HISTOLOGY

Histology

(Gr. histo, web or tissue, + logos, study) the study of the tissues of the body and of how these tissues are arranged to constitute organs.

Histotechnique

A set of laboratory techniques used for specimen preparation.

Gross examination

The initial visual inspection of a specimen.

Fixation

The process of preserving tissue samples to prevent decay.

Dehydration and clearing

The removal of water from tissue samples and replacement with a clearing agent.

Infiltration and Embedding

The process of embedding tissue in a medium for sectioning.

Sectioning

Cutting tissue samples into thin slices for examination.

Mounting

The process of placing sections onto slides for viewing.

Staining

The application of dyes to enhance contrast in tissue samples.

Hematoxylin and eosin stain

The most commonly used stain in histology, where hematoxylin stains acidic components blue and eosin stains basic components pink.

Hematoxylin

Is a BASE that colors the ACIDIC components BLUE

Eosin

Is an ACID that colors the BASIC components of the CELL PINKISH

Basophilic

Stains nucleic acids

Acidophilic

Stains cytoplasmic constituents

Toluidine blue

A stain that targets metachromatic tissue components.

Masson trichrome

A stain that colors nuclei DARK BLUE, muscle-keratin-cytoplasm RED, and mucinogen and collagen LIGHT BLUE.

Weigert elastic stain

Stain elastic fibers in blue.

Silver stain

Stain reticular fibers black.

Iron hematoxylin

Stain that colors striations of muscle and RBC black.

Periodic acid Schiff

Stain that colors glycogen and carbohydrate-rich molecules magenta.

Wright and Giemsa stains

Stains used for differentiating blood cells.

Light microscopy

A technique using visible light to observe specimens.

Cross section

A cut that divides a specimen perpendicular in horizontal

Longitudinal section

A cut that divides a specimen in a vertical direction along its longest axis.

Oblique section

A cut that divides a specimen at an angle with several layers.

Histochemistry

A method of staining tissue to provide information about macromolecules.

Immunocytochemistry

A technique using labeled antibodies for precise localization of macromolecules.

• Cancer cells

• Antigen + Protein

Autoradiography

A method that visualizes radioactive isotopes incorporated into macromolecules.

Radiology

Confocal microscopy

A microscopy technique that increases optical resolution and contrast.

• Clearer

• 3d sample

• Laser

Electron microscopy

A microscopy technique that uses electrons to create an image of the specimen.

Freeze-fracture technique

A technique used to study the structure of membranes.

• Crack to open inside

The Cell

The basic morphological and functional unit of all living things, capable of independent existence under favorable conditions.

3 Basic Functions of the Cell

1. Transport of Molecules

2. Conversion of Energy

3. Reproduction.

How many cells does the human body have

Composed of approximately 1014 or 100 trillion cells in adults, with more than 250 cell types.

Cell membrane

A tri-laminar structure that is comprise of two layers of phospholipid molecules

Cytoplasm

= cytosol + formed elements

Cytosol (cytoplasmic matrix)

Is viscid, translucent, and colloidal in nature

• Made up of 70% water, Inorganic ions and Organic molecules

• Site of biochemical processes

• Provides a suitable milleu for the organelles to perform their function

Mitochondria

The "powerhouse" of the cell because they generate most of the energy needed by the cell

Ribosomes

Site of protein synthesis

Free ribosomes

Proteins for intracellular processes

Attached ribosomes

Intracellular proteins and proteins that are to be exported by the cell

Endoplasmic reticulum

Is an important organelle found in eukaryotic cells. It plays a major role in the production, folding, quality control, and transport of proteins and lipids.

Rough (ER)

• With ribosomes

• Process proteins produced by the Ribosomes

Smooth

Site for the synthesis of cholesterol and phospholipids and transport of fatty acids and other lipids

Golgi complex

The Golgi complex further processes, concentrates, sorts, and packages the proteins that it receives from the rough endoplasmic reticulum.

• It releases proteins into the cytoplasmic matrix

Lysosomes

Contain hydrolytic enzymes released by Golgi complex

Heterophagy

Digestion of extracellular particles

Autophagy

Digestion of unneeded or senescent cell organelles

Peroxisomes

Contain oxidases and catalase

• Breaks down fatty acids, detoxifies harmful substances and decomposes hydrogen peroxide into water and oxygen

• Involved in many metabolic reactions including catabolism of fatty acids resulting in CoA and hydrogen Peroxide

Hydrogen peroxide

Detoxifies various substances and kills microorganisms.

Catalase

Degrade excess hydrogen peroxide into water and oxygen.

Centrosome (MOTC)

A dense spherical region near the nucleus, surrounded by Golgi complex, containing of a pair of centrioles. Consists of a pair of short, cylindrical bodies called centrioles that are surrounded by granular structure called centriolar satellite

Organizes microtubules and form:

• Mitotic spindles during mitosis

• Source of the cilia and flagellum.

Centrioles

Pair of short, cylindrical bodies

• The centrioles are the sources of the mitotic spindles that appear during mitosis

• The centriole (basal body) is also the source of the cilia and flagellum

Centriolar satellite

Centrioles that are surrounded by granular structure

Inclusions

Fat droplets, glycogen, zymogen granules, pigment granules, crystals, lipochrome pigment granules, lipofuscin pigments, and dust particles.

Cytoskeleton

Network of fibers that provides structural support and shape to the cell.

Microfilaments

Made up of F-actin, involved in cell movement and shape. Activities at the cell membrane such as exocytosis and endocytosis.

Intermediate filament

Includes keratin (epithelial cells), desmin (muscle cells), vimentin (fibroblasts and muscle cells), neurofilament (nerve cells), and glial filament (glial cells).

Microtubule

Formed in the centrosome, plays a role in the movement of organelles and is a source of mitotic spindles, cilia, and flagella.

Nucleus

Largest structure inside the cell, commonly round or spherical, consisting of nuclear matrix, chromatin, and one or more nucleoli.

Function:

• Genetic control center

• Controls gene expression and cell activities

• Coordinates cell division

Nuclear envelope

Continuous with rER membrane, has nuclear pores for the exchange of substances.

• Separates the nuclear contents (DNA, nucleolus) from the cytoplasm.

• Regulates exchange of materials

Chromatin

Entangling threads that form the chromosome, containing 46 chromosomes in human cells, except for RBCs and developing gametes.

4 kinds of DNA bases

1. Adenine

2. Thymine

3. Cytosine

4. Guamine

Gene

Segment of the DNA molecule within a chromosome that contains the DNA sequence for the production of a particular protein or nucleic acid.

• Humans have between 30,000 to 40,000

Nuclear matrix

Homogenous substance within the nucleus where chromatin and nucleoli are embedded, composed of water, proteins, metabolites, and ions.

• Structural support

• Organizes chromatin

Nucleolus

A spherical, highly basophilic structure in the nucleus that synthesizes ribosomal subunits.

• rRNA synthesis

• Ribosome assembly

Diffusion

Movement of smaller molecules across the cell membrane. Does not require energy and have difference in concentration.

Carrier/Passive transport

Movement of larger molecule and smaller molecules across the cell membrane via specific transport proteins. Does not require energy.

Active transport

For larger molecules and charged particles. Movement of smaller molecules across the cell membrane against their concentration gradient.

Endocytosis

Process for bigger substances to enter the cell, includes phagocytosis and pinocytosis.

Phagocytosis

Ingest microorganism through which of the following mode molecular transportation

Pinocytosis

It is the process where a cell engulfs extracellular fluid and the dissolved solutes in it by forming small vesicles.

Exocytosis

Process for bigger substances to exit the cell.