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Description
Flashcards by Marissa Alvarez, updated more than 1 year ago
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Created by Marissa Alvarez
almost 8 years ago
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| Question | Answer |
| What is histology? | the study of microscopic structure of cells, tissues, and organs *It is central to biological and medical science to understand pathological situations |
| What is pathology? | the study of ABNORMAL microscopic structures |
| Units of measurements used in histology 10 angstroms (Å) = 1 nanometer (nm) 10,000 angstroms = 1 micrometer (μm) 1,000 micrometers = 1 millimeter (mm) 10 millimeters = 1 centimeter (cm) 100 centimeters = 1 meter (m) | We will mostly use: 1,000 micrometers = 1 millimeter (mm) *RBC's = 7.5-8 microns |
| From Cells to Systems cells --> tissues --> organs | Cells: are basic structural and functional units Cells differentiate to perform specialized tasks Tissues: are functional arrangements of similarly specialized cells Compound tissues contain a mixture of cells with different functions Tissues form organs and systems An organ is an anatomically distinct group of tissues that perform specific functions (examples: heart, liver, kidney) The term system may be used to 1. describe cells with a similar function but widely distributed in several anatomical sites (example: diffuse endocrine system) 2. describe a group of organs which have similar or related functional roles (example: digestive system, urinary system) |
| How to Make a Slide with Tissue | Tissue is harvested and fixed, usually in 4% paraformaldehyde After fixation, tissue is serially transferred through alcohol and finally xylene prior to embedding in wax (paraffin) Sectioning of sample via a Microtome (machine cuts incredibly thin pieces of the tissue embedded in wax into ribbons) Mounting and Staining (for contrast) |
| The four basic tissues | 1. Epithelium 2. Connective Tissue 3. Muscle Tissue 4. Nerve Tissue |
| 1. Epithelium | |
| 2. Connective Tissue | |
| 3. Muscle Tissue | |
| 4. Nerve Tissue | |
| Fundamentals of histological stains | Most (but not all) stains are based on ionic interactions: negatively charged (“acidic”) dyes bind to positively charged tissue components, and vice versa. Tissue components may be acidophilic or basophilic. |
| Acidophilic | “acid-loving binding” binds acidic (-) charged dyes. Usually red or pink. Example: PROTEINS (+ charge) |
| Basophilic | “base loving binding” binds basic (+) charged dyes, usually BLUE Example: nucleic acids & DNA, (- charge) |
| Frequently used histological stains | 1. Hematoxylin and Eosin (H&E) 2. Toluidine Blue (TBO) 3. Periodic Acid-Schiff (PAS) method |
| 1. Hematoxylin and Eosin (H&E) | The combination of two dyes, hematoxylin (dark blue, basic) and eosin (red, acidic). Nucleic acids (e.g., in cell nuclei) stain dark blue, proteins and most other tissue components stain pink/red. *one of the BEST stains |
| 2. Toluidine Blue (TBO) | a basic BLUE dye that binds to nucleic acids. It also stains mast cell granules, mucins, and cartilage metachromatically (purple). (strong dye) |
| 3. Periodic Acid-Schiff (PAS) method | demonstrates complex CARBOHYDRATES either alone (e.g., glycogen) or combined with proteins (glycoproteins), mucin, and some basement membranes, which all stain characteristic PURPLE. Often combined with hematoxylin to label cell nuclei. |
| CELL KNOW difference b/w the nucleus of a cell & the cell itself! | |
| The cell membrane (or plasma membrane) | Main components: 1. Phospholipids (amphipathic) 2. Proteins (inserted or loosely attached to surface) (G: glycocalyx) Main functions: 1. Maintains STRUCTURAL integrity of the cell (MAIN GOAL) 2. Interface between cytoplasm and external environment 3. Controls movements of substances in and out of cells 4. Regulates cell-cell interactions 5. Transduces extracellular signals into intracellular events |
| Nucleus (N), nuclear envelope (NE), and rough endoplasmic reticulum (RER) Note: Appearance of nuclei is often characteristic of cell type and functional state **NE and RER tend to surround the nucleus | |
| NEURON *RER: stains darker than the nucleus | |
| The Golgi Apparatus | Composed of several flattened, slightly curved cisternae, which widen at the periphery to form vesicles. It has an entry (cis) face and an exit (trans) face. It serves as a transit station where proteins synthesized in the RER are modified, packaged, and sorted into vesicles according to their destination. (POST-translational) |
| Golgi Apparatus (major functions?) | Major functions: Modifications: e.g., glycosylation; adding specific “addressing” molecules Packaging: enzymes for lysosomes, proteins for secretion Sorts all materials for lysosomes, secretion, and incorporation into the plasma membrane |
| Protein synthesis, targeting, and secretion: Erythroblast (General Pathway: Nucleus --> RER --> Golgi --> Other cells) | |
| Protein synthesis, targeting, and secretion: Eosinophil leukocyte | |
| Protein synthesis, targeting, and secretion: Plasma Cell | |
| Protein synthesis, targeting, and secretion: Pancreatic Acinar Cell | |
| Mitochondria (Greek: mitos=thread, chondrion=small cartilage) | Mitochondria produce energy in the form of ATP or, in brown fat, as heat ("power house of the cell") They consist of an outer membrane, an inner membrane, which forms the cristae, a central space, the matrix, and the intermembranous space They are visible with routine LM as acidophilic (pink) DOTS |
| Lysosomes (degrade intracellular things) | Membrane-bound vesicles containing “digestive” enzymes The enzymes are synthesized in the RER and packaged and sorted in the Golgi apparatus In a few special cases, the enzymes are secreted into the extracellular space Residual bodies contain undigested remnants, usually lipid-containing pigments such as lipofuscin. They tend to accumulate in aging cells (old stuff). |
| Other Cellular Components: Cytoskeleton | Thin Filaments (actin and myosin) Intermediate Filaments Microtubules |
| Other Cellular Components: Glycogen | Glucose storage |
| Other Cellular Components: Lipids | Stored in the cytosol or the smooth ER Cytosolic storage in form of non-membrane bound LIPID DROPLETS |
| Exam Question The Lysosome is: A. An organelle for storage of glycogen B. Non-organelle that stores intracellular lipids C. Digestive membrane bound vesicle of cells containing enzymes D. Responsible for protein synthesis in cells | C. Digestive membrane bound vesicle of cells containing enzymes |
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