Ch 5 part 1 Flashcards
what is epithelium
- covers body surfaces
- lines body cavities
- constitutes glands
Epithelium covers _________, lines ___________, and constitutes ______.
- body surfaces
- body cavities
- glands
What kind of tissue is epithelium tissue?
avascular
cover exterior body surfaces
line internal closed cavities and body tubes that communicate with the exterior.
what is an exception to what the epithelium covers?
joint cavities which are lined with mesenchymally derived connective tissue cells
what does the epithelium form in regards to glands?
the secretory portion (parenchyma) of glands and their ducts
what does the epithelium form in regards to the senses?
epithelial cells form as receptors for the special senses (smell, taste, hearing, and vision)
what are the three principal characteristics of epithelial tissue?
- they are closely apposed and adhere to one another by cel-to-cell adhesion molecules (C-CAM) that form SPECIALIZED CELL JUNCTIONS)
- they exhibit functional morphologic POLARITY (apical, lateral, basal domains)
- their basal surface is attached to and underlying BASEMENT MEMBRANE
in which tissue does epithelial cells lack free surfaces?
epitheloid tissues (typically most endocrine glands).
what is traditional classification of epithelial tissue based on?
- number of cell layers
- shape of the surface cells
simple epithelium
one cell layer thick
stratified epithelium
has two or more cell layers
what are the three different individual cell shapes
- squamous - width is greater than height (flat)
- cuboidal - width, depth, and height are approx. the same
- columnar - height exceeds the width
“The cells in some exocrine glands are more or less ________, with their ______ directed toward a ________”
- pyramidal
- apices
- lumen
in which epithelium is only the shape of the surface layer cell used for classification?
stratified epithelium
what are specialized apical cell surfaces that can be added to classification?
cilia or keratinization
Pseudostratified epithelium
appears stratified but is actually simple, with all cells resting on the basement membrane.
Transitional epithelium (_________)
- urothelium
- lines the lower urinary tract and can distend (stretch).
Endothelium
lines the blood (vascular) and lymphatic vessels.
Mesothelium
lines the walls and covers the contents of closed body cavities.
“Both __________ and __________, as well as _________, are almost always ____________ epithelia.”
- endo-thelium
- endo-cardium
- meso-thelium
- simple squamous
what do endothelium and mesothelium line?
the vascular system and body cavities
What are the functions of epithelium? STARE
give examples of each
- Secretion (glands, stomach)
- Transportation (respiratory track - mucous)
- Absorption (intestine - microvilli)
- Receptor function (olfactory receptors, retina - major senses)
- mEchanical protection (epidermis - moisture……)
“____________ epithelia are compatible with a high rate of ______________.”
- Simple squamous
- transepithelial transport
“__________ of the epithelium usually correlates with ____________.”
- Stratification
- transepithelial impermeability
Each domain has specific _________ characteristics that determine the ___________ of the cell.
- biochemical
- functional polarity
apical domain
directed toward the exterior surface or lumen.
Lateral domain
COMMUNICATE with adjacent cells via specialized ATTACHMENT areas.
Basal domain
rests on the BASAL LAMINA, anchoring the cell to underlying connective tissue.
____________ in the _________ parts of epithelial cells allow epithelia to regulate _____________ movement and __________ the apical membrane from other domains.
- Junctional complexes
- apical
- paracellular
- separate
“_________ results from reprogramming of epithelial ________ cells that changes the patterns of their _______________”
- Metaplasia
- stem
- gene expression
epithelial cells are _______ together by _________
- tightly
- junctions
meta
changing
cells change due to stress……..
what does metaplasia lead to?
cancer
can be reversed
The apical domain may exhibit special structural surface modifications and contain specific _____________, ______________, and __________.
- enzymes
- ion channels
- carrier proteins
Microvilli
cytoplasmic processes containing a CORE of ACTIN filaments.
Stereocilia (stereovilli)
unusually LONG microvilli.
Cilia
cytoplasmic processes containing a BUNDLE of MICROTUBULES.
Microvilli are _______ -like _________ projections on the ________ surface of MOST epithelial cells.
- finger
- cytoplasmic
- apical
microvilli vary in appearance some are …..
- short and irregular
- others tall, closely packed, uniform
The _________ and ________ of microvilli correlate with the cell’s_________ capacity.
- number, shape
- absorptive
what is the closely packed, tall microvill of FLUID-TRANSPORTING epithelia sometimes referred to?
striated or brush border.
Microvilli contain a core of ____________ filaments _________ by ____________.
- 20-30 actin
- cross-linked
- actin-bundling proteins
The actin bundle extends down into the apical cytoplasm and interacts with the _____________.
terminal web
what is the terminal web composed of?
actin filaments stabilized by spectrin.
The presence of ____________ and __________ in the terminal web explains its contractile
ability
- myosin II
- tropomyosin
- elements similar to muscle cells
Stereocilia
Unusually long, immotile microvilli (stereovilli).
where is stereocillia found>
epididymis, ductus deferens, and sensory cells of the inner ear.
what does stereocilia do in the genital ducts?
facilitates absorption
what is stereocilia made out of?
internal bundles of actin filaments cross linked by fibrin
how does stereo cilia develop?
from microvilli by lateral addition of actin filaments
how do steriocilia constantly renew their structure?
through TREADMILLING of actin monomers
“________________ epithelium of the ear also derive from microvilli. They are exquisitely sensitive to mechanical vibration and serve as ___________________ rather than absorptive structures.” (Pawlina, 2024, p. 333)
- Stereocilia of the sensory
- sensory MECHANORECEPTORS
what are the three types of cilia?
primary, nodal, and motile
“ ________ are common surface modifications present on nearly EVERY cell in the body.”
- Cilia
Cilia are hair-like extensions of the apical plasma membrane containing an _________, the microtubule-based internal structure.
axoneme
what doe motile cilia do?
move fluid and particles along epithelial surfaces
motile cilia contain an axoneme with a ________ arrangement of microtubules
9 + 2
Motile cilia basal basal bodies are ___________-derived _____________ (MTOC) located in the apical region of a ciliated cell and ________ cilia in the apical cell cytoplasm.
- centriole
- microtubule-organizing centers
- anchor
where is motile cilia found in? REO
- respiratory epithelium
- oviducts
“Cilia movement originates from the SLIDING of ______________, which is generated by the ATPase activity of the ________.”
- microtubule doublets
- dynein arms
Cilia beat in a ____________ pattern
synchronous
_____________________ (PCD), also known as __________________ is caused my missing ___________
- primary ciliary dyskinesia
- immotile cilia syndrome
- dynein arms
motile cilia
what does PCD cause? HIRE
- hydrocephalus internus
- infertility in males
- respiratory issues
- increased risk of Ectopic pregnancy in females
Primary cilia (_____) are nonmotile and have a ______ microtubule arrangement.
- monocilia
- 9 + 0
what do primary cilia function as?
- signal receptors
- sensors
- chemo
-osmo
- mechano
what are some examples of primary cilia sensors (chemosensors, osmosensors, and mechanosensors)?
- light sensation
- odorant
- sound perception
- Fluid flow in kidneys, liver, and pancreas
- Cellular signaling devices
“Acting similarly to an antenna on a global positioning system (GPS) device, which receives signals from a satellite to pinpoint the user’s location, primary cilia receive chemical, osmotic, light, and mechanical stimuli from the extracellular environment. In response to these stimuli, primary cilia generate signals that are transmitted into the cell to modify cellular processes in response to changes in the external environment.”
primary cilia = gps
colm stimuli
________ cilia contain a _________ pattern, but are MOTILE (have dynein arms) and establish the _____________ of internal organs during embryonic development. Create a flow of ________________.
- Nodal
- 9 + 0
- left-right asymmetry
- signaling molecules
“When nodal cilia are immotile or absent, _______ does not occur, leading to _______________ of internal body organs.
_____________ (immotile cilia syndrome) often results in ____________, a condition in which the position of the heart and abdominal organs is reversed.”
- nodal flow
- random placement
- Primary ciliary dyskinesia
- situs inversus
Epithelial cells include specialized attachment area making use of ___________
cell adhesion molecules (CAMs)
what represents epithelial cell-to-cell
attachment sites (seen in the light microscope)?
terminal bars
what are junctional complexes?
are responsible for joining individual cells together
what three things (zons) do junctional complexes include?
- occluding junctions
- anchoring junctions
- communicating junctions
what are occluding junctions (__________)?
Zonula Occludens
seals the space between cells.
what are anchoring junctions (_____________)?
Zonula Adherens and Macula Adherens
provide mechanical stability
what are communicating junctions (_____________)?
Gap Junctions
allow direct communication between cells.
Zonula occludens (______________) separates the luminal space from the intercellular space and connective tissue compartment.
tight junction
what does the zonula occludens separate?
the luminal space from the intercellular space and connective tissue compartment
where is the zonula occludens modified?
in areas where three epithelial cells meet
what is it called where three epithelial cells meet?
tricellular zonula occludens
what proteins are involved in the formation of zonula occludens strands?
- Junctional adhesion molecule (JAM)
- occludin
- claudin
“It is now evident that the zonula occludens plays an essential role in the _____________________ from one side of an epithelium to the other.”
- selective passage of substances
What is controlled but the complexity of the strands of the zonula occludens (tight junctions) and the proteins involved in their formation?
permeability
