2.02 Histology Flashcards by Karla Guntayon

Make use of microscopes

Histology

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Encompasses the study of cells, extra cellular components, and their organization into tissues, organs, organ system

Histology

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Makes use of visible light to view a specimen

Light microscope

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Utilizes a beam of energized electrons which passes through or is bounced off by the specimen

Electron microscope

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Electrons pass on the surface

Scanning EM

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Passes through the specimen

Transmission EM

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Bathe in fixative

Fixation

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Terminates cellular processes
Preserves cellular architecture/tissue morphology
Prevents autolysis of organelles
Protection against bacteria

Fixative

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Bathe in progressively increasing concentrations of ethyl alcohol

Dehydration

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Remove water from the cell

Dehydration

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Bathe in lipid-solvent

Clearing

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To remove alcohol and lipids in preparation for next step

Clearing

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Bake specimen in melted paraffin wax (58-60)

Embedding

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Use microtome

Sectioning

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Sections tissue thinly

Sectioning

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To distinguish different structures

Staining

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Basic dye

Reacts with acidic components

Hematoxylin

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Stains the DNA, RNA due to their acidic nature

Hematoxylin

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Acidic dye

Reacts with basic components

Eosin

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Stains collagen and cytoplasm pink

Eosin

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Magenta

Glycogen and carbohydrate rich molecules

Periodic acid schiff stain

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Differential staining for blood cells

Wright and giemsa stain

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Pink: erythrocytes, eosinophil granules
Purple: leukocyte nuclei, basophil granules
Blue: cytoplasm of monocytes and lymphocytes

Wright and Giemsa stain

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Stains Elastic fiber brown

Orcein

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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