Intro to Histology and Cytology 8-26 Flashcards Preview

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Flashcards in Intro to Histology and Cytology 8-26 Deck (80)
1

Anatomy roots

apart, to cut

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Macroscopic

Gross anatomy

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Microscopic anatomy

Cytology, Histology, Organology **Now histology is all of these**

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Cytology

Cells too small for naked eye to study

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Histology

Tissues (epithelial, connective, etc.)

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Organology

Microscopic nature of organs.

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Function always reflects Structure

Physiology always reflects Anatomy

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Organ system level

Cannot survive alone

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Light Microscopy

Extremely thin slices. Specimens examined via transillumination (light going through them).

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Electron Microscopy

Greater resolution, higher magnification - two types (TEM, SEM). Electrons and tissue, uses electromagnetic field as lens.

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TEM

Transmission Electron Microscopy - in a vacuum, uses a beam of electrons that passes through the specimen

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SEM

Scanning electron microscopy - beam of electrons scans the surface of the protein.

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Atomic Force Microscopy

Gets down to molecular and atomic resolution. DNA can be viewed. A probe 1 atom thick passes over surface. When it is deflected it deflects a laser and produces an indirect scan. No vacuum, can use live specimen.

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Resolving power

How far two objects must be separated from one another so that they can be distinguished.

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Human Eye reso

0.2 mm - set by space in rods and cones in retina.

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LM reso

0.2 microm - can't see ribosomes, membranes, actin.

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SEM reso

2.5 nm - in vacuum

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TEM

0.05 nm (theoretical) - 1.0 nm practically on tissue

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Atomic Force Microscopy

50 pm

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Resolution is dependent on...

Optical system, wavelength of light source, specimen thickness, quality of fixation, staining intensity

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Steps for LM

1. Acquisition of cells, 2. fixation, 3. processing, 4. Embedding. Some distortion occurs along this process.5. Sectioning (cut b/w 1-15 microm), 6. Staining (reverse of what they did before getting rid of wax).

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Processing

Preparing tissue to be embedded. 3 steps - dehydration, clearing, infiltration. Idea is to encase in parafin wax to be able to cut a thin slice. Need hard tissue.

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Dehydration

Using a graded series of alcohol. - wax doesn't mix with H20 so it needs to be removed. 3+ steps.

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Clearing

Using a miscible substance - xylene in this instance. This helps parafin wax penetrate cells.

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Xylene

Organic substance that is miscible with parafin. Causes tissue to almost be clear.

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Side effects of LM fixing

Stops metabolism, distorts tissue, avoids autolysis, kills bacterial viruses, hardens tissue. Takes about 12 hours depending on thickness of tissue.

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Gluteraldehyde, Formaldehyde

Fixation - good to preserve protein crosslinks (stops enzymes) and kill all.

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Infiltration

58-60 degrees, allows wax to enter cells.

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Staining

Reverse of what they did before to get rid of wax.

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Problems with LM fixing

Long time - 2.5 days, solvent dissolves liquid, shrinkage of tissue.

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Cryostat

Freezing in liquid nitrogen. Fast - used post surgery. Tissue placed in embedding medium and frozen, cut and stained. Enzymes not destroyed, stain can detect them.

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Double fixation

First uses gluteraldehyde, then osmium tetroxide.

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Osmium tetroxide

Preserves ultra structure, binds to (stains) phospholipids

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Embedding in resin

No shrinkage, used for EM and TEM. Reaction without heat, embedding in plastic. Can also be done for LM but this is not preferable due to expense.

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Acidic dyes

- charge, can form electrostatic linkages with ions in tissues, less specific (more things stained with acidic dyes).

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Eosin

Stains acidophilic tissue (eosinophilic) Pink/red.

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Acidic tissues

Mitochondria, collagen, general cytoplasm, basement membrane, secretory granules.

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Basic dyes

+ charge, bind with anionic charge. Toluidine blue, hematoxylin (no + charge but behaves as such). Stains basophilic tissue.

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Basophilic tissue

phosphate group in DNA/RNA (nucleus, nucleolus, RNA rich parts of cytoplasm), carboxyl groups of proteins, sulfate gruops of cartilage matrix (GAGs).

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Hematoxylin

+ basophilic tissue, blue hue, nuclei affinity.

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Fluorescence microscopy

UV light

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Phase contrast microscopy

use unstained specimen because lens system helps determine refractory index. Light goes through specimen parts at different speeds, so it reads how this occurs.

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Cross linking

Amino acids bind, changes protein shape.

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Enzyme staining

Cryo, section immersed in solution of enzyme substrate, enzyme acts on substrate, section put in contact with a marker compound, marker compound reacts with molecule produced by enzymatic action on substrate. The final product precipiates over site. Lysozyme is a key example.

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Immunohistochemistry

Tag antigen w/labeled antibody. After sectioning incubate in antibody solution.

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Paneth cells

Bottom of intestinal glands.

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Artifact

Extra things in tissue as a result of error or abnormality. These are not present in actual tissue (shrinkage, wrinkles, etc).

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Plasma membrane

7.5-10 nm in thickness. Regulates ion concentration and exchange and regulation. Trilaminar.

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Trilaminar

3 layers (dark light dark). OS tetroxide causes this, as it deposits alongside head groups.

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Cholesterol on head group

1:1

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Phagosome

vacuole containing phagocytosed material.

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Phagocytosis

Cell eating - phagosome fuses with lysosomes

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Pinocytosis

Fluid phase endocytosis. Cell drinking - pinocytotic vesicle fuses with lysosomes.

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Receptor mediated endocytosis

Binding of ligand to receptor causes coated pits made of clathrin to form. Pinches off to form vesicle, fuses with endosomal compartment to form endosomes.

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Lysosomes

0.05 microm to 0.5 microm in diameter. Membrane bound vesicles that contain about 40 different hydrolytic enzymes.

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Ribosomes

20 nm by 30 nm. Protein synth. Composed of two diff subunits. Composed of rRNA and proteins. Can be found in cytoplasm or membrane of ER.

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ER

Intercommunicating channels and sacs of membranes which enclose a space called a cisterna. Rough and smooth.

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Rough ER

Ribosomes on the cytosolic side of membrane, produces protein for secretion.

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Smooth ER

More in liver cells. Stain with general cytoplasm. Regions of ER without Ribosomes. Cisternae are more tubular. Important in phospholipid production. Abundant cells in cells that produce steroid hormones.

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Golgi apparatus

Complete post translational modification, packages and sorts proteins synthesized in Rough ER. Composed of smooth membranous saccules, as cis (entry) and trans (exit) faces.

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RBC diameter

7.8 microm

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Mitochondria

Membrane enclosed organelles with enzyme arrays specialized for aerobic respiration and production of adenosine triphosphate (ATP). 0.5 microm to 10 microm in length. Two membranes and two compartments. Folds give surface area. Can see with LM. Directly related to cell need.

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Parietal cells

Make HCl, pumps across [] gradient.

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Secretory vesicles/granules

Formed at golgi apparatus, store product until it is released via exocytosis. Membrane surrounds product.

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Proteasomes

Degrade denatured and nonfunctional polypeptides. Cytoplasmic protein (no membrane) cylindrical structure made of four stacked rings.

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Peroxisomes

Oxidizes various toxic molecules as well as prescription drugs. 0.5 microm in diameter. Sphericial membrane limited organelle.

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Microtubules

Fine tubular structures found in cytoplasmic matrix, centrioles, basal bodies, cilia and flagella. Forms and maintain cell shape, cellular transport of organelles and vesicles, create repeated beating motion. **outer diameter of 24 nm and dense 5 nm fthick wall. Hollow lumen. Composed of alpha and beta tubulin molecules, form 13 parallel protofilaments**

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Microtubules

in cilia and flagella, same core structure (axoneme). 9+2 pattern (see slide for images). 9 doublets have outer dynein arm that connects to the next doublet. ATP-dependent interaction causes conformational changes (beating movement).

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Microfilaments (actin)

Allow for contractile activity - cell shape for endocytosis, exocytosis, locomotion, cleavage, etc. 5-9 nm. Composed of globular subunits in double stranded helix.

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intermediate filaments

Very stable, provide mechanical strength and stability. 10-12 nm in diameter. Protein subunits different in diff. cell types. Rod like subunit that organize into a cable-like structure.

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Inclusion

Not considered organelles. Cytoplasmic structures or deposits composed mainly of accumulated metabolites or other substances

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Nucleus

Nuclear envelope, chromatin, nucleolus.

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Nuclear envelope

Two parallel unit membranes separated by a narrow space, at sites where inner and outer membranes of the nuclear envelope fuse, nuclear pore complexes form, where regulation of the transport between nucleus and cytoplasm take place.

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Heterochromatin

Course granules in EM and basophilic clumps in light microscopy (low activity)

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Euchromatin

Less coiled, fine granules in EM and lightly basophilic areas in LM.

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Nucleolus

Spherical highly basophilic structure present in nuclei. Active in protein synth, lots of rRNA in this location.

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Homologous chromosomes separate (Meiosis)

Anaphase I

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Sister chromatids separate (meiosis)

Anaphase II

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Apoptosis

Cell suicide - leads to small membrane enclosed apoptotic bodies which undergo phagocytosis by neighboring cells.

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Necrosis

Cell death by cell rupture/injury. cellular contents are not in the membrane (inflammatory response).