Epithelial Tissues and Glands Flashcards
(111 cards)
1
Q
four basic/primary types of tissues
A
epithelial (epithelium), connective, muscular, nervous
2
Q
two main categories of epithelial tissue
A
- covering or lining epithelium
2. glandular epithelium
3
Q
functions of epithelial tissue
A
- Secretion 2. Absorption 3. Filtration 4. Excretion 5. Transport 6. Protection
4
Q
special category of epithelium
A
transitional epithelium (urothelium)
5
Q
naming epithelial tissue
A
surface specialization + number of cell layers + cell morphology + tissue
6
Q
two types of stratified squamous epithelium
A
Nonkeratinized Stratified Squamous Epithelium
Keratinized Stratified Squamous Epithelium
7
Q
characteristics of epithelial tissue:
A
- cellularity
- specialized contacts
- polarity
- supported by connective tissue- lamina propria
- avascular, but innervated
- regeneration
8
Q
polarity of epithelial tissue
A
- free or apical surface/pole/domain
- lateral surface/domain
- basal surface/pole/domain
9
Q
for defining the subclasses of epithelium, look at the _____
A
morphology
10
Q
number of cell layers:
A
- simple
- stratified
- pseudostratified
11
Q
cell height/shape variation
A
- squamous
- cuboidal
- columnar
12
Q
sometimes another name can be added based on specializations at the ____ surface of the cell (ex _____) or at the _____ surface of the tissue (ex ______)
A
apical; ciliated; apical; keratinized
13
Q
steps to naming epithelial tissue
A
- the number of cell layers (simple, stratified, pseudostratified)
- the cell morphology at the surface (squamous, cubiodal, columnar)
- additional details (ciliated or nonciliated; keratinized or nonkeratinized)
14
Q
single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia
A
simple squamous epithelium
15
Q
function of simple squamous epithelium
A
allows passage of materials by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae
16
Q
location of simple squamous epithelium
A
kidney glomeruli (Bowman's capsule); air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae); inner surface of tympanic membrane (eardrum) Forms epithelial layer of serous membranes, such as the peritoneum
17
Q
simple squamous epithelium is present in the ______ of the peritoneum
A
mesothelial lining
18
Q
simple squamous epithelium of the endothelium is present in:
A
arterioles and venules in the dermis
19
Q
single layer of cube-like cells with large, spherical central nuclei
A
simple cuboidal epithelium
20
Q
function of simple cuboidal epithelium
A
secretion and absorption
21
Q
location of simple cuboidal epithelium
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kidney tubules; ducts and secretory portions of small glands, such as in thyroid gland and pancreas; ovary surface; anterior surface of capsule of lens of eye, posterior surface of eye
22
Q
single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells)
A
simple columnar epithelium
23
Q
function of simple columnar epithelium
A
absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action
24
Q
location of simple columnar epithelium
A
nonciliated type lines most of the digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus
25
nonciliated simple columnar epithelium
single layer of nonciliated column-like cells with nuclei near base of cells; contains goblet cells and cells with microvilli in some locations
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location of nonciliated simple columnar epithelium
lines the gastrointestinal tract (from stomach to anus), ducts of many glands, and gallbladder
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function of nonciliated simple columnar epithelium
secretion and absorption
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ciliated simple columnar epithelium
single layer of ciliated column-like cells with nuclei near base; contains goblet cells in some locations
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location of ciliated simple columnar epithelium
lines a few portions of the upper respiratory tract, uterine (fallopian) tubes, uterus, some paranasal sinuses, central canal of spinal cord, and ventricles of the brain
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function of ciliated simple columnar epithelium
moves mucus and other substances by ciliary action
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stratified squamous epithelium
thick membrane composed of several cell layers; basal cells are cuboidally or columnar and metabolically active; surface cells are flattened (or squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
32
function of stratified squamous epithelium
protects underlying tissues in areas subjected to abrasion
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location of stratified squamous epithelium
nonkeratinized type forms the moist linings of the esophagus, mouth and vagina, part of epiglottis and pharynx, and covers the tongue; keratinized variety forms the epidermis of the skin, a dry membrane
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two types of stratified squamous epithelium
keratinized and nonkeratinized
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stratified cuboidal epithelium
two or more layers of cells in which the cells in the apical layer are cube-shaped
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location of stratified cuboidal epithelium
ducts of adult sweat glands and esophageal glands and part of male urethra
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function of stratified cuboidal epithelium
protection and limited secretion and absorption
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stratified columnar epithelium
several layers of irregularly shaped cells; only the apical layer has columnar cells
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location of stratified columnar epithelium
lines part of urethra, large excretory ducts of some glands, such as esophageal glands, small areas in anal mucous membrane, and part of the conjunctiva of the eye
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function of stratified columnar epithelium
protection and secretion
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pseudostratified columnar epithelium
single layer of cells of differing heights, some not reaching the free surface (all cells are attached to the basement membrane); nuclei seen at different levels; may contain goblet cells and bear cilia
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function of pseudostratified columnar epithelium
secretion, particularly of mucus; propulsion of mucus by ciliary action
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location of pseudostratified columnar epithelium
nonciliated type in male's sperm-carrying ducts (epididymis and urethra) and ducts of large glands; ciliated variety lines the trachea and most of the upper respiratory tract
44
transitional epithelium
resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells surface cells dome shaped or squamous like, depending on degree of organ stretch
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function of transitional epithelium
stretches readily and permits distension of urinary organ by contained urine
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epithelial cells exhibit distinct polarity:
- apical domain
- lateral domain
- basal domain
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Apical domain specializations: microvilli are ....
cytoplasmic extensions / processes with core of actin filaments
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average height and width of microvilli
1 micrometer and 0.08 micrometer
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microvilli create a _____ in the intestinal epithelium or a _____ in kidney tubule cells
striated border; brush border
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function of microvilli
increase surface area
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stereocilia are...
considered long microvilli
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function of stereocilia
increase surface area
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produce movement, rapid back and forth
cilia
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length and diameter of cilia
5-10 micrometers, 0.2 micrometers
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cilia contain an _____
axoneme (microtubules in 9+2 arrangement)
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the microtubules of cilia insert into the ____
basal bodies
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lateral domain specifications: in light microscopy, we see _____ at the apicolateral margin of the cells; with EM, the ____ has been shown to be a _____
terminal bars; terminal bar; junctional complex
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components of the junctional complex:
1. zonula occludens or tight junctions
2. zonula adherens
3. macula adherens or desmosomes
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zonula occludens (aka tight junction)
- type of occluding junction
- found closest to apical surface
- transmembrane proteins (occludins and claudins) fuse outer surfaces of adjacent membranes together sealing off the intercellular space
- forms a continuous band around cell which is impermeable, thus it limits the movement of substances between luminal space and tissue compartments via the intercellular space
- diffusion barrier between cells
- prevents integral membrane proteins movement between domains
- provide only limited resistance to mechanical stresses
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the zonula occludens gives the ____ characteristic to epithelial tissue; for items to get across now they must be _____ via the specialized membrane proteins of epithelial cells
"barrier;" actively transported
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zonula adherens
- a type of anchoring junction
- provides mechanical stability by linking the cytoskeleton of one cell to the cytoskeleton of the next; great for resisting separation
- forms continuous band around cell
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process of connecting one cell to the next
microfilaments (actin) of the first cell attach to a plaque on the inside of its plasma membrane; this plaque is attached to transmembrane protein (cadherin) which crosses the plasma membrane of the first cell and attaches to the cadherin of an adjacent cell; this second cell’s cadherin crosses its plasma membrane where it attaches to a plaque just on the inside of the plasma membrane; this plaque is attached to the microfilaments (actin) of the second cell; thus connecting cytoskeleton of one cell to the next.
63
macula adherens (aka desmosome)
- a type of anchoring junction
- provides mechanical stability by linking cytoskeleton of one cell to the next; great for resisting separation
- forms spot welds; not continuous around cell; localized
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process of macula adherens connecting one cytoskeleton to the next
intermediate filaments of the first cell attach to a plaque on the inside of its plasma membrane; this plaque is attached to transmembrane protein (cadherin) which crosses the plasma membrane of the first cell and attaches to the cadherin of an adjacent cell; this second cell’s cadherin crosses its plasma membrane where it attaches to a plaque just on the inside of the plasma membrane; this plaque is attached to the intermediate filaments of the second cell; thus connecting cytoskeleton of one cell to the next.
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gap junctions
- communicating junctions
- transmembrane proteins are in the form of a protein tunnel called a connexon
- allows communication between cells; this is important in tissues where the activity of the cells needs to be coordinated
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how gap junctions allow communication
-the connexon of one cell lines up with the connexon of of the next cell allowing the cells to exchange ions and small molecules; these items can diffuse from the cytosol of one cell to the cytosol of the next
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the basement membrane is associated with ____ microscopy
light
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the basal lamina is associated with _____
electron microscopy
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2 components of basal lamina
1. lamina lucida
| 2. lamina densa
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type of occluding junction found closest to the apical surface
zonula occludens
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type of junction in which transmembrane proteins (occludins and claudins) fuse outer surfaces of adjacent membranes together sealing off the intracellular space
zonula occludens
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type of anchoring junction that provides mechanical stability by linking cytoskeleton of one cell to cytoskeleton of the next ; involves microfilaments (actin)
zonula adherens
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type of anchoring junction that provides mechanical stability by linking the cytoskeleton of one cell to the cytoskeleton of the next ; involves intermediate filaments
macula adherens (desmosome)
74
type of communicating junction ; transmembrane proteins in the form of a protein tunnel called a connexon
gap junctions
75
type of anchoring junction that links the cell to the basal lamina ; specifically, it anchors microfilaments (actin) of the cytoskeleton of a cell to the basal lamina
focal adhesion
76
in focal adhesions, actin filaments are attached to extracellular matrix _____ (ex. laminin and fibronectin) in the basal lamina via _____ (the transmembrane protein used here)
glycoproteins; integrins
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focal adhesions have functional role in _____ and transmitting signals from the extracellular environment to the interior of the cell (mechanosensitivity)
signal detection
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a type of anchoring junction that links the cell to the basal lamina ; specifically anchoring intermediate filaments of the cytoskeleton to the basal lamina
hemidesmosome
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in hemidesmosomes, intermediate filaments are attached to _____ and _____ in the basal lamina via integrins (the transmembrane protein used here)
laminin; type IV collagen
80
hemidesmosomes are found in epithelia subject to ____ and _____; useful for keeping the epithelium from separating from the underlying connective tissue
abrasion; mechanical shearing forces
81
two main categories of epithelial tissue
1. covering or lining epithelium
| 2. glandular epithelium
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proliferation of epithelial cells and their downgrowth into the subjacent connective tissue leads to _____
glandular epithelium
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glands can be classified by their connection to ____ (where they secrete their secretion)
surface
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2 types of glands
endocrine and exocrine
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endocrine glands are ____ glands that secrete into _____
ductless; interstitial fluid
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exocrine glands secrete their products onto a surface either ____ or via an _____
directly; epithelial duct
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endocrine glands secrete ____ which can be classified as:
hormones:
1. circulatory hormones
2. paracrine hormones
3. autocrine hormones
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exocrine glands include ____, ___, and ____ ducts of the skin; digestive glands such as ____ glands, which secrete into mouth cavity, and _____, which secretes into the small intestine
sweat; oil; earwax; salivary; pancreas
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exocrine glands can be classified based on:
1. cellularity
2. structure/morphology
3. type of secretion
4. mode/mechanism of secretion
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exocrine glands can be classified based on the number of ____ that compose the gland (i.e. cellularity)
cells
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cellularity of exocrine glands
unicellular and multicellular
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type of unicellular exocrine gland in the intestinal epithelium that produce and secrete mucin, also found in the epithelial lining of the respiratory tract
goblet cells
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classification of the structure of the duct of an exocrine gland
1. simple- unbranched
| 2. compound- two or more branches
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classification of the structure of the secretory units of an exocrine gland
1. tubular- tube shaped; either short or long or coiled
2. alveolar or acinar - round or globular
3. tubuloalveolar and tubuloacinar - combination
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exocrine glands can also be classified based on the type of secretion:
1. mucous glands
2. serous glands
3. mixed glands
96
polarized, protein-secreting cells that typically produce digestive enzymes and other proteins
serous cells
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produce hydrophilic glycoprotein mucins; cuboidal or columnar in shape
mucous cells
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two major types of secretory cells associated with glands
serous cells and mucous cells
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cells found in the basal lamina of secretory units and the initial part of duct system
myoepithelial cells
100
the basic unit of a salivary gland (i.e. salivon) is composed of the ____ and all related ducts
acinus
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a blind sac composed of secretory cells and is the secretory portion
acinus
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3 secretory acini are found in salivary glands:
1. serous acini
2. mucous acini
3. mixed acini
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serous acini
serous cells only; generally spherically shaped
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mucous acini
mucous cells only; generally tubular shaped
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mixed acini
contain both serous and mucous cells
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in traditional fixation methods, it appears the mucous acini have a cap of ____ cells; these caps are called _____, found in the ____ and _____ glands
serous; serous demilunes; sublingual; submandibular
107
exocrine glands can be classified based on the mode of secretion:
1. merocrine glands
2. holocrine glands
3. apocrine glands
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serous cells are ____ in shape; ___ on basal lamina and _____ apical surface facing lumen
pyramidal; broad base; narrow
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serous cells contain secretory granules called _____- spherical in shape, found in apical cytoplasm
zymogen granules
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serous cells have ____ cytoplasm due to RER and free ribosomes
basophilic
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in serous cells, nuclei are _____
rounded
