10444267
Description
Flashcards by Brianne Schmiegelow, updated more than 1 year ago
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Created by Brianne Schmiegelow
over 6 years ago
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| Question | Answer |
| Parenchyma vs. Stroma | P: cells that make up the functional elements of an organ S: structural framework of an organ (background tissue) |
| Tissue types | Blood Connective tissue Epithelium Muscle Nervous Tissue |
| Tissue preparation | 1. Fix with formalin 2. Place cut tissue in cassettes 3. Dehydrate via series of alcohol baths 4. Clear with xylene 5. Embed in liquid paraffin or plastic resin 6. Microtome (6-7 microns) 7. Mount on slides 8. Remove paraffin 9. Rehydrate with alcohol and xylene 10. Stain and add coverslip |
| What does formalin do? | Cross-links proteins to preserve tissue for slides |
| Hematoxylin vs. Eosin | H: blue, BASIC, stains acids (basophilic materials like nuclei) E: red/pink, ACIDIC, stains bases (eosinophilic materials like proteins) |
| What are special stains used for slide prep? | Gram (bacteria), GMS, silver stain (fungi) |
| Layers of the cell membrane | Hydrophilic: -contains pos-charged N groups and neg-charged phosphate groups -present on both inside and outside of membrane Hydrophobic: -contains two long-chain FA's that are covalently linked to glycerol |
| What is responsible for the tri-laminar appearance of the cell membrane on EM? | 2 electron dense layers (hydrophilic phospholipid heads) separated by the electron lucent layer (hydrophobic FA tails) |
| What is the fluid-mosaic model? | The fluidity of the membrane increases with increased temperature AND decreases with saturation of FA's |
| What does cholesterol do? | Helps regulate fluidity and stabilize the membrane If you have more cholesterol, you increase stiffness in membrane and decrease fluidity |
| What are the types of membrane proteins? | Extrinsic (peripheral): on surface of membrane Intrinsic (integral): within the membrane Transmembrane (transmural): type of intrinsic protein that extends from one side of the membrane to the other |
| Pores vs. Channels | Both openings in transmembrane proteins Pores: always open Channels: can open and close Used for active or passive transport of hydrophilic molecules |
| Categories of membrane proteins | Pumps: serve to transport ions across membrane Channels: allow passage of water-soluble molecules via diffusion Receptor Proteins: allow for cell recognition and binding on cell membrane Transducers: initiate enzymatic reactions following binding with ligand molecules Enzymes: components of ion pumps and digestive action Structural proteins: add mechanical stability to membrane |
| What is the glycocalyx? | Short polysaccharide chains containing glucose molecules conjugated to membrane to form glycoproteins and glycolipids Protects surface of cell membrane, may be involved in cell recognition, and important in mediating exchange b/w internal and external cell environment |
| Types of membrane transport | Simple (passive) diffusion Facilitated diffusion Active transport Bulk (vesicular) transport |
| What is simple diffusion? | Diffusion that occurs down a concentration or ionic gradient Some pass directly through plasma membrane (lipids, gases, water, urea, bicarbonate) Larger water-soluble molecules use pore or channels in transmembrane proteins |
| What is facilitated diffusion? | Diffusion that is passive and concentration-dependent, but requires "carrier molecules" Reversible binding and unbinding to transport water-soluble, hydrophilic molecules (e.g. glucose and amino acids) Uses ion channels in integral proteins (either gated or ungated) and requires presence of stimulus to open |
| What is the affect of membrane folding on diffusion? | BOTH passive and facilitated diffusion is enhanced by increased surface area of membrane via folding (e.g. microvilli) |
| What kinds of stimuli can affect facilitated diffusion | Change in membrane potential (voltage-gated) Binding of signaling molecule or neurotransmitter (chemical-gated) |
| Aquaporins | important type of channel that uses facilitated diffusion Allows water to cross plasma membrane faster than by simple diffusion alone |
| What is active transport? | Transport that is independent of concentration (usually against concentration gradient) Requires energy (ATP -> ADP, Na/K pump) Occurs at specialized "dynamic pore sites" (usually transmembrane proteins) |
| What is bulk (vesicular) transport? | Transport that requires energy and consists of the engulfment of molecules/particles by cytoplasmic extensions AKA endocytosis Results in formation of membrane-bound, endocytic vacuoles called endosomes or phagosomes |
| Types of endocytosis | Phagocytosis: engulfment of solid, particulate matter Pinocytosis: engulfment of liquids |
| What is receptor-mediated endocytosis? | Types of endocytosis in which extracellular molecules (ligands) bind to receptor proteins (clathrins) located in coated pits (caveolae) of cell membrane |
| What is exocytosis? | Any bulk transport or vesicular movement from the cytoplasm to the extracellular space |
| What is transcytosis? | transport of material across or through a cell via sequential endocytosis followed by exocytosis |
| What are the two major categories of organisms? | Prokaryotes (no nucleus) Eukaryotes |
| Differences b/w prokaryotes and eukaryotes | Eukaryotes have a nucleus, organelles, histones, chromosomal DNA, and axonemal flagella Prokaryotes have plasmids and cell walls |
| What is protoplasm? Types? | ~70-85% water + electrolytes, proteins, lipids, and carbohydrates Cytoplasm: between cell membrane and nuclear membrane Nucleoplasm: within nucleus |
| How much of the nuclear mass is consisted of DNA? | <20% |
| Chromatin vs. Chromosomes | Chromatin: DNA complexed with nucleoproteins Chromosomes: packaged chromatin |
| Genes | Segments of DNA within individual chromosomes that code for particular traits |
| Alleles | Different forms of the same gene |
| Diploid vs. Haploid | Types of homologous pairs in chromosomes Diploid in humans: 2n =46 Haploid in humans: n = 23 (eggs and sperm) |
| Karyotyping | sorting of chromosome pairs according to size and shape |
| Heterochromatin | Electron-dense, darkly-staining, INACTIVE DNA & nucleoproteins In females, find Barr body (permanently inactive DNA; degenerate X chromosome) Most chromatin in nucleus is heterochromatin |
| Euchromatin | Dispersed DNA that is ACTIVE in transcription (RNA synthesis) Cells active in translation will have a prominent nucleolus and abundant euchromatin |
| What are lamp brush chromosomes? | Active portions of chromosomes that unravel to to undergo transcription and become visible |
| Histones | Most of DNA-associated proteins in eukaryotes Assist with DNA folding => chromatin organization into chromosomes |
| Nucleosomes | Segments of DNA wrapped around several histones Regulate DNA activity |
| Non-histones | additional category of nucleoproteins may also be involved in regulation of gene activity |
| Nuclear envelope | Surrounds nucleus and separates the nucleoplasm from the cytoplasm Contains inner and outer nuclear membrane separated by perinuclear cisterna |
| What is a nuclear pore complex? | ~70-80 nm diameter channels that connect the inner and outer nuclear membranes Regulate the exchange of macromolecules between the nucleus and cytoplasm |
| Difference between the inner and outer nuclear membranes | Inner: associated with network of lamin filaments for support (called nuclear lamina) Outer: studded with ribosomes, continuous with rER |
| Ribosomes | Bipartite (two subunits, 40S & 60S) Proteinaceous structures (contain rRNA) Synthesized and assembled in nucleolus, then migrates to cytoplasm where it's found free and attached to rER and outer nuclear membrane Often grouped together as polyribosomes or polysomes (aggregates or ribosomes and mRNA) Sites of protein synthesis |
| Mitochondria | Produce energy (ATP) via Kreb's cycle and oxidative phosphorylation (both aerobic) Vary greatly in size, shape, and number within cell Oblong to oval, move freely within cytosol present in all cells except RBCs and keratinocytes |
| What is porin? | Pore-forming protein found in the permeable outer membrane of mitochondria |
| What are cristae? | Folds in the inner membrane of mitochondria Lined with elementary particles that contain enzymes for oxidative phosphorylation |
| What is in the inner cavity of mitochondrion? | Amorphous matrix material that contains dense granules (thought to be binding/storage sites for Ca2+) |
| How do mitochondrion replicate? | Possess circular DNA and are self-replicating Reproduce by binary fission, similar to bacterial division |
| How are mitochondrion replicated? | Maternally inherited but unique from the rest of DNA Structurally similar to bacterial ribosomes |
| What is cellular respiration? | Energy released from chemical breakdown of organic molecules from diet and stored in the form of ATP |
| Where does cellular respiration occur? | Begins in the cytosol (glucose -->pyruvate) via anaerobic glycolysis Then diffuses into mitos where aerobic respiration occurs in the matrix via Kreb's cycle (pyruvate --> CO2+H2O+ATP) |
| How is most ATP produced in the cell? | Via oxidative phosphorylation by cytochromes of the electron transport system |
| What are cytochromes? | Enzymes on the inner membrane of cristae in the mitochondria |
| What is the endoplasmic reticulum? | Series of membranous sheets and tubules throughout the cytoplasm Can be smooth or rough |
| Smooth vs. rough ER | Rough: has surface receptor molecules for ribosomal attachment; specializes in protein synthesis Smooth: functions in lipid synthesis, transport of proteins from rER to Golgi, membrane formation & recycling, synthesis of cholesterol & steroid hormones; principle organelle involved in detoxification and conjugation of drugs & toxins |
| What are coated vesicles? | Vesicles that surround and coat proteins for transport, bud off the sER, then transport proteins between sER and Golgi and between Golgi and cell surface Act as "taxi" for proteins |
| Golgi apparatus | Complex of flattened, stacked, membrane-bound cisternae Functions in post-translational modification, packaging, & sorting of proteins synthesized in rER (e.g., sulfation, phosphorylation, glycosylation) |
| Cis vs Trans Golgi | Cis: "forming face"; convex; where proteins arrive from rER in coated transfer vesicles Trans: "maturing face"; concave; where proteins are packaged into clathrin-coated vesicles for secretion |
| How does the Golgi complex work? | Vesicles bud off maturing face as condensing vacuoles, sorted into secretory vesicles for extracellular export via exocytosis or as membrane-bound vesicles for intracellular use, or as secretory granules for long-term storage |
| What is membrane trafficking? | During exocytosis and secretion, large amounts of intracellular membrane are incorporated into outer cell membrane These are recycled by the Golgi |
| Lysosomes | Membrane-bound vesicles containing hydrolytic enzymes (e.g. acid phosphatase) Used to degrade organelles and cells with finite lifespans during apoptosis or programmed cell death (aka autophagy) |
| 1' lysosomes | Newly-formed lysosomes produced by rER and Golgi INACTIVE |
| 2' lysosomes | What occurs when 1' lysosomes fuse with phagocytic vesicles (phagosomes) AKA phagolysosomes ACTIVE Function in intracellular digestion |
| 3' lysosome | Result of hydrolytic breakdown AKA residual body May be excreted or remain in cells for life (e.g., lipofuscin pigment granules in neurons) |
| Endosomes | type of endocytic vesicle with acid pH in the lumen due to proton pumps in membrane which pump H+ into interior |
| Peroxisomes | Membrane-bound organelles containing oxidative enzymes (oxidases) Resemble lysosomes (also contain catalase and peroxidase) Use enzymes, free radicals, and hydrogen peroxide to oxidize toxic metabolites |
| What are inclusions? | Non-living components of the cell Include neutral fat droplets, lipids, glycogen, secretory & pigment granules Also viral inclusions (can be found in cytoplasm or in nucleus) |
| Intracytoplasmic pigments | Melanin: black, brown, granular pigment; produced by melanocytes and transported to other cells Lipofuscin: gold-brown granules; frequently seen in neurons; sometimes called "old age pigment" |
| Functions of cytoskeleton | Provide structural support for plasma membrane and cell organelles Intracellular movement/transport of substances (large molecules/organelles) Cell locomotion (amoeboid movement, embryonic development, cilia, flagella) Muscle contraction (specialized cells) |
| 3 main elements of cytoskeleton | Microfilaments, intermediate filaments, and microtubules |
| Microfilaments | Distributed in 3D network throughout cytoplasm Important in maintaining cell shape; facilitate shape changes during movement (e.g., wound contraction during healing and muscle contraction) |
| What is actin? | Type of microfilament AKA thin filament; 6-8 nm in diameter Made up of smaller G-actin subunits (small, globular protein monomer that polymerizes to form protofilaments) Two protofilaments twist together to form a double helix (F-actin), then these combine to form larger actin filaments |
| What is the terminal web? | Support meshwork that prevents cell from deformation Formed by actin linking with filamin protein |
| Myosin | Type of microfilament AKA thick filament; ~15 nm in diameter Also classified as "motor protein" along with dynein and kinesin Long and rod-saped with globular heads; form thick "cables" with myosin heads sticking out sides Myosin heads form cross-bridges between adjacent filaments |
| What is required for movement of myosin filaments for muscle contraction? | Ca2+ and ATP |
| Intermediate filaments | 8-10 or 10-15 nm in diameter 1' structural function Heterogenous group, so molecular make-up varies between cells (generally form large filaments that bind with intracellular structures) Several different classes, each expressed in different cell types (1 cell may produce more than 1 type of filament) Useful in immunohistochemistry and tumor ID |
| Types of intermediate filaments | Cytokeratin: all epithelial cells; forms tonofibrils in epidermis Vimentin: found in mesodermal cells Desmin: unique to muscle cells Neurofilament proteins: nerve cells GFAP: found in glial cells Lamin: forms layer on inside of nuclear membrane |
| Microtubules | Larger than microfilaments or intermediate filaments (~24 nm diameter) Composed of 2 types of globular protein subunits (alpha and beta tubulin) arranged in a coiled, spiral pattern that polymerize to form hollow tubes so they can readily assemble and disassemble Involved in cell movement, maintenance of cell shape, and intracellular transport of substances |
| How does microtubule movement occur? | Via addition or subtraction of tubulin subunits from microtubules Motor proteins dynein and kinesin attach them to organelles and allow movement in the cytoplasm |
| What provides microtubules with energy? | Microtubule-associated proteins (MAPs) as ATPase Stabilize microtubules along with capping proteins |
| What drugs affect microtubules? | Colchicine, vincristine, and vinblastin Inhibit polymerization of microtubules and therefore cell division |
| Where are microtubules found? | Cilia and flagella, centrioles, basal bodies of cilia, and mitotic spindles |
| Axoneme | 9 pairs of microtubules (peripheral doublets) containing dynein arms arranged in a circle with a central doublet in the middle (9+2) Central doublet connects to peripheral doublets by radial spokes and peripheral doublets connect to each other via nexin protein In cilia, grows from basal body and is derived from a modified centriole |
| Centrioles | Normally located in region of cell called centrosome near nucleus Function in cell division Each consists of 9 triplets of microtubules arranged in a cylinder |
| Function of centrioles in cell division | Pair of centrioles (diplosome) oriented at right angles to each other within centrosome acts as a nucleation center for microtubules Centrioles divide and go to opposite poles, forming mitotic spindle which controls distribution of chromosomes |
| How does movement of chromosomes occur during cell division? | Addition and subtraction of tubulin subunits and attachment proteins (dynein and kynesin) to chromatids at kinetochore (aka centromere) |
| Interphase | "resting phase" between divisions Occupies most of the life of the cell Three subphases: G1, S, G2 |
| G1 phase | Part of interphase Longest of the cell phases (lasts hours to days) When cell growth, maturation, and differentiation occur |
| What is hypertrophy? | Increase in cell size Occurs in G1 phase |
| What is hyperplasia? | Increase in cell number Occurs during mitosis |
| S phase | Part of interphase Replication of DNA prior to division At beginning, chromosome # is 2n, at end is 4n for a brief period of time Prior to replication, each chromosome has a single chromatid with attached centromere, but afterward each contains 2 chromatids connected by centromere Replication of centrioles also occurs in S (=> 2 diplosomes) Takes several hours |
| G2 phase | Part of interphase Preparation for mitosis Synthesis of ATP and tubulin for mitotic spindle "last minute prep stage" Takes several hours |
| M phase | Cell division portion Characterized by karyokinesis (nuclear division) followed by cytokinesis (cell division) Results in 2 daughter cells Takes several hours |
| Go phase | Occurs when cells lose capacity for cell division May be permanent (terminally differentiated) or reversible (facultative dividers), depending on cell type |
| Phases of mitosis | Prophase: -microfilaments & microtubules of cytoskeleton disaggregate -centrioles migrate to poles of cell and form spindle apparatus w/ interpolar microtubules Prometaphase: -Nuclear membrane and nucleoli disappear -Mitotic spindle attaches to chromosomes at kinetochore Metaphase: -Chromosomes line up at equator Anaphase: -Centromeres split apart and chromosomes are pulled by MTs connected to centriole Teloophase: -Mitotic spindle disintegrates, nuclear envelope reassembles, nucleoli reappear -Plasma membrane forms cleavage furrow and cytokinesis begins |
| What is mitotic index? | Proportion of cells in a tissue in mitosis at any given time (normally <1) Important in tumors |
| Differences in meiosis from mitosis | During prophase I, homologous pairs of chromosomes form tetrads with exchange of chromatin via crossing over (chiasmata formation) that results in hybrid chromatids different from parents Centromeres don't split during anaphase I |
| Second meiotic division steps | Brief interphase II (interkinesis) with NO replication of DNA NO crossing over during prophase II During anaphase II centromeres split During telophase II cytokinesis yields four haploid gametes, each genetically unique |
| What is produced during gametogenesis? | In male, 3-4 viable gametes (sperm) produced In female, 1 functional gamete (ovum) and 2-3 non-functional polar bodies |
| What is the process of oogenesis? | Begins during fetal development Germ cells enter prophase I ~5th month gestation and then remain there until ovulation (12-50 years later) |
| What triggers apoptosis? | Timing in fetal development (programmed cell death) Some cells have finite, predetermined lifespans Growth and regression of ovarian follicles and CL Destruction of virus/tumor-infected cells Clonal deletion in thymus (removal of t-cells that react to self molecules |
| What is pyknosis? | Shrinkage of nucleus that occurs during apoptosis |
| Process of apoptosis | 1. Condensation of nuclear chromatin and shrinkage of nucleus 2. Cell swells as result of water influx due to loss of ATP to maintain cell membrane pumps 3. Lysosomes release catalytic enzymes into cytoplasm (autolysis) 4. Cytoplasm becomes bright pink (eosinophilic) as membranes start to break apart and leak 5. Final pathway initiated by caspace cascade (which are usually inactive enzymes) 6. Chromatin in nucleus begins to degenerate (karyolysis) 7. Nuclear material begins to fragment and nuclear membrane disintegrates (karyorhexis) 8. Dead, necrotic cells are later phagocytosed by neutrophils and macrophages |
| Erythropoeitin | Hormone secreted by the kidney that controls blood cell production |
| Where does hemopoiesis occur? | IN adult humans, occurs in vascular sinuses of bone marrow (especially in flat bones) 2.5 billion RBCs/day In fetus, first in blood islands in wall of yolk sac (1st trimester) then in liver and lymphatic tissue (2nd trimester) then in bone marrow (last month of pregnancy) |
| Bone marrow | Red marrow is active and contains large #'s of mature RBCs Yellow (fatty) marrow is inactive |
| Erythropoiesis | Stem cell (CFU-E) -> proerythroblast -> erythroblast/normoblast -> reticulocyte -> mature RBC Overall trends: progressive decrease in cell size, loss of nucleus and organelles, increase in hemoglobin concentration |
| What are Howell-Jolly bodies? | Occasional, basophilic nuclear remnants visible within the cytoplasm |
| What are reticulocytes? | Immature RBCs with stippled cytoplasm (still have some rRNA) Slightly larger than mature RBCs |
| What is reticulocytosis? | Increase in reticulocytes in circulation associated with chronic blood loss and/or hemolytic anemia AKA left shift Also seen in severe/chronic infections |
| What is megaloblastic anemia? | Anemias where there are large numbers of erythrocyte precursors in peripheral blood Lots of free stem cells in blood! |
| What is the makeup of blood? | Plasma: liquid, extracellular matrix that makes up 55% of blood volume -91-92% water, 1-2% electrolytes (Na, Ca, K, HCO3), 7-8% protein Serum: plasma-clotting factors |
| Plasma proteins | Albumins: bulk of plasma proteins, all synthesized in liver; function as transport proteins for insoluble metabolites; responsible for colloid osmotic pressure in blood vessels b/c of large size Globulins: large molecules used as transport proteins for lipids and heavy metal ions; largest fraction are immunoglobulins (antibodies synthesized by plasma cells) Fibrinogens: largest proteins; soluble, synthesized by liver; polymerize to form insoluble fibrin during clotting (prothrombin -> thrombin catalyzes fibrinogen -> fibrin) |
| Formed elements of blood | Hematocrit (volume of RBCs) -45% in males, 42% in females Plasma Buffy coat (WBCs and platelets) -1-2% Hematocrit +/- buffy coat = packed cell volume |
| What is the modified Romanovsky method? | Process of producing a blood smear Uses Wright, Giemsa stain |
| Erythrocytes | ~6-8 microns in diameter Biconcave discs (--> deformability and increased surface area for gas exchange) Primary structural protein is spectrin (binds to inner surface of plasma membrane and provides both resiliency and defomability) |
| What is sickle cell anemia? | Disease caused by single amino acid substitution (valine for glutamic acid @ position 6 of beta-globulin chain) that leads to a change in the 3D structure of hemoglobin Causes conformational change in cell to "sickle" shape that is more fragile and easily damaged Can also cause damage to endothelial cells of capillary walls b/c of rough edges Confers resistance to malaria |
| What is the lifespan of a RBC? | ~120 days |
| How can RBCs make ATP? | anaerobic glycolysis |
| What happens to senescent RBCs? | They are removed from the circulation by the liver and the spleen |
| Platelets | Small non-nucleated cells containing organelles (2-4 micron diameter) Formed from megakaryocytes (huge cells with multi-lobed nucleus) in bone marrow Lifespan of 8-12 days Function in blood clotting Impaired by aspirin (inhibits clotting) |
| What are demarcation channels? | Pleated channels in megakaryocyte cytoplasm Where platelets "tear off" |
| What is coagulation? | Result of cascade interaction between plasma proteins and coagulation factors Occurs ONLY if endothelial lining of vessel is injured Extrinsic (Faster, initiated by thromboplastin) and intrinsic (slower, initiated by exposure of collagen and requires clotting factors) pathways |
| Process of coagulation | 1. Wall of blood vessel breaks 2. BV releases thromboplastin to initiate extrinsic and exposes collagen to initiate intrinsic 3. Platelets adhere to exposed collagen and release serotonin (vasoconstrictor) 4. Extr. and intr. pathways converge to form common pathway (at point where Factor X activated) which results in prothrombin -> thrombin which converts soluble fibrinogen into insoluble fibrin 5. Platelets and RBCs trapped |
| What stops clotting? | Exhaustion of fibrinogen and removal of thrombin from blood during conversion of fibrinogen to fibrin Also anticoagulants antithrombin III and heparin |
| What is hemophilia? | Deficiency in clotting factor(s), so blood can't clot; defect in intrinsic pathway Sex-linked, in males; present on X chromosome |
| Types of hemophilia | A: deficiency of clotting factor VIII B: Factor IX C: Factor XI Von Willebrand's disease: von Willebrand's factor |
| What is pseudopodia? | Process by which WBCs stick to endothelial cell surface and then squeeze between endothelial cells of capillaries and venules |
| What is chemotaxis? | Attraction of WBCs to endothelial surface of BVs at inflammatory sites Occurs via cytokines |
| 1' granules | Found in ALL WBCs AKA azurophilic granules (stain blue) Contain lysosomal enzymes (e.g., acid hydrolases) |
| 2' granules | AKA specific granules Found only in granulocyte WBCs Contain lysozyme and alkaline phosphatases Exhibit variable staining Includes: neutrophils, basophils, and eosinophils |
| Neutrophils | Most common WBC 12-14 micron diameter Multi-lobed nucleus (aka polymorphonuclear cells or PMNs) Lifespan: several hours to days Few mitochondria, so use 1' anaerobic glycolysis 1' granules contain antimicrobial myeloperoxidase, 2' granules contain inflammatory mediators, proteases, defensins, lactoferrin, and lysozyme, 3' granules contain gelatinase |
| When are neutrophils released? | During inflammatory reaction via degranulation Associated with acute inflammation, generally lasts several days Attracted to bacteria and damaged tissue by chemotactic factors |
| How do neutrophils move? | Amoeboid movement |
| What is the primary function of neutrophils? | Phagocytosis Leads to formation of phagolysosome to digest bacteria and enhanced via opsonization (coating of bacteria with antibodies) |
| What is respiratory burst? | Bacterial killing by generating hydrogen peroxide and hypochlorous acid Assoc. with neutrophils |
| what are Stab cells? | AKA band cells Immature (u-shaped nucleus) neutrophils |
| What is a Barr body? | Inactive X chromosome in females Presents as "drumstick appendage" in neutrophil nuclei |
| Basophils | Least common WBC 14-16 micron diameter, bilobed nucleus May be the same as mast cells, lifespan uncertain Characterized by large, basophilic specific granules Used in Type I hypersensitivity reactions and counteracted by eosinophils |
| What is found in the specific granules of basophils? | Hydrolytic enzymes, heparin sulfate (anticoagulant), chondroitin sulfate (proteoglycan), histamine, and leukotrienes (e.g., slow reacting substance of anaphylaxis which causes asthma attacks; eosinophilic chemotactic factor) |
| Eosinophils | 1-6% of WBCs; 16 micron diameter, bilobed nucleus Remain in circulation 3-6 hours before entering tissue and have a tissue lifespan of 8-12 days Have surface receptors for IgE |
| What is found in specific granules of eosinophils? | Hydrolytic enzymes E.g. histaminase (neutralizes histamine), eosinophil peroxidase, lysosomal enzymes, and major basic protein (neutralizes heparin and kills parasites) |
| How do eosinophils counteract basophils? | Chemotactically attracted to basophils/mast cells via eosinophilic chemotactic factor Release eosinophil-derived inhibitor (inhibits basophil/mast cell degranulation) Major basic protein destroys parasites and Ag-Ab complexes |
| Monocytes | Largest WBCs 2-10% of WBCs, 16-20 micron diameter Abundant lavendar cytoplasm and kidney bean-shaped nucleus Present in bloodstream 2-3 days, then enter tissue and become macrophages where lifespan is several months (remains in same tissue) Highly mobile and phagocytic (contains hydrolytic enzymes) Active in subacute to chronic infections Also function as antigen presenting cells in lymphoid organs |
| What are epithelioid giant cells? | Fused macrophages in chronic granulomas |
| Lymphocyte | Most common type of agranulocyte WBC (20-45%) Active in subacute to chronic infections Lifespan of days to years Round, densely staining nucleus surrounded by thin rim of cytoplasm Primary cell of immune system 2 Types: b-cells and t-cells (90% t) |
| B-cells | Type of lymphocyte that is formed and matured in bone marrow Functions in humorally-mediated immune response and produces antibodies (as plasma cells) Can also function as antigen-presenting cells (have HLA Type II surface markers and surface immunoglobulins) |
| What is clonal expansion? | AKA amplification After b-cells encounter an antigen, they undergo multiple divisions to produce clones of antibody-producing plasma cells |
| T-cells | Type of lymphocyte formed in bone marrow but matured in the thymus Have paratopes (receptors on cell surface that recognize foreign proteins of antigens, called epitopes) Also have CD molecules on surface that recognize HLA receptors on surface of other cells to prevent self-destruction |
| Types of T-cells | Cytotoxic: AKA killer; primary effectors in cell-mediated immunity; recognize cells with foreign surface antigens/receptors and kill them by punching holes in plasma membranes Suppressor: suppress activity of b-cells, dampen immune response (especially to self molecules; loss of control of these in autoimmune diseases Helper: detect invaders by recognizing antigens (usually presented by macrophage or b-cells) then secrete lymphokines that stimulate antibody production and/or arrival of killer T cells |
| What are Null cells? | Lymphocytes that possess Fc receptors but lack specific cell surface markers of either b or t-cells Includes natural killer cells and possibly some pleuripotential stem cells Responsible for nonspecific cytotoxicity against virus-infected and tumor cells (also in antibody-dependent cell-mediated cytotoxicity) |
| What does an increase in WBC count tell you? | Infection/tumor Neutrophils: acute, bacteria Lymphocytes/monocytes: subacute, viral Eosinophils: allergies, parasites |
| What does a decrease in WBC count tell you? | Immune suppression/tumor |
| What is the function of connective tissue? | Provides structural/metabolic support for tissues and organs; carries blood vessels; tissue repair; nutrient/metabolite/waste exchange between tissue and circulation |
| What is connective tissue derived from? | Mesodermal mesenchyme |
| W | Stellate to spindle-shaped cells, jelly-like extracellular matrix, and occasional fibers Cells and extracellular material (determines physical properties of tissue) secreted by cells |
| Fibroblasts | Pointed, elongate, spindle-shaped cells in connective tissue Synthesize and maintain proteinaceous ground substance and connective tissue fibers (collagen, elastin, and reticular fibers) |
| What are myofibroblasts? | Fibroblasts with contractile ability |
| Reticular cells | Type of fibroblast found in lymph nodes and bone marrow Morphologically similar to primitive mesenchymal cells (look like branched fibroblasts) Synthesize reticular fibers made of reticulin May have phagocytic function |
| Adipocytes | Connective tissue cells responsible for storage and metabolism of lipids Generally large, balloon-shaped, clear spaces filled with "lipid" |
| What is ground substance? | AKA extracellular organic matrix Amorphous material made of long unbranched polysaccharide chains of repeating disaccharide units (one of these is always an amino sugar) Various fibers embedded within (e.g. collagen, reticulin, and elastin) |
| Collagen | Principal type of fiber in extracellular matrix 67-68 nm banding pattern Provides tensile strength |
| Types of collagen | Type I: 90% of collagen in body; loose & dense connective tissue of skin, tendons, ligaments, bone, and fibrocartilage; supports blood vessels; MOST important protein in the body Type II: i.e. hyaline and elastic Type III: AKA reticulin; thin, branching, net-like fibers for structural support in organs; produced by reticular cells in lymph nodes and bone marrow and by fibroblasts elsewhere; argyrophilic (stains black with silver stain) Type IV: found in basement membrane Type V: cornea Type VII: dermoepidermal junctions |
| What is Ehlers-Danlos syndrome? | Collagenopathy characterized by hyperextension of joints, skin fragility, and poor wound healing |
| How is collagen made? | 1. Precursor proteins produced by fibroblasts 2. Initially synthesized as procollagen, composed of three alpha polypeptide chains, form triple helix 3. Packed into secretory vesicles and secreted into the extracellular space 4. Extracellular enzymatic modification to form tropocollagen monomers 5. Polymerization of tropocollagen into larger bundles results in final formation of collagen microfibrils 6. Several microfibrils combine to form larger collagen fiber, then several fibers make up the collagen bundle |
| Elastic fibers | Highly branched refractile fibers synthesized by fibroblasts as tropoelastin precursor that polymerizes in ECM to form elastin Composed of elastin (protein core similar to collagen) and fibrillin (structural glycoprotein microfibrils) |
| What is Marfan's syndrome? | Autosomal dominant condition resulting in abnormal elastic fibers Characterized by tall stature, long limbs, and long thin fingers Enlarged aorta with increased regurgitation and risk of developing a dissecting aneurysm |
| Structural glycoproteins | Includes fibrillin and fibronectin Large polypeptides with branched polysaccharide side-chains Fibronectin found in BM; aids in adhesion b/w cell membrane and ECM via interaction of adhesion molecules (INTEGRINS) |
| What is laminin? | Non-filamentous sulfated glycoprotein Major component of basement membrane Produced by most epithelial and endothelial cells |
| What is entactin? | Non-filamentous sulfated glycoprotein Binds with laminin |
| What is tenascin? | Non-filamentous glycoprotein Binds cells to extracellular matrix Thought to be important in cell migration in developing nervous system |
| What are GAGs? | Glycosaminoglycans Disaccharide sugar usually covalently bound to proteins to form proteoglycans Most are sulfated! Negatively charged due to sulfate and carboxyl side groups (=> hydrophilic) Incompressibility of water provides the turgor pressure of connective tissue Reinforced with fibrous proteins |
| Types of GAGs | Hyaluronic acid: found in most connective tissue; predominant GAG in loose CT; longer than most GAGs; not bound to proteins; destroyed by hyaluronidase from bacteria Chondroitin sulfate: found in cartilage and bone Keratan sulfate: found in cartilage, bone, cornea, and intervertebral disk Dermatan sulfate: found in dermis of skin, blood vessels, and heart valves Heparan sulfate: found in BM, lungs, and liver |
| Loose connective tissue | Sparse fibers and abundant ground substance, so has a viscous gel-like consistency Has supportive function Located beneath epithelia and around nerves and vessels |
| Dense connective tissue | Provides structural support with abundant fibers, moderate # of cells, and lesser ground substance Regular: collagen fibers oriented parallel to each other and densely packed Irregular: collagen fibers oriented randomly with moderate number of fibers and few cells |
| Adipose tissue | White fat: AKA unilocular; distributed in dermis and around intraperitoneal organs; 20% of weight in males (25% in females) Brown fat: AKA multilocular; highly specialized; present in infants and hibernating animals; many smaller vacuoles to store triglycerides; used in thermoregulation; lots of mitochondria; located in adrenals |
| What characterizes epithelial cells? | Production of keratin intermediate filaments Different epithelia produce different keratin |
| Histogenesis of epithelia | Ectoderm --> epidermis, cornea, enamel, anterior pituitary, inner ear Neuroectoderm --> neural tube (posterior pituitary), neural crest (ganglia, nerves, glial, adrenal medulla) Mesoderm --> kidneys, mesothelium, endothelium, adrenal cortex Endoderm --> respiratory epithelium, alimentary epithelium, liver, pancreas, thyroid, bladder, parathyroid, thymus |
| Types of epithelium | Mucosa: lines cavities that connect with outside; contains ectoderm, BM, lamina propria, and sometimes smooth muscle Serosa: lines closed body cavities; lacks smooth muscle layer Endothelium: lines blood and lymph vessels (varies depending on which) |
| Components of basement membrane | GAGs (heparan sulfate), type IV collagen, & structural glycoproteins (laminin, fibronectin, and entactin) On EM, lamina densa (electron dense layer) and two electron-lucent layers (lamina lucida and lamina reticularis) |
| Types of cell junctions | Occluding: AKA tight junctions; located immediately beneath luminal surface of simple columnar epithelia; act as gaskets Adhering: AKA anchoring junctions; bind cells together and act as anchoring points for cytoskeleton Communicating: AKA gap junctions; focal adherent zones located on lateral border of cell; permit passage of small molecules between adjacent cells and allow transport of info and metabolites |
| What is the zonula occludens? | Type of occluding junction Portions of opposing cell membranes fuse together, forming continuous circumferential band around cell |
| What is a fascia occludens? | Type of tight junction Present between endothelial cells in wall of blood vessels Discontinuous to allow for WBC movement |
| What is zonula adherens? | Type of adhering junction Continuous band characterized by transmembrane glycoproteins called cadherins (class of cell adhesion molecules) |
| What is macula adherens? | AKA desmosomes Small circular patches located on lateral surface of cell Most common type of cell junction Assoc. with attachment plaques containing attachment proteins (desmoplakins, desmogleins, and tonofilaments) |
| What are hemidesmosomes? | Type of adhering junction Found on basal surface of cell to anchor it to BM via integrins Assoc. with high mechanical abrasion/shearing forces (e.g. skin) |
| What is the terminal bar? | AKA junctional complex Specialized, circumferential, intercellular connection Hybrid between adhering and occluding junctions (forms diffusion barrier between cells Consists of zonula occludens, zonula adherens, and macula adherens |
| What are connexons? | Channels formed by ring of 6 integral proteins (connexins) surrounding 2 nm diameter pores Part of communicating junctions |
| Microvilli | Finger-like cytoplasmic projections that contain actin filaments Increase surface area for absorption or secretion Supported by terminal web (network of actin at base) |
| Stereocilia | Long microvilli found in epididymis and inner ear Non-motile Contains actin filaments Appear to function in fluid reabsorption |
| Cilia | Long, motile cytoplasmic extensions Possess axoneme (9+2 arrang. of microtubules with dynein arms) Each arises from individual basal body developed from centrioles Beat in synchronous metachronal rhythm |
| What happens if cilia microtubules lack dynein arms? | Kartagener's syndrome: non-functional flagella on sperm Dextrocardia (situs inversus): inverted location of organs Hydrocephalus: cilia on ependymal cells can't circulate CSF |
| What type of gland is the parotid? | SEROUS |
| What type of gland is the palatal gland? | MUCOUS |
| What type of glands are the sublingual and submandibular? | SEROMUCOUS |
| Endocrine vs. exocrine glands | Endocrine: lack ducts; secrete products directly into bloodstream Exocrine: secrete product onto epithelial surface via ducts; contain myoepithelial cells that lie between secretory cells and BM to assist in secretion; have Goblet cells that secrete mucus |
| What phase are all neurons in? | Go All are terminally differentiated and DO NOT divide |
| What are the three categories of supporting cells? Where are they found? | Neuroglia in CNS Schwann cells in PNS Satellite cells in ganglia |
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