Glossary of Histology Exam 1

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Describe clinical use for histology techniques
Unfixed frozen sections are used in surgery when time is vital, but get lower resolution
Fixed samples have better resolution but require more time
Discuss reasons for and results of fixation
Fixation terminates metabolism, prevents enzymatic self digestion, kills microorganisms, hardens tissue by cross linking and/or protein denaturation
Describe common fixatives
1.Formaldehyde- reacts with amino groups but POOR fixative of cell membranes
2.Glutaraldehyde- produces better fixation then formaldehyde but incompatible with some immuno and silver stains. Used for electron microscopy
3.Osmium tetroxide- excellent for electron microscopy, including membranes
Describe basic dyes
Bind to ACIDS (basophilic structures) such as DNA, RNA, acidic sugars
Also called Nissl stains
Examples- methylene blue, hemotoxilin
Describe acidic dyes
bind to BASES (acidophilic structures), like cytoplasmic molecules, collagen, red blood cells
Example - eosin
What does Golgi stain bind to
Binds to aldehydes in sugars, used to visualize neurons
How does heavy metal stains work
Heavy metals- lead and uranium- are used to bind to inside and outside of the cell membrane
What does lipid bilayer composed of
Phospholipids and cholesterol with embedded proteins
What does cholesterol do for the membrane
It stabilizes membrane fluidity
What can proteins do after they are synthesized
They can free float, channel in rough ER or transfer to smooth ER
Name major types of membrane proteins
Pumps - Na/K pump
Channel- glucose channel of muscle, select certain things to come in the cell
Receptors- molecules bind outside, changes occur inside
Linkers - anchors molecules down, collagen
Enzymes - ATPase
Structural- forms tight junctions
dark clumps of highly coiled DNA, predominates in cells with low metabolic activity
Pale, staining unwrapped and actively transcribing DNA
Describe nucleus
-surrounded by membrane
-nucleoplasm is fluid
-nucleus active- light, non active - dark
DNA and ribosomal proteins associated with transcription to rRNA
Pars granulosa
Portion of nucleolus that stains LIGHTLY - contains actively developing ribososmes
Pars fibrosa
portion of nucleolus that stains DARK - inactive DNA and some recently translated RNA
Nuclear membrane
Two bi layer membranes
Perinuclear space between them, continuous with ER
Nuclear lamina is scaffolding for chromosomes and nuclear pores
During division nuclear envelope breaks up
Nuclear Pore
-regulates bidirectional transport of molecules
-RNA transported out
-water and small ions passively diffuse through pore
Rough ER
Processing of proteins that will become
1. Inserted in membrane - integral membrane proteins
How are proteins transported
Vesicles pinch off ER and transport proteins to Golgi
Smooth ER
NO RIBOSOMES (dont have ribosome docking proteins)
contains enzymes involved in LIPID synthesis, STEROID synthesis, GLYCOGEN metabolism and MEMBRANE sysnthesis
In muscle take up and release Ca together with sarcoplasmic reticulum
In liver contain cytochrome P450 and other detoxification enzymes
What is the signal for protein to go to lysosome
Mannose phosphorylation
Main function of Golgi apparatus
Sorting of proteins
Define pinocytosis
Cell drinking, nonspecific ingestion of fluid and small molecules
Cell eating, ingestion of large particles, debris, bacteria and other foreign materials
substances enter cell
substances leave cell
In between proteins, also do sorting - separate receptor proteins for recycling
Late endosomes
Develop in lysosomes
Describe Tay Sachs disease
-caused by absense of lysosomal galactosidase ( beta hexosaminidase) in neurons
-GM2 ganglioside abnormally accumulates
-children appear normal first, slower growth, changes in facial features,bone deformities, lose attained speech, mental retardation, finally death
-contain hydrogen peroxide, very hostile environment
-degrade lipids (beta oxidation)
-found in most cells but most in liver and kidney
Zellweger syndrome
Dysfunctional peroxisomes
contains its own circular DNA, ribosomes and proteins, has ability to divide
1. Incubate tissue with Ab to specific molecule - Primary Ab
2.Wash off all Ab's that did not find target
3.Incubate with secondary Ab's that will recognize primary Ab's
similar to immuno except that it uses single stranded DNA or RNA to find complementary nucleic acid
vesicular transport
cilia and flagella
mitotic spindle
elongation, movement and shape
Intermediate filaments
Intermediate in thickness between actin and tubulin
4 classes - keratins, vimentins, neurofilaments, lamins
G1 phase
gather nutrients for DNA replication
Restriction point - sensitive to size, if DNA damaged, can send back to G0, or p 53 will initiate apoptosis
S phase
DNA replication, damage checkpoint
G2 phase
DNA damage checkpoint, prepare for cell division
tumor suppressing protein
becomes active if DNA damaged
blocks cyclins
blocks DNA synthesis
initiates apoptosis
Factors that can trigger apoptosis
TNF, lack of growth factor, DNA fragmentation
General characteristics of epithelium
Closely apposed cells covering open surface
Functional and morphological polarity
Resting on basement membrane
Functional classification of epithelium
SURFACE E. - creates barrier - epithelium of skin, body cavities, inside of vessels, inside of hollow organs
GLANDULAR - secretory role - forming glands
SPECIALIZED - sensory role- receptors for special senses
Morphological classification
Simple epithelium(one layer)
Striated epithelium (multiple layers)
Domains of epithelial cell
APICAL - microvilli, stereocilia, cilia
LATERAL - junctional complexes- occluding junctions, anchoring junctions, communicating junctions
BASAL- basement membrane, cell to extracellular matrix junctions, plasma membrane infoldings
Finger like cytoplasmic projections of apical surface
Function of microvilli
Increase cell surface
intestine- striated border
kidney - brush border
vary in length and sickness
Microvilli fine structure
1. VILLIN at tip
2. TERMINAL WEB at base, horizontal network of actin filaments, spectrin cross links and anchors actin to plasma membrane, myosin and tropomyosin provide contractility
3. CORE OF ACTIN filaments between villin and terminal web, cross linked by fascin and fimbrin (gives support and rigidity), linked to plasma membrane by myosin I
Extremely long processes
Only in
Function of sterreocilia
Increase cell surface
Stereocilia fine structure
1.NO VILLIN at tip
2. CORE OF ACTIN cross linked by FIMBRIN (support and rigidity),linked to plasma membrane by ERZIN
3. A-ACTININ - cross links actin filaments at stem and base of stereocilia
Cilia (Kinocilia)
beat in synchronous pattern, wave of sweep
RESPIRATORY SYSTEM - transport mucus
OVIDUCT- transport of egg
Sensory role of kinocilia
Some cells contain single cilium - epithelial cells of rete testis, vestibular hair cells of ear
Basal bodies
dark staining band at the base of cilia
Fine structure of kinocilia
CENTRAL PAIR OF MICROTUBULES - partially enclosed in sheath, end at level of basal body, regulate movement
MICROTUBULE DOUBLETS - A MICROTUBULE 13 tubulin subunits, B MICROTUBULE - 10 tubulin structures. Also has ciliary dynein, nexin, radial spokes
BASAL BODY- modified centriole, cilia grow from basal bodies
Lateral domain
in close contact with neighbouring cells, forms interdigitations with some cells, has unique adhesion molecules that form junctions
show up in normal light microscopy
Fine structure of lateral domain
ZONULA OCCLUDENS- impermeable, close to apical surface, prevents migration of apical proteins to lateral domain
ANCHORING JUNCTIONS - link cytoskeletons, can be found at lateral and basical domains, has zonula adherens and macula adherens
COMMUNICATING JUNCTIONS - permits coordinated cell activity
Occluding junction- zonula occludens
plasma membranes cells come in close contact, protein occludin is sealing protein
Anchoring junction - zonula adherens
belt like junction to zonula occludens
limited resistnace to stress
Structural components of basement membrane
COLLAGEN - type IV collagen mostly, product of epithelial cells, short fillaments building basal lamina , also type VII collagen - binds basal lamina to underlying reticular lamina
PROTEOGLYCANS- high negative charge, regulation of ion transport through basal lamina
LAMININ - cross shaped glycoprotein,links basal lamina to cell
ENTACTIN and FIBRONECTIN - other glycoproteins, unknow function
What attaches actin filaments to basement lamina
Integrins - anchoring proteins
What attaches intermediate filaments to basement lamina
characteristic for kidney ducts and duct of salivary glands
contain mitochondria
provide energy to active transport
What is the functional division of glandular epithelium
EXOCRINE - releasing on surface - merocrine, apocrine, holocrine
ENDOCRINE - releasing secretion (hormones) to blood
PARACRINE - releasing product to neighboring cells

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