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270 Cards in this Set
- Front
- Back
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Steps to preparing specimen
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fixate, dehydrate, section, stain, microscope
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Why fixation?
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prevent autolysis, preserve cellular structure, minimize redistribution of organelles
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2 most commonly used fixatives
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aldehyde and formaldehyde
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How do formaldehyde and aldehyde work?
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form cross links between amino groups
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What is formaldehyde called in solution?
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formalin
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Osmium tetroxide
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preserve lipids, in L/M adds brown and in E/M adds density
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What do conventional stains do?
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bind to elements based on charge interactions
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Hematoxylin
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binds to negative structures, turns structures blue, implying they are basophilic
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Eosin
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stain pink or orange
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Usual heavy metals used for E/M staining
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lead and uranium
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How do heavy metal stains work?
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bind to areas of negative charge and block electrons from passing through that area --> dark spot on the image
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Electron dense
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dark on E/M, area that has bound the metal
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Electron lucent
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light on E/M, area that has not bound the metal
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Periodic acid Schiff stain
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stains carbohydrates bright magenta
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Artifact
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anything in the tissue section that is a result of the processing (tears, folds, shrinkage, spaces, etc.)
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Compound microscope
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passes a beam of light through the specimen, 40-1000x magnification, 2 lenses (objective and ocular)
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Transmission electron microscope (TEM)
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beam of electrons passed through the specimen, electro-magnetic lenses used to focus it, up to 400,000x magnification, can see antibodies and DNA
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Scanning electron microscope (SEM)
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electrons reflected off surface of specimen, creating a 3D image, lower magnification than TEM
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Resolution
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the smallest degree of separation at which two objects can still be distinguished as separate
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What is resolution based on?
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wavelength of illumination
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What is the resolution of L/M?
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200 nm
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What is the resolution of E/M?
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1 nm
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Magnification
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the enlargement of an object
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How many cell types in human body?
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over 200
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How do cells vary?
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shape, size, life span, function, internal structure
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Cytoplasm
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aqueous mixture containing internal structures of cell and cytosolic metabolic pathways (glycolysis)
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Nucleus
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houses DNA, production of mRNA, initial ribosome assembly
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Unit membrane
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basic structure of membranes, not resolvable with L/M but can be distinguished with E/M
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Phospholipid bilayer
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hydrophilic heads on the outside and hydrophobic cores on the inside
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Integral membrane protein
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protein that extends into one or both of the phospholipid layers
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Transmembrane protein
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protein that spans across entire membrane
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Peripheral membrane protein
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associated with polar head group or with integral membrane proteins, do not contact hydrophobic core
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Freeze fracture technique
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tissue frozen, mechanically fractured, membrane is split into E-face (external) and P-face, coat surface with thin metal film, viewed with TEM, can see membrane proteins
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Glycocalyx
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complex carbohydrates on the surface of the plasma membrane, attached to proteins or lipids covalently
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Endocytosis
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internalization of small membrane vesicles from the plasma membrane
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Pinocytosis
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cell drinking, continuous uptake of fluid by the cell to sample the environment, allows for membrane recycling
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Receptor-mediated endocytosis
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requires receptor-ligand binding for vesicle formation (clathrin coated pit) and internalization
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Phagocytosis
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ingestion of large particles restricted to macrophages and some leukocytes
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Opsonization
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cell coated with antibody and recognized and internalized
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Exocytosis
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fusion of cytoplasmic vesicles with the plasma membrane and release of vesicle contents
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Constitutive exocytosis
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continuous process, constant release of secretory materials and addition of new membrane
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Regulated exocytosis
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requires extracellular signal for vesicular fusion and release
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Functions of cell junctions
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attach and anchor cells to each other and the ECM, establish apical and basolateral membrane domains, provide channels for ionic and metabolic coupling
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Tight junction
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zonula occludens, belt-like around the apical portion of the cell, occludes the intercellular space
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2 functions of tight junctions
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prevent diffusion down intercellular space, establishes apical and basolateral domains by preventing the migration of membrane proteins
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Adherent junction
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attach cells to each other and anchor them to the basal lamina
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Spot desmosome
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macula adherens, type of adherent junction, disk-like, all over cell and paired with those on adjacent cells, associated with intermediate filaments
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Hemidesmosome
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half desmosome, anchor basal surface of cell to basal lamina
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Belt desmosome
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zonula adherens, belt-like junction that encircles the apex of the cell, just under the zonula occludens, holds cells together, associated with actin filaments
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Junctional complex
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zonula occludens, zonula adherens and desmosomes (epithelial cells only)
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Gap junctions
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6 connexons (transmembrane proteins) in a circle around a pore, connexons create continuity between cells, allows for metabolic and electrical continuity between cells
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3 functions of nucleus
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houses DNA, site of rRNA synthesis, produces pre-ribosomal particles
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Structure of nuclear envelope
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2 membranes, separated by perinuclear space, all continuous with ER, outer membrane has ribosomes
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Nuclear pore
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hole in the nuclear envelope that provides bidirectional continuity between nucleus and cytoplasm
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Structure of nuclear pore
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inner and outer nuclear membranes become continuous, octet of protein complexes that serve to regulate
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Nuclear lamina
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intermediate filaments on the inner nuclear membrane that provide support for the nuclear envelope
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What happens inside nucleolus?
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rRNA synthesis and ribosomal subunit assembly
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Why does the nucleolus stain heterogenously
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reflects different stages of ribosome production
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Structure of nucleolus
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no membrane
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What is chromatin?
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DNA + protein, mostly histones
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Euchromatin
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transcriptionally active, loosely wound, stains lightly
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Heterochromatin
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transcriptionally inactive, condensed, dark staining
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Structure of rER
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flattened membranous sacs, continuous with nuclear envelope, ribosomes on surface
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Function of rER
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site of protein synthesis and some phospholipid synthesis
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Structure of sER
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tubular membranous system, continuous with rER but no ribosomes
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3 functions of sER
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lipid biosynthesis, Ca2+ storage, detoxification
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Where is sER found in high quantities?
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liver, adrenal cortex, striated muscle cells
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Function of ribosomes
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sites where mRNA is translated into protein
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Structure of ribosomes
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2 subunits, each with rRNA and protein
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What are polysomes?
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cytoplasmic "free" ribosomes, arranged in spiral cluster with mRNA
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What proteins do polysomes make? 4 destinations
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make proteins that are used in the cytoplasm, nucleus, mitochondria or peroxisomes
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Where do membrane associated ribosome proteins go? 5
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integral membrane proteins, golgi, ER, lysosomal, proteins for secretion (all get sent to golgi for processing)
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Structure of the golgi
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flattened membranous sacs (cisterns) near the nucleus, not continuous with ER
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Golgi function
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site of post-translational modification of proteins and vesicle packaging
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Cisternal progression model
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entire cisterns advance through Golgi
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Function of transfer vesicles with Golgi
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derived from rER, carrying newly synthesized proteins and lipids
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Where do transfer vesicles arrive on the Golgi?
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cis face
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What is the trans face?
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the last Golgi cistern
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Trans Golgi network
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site of release of vesicles from the trans face
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4 possible fates for vesicles leaving Golgi
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pre-lysosome, return to ER or Golgi, secretory vesicle, fuse with plasma membrane to deliver proteins or lipids
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Lysosomes
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single membrane vesicle that is a site of intracellular digestion and turnover of cellular contents, contains hydrolase
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Where are lysosomes?
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in cells with a lot of phagocytic activity
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How are lysosomes made?
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hydrolase vesicle from Golgi fuses with endosome, phagosome or autophagosome --> luminal pH decreases --> activates hydrolase --> lysosome
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What does hydrolase do?
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digests the contents of the cell it fuses with, leaving undigesting material (residual body) that contains pigmented material (lipofuscin)
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Secretory granules
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single membrane, full of secretory product that fuses with membrane after a signal
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Mitochondria function
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site of ATP production
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Mitochondria structure
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inner and outer membranes, inner is highly folded and forms cristae, intermembranous space = in between membranes, intercristal space = matrix
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What is inside the matrix?
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enzymes for ATP production, Krebs cycle is in the matrix and electron transport chain in the inner membrane, mitochondrial DNA, RNA and calcium containing granules
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Composition of lipid droplets
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cholesterol and triglycerides
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Glycogen granules
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small clusters that are electron dense, no remembrane, stain pink with PAS, high concentration in liver and striated muscle
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Lipofuscin pigment
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residue of oxidation, within residual body (w single membrane), accumulates in older cells
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Melanin
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contained in melanosome, synthesized by melanocytes and responsible for hair and skin color
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3 functions of cytoskeleton
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facilitates intracellular transport, gives cell shape and stability, provides cell mobility
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Microfilament
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4-6 nm, made of actin, function: cell movement and support of plasma membrane
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Intermediate filament
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8-10 nm, heterogenous, provide structure and stability
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Microtubules
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18-20 nm, composed of tubulin
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Centriole
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made of microtubules, 9 x 3, occur in pairs near the nucleus, located in centrosome, form a diplosome (right angles to each other)
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Basal body
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same 9x3 structure, located at the base of cilia and flagella, made of microtubules
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8 characteristics of epithelium
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lines internal and external surface, avascular, little intercellular space, keratin, can be single or multiple layers, cell junctions, polarized, separated from connective tissue by basement membrane
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6 functions of epithelium
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protection (epidermis), absorption (intestines), secretion (pituitary gland), excretion (kidney), sensation (neuroepithelial cells), contraction (sweat glands)
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Describe single layer epithelium
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one layer of cells resting on basal membrane, little protection, good for absorption or secretion
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Describe stratified layer epithelium
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multiple layers resting on basal membrane, protective
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Describe simple squamous
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single layer, flat cells, good surface for diffusion, in endothelium (lining of blood vessels) and mesothium (lining of body cavities)
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Function of mesothelium
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forms serosa with underlying connective tissue, permits passage of fluids in and out of body cavities
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Describe simple cuboidal
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single layer of cells that are square shaped, may look pyramidal
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Describe simple columnar
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rectangular, nuclei at the same level, show polarity, often for absorption/secretion, may have specializations like cilia or microvilli
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Pseudostratified columnar
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cells all touch basement membrane but do not all make it to the free surface so it looks stratified
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Describe stratified squamous
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5-25 layers thick, cuboidal on basement membrane and squamous on top, good in areas of wear and tear, could be keratinized or non-keratinized
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Describe keratinized surface
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usually exposed to external environment, top layers not viable and have no nuclei, top layers contain mostly keratin
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Describe non-keratinized surface
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all cells, including surface cells, are viable, all cells have nuclei
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Where are stratified cuboidal or columnar cells found
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site of transition from one epithelium to another
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Transitional (urinary) epithelium
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changes in thickness due to the stretch of the hollow organ (relaxed: cells are more cuboidal, distended: cells are more squamous)
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Why is transitional epithelium important in the bladder?
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helps protect against toxic substances in the urine
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Structure of microvilli
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1x0.01 micrometers, evagination made of actin filaments that extend into the cytoplasm, covered with glycocalyx
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Function of microvilli
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increase surface area for absorption and might have enzymes that enhance digestion
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Stereocillia
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very long microvilli
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External structure of cilia
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2-10 micrometers, evaginations
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Internal structure of cilia
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core = axoneme which is a 9x2 + 2 microtubules, covered in plasmalemma, base = basal body (9x3 + 0 microtubule pattern)
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Components of basal lamina
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type IV collagen, laminin (laminin densa and laminin lucida produced by epithelial cells), proteoglycan
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Components of basement membrane
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basal lamina + reticular lamina (produced by connective tissue cells)
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3 functions of basal lamina
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positive charge, recognition and regulatory factors, barrier and support
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What forms ground substance?
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glycosaminioglycans (GAGs) and structural glycoproteins
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3 functions of ground substance
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lubricant/protection against foreign invaders, adhesive proteins for cell movement, transport material to and from cells
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5 primary GAGs
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heparin sulfate, chondroitin sulfate, hyaluronic acid, dermatan sulfate, keratin sulfate
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Proteoglycan
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GAG with a protein core (all of them except hyaluronic acid)
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Characteristic of GAGs
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very negative --> a lot of hydration
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Glycoprotein
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predominate protein associated with variable amounts of carbohydrate
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Glycoproteins associated with CT matrix
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fibronectin, laminin, chondronectin
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Tissue fluid
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filtrate of blood similar to plasma (leaks out of blood vessel --> tissue --> lymphatics), causes edema, contains ions/diffusible substances/plasma proteins
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Primary structural unit of collagen
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tropocollagen (causes banding)
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Collagen Type I
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most common form, in dermis, bone, tendon, dentin, fascia, sclera, organ capsules, fibrous cartilage
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Collagen Type II
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very thin fibrils, in hyaline and elastic cartilage
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Collagen Type III
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major component of reticular fiber
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Collagen Type IV
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does not form fibrils or fibers, found in the basal lamina
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Structure of reticular fibers
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collagen type III, non-banded, thin, amorphous coat
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Staining of reticular fibers
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agyrophilic: stains black with silver (not visible with H&E)
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Where are reticular fibers?
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smooth muscle, endoneurium, hematopoietic organs
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Function of reticular fibers
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inflammatory process, wound repair, prominent during embryogenesis
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Structure of elastin fibers
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amorphous core of elastin surrounded by sheath of microfibrils
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Production of elastin fibers
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produced by fibroblasts or smooth muscle cells
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Occurrence of elastin fibers
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intermixed with collagen bundles, may be fenestrated or branching sheets
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Appearance of active fibroblast
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large, oval nucleus, very euchromatic, at least 1 nucleolus, very large, cytoplasm in E/M: a lot rER and Golgi
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Function of active fibroblast
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synthesize and secrete CT fiber and ground substance
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Appearance of inactive fibroblast
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spindle-shaped, heterochromatic, cytoplasm only apparent on E/M
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Appearance of monocyte
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large, spheroid, 12-20 micrometer, basophilic cytoplasm, indented nucleus, Golgi and centrioles located in the indent
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Function of monocyte
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precursor to macrophage
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Appearance of macrophage
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nucleus is football shaped (sinister fish), chromatin peripheral, lysosomes and phagosomes discernible at E/M
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Function of macrophage
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Phagocytosis and process antigen
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Size of lymphocytes
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6-7 micrometers
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Appearance of lymphocytes
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large, spheroidal heterochromatic nucleus and small rim of cytoplasm
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Function of lymphocytes
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front line of immune system, makes B and T lymphocytes
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B-lymphocytes
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precursors of plasma cells
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Appearance of plasma cells
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ovoid with basophilic cytoplasm (E/M: a lot of rER), well developed Golgi and centrioles, nucleus with heterochromatin clock-faced
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Function of plasma cells
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produce humoral antibody
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Appearance of mast cells
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spheroid or oval with cytoplasm that has many dense granules in it, small central nucleus with peripheral heterochromatin
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Granules inside a mast cell contain:
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GAGs, histamine, proteases and heparin
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Appearance of neutrophils
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nucleus with 3-5 lobes, granules in cytoplasm (contain lysosome and non-enzyme protein)
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Function of neutrophils
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attracted to site of infection, phagocytic, attack bacteria, cause signs of inflammation
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Signs of inflammation
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rubor, tumor, calor, dolor
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Size of eosinophil
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12-14 micrometer
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Structure of eosinophil
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bilobed nucleus (in section, looks like two), cytoplasm has bright red granules
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Function of eosinophil
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contains granuls with lysosomes and are phagocytic to parasites
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Size of adiopocyte
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70-100 micrometers
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Appearance of adiopocyte
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large lipid droplet, organelles/cytoplasm/nucleus confined to rim
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Function of adipocyte
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store lipid for nutrition and insulation
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Difference between yellow fat and brown fat
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yellow is predominant form and is uniloculart, brown is multilocular with many mitochondria and central nucleus
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Size of RBC
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7.5 micrometer
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How much RBC in peripheral blood?
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4-7 x 10^6 per microliter
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Appearance of RBC
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biconcave with actin containing cytoskeleton that maintains shape, no organelles
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Function of RBC
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carry oxygen using Hb
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How many leukocytes (WBC) in peripheral blood?
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6,000 - 10,000 per microliter
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Compositional breakdown of leukocytes
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neutrophils (40-75), eosinophil (5), lymphocyte (20-50), monocytes (1-5), basophil (.5)
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Appearance of basophil
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large basophilic cytoplasm with granules containing heparin and histamine
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Size of basophil
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12-15 micrometers
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Function of basophil
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May assist mast cells in reactions
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Size of platelets
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2-4 micrometers
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Concentration of platelets in peripheral blood
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2-4 x 10^5 per microliter
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Appearance of platelets
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non-nucleated cell fragments
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Function of platelets
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blood clotting
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Formation of platelets
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megakaryocyte (35-150 micrometers, found in hematopoietic compartments, irregular nucleus), reaches into blood vessel and parts of its arms break off
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3 phases of hematopoieses
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mesoblastic, hepatic, myeloid
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What happens during mesoblastic portion of hematopoises?
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3rd week, mesenchymal cells in yolk sac and body stalk form nucleated blood cells
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What happens during hepatic portion of hematopoises?
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4-8 wk, bloods cells form in the liver, thymus and spleen
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What happens during myeloid portion of hematopoises?
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12 wk, blood cells form in bone marrow
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Pluropotential hematopoietic stem cell
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form either lymphoid multipotential cells or myeloid multipotential cells
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Storma
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meshwork of reticular fibers with rich vascular supply of multipotential cells
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Endocrine
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lack ducts and secrete products into connective tissue
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Unicellular gland (endocrine)
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some epithelia
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Multicellular glands (endocrine)
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composed of secretory and supportive cells (parenchymal and stromal)
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Exocrine
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secrete products via ducts formed by epithelial cells, cells show polarization
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What role do ducts have?
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may simply convey product or may modify it
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Unicellular gland
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single secretory cells among non-secreting epithelial cells
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Multicellular gland
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more than one cell with varying complexitiy
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Sheet gland
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simple arrangement where all cells are secretory
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2 forms of ducts
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simple or compounded
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Tubular duct
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secretory cells arranged as a tube (could be straight, coiled or branched)
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Acinar duct
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secretory cells arranged as a circle or flask
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Where is an intralobular duct?
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within a lobule
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What does an interlobular duct do?
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receives numerous intralobular ducts
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What does an interlobar duct do?
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receive interlobular ducts, between lobes
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Serous demilunes
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cap of serous cells around end of mucous tubule (only in compound tubuloacinar)
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Myoepithelial cells
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come from epithelial cells, resemble smooth muscle, surrounded secretory gland and help with excretion, in sweat and mammary glands
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Mucous (exocrine)
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viscous glycoprotein, protects and lubricates
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Serous (exocrine)
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watery secretion, rich in enzymes and ions
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Lipids (exocrine secretion)
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oily secretion from sebaceous glands and lipid portion in milk
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Cerumen (exocrine)
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waxy material from sebaceous and cerumenous gland
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2 endocrine secretions
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polypeptide or steroid
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Merocrine
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product released by exocytosis
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Apocrine
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part of apical plasma membrane released along with secretory product (pinch off part of cell)
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Holocrine
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entire cell and contents are released
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Diffusion as secretion
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used only by endocrine
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Skeletal muscle
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striated, voluntary, attached to skeleton
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Cardiac muscle
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striated, involuntary, heart and connections of great vessels
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Smooth muscle
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smooth, involuntary, lines hollow organs
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Structure of skeletal muscle fibers
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cylindrical, unbranched, multinucleated (peripheral), cytoplasm filled with microfibrils, extensive SR, surrounded by basal lamina
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Composition of myofilaments
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thin filament = actin, thick filament = myosin
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A band
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dark, contains both actin and myosin (length of myosin)
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I band
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light, contains just actin (between myosin and Z disk)
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Z disc
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located in the center of the I band, contains alpha actinin
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H band
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center of A band, contains myosin only
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Sarcomere
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contractile unit, from Z-to-Z, repeated in series the length of the myofibril
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Changes in sarcomere during contraction
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H band shortens, I band shortens, Z-to-Z shortens (A remains unchanged)
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2 ways triads ensure coordinated contraction
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nervous impulse penetrates and reaches all parts of the fiber and releases Ca2+ in response to nervous impulse
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Triad
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1 T-tubule and 2 terminal cisterns
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T-tubles
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invagination of sarcolemma
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Terminal cistern
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expanded portions of SR, release Ca2+
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Role of triad in muscle contraction
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impulse propagates along sarcolemma --> reaches T-tubule --> T-tubule depolarization is transmitted to terminal cisterns --> release Ca2+ --> interaction between actin and myosin
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Motor unit
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motor neuron and all the muscle fibers it innervates
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2 functions of connective tissue of skeletal muscle
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transmit force of contraction to connection points and separate muscle into compartments
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Endomysium
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reticular fibers surrounded each muscle fiber + its basal lamina
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Perimysium
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dense connective tissue surrounding groups of fibers and dividing the muscle into fasicles
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Epimysium
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dense connective tissue surrounding the entire muscle, blends with deep fascia and tendon
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Structure of cardiac muscle fibers
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cylindrical, branch, form interwoven bundles, centrally located nucleus, intercalated discs, myofilament organization like skeletal muscle
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Intercalated discs
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specialized cell junctions (adherent junctions, gap junctions, desmosomes) and interdigitations of sarcolemma
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T-tubules in cardiac muscle
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triads do not exist because SR is not well developed, T-tubules still stimulate release from SR, initiating contraction
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Relative sizes of muscle fibers
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skeletal muscle > cardiac > smoot
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Structure of smooth muscle fibers
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spindle shaped, unbranched, single central "inch worm" nucleus, non-striated, abundant gap junctions
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Types of muscles capable of hypertrophy
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skeletal, smooth and cardiac
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Muscle capable of hyperplasia
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smooth
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Organization of contractile proteins in smooth muscle
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actin and myosin are present but not organized into myofibrils, organized in crisscross pattern
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Dense bodies
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insertion points of myofilaments to transmit force, contains alpha actinin
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Composition of a neuron
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cell body, dendrite, axon
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Function of supportive cells
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metabolic and structural support for neurons, insulation, homeostasis and phagocytic functions
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Neuron nucleus
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very euchromatic, prominent nucleolus
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Neuron cytoplasm
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Nissl, well-developed cytoskeleton (microtubules and neurofilaments), golgi and multiple mitochondria
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Structure of dendrite
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organelles, Nissl, highly branched
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Nissl substance
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rER and polysomes
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Axon hillock
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part of cell body, no basophilia or Nissl
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Initial segment
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first portion of the axon, highly electrical and excitable
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Structure of axon
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no Nissl or Golgi, contains mitochondria, cytoskeleton, terminal bouton
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Inside terminal bouton
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neurotransmitter and mitochondria
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Size of synapse
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20-30 nm
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Shape of motor neuron
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multipolar
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Pseudounipolar
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general sensory modalities (pain, pressure, touch)
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Bipolar
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special sensory modalities (vision and olfaction)
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Astrocyte
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CNS, physical and nutritional support, ionic and neurotransmitter homeostasis, scar formation
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Oligodendrocyte
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produces myelin in CNS
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Microglia
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CNS, highly phagocytic, derived from mesoderm
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Satellite schwann cells
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surround cell bodies in PNS ganglia
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Ensheathing schwann cells
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surround axons in PNS (myelinated or unmyelinated)
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Internode
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single myelin segment
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Node of Ranvier
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area of axon between internode, Na+ and K+ channels
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Myelinated axons in PNS
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Schwann cells associated with only one axon and forms a single internode of myelin
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Unmyelinated axons in PNS
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Schwann cells associates with many axons, axons are in grooves in the Schwann cells
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Oligodendrocyte association
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each oligodendrocyte associates with 40-50 axons
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Ganglion
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collection of cell bodies with similar function
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Nerves
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bundles of axons coursing together
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Endoneurium
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connective tissue surrounding Schwann cells, includes the basal lamina and reticular fibers
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Perineurium
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Dense connective tissue surrounding groups of axons and their surrounding Schwann cells, forms fasicles, creates blood-nerve barrier
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Epineurium
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connective tissue surrounding the fasicle and entire nerve
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