Chapter 1 Flashcards
General functions of epithelium
- Absorption (bile duct)
- Secretion (stomach cells, HCL)
- Provide a barrier (all types of epithelium do this)
Specialized functions of Epithelium
- Transportmoleculesacrossepi.
- Preventtransportofmaterialsacrossepi.=selectivepermeability
- Sensory(ex.Tastebuds,retinaineye)
Cells are ____________ to each other
adjacent
Associated with __________ or __________ basement membrane
Complete or Partial
Parts of Complete Basement Membrane
A. Basal Lamina- produced by epithelial cells
B. Reticular Lamina- produced by fibroblasts in CT
Part(s) of Partial Basement Membrane
Basal Lamina Only
Functions of a basement membrane
a. provides a surface for epithelial attachment
b. molecular filter- limited
c. limit stretch- protects
Epithelium is ___________. Cells obtain nutrition by __________.
avascular
diffusion
Functions of CT
- provides nutrition for associated epithelium
2. source of defensive cells
Cells are held together by ____________
cell junctions
Zonula Occludens (name)
Tight Junctions
Zonula Occludens (tight junctions) involve the sharing of intrinsic membrane proteins between ________ _______.
adjacent cells
Zonula Occludens (tight junctions) functions
- provides strong attachment
2. prevents the passage of material between cells
Zonula Adherens (name)
Adhesion Belt
Zonula Adherens (Adhesion Belt) consist of ________ (________) between cells & _______ (________) which attach the cytoskeleton to the cell membrane at these areas
cadherins (linkage proteins)
Marginal bands (microfilaments)
Zonula Adherins (Adhesion Belt) functions
- provides strong attachment
2. provide cell structural stability
Macula Adherens (name)
Desmosomes
Macula Adherens (Desmosomes) function
Provides strong attachment
Gap Junctions are six ______ (______) arranged in a cylinder.
connexins (proteins)
The size of the openings in gap junctions can be controlled _______________.
by the cell
Gap Junctions function
- provides strong attachment
2. Transport materials (purpose: communication) [Primary Function]
Junctional complex = 3 junctions beginning with free cell surface
- Zonula Occludens
- Adhesion Belt- Zonula Adherens
- Macula Adherens
What junction type is NOT included in the junctional complex
Gap Junctions
Helps to connect epithelial cells to the basal lamina.
Hemidesmosomes
essentially half a desmosome
Integrin (a transmembrane protein of the cell membrane) binds to structural CT glycoproteins and also connects to cytoskeleton.
Focal Point Contacts
Single Epithelium
epithelium that is a single cell thick
Simple squamous- example locations
lung, parietal layer of the Bowman’s capsule in the kidney, serosa on the outside of organs
Simple squamous cells are…
a single layer of flattened cells
Simple squamous cells- functions
- provide a barrier
2. living filter
Simple cuboidal- example locations
exocrine ducts, thyroid follicular cells, kidney tubules
Simple cuboidal cells are…
a single layer of cube shaped cells; nucleus occupies much of the cell cytoplasm; typically looks like a square when sectioned for a slide
Simple cuboidal cells- functions
- Provide a barrier
- Secretion
- Absorption
Simple columnar- example locations
stomach, small intestines, gallbladder, larger exocrine ducts
Simple columnar cells are…
a single layer of cells that have height; more cell cytoplasm than simple cuboidal; typically look rectangular when sectioned for a slide
Simple columnar cells function
- provide a barrier
- secretion
- absorption
Ciliated Pseudostratified Columnar Epithelium Example Locations
trachea, respieratory region of nasal cavity, bronchi
Ciliated Pseudostratified Columnar Epithelium is…
three cell types of various heights so it can have the appearance of a stratified epithelium.
Ciliated Pseudostratified Columnar Epithelium cell types:
- Goblet cells
- Ciliated Columnar cells
- Basal Cells
Goblet cells are…
Function
modified columnar cell
function: to produce mucus
Ciliated columnar cells are…
Function
columnar cells that contain cilia. Cilia are anchored in the apex of the cell by basal bodies.
function: to move mucus over the surface
Basal cells are…
Function
short pyramidal shaped cell that does not reach the surface
function: to be the stem cell for this type of epithelium
Microvilli are…
finger-like projections at the apical surface on some epithelial cells.
Microvilli are also called:
a brushborder or a striated border
Microvilli function
to increase surface area so as to increase absorption function
Microvilli example locations
kidney tubule cells, small intestines
Stereocilia are…
extremely long microvilli; usually fewer present than in microvilli
Are stereocilia related to true cilia
NO
Stereocilia function
usually to increase surface area
Stereocilia example locations
epididymis, cochlear hair cells
Cilia are…
thin apical hair-like extensions of the cytoskeleton
Cilia function
to move something over a surface
Cells with Cilia have…
- many mitochondria
2. basal bodies that block the free surface so there is NO secretion or absorption
Cilia example locations
trachea, fallopian tubes
Glycocalyx is…
surface layer of glycoproteins and carbohydrates that covers some epithelium
Glycocalyx is produced by:
epithelial cells
Glycocalyx functions:
- protective function (particularly in digestive system)
2. cell recognition
Glycocalyx example locations
stomach and small intestines
Stratified epithelium is…
Epithelium that is two or more cell layers thick. Named for the shape of its superficial cells.
All have a protective function
Stratified squamous example locations
esophagus, oral cavity, tongue, vagina
Stratified squamous are…
multiple layers of cells that tend to flatten out from basal layer to superficial layer; superficial layer of cells are flat and alive.
Stratified squamous function
protection from abrasion
Stratified squamous problems/limitations
- no protection from drying
2. limited thickness so protection is limited.
Keratinized Stratified Squamous example location
skin
Keratinized Stratified Squamous are…
multiple layers of cells that also tend to flatten from basal layer to superficial layer of cells; superficial cell layer is covered by an added nonliving layer of keratin.
Keratinized Stratified Squamous function
protection in a dry environment
Keratinized Stratified Squamous layers in epithelium of skin
Stratum Basale (germinativum) Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Stratum Basale (Germinativum)
1-2 layers of keratinocytes which are mitotic and closest to the dermis
Stratum Spinosum
multiple layers of “spiny shaped” keratinocytes that produce lipids and keratohyaline vacuoles. Kertinocytes have cytokeratin tonofilaments that radiate outwards from the nuclear region. Thickness of this layer can vary.
Stratum Granulosum
uppermost 2-5 layers of flattened living keratinocytes that contain flattened, condensed keratohyaline granules. Exocytosis of lipid-filled lamellar granules will occur from these cells.
Stratum Lucidum
thin layer of recently dead or dying keratinocytes present ONLY IN THICK SKIN. This layer is not easy to see. Nucleus & organelles are not present.
Stratum Corneum
Layer of dead cells, keratin and lipids. Thickness of this layer varies.
Stratum Corneum functions
a. Prevents water loss
b. Provides a barrier to microbes
c. Protects against abrasion/friction
Epidermal pegs (rete ridges) and dermal papillae contribute strength to this epithelium by __________
increasing surface area for attachment of the epithelium to the CT below
Keratinized stratified squamous cells have a ____ life cycle
~28 day
Melanocytes (function)
protect against UV radiation
Melanocytes are found in what layer
stratum basale
How do melanocytes function
Keratinocytes phagocytize the cytoplasmic tips of the melanocytes containing the melanosomes with the melanin
Skin color is generally influenced by
A. environmental factors
B. Genetics
C. Number of blood vessels in dermis
Environmental (melanocyte) influences are:
increased UV light exposure: increase melanocytes numbers and increase melanin
Genetic (melanocyte) influences are:
Eumelanin or Pheomelanin
Placement of melanin
Destruction rate of melanin by lysosomes
Langerhans cells (function)
recognize forein antigens
Langerhans cells found in:
Stratum Spinosum
Merkel Cells (function)
provide touch receptors
Merkel Cells found in:
Stratum Basale
Merkel Cells are assoicated with
free nerve endings
Melanocyte numbers _______ when exposed to UV light repeatedly
increase
Langerhans cells ________ with repeated UV exposure
decrease
Stratified Cuboidal example locations
larger ducts in sweat glands and salivary glands
Stratified cuboidal are…
Two layers of cells.
Basal layer is typically flattened.
Superficial layer of cells is cuboid in shape.
Not common.
Stratified cuboidal function
to increase protection
Stratified columnar example locations
large ducts in pancreas, parts of the male urethra, conjunctiva of the eye.
Stratified columnar are…
Two layers of cells.
Basal layer is flattened to cuboid in shape.
Superficial layer is columnar in shape.
Very rare.
Stratified columnar function…
- to increase protection
2. to provide a transition between epithelial types
Transitional (urinary) [name]
Urothelium
Transitional (urinary) example locations
most of urinary tract
Transitional (urinary) are…
multiple layers of cells.
Transitional (urinary) function
protection to stretch
Specializations of Transitional (Urinary) epithelium
- Thin, fenestrated basement membrane
- Large, rounded superficial cells
- Well-developed zonula occludens (tight junctions)
Why are well developed zonula occludens important in Transitional (urinary) epithelium?
- Need due to fenestrated basement membrane
2. Prevents wastes from seeping between epithelium cells.
Unusual Superficial Cell features in Transitional (urinary) epithelium:
some bi-nucleate cells
Urothelium cells obtain more oxygen because:
- Fenestrated basement membrane
2. when stretched, the diffusion distance is decreased
Psoriasis Vulgaris appearance
patchy skin lesions
Psoriasis Vulgaris \_\_\_\_\_\_\_\_\_\_\_\_\_\_ life cycle ~ 1 week Cells accumulate in \_\_\_\_\_\_\_\_\_\_\_\_ Inflammation in \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_ and \_\_\_\_\_\_\_ is unknown
Accelerated kertinocyte
stratum corneum
dermal papillae
cyclic and etiology
Freckles are due to:
an increase in melanin without an increase in melanocyte numbers
Vitiligo appearance
patches which lack melanocytes
Vitiligo cause:
unknown. Often associated with systemic diseases
i. e. hypothyroidism, hyperthyroidism, diabetes, Addison’s disease, pernicious anemia, leprosy
Moles (naevi) appearance and cause
discoloration due to a proliferation of melanocytes
Malignant Melanoma: description and treatment
Melanocytes become mitotically active and invade dermis, very invasive and metastatic
treatment: surgery and chemotherapy
Albinism: cause
melanocytes fail to produce melanin
Albinism: most common form
Tyrosinase (enzyme) is missing form melanocytes. Tyrosinase is a catalyst in the conversion of tyrosine to melanin.
2 subcategories of epithelial glands
Endocrine & Exocrine
Exocrine secretion: definition
method of secretion by which the product is released into a duct or directly onto an epithelial surface
What is parenchyma?
components directly involved with a primary function
What is stroma?
components providing mechanical/metabolic support
Morphology: methodology
This method classifies the gland according to the shape of secretory units and the ducts arrangements
Morphology: example
compound branched tubular gland
secretory units: tubular vs acinar (alveolar)
duct arrangment: unbranched vs branched
Method of Secretion:
Merocrine (eccrine): examples
goblet cell, salivary glands, pancreas, all sweat glands in children, many adult sweat glands.
Method of Secretion:
Merocrine (eccrine):
_________ method of secretion
Secretion by exocytosis therefore:
Most common
No cell damage, no cell cytoplasm or membranes in the secretory product, no odor associated
Method of Secretion:
Holocrine: examples
sebaceous glands, tarsal (meibomian) glands of eyelid
Method of Secretion: Holocrine: Cell matures and \_\_\_\_\_\_\_ Secretory product = \_\_\_\_\_\_\_\_ Associated with \_\_\_\_\_\_\_
cell matures and dies
secretory product = some cytoplasm & membrane + intact vacuoles
associated with odor
Product secreted:
Acinus
smallest division of a gland; a group of cells surrounding a cavity
Product secreted:
Serous Demilune
a small group of serous cells attached to a mucus acinus
Product secreted:
Myoepithelial Cells
contractile cells with epithelial origin. These cells warp around the acini and sometimes the ducts in some exocrine glands.
Product secreted:
Myoepithelial cells
Found in:
Salivary glands and sweat glands
lacrimal glands
Lactating mammary glands
Product secreted:
Myoepithelial Cells
Function:
Assist secretion
Serous Glands
Produce:
Examples:
produce proteins
ex. pancreas, parotid gland, chief cells in stomach
Serous Glands
Characteristics:
cell is trapezoid shaped
Nucleus is typically round and noticeable
cells pick up stain
Mucus Glands
Produce:
Examples:
produce mucus
Examples. Goblet cells, mucus cells in stomach, minor salivary glands in tongue and palate
Mucus Glands
Characteristics:
Cells typically stain light
Nucleus is often flat and peripheral
Mixed Glands
Produce:
Example:
produce serous & mucus
Sublingual and submandibular salivary glands
Mixed Glands
Characteristics:
Serous demilunes are possible
Exocrine Regulation: how
Myoepithelial cells
Hormones
Blood Supply
