface specialization located beneath the adherens junction that also assist in cell-to-cell attachment and have intermediate filaments on either side

desmogleins and desmocollin

What are the 2 transmembrane proteins involved with desmosomes?

gap (communicating) junctions

lateral surface specialization that provide a low-resistance channel to permit passage of ions and small molecules between adjacent cells; they contain 2 barrel-shaped transmembrane proteins called connexons

claudins and occludins

The two proteins that form tight junctions.

connexons

Gap (communicating) junctions contain two barrel-shaped transmembrane protein called ______.

basement membrane

a thin, delicate membrane of protein fibers and glycosaminoglycans separating an epithelium from underlying tissue

lamina lucida (type IV collagen), lamina densa (type IV collagen), reticular lamina (type III and VII collagen)

* lamina layers make up the basal lamina

What are the 3 layers of the basement membrane, from inner to outer?

hemidesmosomes

junctions that anchor cells to the underlying basement membrane

integrins

Hemidesmosomes contain what protein?

basal plasma membrane enfolding

a corrugation of the cell membrane in the basal regions of the cell which increases cell surface area and is involved in ion and fluid transport; lots of mitochondria

mesothelium

The simple squamous epithelium that lines the ventral body cavities and is able to produce lubricant

endothelium

the simple squamous epithelium that lines blood vessels to allow for smooth blood flow

kidney tubules, normal thyroid gland, salivary and sweat glands

Where in the body can simple cuboidal epithelium be found?

small intestine

Where in the body can simple columnar epithelium be found?

respiratory tract and fallopian tubes

Where in the body can pseudostratified columnar epithelium be found?

pseudostratified columnar epithelium

On what type of epithelium can cilia be found?

hyperthyroidism

overproduction of thyroid hormone, leading to nervousness, irritability, and increased heart rate

hypothyroidism

low levels of thyroid hormone secretion, leading to weight gain, fatigue, and depression

simple columnar

Normal thyroid follicular cells are simple cuboidal. What shape do they become in cases of hyperthyroidism?

simple squamous

Normal thyroid follicular cells are simple cuboidal. What shape do they become in cases of hypothyroidism?

skin and skull

Where in the body can keratinized stratified squamous epithelium be found?

oral mucosa and GI tract

Where in the body can nonkeratinized stratified squamous epithelium be found?

salivary gland, sweat gland, mammary gland

Where in the body can stratified cuboidal epithelium be found?

the eye

Where in the body can stratified columnar epithelium be found?

urinary bladder

Where in the body can transitional epithelium be found?

endocrine glands

Ductless glands that empty their hormonal products directly into the blood or interstitial fluid

endocrine glands

What are the following examples of: pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pineal gland, Islets of Langerhans?

exocrine glands

Glands that secrete substances into the lumen of the organ through the duct system

exocrine glands

What are the following examples of: salivary glands, sweat glands, sebaceous glands, glands in the digestive tract, mammary glands, exocrine pancreas, lacrimal glands?

serous-secreting cells

cells that produce thin proteinaceous fluid and have an apical cytoplasm containing secretory granules and round, central or basal nuclei with prominent nucleoli and well developed RER; often organized in acini

mucus-secreting cells

cells that produce gel-like glycoprotein + water, have a pale apical cytoplasm containing secretory granules, have small and flattened basal nuclei with prominent nucleoli, have well developed RER, and are often arranged in tubules

mucin

the gel-like glycoprotein + water produced by a certain type of secretory cells named after this product

myoepithelial cells

spindle-shaped contractile cells with flat nuclei, located beneath the serous cell, that contain smooth muscle myosin

serous glands, mucous glands, mixed glands, sebaceous glands

What are the four classifications of exocrine glands based on product?

serous glands

exocrine glands that produce watery proteinaceous fluid, such as the parotid gland, the gland von Ebner of the tongue, sweat glands, and the exocrine pancreatic gland

mucous glands

exocrine glands that secrete a viscous mixture of glycoprotein and water, such as SI and LI goblet cells and some glands in the hard and soft palates and stomach epithelium

mixed glands

exocrine glands that include both serous and mucous secretion, such as submandibular glands, sublingual glands, and glands in the trachea and esophagus

sebaceous glands

exocrine glands that produce lipid secretion, such as glands in the thin skin (hair-rich areas like the scalp)

merocrine secretion

exocrine secretion when the product is released from the cell by exocytosis without the loss of cytoplasm

merocrine

the most common mode of exocrine gland secretion

merocrine

What is the mechanism of secretion used by salivary glands, pancreatic glands, and eccrine sweat glands?

apocrine secretion

exocrine gland secretion when product is released together with part of the apical cytoplasm of the secretory cell

apocrine

What is the mechanism of secretion used by mammary glands?

holocrine secretion

method of secretion where product is released by disintegration of the entire secretory cell (most damaging type)

holocrine

What is the mechanism of secretion used by sebaceous glands and the tarsal gland of the eyelid?

unicellular glands

exocrine glands composed of only a single cell, such as goblet cells

multicellular glands

exocrine glands that consist of numerous secretory cells arranged in different organizations, such as simple and compound glands

simple tubular glands

simple glands with no duct, arranged in straight tubules, such as the secretory gland in the LI

simple branched tubular glands

simple glands with no duct where the secretory cells are arranged in 2 or more branched tubules, such as gastric glands in the stomach

simple coiled tubular glands

simple glands that have a long unbranched duct, and the secretory portions are formed by coiled tubules, such as sweat glands

simple acinar glands

simple glands that have a short unbranched duct and secretory cells arranged in an unbranched acinus or alveolus, such as Littre glands in the submucosa of the male urethra

simple branched acinar glands

simple glands that have a short, unbranched duct and secretory portions are branched acini, such as sebaceous glands

compound tubular glands

compound glands that have branched ducts and secretory cells arranged in branched tubules, such as Brunner glands in the duodenum of the SI

compound acinar glands

compound glands with branched ducts and secretory portions are branched acini, such as the exocrine pancreas

compound tubuloacinar gland

compound glands with branched ducts and secretory portions are branched tubules and acini, such as submandibular glands and sublingual glands

Intralobular ducts

ducts located inside of lobules of glands (ex: intercalated ducts and striated ducts)

interlobular ducts

ducts located between lobules of glands

striated ducts

ducts that collect primary saliva to form secondary saliva and remove Na+ and Cl- and then add K+ and HCO3- to create hypotonic alkaline saliva

d

Under the microscope you see a cell which contains rER and flattened cristae within the mitochondria. Which statement about the cell is correct?

a) The cell is active in lipid synthesis and secretion located in glands classified morphologically as simple tubular glands.

b) The cell is classified morphologically as a secretory sheet.

c) The cell is located in the intralobular ducts of a simple acinar gland.

d) The cell is actively engaged in protein synthesis and releases its product by the process of merocrine secretion.

b

Glands can be classified based on the type of product they synthesize. A gland consisting of secretory cells with numerous granules in their apical cytoplasm usually produce:

a) a combined watery serous and milky lipid based product

b) a watery serous product

c) a lipid based product

d) a mixed product containing both lipid and mucus

e) a mucus product

holocrine

Exocrine glands whose product is lipid in nature release their contents via __________ secretion.

compound branched tubuloalveolar

How would you classify a gland with branched secretory acini composed of tubular and alveolar units?

adenocarcinoma

a tumor arising from glandular epithelium

false (merocrine secretion of serous saliva)

T/F: The parotid salivary gland is characterized by holocrine secretion of a sebaceous product.

false (simple cuboidal)

T/F: The epithelium lining the duct system of an exocrine gland is classified as pseudostratified squamous epithelium.

carcinoma

a malignant tumor that occurs in epithelial tissue (not glands)

sebaceous gland

When viewing an exocrine glands you see the following: (1) aggregation of secretory cells with obvious nuclei in each cell nestled in connective tissue, (2) pale staining cytoplasm, (3) obvious cell borders, and (4) no obvious ducts. You classify this gland based on its type of product as a _____________.

d

When viewing secretory cells within a secretory acinus, you see triangular shaped cells with basally located nuclei and densely packed secretory granules in the apex of cells. You are confident that this secretory acinus is:

a) emptying its mucus product directly into a stratified cuboidal duct located within the interlobular connective tissue

b) releasing the stored lipid product via constitutive secretory pathway

c) classified morphologically as a simple branched tubular gland

d) synthesizing a serous product for exocytotic release via the regulated secretory pathway

based on their shape

How are epithelial cells named?

“flattened cell”

What shape is squamous

Make slide of ppt slide 58 (duct systems image)

claudins and occludins

What are the junction associated proteins for tight junctions?

• moistening and cleansing the oral cavity

• helping repair oral tissues

• stimulating the taste buds

• helping digest food

• hardening tooth enamel

• destroying bacteria

What is the function of the saliva

What is the difference in identify and classify?