2.02 Histology Flashcards
Make use of microscopes
Histology
Encompasses the study of cells, extra cellular components, and their organization into tissues, organs, organ system
Histology
Makes use of visible light to view a specimen
Light microscope
Utilizes a beam of energized electrons which passes through or is bounced off by the specimen
Electron microscope
Electrons pass on the surface
Scanning EM
Passes through the specimen
Transmission EM
Bathe in fixative
Fixation
Terminates cellular processes
Preserves cellular architecture/tissue morphology
Prevents autolysis of organelles
Protection against bacteria
Fixative
Bathe in progressively increasing concentrations of ethyl alcohol
Dehydration
Remove water from the cell
Dehydration
Bathe in lipid-solvent
Clearing
To remove alcohol and lipids in preparation for next step
Clearing
Bake specimen in melted paraffin wax (58-60)
Embedding
Use microtome
Sectioning
Sections tissue thinly
Sectioning
To distinguish different structures
Staining
Basic dye
Reacts with acidic components
Hematoxylin
Stains the DNA, RNA due to their acidic nature
Hematoxylin
Acidic dye
Reacts with basic components
Eosin
Stains collagen and cytoplasm pink
Eosin
Magenta
Glycogen and carbohydrate rich molecules
Periodic acid schiff stain
Differential staining for blood cells
Wright and giemsa stain
Pink: erythrocytes, eosinophil granules
Purple: leukocyte nuclei, basophil granules
Blue: cytoplasm of monocytes and lymphocytes
Wright and Giemsa stain
Stains Elastic fiber brown
Orcein
Stains reticular fibers black
Silver stain
Stains striations of muscles, nuclei, erythrocytes
Iron Hematoxylin Stain
Stains collagen fibers light blue
Nuclei, dark blue
Cytoplasm and muscle, red
Massom’s trichome
Contains DNA that encodes the instructions for synthesis of all proteins and enzymes of the cell
Nucleus
Contains organelles and inclusions suspended in a fluid medium called the cytosol
Cytoplasm
Principal site of metabolic function of cell
Cytoplasm
Metabolically active
Internal cellular organs carrying out specific essential functions
Bound by membrane
Organelles
Metabolically inert
Accumulation of cell products
Dispensable
Not bound by a membrane
Inclusions
Plasmalemma
Trilaminar structure due to phospholipid bilayer
Composed of phospholipids and proteins
Cell membrane
Two components of lipid bilayer
Responsible for cellular form and permeability
Phospholipids
Kinds of protein
Spans the entire width of plasma membrane
Intrinsic protein
Kinds of protein
Found only on inner or outer surface of Plasmalemma
Extrinsic protein
Transports a substance from the external environment inracellularly
Carrier proteins
Allows communication between external and internal environment of the cell
Allow molecules to go in and out
Channel protein
Binding domain for substances such as hormones
Receptor
Carbohydrate chains attached to proteins and phospholipid molecules in outer leaflet
Mat of delicate branching polysaccharide filaments
Glycocalyx
Functions of glycocalyx
Cell recognition
Intercellular adhesion
Mechanical and chemical protection for cell membrane
Largest organelle of the cell
Contains the genetic material of the organism
Site of transcription
Nucleus
Components of nucleus
Chromatin
Nucleolus
Nuclear envelope
Nucleoplasm
Contains mRNA therefore present in active cells
Nucleolus
Two chains containing nucleotide subunits
Nucleotides, sugar, phosphate base
Specific pairing of bases
DNA
Folded polypeptides composed of specific sequence of amino acids
Proteins
Functions of proteins
Structural component of cells
Enzyme catalyzing metabolic reactions
Secretory products
Sequence of three nucleotides that encodes a specific amino acid
Triplet or codon
Sequence of triplets providing the information for the synthesis of a particular protein
Gene
Single chain of nucleotide subunits
RNA
Types of RNA
Messenger RNA
Transfer RNA
Ribosomal RNA
A single strand RNA molecule transcribed from template DNA within the nucleus with the help of RNA polymerase II
mRNA
A triloop cloverleaf shaped single RNA strand that delivers amino acids to the translation site
tRNA
Complement codon in the mRNA
Loop on the tip of the clover leaf contains a group of three bases called ____________
Anti codon
An RNA and protein complex that catalyzes the attachment of each new amino acid onto the growing peptide chain
rRNA
Clumps of basophil ice material seen in the nucleus
Consists of DNA and associated proteins
Chromatin
Beads on a string
Consists of a core of eight histone molecules with two loops of DNA wrapped around the octomer
Nucleosome
Discrete bodies containing condensed and tightly coiled chromatin
Found in dividing cells
Chromosomes
Dark dense clumps adjacent to nuclear membrane
Inactive chromatin in a condensed state
More basophilic
Coiled
Heterochromatin
Active chromatin
Chromatin stretched out so genetic information of DNA can be read and transcribed
Euchromatin
Two parallel membranes separated by a perinuclear cisterna
Nuclear envelope
Avenue of communication between nucleoplasm and cytoplasm
Nuclear pore
Nuclear pore is closed by ______
Pore diaphragm
Nonmembranous structures associated with nuclear pore
Nuclear pore complex
Components of nuclear pore complex
8 particles attached to the inner and outer ring
8 radially arranged spokes projecting inward
Principal barrier to movement of particles >10 nm
Nuclear pore complex
Consists mainly of RNA and protein
Site of ribosomal RNA synthesis
Nucleolus
Extensive system of membrane bounded canaliculi
Consists of a series of flattened sacs arranged in parallel array
Endoplasmic reticulum
Series of flattened sacs in ER
cisternae
Two kinds of ER
Rough ER
Smooth ER
Continuous with nucleus
Outer surface of membranes contain ribosomes
Rough ER
Functions of rough ER
Synthesis of proteins for export from the cell
Synthesis of integral protein of the plasma membrane
Abundant in protein secreting cells
Absence of ribosomes in the membranes
Smooth ER
Functions of smooth ER
Synthesis of fatty acids and other lipids
Detoxification and metabolism of lipid-soluble exogenous drugs and alcohols
Abundant in steroid secreting endocrine glands
Complex structures composed of RNA and proteins
Composed of large and small subunit
Ribosomes
10 or more ribosomes may be associated with mRNA
Free ribosomes
Another term for free ribosomes
Polysomes
Involved in the synthesis of proteins to be used in cytosol
Free ribosomes
Involved in synthesis of proteins for export or for membrane system
Ribosomes attached to ER
Abundant in cells that produce a lot of secretion
Does not stain hence produces a negative image
Usually presents as an empty space in plasma cells
Golgi apparatus
Functions of golgi apparatus
Packaging
Concentrating
Sorting
Membrane synthesis
Convex side, outer, immature
cis-phase
Concave side, inner, mature
trans-phase
Provides energy for the biosynthetic and motor activities of the cell
Mitochondria
Principal biochemical activity
Oxidative phosphorylation
Two membranes of mitochondria
Smooth outer membrane
Cristae mitochondrialis
Two spaces of mitochondria
Intermembrane space
Intercristal space
Round, electron dense bodies
Assembled by fusion of vesicles coming from the Golgi complex and endosomes
Lysosome
Important in programmed cell death
Lysosome
Function similar to smooth ER
Oxidation of long chain fatty acids
Peroxisome
Microbodies
Peroxisomes contain _________
Oxidative enzymes
Catalase
Not membrane bound
Granular area witin the cytoplasm containing a pair of centrioles
Centrosome
Paired, short, rod-like bodies found near the nucleus in nondividing cells
Arranged perpendicularly with each other
Centrioles
Function of centrioles
Provide basal bodies (flagella and cilia)
Cytoplasmic inclusion
Visible through PAS stain
Glycogen
Cytoplasmic inclusion
Signet ring appearance
Lipid
Cytoplasmic inclusion
Pigment
Residual granules/bodies in a cell
Lipofuscin
Function of cytoskeleton
Structural support for the plasma membrane and cellular organelles
Movement of cellular organelles
Movement of cilia and flagella
Contractility of muscles
Composed of fine strands of the protein actin
Gives the peripheral region of the cytoplasm a firm gel-like consistency
Microfilament
Largest structural element of the cytoskeleton
Microtubules
Arises from the centrosome
Important role in deirecting movements of organelles and vesicles
Microtubules
Functions of microtubules
Transport of vesicles and organelles Cell elongation and movement Maintenance of cell shape Beating of cilia and flagella Movement of chromosomes
Stable supporting function of the cytoskeleton
intermediate in size between microfilament and microtubule
Intermediate filament
Main structural component of skin cells
Keratin filament
Study of the tissues of the body and how these tissues are arranged to constitute organs
Histology
Name the two interacting components of the tissues
Cells
Extracellular matrix
Consists of many kinds of macromolecules, most of which form complex structures
ECM
Supports the cells and the fluid that transports nutrients to the cells and carries away their catabolites and secretory products
ECM
Small pieces of tissue are placed in solutions of chemicals that preserve by cross-linking proteins and inactivating degradative enzymes
Fixation
Tissue is transferred through a series of increasingly concentrated alcohol solutions, ending in 100%
Remove water
Dehydration
Alcohol is removed in toulene or other agents in which both alcohol and paraffin are miscible
Clearing
Tissue is then placed in melted paraffin until it becomes completely infiltrated with this substance
Infiltration
Paraffin-infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden
Embedding
The resulting paraffin block is trimmed to expose the tissue for sectioning on a microtome
Trimmming
Used for sectioning paraffin-embedded tissues for lilght microscopy
Microtome
Avoid tissue degradation by enzymes present within the cells or bacteria
Preserve cell and tissue structure
Fixation
Diffuse through the tissues to preserve all cells
React with the amine groups of tissue proteins to avoid degradation
Fixative
Widely used fixative
Formalin
Buffered isotonic solution of 37% formaldehyde
Fixative often used for electron microscopy
Glutaraldehyde
Using a buffered glutaraldehyde solution followed by immersion in buffered osmium tetroxide
Double-fixation procedure
Preserves membrane lipids as well as proteins
Osmium tetroxide
Embedding material for light microscopy
Paraffin
Embedding material for both light and electron microscopy
Plastic resin
Water is extracted from the fixed tissues by successive transfer through a graded series of ethanol and water
Dehydration
As organic solvent (miscible with both alcohol and embedding medium) infiltrates the tissues, they become more transparent
Clearing
The fully cleared tissue is then placed in melted paraffin in an oven at 52-60 deg C. The clearing solvent evaporates and the tissue is filled with liquid paraffin
Embedding
Avoids the higher temperatures needed for paraffin embedding, which helps avoid shrinkage and major distortion of the tissue
Plastic embeddin
Micron
Micrometer
Angstrom
Nanometer
Cells components with a net negative charge stain more readily with basic dyes
Basophilic
Cationic components that have affinity for acidic dyes
Acidophilic
Toluidine blue
Alcian blue
Methylene bluie
Hematoxylin
Basic dye
Eosin
Orange G
Acid fuchsin
Acid dye
Stain that can show nuclei and cytoplasm very well and distinguish extracellular components better than H&E
Trichomes
Masson stain, Mallory stain
Deoxyribose sugars are hydrolyzed by mild HCl
Feulgen reaction
Glycogen in liver and striated muscle can be demonstrated by ______
PAS
Short branched chains of sugars attached to specific amino acids
Glycoprotein
Anionic, unbranced long-chain polysaccharides containing aminated sugars
Glycosaminoglycan
GAGs attached to a core protein
Proteoglycan
Pretreatment of a tissue section with an enzyme that specifically digests one substrate
Enzyme digestion
Single stain that is applied separately to allow better recognition of nuclei and other structures
Counterstain
Lipophilic dye
Sudan black
Final step before microscopic observation
Mounting (Protective glass coverslip on the slide with clear adhesive)
Conventional bright-field microscopy Fluorescence Phase-contrast Differential interference Confocal Polarizing microscopy
Light microscopy
Bright field microscope
Name the 3 optical components
Condenser
Objective
Eyepiece
Collects and focuses a cone of light that illuminates the object to be observed
Condenser
enlarges and projects the image of the object in the direction of the eyepiece
Objective lens
Further magnifies this image and projects it onto the viewer’s retina or a charge-coupled device highly sensitive to low light levels with a monitor and camera
Eyepiece
Critical factor in obtaining a crisp, detailed image with a light microscope
Smallest distance between the two particles at which they can be seen as separate object
Resolving power
Based on the interaction of tissue components with beams of electrons
Electon microscopy
Imaging system that permits resolution around 3nm, which allows magnifications up to 400, 000x
Images are always black, white and shades of gray
Transmission electron microscopy
Imaging system: focused electron beam does not pass through the specimen, but rather is moved sequentially from point to point across its surface similar to the way an electron beam is scanned across the television tube or screen
Scanning electron microscope
Techniques that allow TEM study of cells without fixation or embedding (unfixed frozen cells, with fractured membranes or cut surfaces coated with carbon and heavy metal to make a replica of the surface for analysis)
Cryofracture
Freeze etching
Outermost component of the cell, separating the cytoplasm from its extracellular environment
Cell/Plasma membrane
Plasmalemma
Plasma membrane contains proteins called _____ linked to both cytoplasmic protein filaments and ECM components
Integrins
Fluid component of the cytoplasm
Cytosol
Metabolically active structures in the cytoplasm
Maybe membranous or nonmembranous protein complexes
Organelles
Determines the shape and motility of eukaryotic cells
Cytoskeleton
Minor cytoplasmic structures that are generally deposits of carbohydrates, lipids or pirgments
Inclusion
Functions as a selective barrier regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules
Keeps the ion content of the cytoplasm constant
Cell/Plasma Membrane
Delicate cell surface coating
Some of the outer lipids include oligosaccharide chains that extend outward from the cells surface are called __________
Glycocalyx
Proteins in cell membrane that are directly incorporated within the lipid bilayer itself
Integral proteins
Proteins in cell membrane that exhibit a looser association with one of the two membrane surfaces
Peripheral proteins
Amphipathic, with a phosphate group charge on the polar head and two long, nonpolar fatty acid chains
Phospholipid
Membranes of animal cells have as their major lipid components ______ and _____
Phospholipid and cholesterol
Small electron-dense particles
Assemble the protein chain from amino acids
Ribosome
Synthesize cytosolic and cytoskeletal proteins and proteins for import into the nucleus, mitochondria, and peroxisomes
Free ribosome
Synthesize proteins that are to be incorporated into membranes, stored in lysosomes or eventually secreted from the cell
Ribosomes attached to the membranes of ER
Convoluted membranous network
Endoplasmic reticulum
Network of ER extends from the surface of the nucleus to the cell membrane and encloses a series of intercommunicating channels and sacs called ____
Cisternae
Prominent in cells, specialized from protein secretion
Consists of saclike as well as parallel stacks of flattened cisternae
Presence of ribosomes
Rough ER
Synthesis and segretation of proteins not destined for cytosol
Initial glycosylation of glycoproteins
Posttranslational modifications of newly formed polypeptides
Assembly of multichain proteins
Rough ER
Not basophilic (lack ribosomes)
Have enzymes for glycogen and lipid metabolism, detoxification reaction and temporary calcium sequestration
Phospholipid and steroid synthesis
Smooth ER
Completes the posttranslational modifications of proteins synthesized in the RER and then packages and addresses these proteins to proper destinations
Golgi apparatus
Transport material from RER cisternae to the golgi apparatus
Move along cytoskeletal polymers by motor proteins
Transport vesicles
Golgi-receiving region
cis face
Golgi-shippineg region
trans face
Site of intracellular digestion and turnover of celluar components
Lysosomes
Contain hydrolytic enzymes
Particularly abundant in cells with great phagocytic activity
Lysosomes
Enzymes of lysosomes have optimal activity at an ____ pH
acidic (around 5.0)
Indigestible material is rerained within a small vacuolar remnant (after digestion of macromolecules by lysosome)
Residual body
In some long-lived cells (neurons, heart muscle), residual bodies can accumulate over time as granules of ______
Lipofuscin
Process of digestion of excess or nonfunctional organelles and other cytoplasmic structures
Autophagy
Membrane-enclosed organelles with arrays of enzymes specialized for aerobic respiration and production of ATP
MItochondria
Two compartments of mitochondria
Matrix
Intermembrane space
Inner membrane of mitochondria is folded to form a series of long infoldings called _____
Project into the matrix and greatly increase this membrane’s surface area
Cristae
Spherical organelles enclosed by a single membrane and named for their enzymes producing and degrading hydrogen peroxide
Peroxisomes
Peroxidase that can break down hydrogen peroxide
Catalase
Peroxidase that oxidize substrates by removing hydrogen atoms that are transferred to molecular oxygen, producing hydrogen peroxide
Oxidase
Complex array of microtubules, microfilaments and intermediate filaments
Determine the shape of cell
Movement of organelles and cytoplasmic vesicles
Movement of entire cells
Cytoskeleton
Microtubules are organized into larger arryas called axonemes in the cytoplasmic extensions called ___ and ___
Cilia
Flagella
Composed of actin
Allow cellular motility and most contractile activity in cells, by reversible assmebly of the actin filaments and interactions between these filaments and the associated protein
Microfilament
Class of filaments intermediate in size between the other two
More stable than the other two
Intermediate filaments
Have little or no metabolic activity but contain accumulated metabolites or other substances not encolsed by membrane
Inclusion
Accumulation of lipid molecules
Fat droplets
Aggregates of the carbohydrate polymer in which glucose is stored
Visible when stained with PAS
Glycogen granules
Yellowish-brown pigment visualized by H&E staining in many cells, especially in stable nondividing cells
Wear-and-tear piagment
Lipofuscin
Dense brown aggregate of denatured ferritin proteins with many atoms of bound iron
Hemosiderin
Viscous fluid medium of cytoplasm with dissolved solutes
Provide support for organelles
Cytosol
Command center of the cell
Nucleus
Forms a selectively permeable barrier between the nuclear and cytoplasmic compartments
Nuclear envelope
Mass of DNA and associated protein
Chromatin
Nuclear envelope has two concentric membranes are separated by a narrow ______
perinuclear space
The inner and outer nuclear membranes are bridged at _____
Large assemblies of nucleoporins with eightfold symmetry through which proteins and protein-RNA complexes move in both directions
nuclear pore complexes
DNA molecule wraps around histones to form ___
nucleosome
Very basophilic or electron-dense area of chromatin localized where rRNA transcription and ribosomal subunits assembly occur
Nucleolus
