Cytology and Epithelium Flashcards
What is the glycocalyx?
It is a cell coat. Carbohydrates extend from cell membrane.
-made from either proteins in external face of plasma membrane (glycoproteins).
or from phospholipid molecules (glycolipids)
What is the function of the glycocalyx?
Cell-cell recognition and cell to cell adhesion
What are Globular proteins? Give example.
They move within the plasma membrane.
Ex: ion channels, pumps, receptors, transducers, enzymes
What is heterochromatin? How does it look stained?
Dense coiled DNA. EM: dark staining LM: basophilic stains blue
Where can the heterochromatin be found?
Marginal chromatin (near edge), karysomes (not near the edge), nucleolar associated chromatin.
What is Eucharomatin? How does it looked stained?
uncoiled DNA more active, EM: light stain
Where is the site of rRNA synthesis?
Nucleolous
What is the function of Nuclear Lamina?
intermediate filament proteins; it serves as scaffolding for nuclear components
What is the difference between Laminin, Lamina, and Lamin
-Lamina: made of lamins (cytoskeletal structure) 10nm thick
Ex: think nuclear lamina
- Lamin: lie between nuclear membrane and marginal heterochromatin. They are fibrous proteins that form structure of nucleus. Disassemble during mitosis and reassemble
- Laminin: not associated with nucleus. glycoprotein.
What are nuclear pores?
(75 nm diameter) allow passage of mRNA into the cell.
What are Ribosomes?
150A made of r RNA and protein - involved in translation
What is the classification of ribosomes?
- Free ( in the cytoplasm _ proteins they make stay in the cell.
- ER
Where does intracellular protein sythesis occr?
Free polyribosomes
Where does extracellular protein synthesis occur? What type of proteins do they secrete?
- In the ribosomes bound to ER.
- integral proteins or secretory proteins
What is a polyribosome?
A cluster of any type of ribosomes linked by mRNA
What is RER?
- studded with ribosomes.
- protein synthesis for insertion into membrane or export.
What is SER?
contains no ribosomes= no protein synthesis
What is the function of SER?
- ) synthesis of steroid hormones,
- ) glycogen and lipid synthesis
- )HCl formation (gut)
- ) calcium stored in the sarcoplasmic reticulum (muscle)
- ) drug detoxification (liver)
What is the function golgi Apparatus?
- ) Site of protein modification
- ) transfer vesicles containing protein move from RER to form facing (cis) of the golgi–golgi are added to form glycoproteins–these are then packaged into secretory granules for cellular export.
- ) produces glycocalyx for integral membrane
what are lysosomes formed by and what does it contain?
- formed at the golgi (membrane bound)
- contain hydrolytic enzymes used for digestion of extracellular or intracellular components
What is the function of lysosomes?
- ) breadkdown the cell constituents
- ) cell remodeling
- ) normal turnover of organelles
- )normal turnover of macromolecules
- ) breakdown of bacteria and viruses
What is the difference between primary and secondary lysosome?
- ) newly formed and doesn’t have digesting material. light on EM
- ) has actively digesting material. dark plaque on EM.
Lysosomes have enzymes specific for? List the enzyme target and classification of enzyme.
1.) Proteins: proteases
2.)Nucleic acids: nucleases
3.)Polysaccharides: glycosidases
4.)Lipids: lipases
5.)Organic linked phosphates: phosphatases
“POPLN”
What is Tay Sachs:
Lipid metabolism defect (autosomal recessive trait)
-missing enzyme (hexosaminidase) for splitting off hexose from a ganglioside
What is ganglioside? What happens when gangliosides accumulate?
complex form of a glycolipid found in gray matter cells in CNS.
-in neural tissue in Tay sacs causes retardation and childhood death.
what are Peroxisomes?
Contain many oxidative enzymes (catalase) that break down peroxide (H2O2).
What does H2O2 do to cells?
It is toxic; it causes free radical formation. the free radical cross link proteins, rendering them non-functional.
What are the characteristics of mitochondria?
- ) provide energy for the cell in the form of ATP (.5-1.0 micrometer in diameter, 2-5 micrometer long)
- ) contain their own DNA and ribosomes for self replication
What is a cytoskeleton?
Non-membrane bound organelles
What are the characteristics of microtubules (MT)?
- The largest of cytoskeleton (25nm in diameter)
- present in all cells
- line up to form spindle fibers in mitosis
What is MAP? (microtubule associated proteins)
- LINK MT to other cytoskeletal components and organelles. (ex. dynein)
- associated with vesicle and organelle movement (ATTACH MT to things in the cell)
- help STABILIZE MT in cilia and flagella
What is the function of microtubules?
- Provide physical support for cells via cytoskeleton.
- Chromosome movement during cell division
- involved with ciliary movement
- intracellular transport of secretory products
- involved with cell division
What are intermediate filaments and its function?
- 10-12 nm, protein polymer-;stable compared to MT or MF
- all cells contain some type of intermediate filament
- function: structure
What are the 4 major families of intermediate filament?
- ) Keratins: found in all epithelial cells
- )Vimentin and Vimentin-like intermediate filaments : not found in all cells (RBC particularly)
- )neurofilaments: only found in neurons
- )Lamins: found in all nucleated cells
What are the characteristics of microfilaments (MF)?
- 5nm diameter
- protein polymer present in all cells.
What are the 2 basic types of proteins in MF?
Actin and myosin
What is the function of MF?
- contraction (cellular movement)
- cytokinesis (pinching of cell division)
- endocytosis
- ameboid movement
- structural support
What is centrioles made of. Describe location and pattern.
- it is made made of microtubules.
- location near the nucleus (2 per cell)
What is the structure of centrioles?
-Structure: short cylinder comprised of microtubules arranged in 9x3 triplets (CCO) connected by protein links
what is the function of centrioles?
During cell division, migrate to opposite poles of cell-serve as organizing centers for mitotic spindles.
What is cilia?
5-10 micrometer length
.2-.5 micrometer in diameter
What are the 3 portions of cilia?
- ) shaft (axoneme): (9x2) +2 MT arrangement, surruounded by PM
- )basal body: (9x3) MT 9similar to centriole0
- )rootlet: anchors cilia to cytoskeleton
What is the Axoneme (shaft)?
- 9 peripheral doublets-each contains 2 MT.
-CO arrangement
-dynein protein arms- cause movement
2 central singlets connected by protein - central sheath (protein)
-radial spikes (protein)
What is the function of cilia?
- movement
- dynein arms cause movement, use energy of ATP to move
- found in respiratory tract and oviduct
What component of the cell does not posses metabolic activity?
Inclusions. They also don’t perform energy-requiring functions.
What are the types of inclusions:
1.) lipid or fat
2.)glycogen
(beta glycogen: single subunit, 2 size of ribosome)
alpha glycogen: cluster of beta glycogen
3.) Residual body:
tertiary lysosome. Ex: lipofuscin (brown pigments; it accumulates with age)
What is microvilli?
- regular or irregular finger-like projections that are extensions of plasma membrane.
- function: increase surface area for exchange of material. aid in absorption
What is sterocilia and where can they be found?
-very LONG MICROVILLI
- found in sensory organ of the ear and male reproduction system
(* They are NOT cilia!)
What does epithelia cover?
Cells that cover a free surface or line a tube (glands) or cavity.
What type are the 3 basic types attachment for epithelia ?
- ) tight junction (zonula occludens)
- )belt desmosome (Zonula adherens)
- ) desmosome (macula adherens, spot desmosomes)
What are tight junctions (zonula occludens and its function)?
- Connects epithelial cell to epithelial cell
- membranes are in direct contact
- function: makes tight seal between cells-prevents material from leaking between cells- not a strong attachment
What are belt desmosome (zonula adherens)? Function and structure
- connects epithelial cell-epithelial cell
- function: keeps cells from being pulled apart
- consist of microfilament (5 nm) : ACTIN, dense cytoplasmic material, 15-20 nm space b/w 2 membranes
- intracellular material- linker protein b/t cell
What are fascia adherens?
attachments found between non-epithelial cells (most found in cardiac muscle cells-similar in structure to belt desmosomes)
Function and form of desmosome (macula adherens, spot desmosome)?
- connects cell-cell,
- function: holds cells together tightly (all tissue types)
- contains tonofilaments (10 nm intermediate filaments), cytoplasmic plaque, transmembrane linker protein,
- dense intermediate line ;Central stratum (think bridge).
- 30-40 nm space between cells
What is the function and structure of hemidesmosome?
connects epithelia- connective tissue.
consist of tonofilaments, cytoplasmic plaque, linker proteins
What are gap junctions function (nexus junction)?
Function:
- ) allows for cell to cell communication
- ) electrochemical coupling
- ) small peptides can move from cell to cell. moves ions, so it moves charge important for cardiac and smooth muscle (Ca2+ ions)
What does junctional complex consist of
tight junction, belt desmosome, and desmosome
What is phagocytosis (clathrin independent and actin dependent endocytosis)?
- used for ingestion of larger particles (>1 micrometer)- material not in solution
- involves actin depolymerization and repolymerization
- involves cell surface receptors that specifically bind a certain susbstance- effects changes in the cell
What is pinocytosis?
(clathrin independent endocytosis)
- nonspecific ingestion of material in solution
- caveolae
- doesn’t involve receptors
What are the characteristics of receptor mediated endocytosis (clathrin dependent endocytosis)
- specific ingestion of molecules into the cell
- coated pit
- coated vesicle
- clathrin coat
clathrin coat
- (made of proteins called triskelions)
- involved in invagination and pinching off of the vesicle
What are the possibilities of the fate of receptor/ ligand?
- ) the receptor is recycled and ligand degraded.
- ) both the r and l are recycled
- )r and l are degraded
- ) the r and l are transported through the cell
What is nuclear lamina?
Intermediate filamennt proteins-serves as scaffolding for nuclear components
What are Coatomers? What are the types?
- a coated vesicles that moves proteins between RER and Golgi
-the types of of coatomers are COP1: retrograde (to the er)
G->ER
COP2:anterograde(to golgi)
ER->G
What are connexons?
HOW MUCH connexons make up an entire channel?
If there were 2 connexons how many connexins?
- MAde of 6 connexins
- 2
- 12
what are microtubules made of?
- made up of tubulin (alpha and beta tubulin subunit)
- tubulin dimers polymerized to from a microtubule
What is the most distributed IF in the body?What is Spectrin and where is it found?
Vimentin
-Spectrin is found in RBC; (its vimetin like IF)
what is the function of mitochondria?
atp production, calcium sink, and heat production.
Where does glycolysis occur? where does krebs cycle take place? Where does the electron transport take place
- cytoplasm
- matrix of mitochondria
- inner membrane of mitochondria
What are microtubules reversible and dependent on?
- ATP, pH, calcium concentration
- can change length depending on physiological conditions within the cell
What does microvilli contain?
-contain villin, actin filaments, fascin, fimbrin, and myosin 1, terminal web with spectrin, myosin 2, tropomyosin
What is the arrangement of axoneme, basal body and centriole?
Shaft: (9x2 CO) +2 MT
Basal body: (9x3) MT like centriole
centriole (9x3) CCO patterns
What is dynein associated with
dynein arms cause movement; it uses energy of atp to move
-dynenin asscoiated with MAP
What does actin do to microvilli?
Plural: Villi
Sing:Villus
keeps MV rigid and discrete.
Where can microtubles be found?
Cilia, flagella, and centrioles
What are the 3 junctional complexes that connect epithelia to epithelia?
Which junctions aren’t related to epithelium?
- Tight junction, Belt Desmosomes, and Desmosomes
- FAscia adherens and gap junctions
WHAT is the distance in space between 2 membranes in belt desmosomes? What is the distance in space of spot desmosome?
15-20 nm space
30-40 nm
What are the differences in structure in between fascia adherens, macula adherens, tight junction, gap junction and belt desmosomes,
- tight junctions the cells fuse together leaving no space to prevent cells from leaking
- belt desmosomes contain actin and linker protein
- fascia adherens: similar structure to belt desmosomes ( found in cardiac muscle)
- macula adherens:Dense intermediate line (central stratum), 10 nm size of tonofilaments,
- gap junctions:connexon made up of 6 connexins
- hemidesmosomes: tonofilaments, cytoplasmic plaque, plamsa membrane, linker proteins
What are the characteristics of nexus junction
- 15-20A gap between cells
- made of 6 connexins to form 10-15 A channel when opened
- connexin subunits are aligned between adjacent cells
What are the three forms of endocytosis?
phagocytosis ( actin dependent endocytosis), pinocytosis, receptor mediated endocytosis
Which ones are clathrin independent endocytosis?
Pinocytosis, phagocytosis
What are the steps of phagocytosis?
- )phagocyte encounters a particle
- ) Ligand binds to surface receptors
- Actin polymerization froms pseudopods
- ) Engulfs particle complete internalization
What is caveolae?
uncoated (no protein coat) vesicles involved with pincytosis
What is cholesterol needed for?
steroid synthesis and plasma membrane compounds.
What does HDL (high density lipoprotein) do?
-carry cholesterol to liver disposed in bile
What are the steps for Receptor mediated endocytosis with LDL particles?
a. ) LDL particle attaches to the receptor of PM
2. ) clathrin coated vesicle pinches off to be a coated vessicle
3. ) clathrin depolymerizes into Triskeletons–> endosomes (loss its coat)
4. ) ph change from 7 to 5. low ph cause receptors to dissociate from LDL receptors
5. ) LDL fuses with primary lysosome forming 2ndary lysosome.
6. ) apoB proteins is degraded into amino acide and cholesterol esters are hydrolyzed to fatty acids and cholesterol
What are the general characteristics of epithelium?
- highly cellualar
- avascular
- regeneration capacity-wound healing, normal turnoover -renewal
- cells frequently exhibit polarity with respect to orientation of cell and organelles
What are the types of epithelium?
- lining of membraneous epithelium
- glandular epitelium
What does membranous epithelium cover?
surface of body, lines organs (digestion, respiratory, urogenital tracts)-lines blood vessels, heart and body cavities
What is grandular epithelium?
form exocrine and endocrine glands and is specialized for secretion
What is the function of epithelium? Epithelium: singular, Epithelia: plural
SELF PARTs
- Secretion: glands and hormones
- Excretion: kidney
- Lubrication: secretion of gland cells in the GI tract
- Filtration: renal corpuscle of the kidney
- Protection: skin against mechanical trauma
- Absorption: lining the small intestine
- Reproduction: germinal cells of the testis
- Transport: cilia on epithelial cells of respiratory tract move mucus
- Sensory perception: taste beds and olfactory epithelium
What is cell membrane polarity?
Microdomain: region of cell membrane that has a distinct structure of function
What are the surface specializations of apical surface? What is the general function
a. ) cilia, microvilli, stereocilia
b. )Clathrin coated vesicles
c. ) glycocalyx
function: absorption recognition
-free surface to air, fluid
What Is the lateral surface attached to? What are its surface specializations? Function.
-to other epithelial cells
a. Junctional complex
b. gap junctions
c. cell adhesion molecules (CAMs)
functionL attachment and communication
What Is the basal surface attached to? What are its surface specializations? Function.
often attached to connective tissue
a. hemidesmsomes
b. membrane folds
function: attachment,transport, absorption
What are zymogen granules?
Certain precursors made of protein (not in all epithelial cells)
What is maturing face and forming face?
Golgi:
M: points away from nucleus
F: Points torward Nuclues
What does the basement membrane consist of?
Basal lamina and Reticular lamina
What are Basal Lamina produced by? What is it made up of?
-produced by Epithelia
Contains 2 parts:
-Lamina Lucida and lamina densida
- Glycoaminoglycans (GAG)
- Collagen type 4
- Laminin
What is Reticular Lamina produced by and what is it made up of? Function
produced by connective tissue
- collagen 3 fibrils, aka reticular collagen
- GAGs
Function:
- support: physical, and functional
- selective filtration
What are the places where simple squamous could be found?
a. )Bowman’s capsule, lines alveoli of lungs
b. )mesothelium
c. ) endothelium:
Where could simple cuboidal be found?
ducts of kidney and glands, sheets covering ovary
Where could simple columnnar be found? What is its characteristics?
- lines the intestine
- may be cilated (bronchioles, oviducts, fallopian tubes and efferent ducts
- may have goblet cells; which produce mucus for lubrication
function: absorption and secretion
What are the charcteristics of pseudostratified columnar?
- Some cells don’t reach the luminal surface
- all cells attach to the basement membrane
- consist of cilia, stereocilia or noncilated regions
Function: absorption of material (particles, Mucus)
What is the role of cilated with goblet cells in pseudocolumnar?
-cilated with goblet cells (lines respiratory passages (trachea, bronchi)
Function of cilated: moving surface material
What is the purpose of sterocilia?
Lines part of the male reproductive system (epididymis)
What is the difference between cornifed and non-cornified stratified squamous?
Cornified: Contains flaggrin, cross linking protein- cross links keratin intermediate filaments
Non-cornified: keratin intermediate filaments present but not cross linked
What does all epithelia posses?
- keratin intermediate filament, but not all is crosslinked
- all epithelium rests on basement membrane?
What is stratified cubodial/ Columnar
rare (line large ducts of some glands)
What are transitional epithelium?
- Large dome shape surfaces
- binucleated
- thin basement membrane
- not all cells attach to basement membrane
- lines urinary bladder and ureter
function: accommodates stretch, protects underlying tissue from hypertonic urine
What is Acinus? (pl. acini)
secretory units that have grape cluster like shape and small lumens.
What are the types of lubrication membrane classification of epithelia
Serous membranes: watery secretion
mucous membrane: mucous secretion
What is mucous membranes composed of?Where does it line and what is its function in the areas in aligns?
- rich in proteins O-glycosylated with anionic oligosaccharides
- lines gi and respiratory tract
-Function:
in gi tract: viscous fluid protects against chemical irritation
-respiratory tract: traps inhaled particles
What does goblet cells secrete?
mucus
All exocrine and most endocrine glands are made up of epithelia. What are the 2 exceptions?
posterior pituitary and adrenal medulla; these are nerves
What is exocrine duct?
-products are secreted into ducts
What is Endocrine duct?
Ductless; produce hormones that are secreted into the bloodstream. (wrapped in capillaries)
What are the exocrine gland classified in?
- based on cell number
- unicellular (globet cells) and multicellar
What are multicellular further classified based on?
- shape (simple vs complex– Tubular or alveolar)
- type of secretion (mucus vs serous)
- mode of release of secretory product (eccrine vs. apocrine vs holocrine)
What is the shape and complexity features in multicellular exocrine gland?
Shape:
- tubular
- Alveolar or acinar (flask shaped)
Complexity:
- )simple-one duct
- ) compound-multiple duct
what are the 3 types of acini
serous, mucous and mixed( may or may not have serous demilunes.
Give description of serous acinus. What is its secretory product.
- serous secretion (watery)
- pyramidal shaped cells
- cell boundary indistinct
- apical secretory granules: stain acidophilic with H and E
- Basophilic cytoplasm
-secretory product : proteinaceous, thin, watery and contain enzymes
Give description of mucous acinus. What is its secretory product.
- mucoid secretion
- pyramidal shaped cells
- nucleus flatted at base of cell
- secretory product : mucinogen (white loss during H and E) PAS: purplish
- glycoprotein and mucoprotein is slightly basophilic (glycogprotein or mucoprotein)
- secretory product is thick and may act as a lubricant
What are the modes of secretory product release?
Merocrine, Apocrine, holocrine, cytogenous
What are the characteristics of merocrine (eccrine)?
- secretory granules fuse with cell membrane and contents ONLY are released (serous or mucus); secrete without losing cellular material
- exocrine gland
- Ex: pancreas or some sweat glands
What are the characteristics of apocrine?
Secretion released: with plasma membrane enveloping the particle (part of cytoplasm leaves the cell) Apo= a part of
Ex: mammary gland, axillary, and circumanal modified sweat glands
What are the characteristics of holocrine?
Whole cell dies and is secreted.
holo (whole)
Ex: sebacous glands of skin
Cytogenous
Whole living cell is released
Ex: ovary and testis (sperm and egg relesed)
What are epitheloid cells? Give examples
Cells with epithelial characteristics but lack a free space.
- Leydig cells (testis)
- Luteal cells (ovary)
- Adrenal parenchyma
- reticulo-epithelial cells of thymus
What is Laminin?
glycoprotein, connects basal lamina to epithelial cells
What is flaggrin?
cross links protein. In cornifed squamous epithelium
Which membrane enclosed organelles produce oxidative enzymes that free radicals cross link proteins, making them nonfunctional?
peroxisome using H2O2 causes free radical formation with unpaired electrons.
Which organelle contain hydrolytic enzymes and which forms oxidative enzymes?
- Lysosomes use hydrolytic enzymes for digestion of extracellular or intracellular components.
- Peroxisomes us oxidative enzymes to break down H2O2
Which cells don’t have mitochondria?
Mature RBCS in circulation and terminal keratinocytes.
What controls cell movement?
Microtubule lattice
Which cell does not have a nucleus and what does that entail?
RBCs they don’t have lamins
What is the purpose of actin in microvilli?
keeps MV rigid and discrete
List the function of each type polarity surface and give examples .
Apical: absorption and recognition Examples: a.) suface specializations like cilia, microvilli, sterocilia b.) clathrin coated vesicles c.)glycoalyx
Lateral: attachment, communication
Junctional complexes, gap junctions, cell adhesion molecules (CAM)
Basal surface: attachment, transport, absorption
Hemidesomosomes and membrane folds
Where can mesothelial and endothelial cells be found?
Mesothelium: lines surface body cavities (peritoneal, pleural, pericardial cavities)
endothelium: lines blood vessels and lymphatic vessels
Which membrane consist O-glycosylated with anionic oligosaccharides and what does it do? (serous or mucous)
Mucous makes it more viscous
