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273 Cards in this Set
- Front
- Back
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What are the 4 basic types of tissues?
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Epithelial, connective, muscle, nervous
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TEM can provide magnifications up to what?
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50,000X
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TEM can resolve details how far apart?
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0.2 nm
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Lower limit of vesicle size due to membrane flexibility?
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25nm
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Glycolipids only appear where in the plasma membrane?
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In the layer that faces the extracellular fluid.
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Phospholipids in the outer leaflet?
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phosphatidylcholine & sphingomyelin
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Phospholipids in the inner leaflet?
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Phosphatidylethanolamine & phosphatidylserine.
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Flippases are usually associated with what?
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Endoplasmic reticulum
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Glycolipids ALWAYS face?
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Away from the cytosol
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Where are lipids produced?
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Cytosolic side of smooth endoplasmic reticulum bilayer.
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Lipids, lipoproteins, and steriod-derivatives of cholesterol are produced where?
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Smooth endoplasmic reticulum
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Lipochrome is...
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a group of lipid-soluble pigments that include carotene.
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Where are the large and small ribosomal subunits manufactured?
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In the nucleolus
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5 examples of glycosylated proteins.
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Integral plasma membrane proteins, ER proteins, Golgi proteins, lysosomal proteins, and secreted proteins.
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5 examples of nonglycosylated (cytosolic) proteins
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enzymes, actin, tubulin, histones, intermediate filaments.
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Proteins are marked for destruction by the covalent attachment of what small protein?
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Ubiquitin (several are attached to a lysine residue of the candidate protein).
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What signal do proteins destined for the mitochondria carry?
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Positively charged signal at the N-terminal end, longer than the ER-directing signals, 20-80 amino acids in length. (amphipathic alpha-helix)
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Drug detoxification of liver hepatocytes occurs in what organelle?
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Smooth ER
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What is dolichol?
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Specialized lipid in the ER membrane which holds a 14 sugar oligosaccharide (9 of which are mannose) that is used for glycosylating proteins "en bloc"
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A protein which is "N-linked" has sugars attached to what amino acid?
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Asparagine
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Intramuscular drug injections get into the blood unaltered through what process?
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Transcytosis. Does not involve lysosomes or Golgi.
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Difference between vesicles of regulated secretion vs constitutive secretion.
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Regulated = clathrin-coated. Constitutive = coatomer
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The fusion event of regulated vesicles with the plasma membrane requires what?
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Ca 2+
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Acid phosphatase is known to be on all of what type of organelle?
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Lysosomes
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Lysosomes posses proton pumps to keep the pH at what value?
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~5
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Lysosomal membrane proteins are unusually highly glycosylated. Why?
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To protect the proteins from digestion by the lysosomal proteases.
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Size of primary lysosome
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0.05 micrometer
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Lysosomal enzymes are tagged with what phosphorylated sugar group?
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mannose 6-phosphate
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Secondary lysosome?
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A primary lysosome which has fused with a phagosome, pinosome, or autophagosome
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Size of secondary lysosome?
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0.2 - 2 micrometers
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KFERQ
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If on the surface of cytosolic proteins, signals lysosome to take up the protein.
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heterophagy
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process of digestion of endocytosed material
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2 "professional" phagocytes
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macrophages and neutrophils
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Lysosomes serve 3 functions.
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1) defense
2) digestion 3) self-destruction |
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Autophagy is...
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the process by which worn-out organelles are digested
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2 types of coated vesicle are...
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clathrin-coated and coatomer-coated.
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Adaptin is...
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made by free ribosomes and binds clathrin and cytosolic domain of transmembrane receptors.
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Clathrin-coated vs. Coatomer-coated vesicles
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Clathrin-coated mediate selective transmembrane proteins, while coatomer-coated mediate nonselective vesicular transport of the default pathway.
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Two types of coatamers
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COP-I (retrograde) and COP-II (anterograde)
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KDEL receptor binds to COP-I proteins to...
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form a vesicle in the Golgi which is bound for the ER.
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Function of tropomyosin?
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Strengthens filaments
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Function of Myosin II?
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Slide filaments
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Function of Myosin I?
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Move vesicles on filaments
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Function of Filamin?
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Cross-links filaments into gel
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Function of Spectrin (Spectrin-II = nonerythroid, Spectrin I = erythroid)?
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Cross-links filaments, by their sides, to plasma membrane
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Function of Fimbrin?
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Bundle filaments
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Function of alpha-actinin?
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Bundle filaments
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Function of gelsolin?
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Fragment filaments
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Function of Cap Z?
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Caps plus-end of filament
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Function of Profilin?
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Binds actin monomers
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Function of Villin?
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Bundle filaments
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FAK
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Focal Adhesion Kinase. Phosphorylates focal contact proteins so they fit together
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Proteins from the myosin family are...
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actin-dependent motor proteins that bind and hydrolyze ATP which provides the energy for their movement along actin filaments from the minus end of the filament toward the plus-end.
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Filopodia and lamellipodia
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protrusions of cell membrane
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Three steps for a cell to crawl
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1) Protrusion
2) Attachment 3) Traction |
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Lamellipodia vs. filipodia
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sheet-like projection vs spike projection
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outer diameter of microtubule
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25 nm
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diameter of microfilaments
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5-9 nm
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Polymerization of tubulin heterodimers requires the presence of what?
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Mg2+ and GTP
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Nucleation site for microtubules?
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gamma-tubule ring
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Two families of motor proteins that move along microtubules
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kinesins and dyneins
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kinesin moves vesicle...
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toward (+) end. (away from centrosome)
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dynein moves vesicle...
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toward (-) end. (toward from centrosome)
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What organelle is associated with kinesin?
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ER
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What organelle is associated with dynein?
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Golgi
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What does colchicine do?
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Binds tightly to free tubulin and prevents polymerization into microtubules.
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What does taxol do?
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Binds tightly to microtubules and prevents them from depolymerizing.
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Diplosome
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centriole pair
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Nexins...
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link adjacent doublet in a cilium
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Intermediate filaments...fibrous or globular?
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Fibruous
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diameter of intermediate filaments
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10 nm
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Polarity of intermediate filaments?
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None
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Keratin
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Epithelials and their derivatives (hair, skin, nails)
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Vimentin
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Cell of mesenchymal origin
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Desmin
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muscle cells
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Glial fibrillary acidic protein
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Glial cells (astrocytes and Schwann cells)
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Neurofilaments (NF-L, NF-M, NF-H)
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Neurons
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Lamins (A, B, C)
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All nucleated cells
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Flaggrin is a bundling protein associated with what type of intermediate filament?
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Keratin
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Zonula occludens
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tight junction
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Striated border microvilli
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only in small/large intestine
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Brush border microvilli
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Kidney tubules
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Stereocilia
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NOT cilia - longest, branching
found in: 1) epididymis 2) inner ear |
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How large are microvilli?
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80 nm
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Villin
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Actin-binding protein found only in microvilli
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Cadherins
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Adherens junctions and desmosomes
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Where do we find integrin?
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Focal adhesions and hemidesmosomes
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Major transmembrane proteins in tight junctions
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claudins and occludins
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Transmembrane linker glycoprotein that mediates adhesion between epithelial cells
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E-cadherin
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Fascia adherens is part of what?
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Intercalated disc
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Main mechanical interconnection in epidermis?
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desmosomes
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Hemidesmosomes connect what?
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Basal surface of epithelial to basal lamina
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Transmembrane linker proteins in hemidesmosomes?
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integrins
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Junctional complex consists of what?
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zonula occludens, zonula adherens, desmosomes
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Size of gap junction pore?
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1.5 nm
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What are gap junction proteins which form the pore?
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Connexons
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Steroid hormone groups?
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Vitamin D
Estrogens Glucocorticoids Mineralocorticoids Androgens Progestins |
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Size of nucleus
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5-10 micrometers
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True or False. The outer nuclear envelope is continuous with the endoplasmic reticulum
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True
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RNA polymerase which transcribes rRNA in the nucleolus?
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RNA Pol I
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Chromosomes containing the nucleolar-organizing regions (NORs)
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13,14,15,21,22
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Types of constituitive heterochromatin?
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centromeric DNA & satellite DNA
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Histone synthesis occurs during which phase?
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S phase
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Cell specialization occurs in which phase?
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G1 phase
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Length of S phase?
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7 hours
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Length of G2 phase?
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1 hour
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Length of M phase?
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1 hour
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Three types of stem cells
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Multipotential, Pluripotential, Unipotential
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Example of multipotential cell?
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Bone marrow
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Example of pluripotential cell?
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epithelial ling cells of the intestine
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Example of unipotential cell?
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stratum basale of the epidermis of the skin
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Five pairs of acrocentric chromosomes have satellites
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13,14,15,21,22
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How is the 45S rRNA processed?
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45S is cleaved to give 28S, 18S, and 5.8S. 5S genes are transcribed by RNA Pol III in the nuclear sap.
28S + 5.8S + 5S -->60S 18S --> 40S |
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Mitotic figure
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a cell in any phase of mitosis
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Mitotic index
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# dividing cell / # non-dividing cells
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Examples of multinucleated cells
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Osteoclasts, skelatal muscle
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Amitosis
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Karyokinesis without cytokinesis
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Example of endomitosis
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Megakaryoblasts
Become polyploid. Single nucleus. |
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What family of enzymes regulates apoptosis?
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Caspases - degrade regulatory and structural proteins in the nucleus and in the cytoplasm. Activation induced by cytokines, such as tumor necrosis factor (TNF)
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4 steps of apoptosis
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1) cell shrinkage
2) pyknosis (Chromatin condensation) 3) Formation of cytoplasmic blebs and apoptotic bodies 4) Phagocytosis of apoptotic bodies |
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Most characteristic feature of apoptosis?
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pyknosis
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Difference between apoptosis and necrosis?
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Apoptosis does not elicit inflammation
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Examples of Family I steroids
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cortisol, aldosterone, androgen, progesterone, and estrogen
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Examples of Family II steriods
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thyroid hormone T3, retinoic acid, and vitamin D
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Where are disulfide bonds formed?
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In the ER
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Principal extracellular matrix-producing cell is the ...
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fibroblast
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Three major kinds of extracellular macromolucules composing the extracellular matrix?
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1) glycosaminoglycans(GAGs) and proteoglycans - give connective tissue a gel-like nature
2) fibrous protein (principally collagen [strength] and elastin[resilience]) 3) Adhesive glycoproteins (fibronectin and laminin) |
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Which part of the extracellular matrix is responsible for signaling repair of tissue?
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Adhesive glycoproteins
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Major types of adhesive glycoproteins
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fibronectin, laminin, entactin
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Peptide sequence of adhesive proteins that bind to integrins?
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RGD sequence (arginine, glycine, aspartate)
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Fibroblasts mainly produce what?
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Fibronectin.
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90% of all collagen is of what type?
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Type I
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What type of cell synthesizes type I collagen?
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fibroblasts
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Another name for Type III collagen?
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Reticular fiber
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Reticular fiber locations?
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1)support for capillaries, small nerves, and muscle cells
2)component of basement membranes 3)main stromal fibers for myeloid and lymphoid tissues and glands |
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length of type I, II, III, and VII collagen banding pattern?
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64-67 nm
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Net-like polymer sheets that assemble in to the basal lamina beneath epithelia and around muscle, fat and nerve cells?
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Type IV Collagen
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Type of collagen associated with hyaline and elastic cartilage?
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Type II
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Type of collagen associated with all basal and external lamina?
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Type IV
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Collagens are rich in what 2 amino acids?
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Proline and glycine
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Unique amino acids found in collagen?
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hydroxyproline and hydroxylysine
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Enzyme which crosslinks collagen
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lysyl oxidase
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Examples of where elastic fibers are found?
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Blood vessels, skin, lungs, and bladder
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properties of elastin
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highly hydrophobic, non-glycosylated, 750 AAs long. High in glycine and proline. Unique AAs: desmosine and isodesmosine.
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Elastic fibers are made of elastin as well as what glycoprotein?
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Fibrillin (extremely thrombogenic)
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What enzyme crosslinks elastin?
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lysyl oxidase
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Locations of elastic fibers?
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1) Ordinary connective tissue (dermis of the skin)
2) vocal cords 3) elastic ligaments (ligamentum nuchae) 4) elastic cartilages (pinna, auditory tube, epiglottis) 5) muscle layers of all blood vessels except capillaries (here elastin exists as discontinuous sheets called "elastic laminae" and not as fibers) |
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Smooth ER is associated with what processes?
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lipid metabolism, steroid hormone synthesis, glycogen breakdown (glucose-6-phosphatase), and detoxification.
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Alcohol detoxification occurs where?
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Peroxisomes
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N-CAM
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neural/glial cell-cell calcium-independent adhesion molecule
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Cadherin
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cell-cell calcium-dependent adhesion molecule. (E-epithelial, P-placenta and epidermis, N-nervous and muscle)
Concentrated in zonula adherens and macula adherens. |
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Integrins
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Cell-ECM adhesion molecule (Some are cell-cell). Ca++ or Mg++ dependent. Binds linkers such as fibronectin and laminin. Recognize RGD sequences.
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Selectins
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heterophillic cell-cell calcium dependent. Selectins bind oligosaccharide in neutrophils (WBC).
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Nernst Equation
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deltaEm = -(60mV/Z)*log([S]b/[S]a)
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General flow equation
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Flow=(concentration)*(mobility)*(area)*(driving force)
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Stokes-Einstein relation
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x=sqr(2Dt)
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Signal for proteosomes to destroy molecule?
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ubiquitin
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Lysosomal proteins have their mannose phosphorylated. Where does it happen?
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CGN and cis-cisterna
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Difference between regulated and constitutive secretion pathway?
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Regulated secretion vesicles are clathrin-coated, which constitutive secretion vesicles are coatomer coats.
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KFERQ
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Signal for lysosome to digest
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Mannose-6-phosphate is a signal for what?
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It is a signal for lysosome-destined proteins.
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Cytochalasins
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bind to the plus end of microfilaments and block further polymerization.
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Protein bridges which link adjacent microtubule doublets in cilia?
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nexins
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Keratin intermediate filament binding protein which bundles tonofilaments?
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Filaggrin
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Glycolipids acquire their sugars where?
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Golgi
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What makes up the adhesion complex?
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hemidesmosome, anchoring filaments, and anchoring fibrils (Type VII Collagen).
Type I,II,IV, and VII collagen |
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What three layers make up the basement membrane?
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Lamina rara, Lamina densa, Lamina reticularis
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Basal lamina are found where?
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Base of ALL epithelial cell sheets and tubes, muscle, fat, and Schwann cells.
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True or False. In normal healthy tissue, blood vessels do not cross the basal lamina?
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True
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Functions of basal lamina
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1) Structural support
2) Selective filter 3) determine cell polarity 4) influence cell metabolism 5) organize proteins in adjacent plasma membranes 6) induce cell differentiation 7) assist in cell migration |
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All basal laminae contain...
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Type IV collagen, proteoglycans (primarily heparan sulfate), and glycoproteins laminin and entactin.
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Thickness of lamina rara and lamina densa?
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50 nm
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What form of collagen is secreted?
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procollagen
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Perlecan is made where?
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In all cells making basal lamina (epithelia, muscle, nerve)
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Lamina reticularis collagen?
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Type III collagen
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Lamina densa collagen?
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Type IV collagen
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Lamina rara GAG?
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Heparan sulfate
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p16 and p21 are examples of what?
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Cdk inhibitors
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p21 is under the control of what?
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p53
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p16 binds to which Cdk? And thereby inhibits entry into which phase of the cell cycle?
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Cdk-4
S phase |
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Transverse portion of the intercalated disc is reinforced by...
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desmosomes and fascia adherens
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Longitudinal portion of the intercalated disc consists of...
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gap junctions
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What cell functions does cytochalasins inhibit?
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motility, phagocytosis, microfilament-based trafficking of organelles and vesicles, and the production
of lamellipodia and filopodia. |
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True or False. Fimbrin is a bundling protein that is enriched in the parallel filament bundles at the leading edge of
cells, particularly in filopodia? |
True
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Anchoring filaments are made of what protein?
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kalinin
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Anchoring fibrils are made of what?
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Type VII collagen
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Needed for RBC DNA synthesis
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Transferrin and Transcobolamin
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Variable and constant regions of light chain? Heavy chain?
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V J, C. V D J, C
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What accounts for the vast diversity of amino acid sequences in the variable regions?
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Somatic recombination
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Coagulation proteins' mission?
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To form a stable plus (fibrin and platlets)
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Components of coagulation are all synthesized in the liver except for
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VIII
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Vitamin K is important for clotting because
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gamma carboxyglutamate formation
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Fibrinolysis
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tPA cleaves plasminogen to plasmin
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Platelets are
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cell components for homeostatis.
-activate coaggulation factors -aggregate -interlace w/ fibrin |
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3 granulocytes are
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eosinophils, basophils, neutrophils
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Hematopoiesis sites
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Yolk sac: 2 weeks (nucleated RBC, no lympho)
Hepatosplenic: 6 weeks (nucleated RBC, some lympho) Bone marrow: 5 months (mature) |
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Capabilities of stem cell
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differentiation or self-renewal
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asymmetric mitosis
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self-renewal and differentiation
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Bone marrow stromal cells
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Fibroblasts, endothelial cells, reticular cells, macrophages
Also, ECM proteins (collagen, laminin, fibronectin) and growth factors. |
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Hematopoietic growth factors
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Myeloid: CSFs(GM/G/IL-3)
Lymphoid: IL-6 Erythroid: Epo Thromboid: Tpo |
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Feedback mechanisms of hematopoiesis:
|
trigger/sensor/growth factor/target/effect
Drop in O2/kidney baroreceptors/erythropoietin/CFU-E in BM/erythropoiesis Microbial invasion/immune system alert/CSFs+interleukins/GEMM-CFU in B.M./WBC Injury/bleeding+hypoxia/thrombopoietin/megakaryoblast in B.M./platelet production |
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Acute Leukemia
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Results from a block in differentiation of leukemic stem cells. Leukemic blasts accumulate because of a failure of maturation into functional end cells. Leukemic blasts diffusely replace the bone marrow and usually spill over into the blood. Clinical presentation will be bacterial infection.
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Growth factor needed for erythropoiesis
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Erythropoietin (Epo) synthesized by kidney.
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Role of RBC in CO2 transport
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CO2 diffuses thru RBC membrane->carbonate (carbonic anhydrase)->bicarbonate->transported out of cell by Band 3.
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Cofactors of enzymes needed for DNA synthesis
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Vitamin B12 & folate
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Anemia
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decrease in total circulating RBC, in hemoglobin concentration in blood, or in hematocrit.
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Microcytic, hypochromic anemias
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Conditions that interfere with hemoglobin production
1) iron deficiency 2) disorders of globin synthesis (thalassemia) 3) disorders of porphyrin and heme synthesis |
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Macrocytic: megaloblastic anemia
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Defective DNA synthesis that interferes with red cell maturation, resulting in large red cells that do not function properly. Vit B12, IF, or folate deficiencies.
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Granules in neutrophil
|
primary/azurophilic; secondary/specific.
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Eight steps of phagocytosis
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1) Adherence/transendothelial migration (diapedesis)
2) Chemotaxis 3) Recognition 4) Ingestion 5) Degranulation of granules content to the interior of phagosome 6) Formation of reactive oxygen products 7) Release of particles after killing and release of inflammation mediators for cell recruitment 8) Detoxification of reactive oxygen products |
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WBC exits blood vessel by
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1) rolling and initial contact (through selectins)
2) diapedesis (throught integrins) |
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Enzyme which forms 1) reactive oxygen 2) hypochlorite
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1) NADPH oxidase
2) myeloperoxidase |
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Buffering enzymes
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SOD/glutathione system and catalase
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Exhaustion in overwhelming infection means
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exhaustion of marrow granulocyte reserves. Neutropenia in the course of infection is a poor prognostic sign.
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Voltage gated Na and K channels mediate
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electrical signaling in neurons, cardiac muscle and skelatal muscle.
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Voltage gated Ca channels mediate
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hormone and neurotransmitter release. When they open, intracellular Ca concentration increases, which stimulates calcium-dependent processes such as exocytosis.
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What causes the negative RESTING POTENTIAL of an excitable cell?
|
K concentration gradiants, and that there are only K-channels open @ resting potential, allow K ions to diffuse.
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Voltage-gated ion channels are formed by how many domains?
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4
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Each domain in a voltage gated ion channel is made up of how many transmembrane segments?
|
6, plus a p-loop
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Which segment of the voltage gated ion channel is the voltage sensor?
|
S4. It contains charged amino acids.
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Difference between genes for (Na and Ca channel) and (K channel)?
|
K channel encodes for only 1 domain. 4 domains must come together to form pore. Na and Ca encodes for all 4 domains.
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Voltage-gated Na channel open @ what voltage?
|
begin @ -50mV. Max open @ -10mV.
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Most voltage-gated ion channels have 2 states, open and closed. Na channels have 3. What is the third? Why is it considered a third state?
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Inactivated. It has a different conformation from the "closed" state. Part of the protein moves into the pore and blocks it. This happens when the cell is more positive than the resting potential for a long time. In order to "reactivate", the membrane potential must return to a very negative potential.
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Hyperkalemic periodic paralysis
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associated with a mild elevation of blood potassium (exercise, stress, fasting, or eating K+ rich foods).
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Tetrodotoxin
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Puffer fish toxin. Highly specific, reversible blocker of Na channels. Paralysis and death at very low concentrations.
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Lidocaine and Novacaine
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local anesthetics that act by blocking Na channels.
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Calcium channels
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T-type channels open around -50 to -40 mV similar to Na. High voltage activated (HVA) ~ +10mV: long openings (L-type) and short openings.
Diversity allows performance of unique functions. |
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Agents that block voltage-gated L-type Ca channels
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Nifedipine and Verapamil
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Lambert Eaton Myasthenic Syndrome
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Patients produce antibodies to N,P,Q voltage-gated calcium channels, causing destruction of calcium channels at the presynaptic nerve terminal. Synaptic transmission is impaired causing muscle weakness and fatigue.
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6 different types of voltage gated Ca channels
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LNPQRT
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Ca channel blockers are primarily used in the treatment of ?
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Cardiovascular diseases including angina, arrhythmia and hypertension.
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Nerve and muscle synapse have what type of neurotransmitter receptors?
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Acetylcholine
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Reversal potential is
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the potential at which no net current occurs when a channel is open. It is an important characteristic of a ligand-gated ion channel.
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Reversal potentials are
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equal to the Nernst potential for the ion that they pass.
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Ach receptors pass what? It's reversal potential is what?
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Na and K. 0mV
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Ach receptor is EXCITATORY because
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it make the cell potential more positive
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Inhibitors of Ach receptor
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d-tubocurarine and Vecuronium
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Agonists of ionotropic and metabotropic ACh receptors
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Nicotine (ionotropic). Muscarine (metabotropic). Therefore, nicotinic receptor means ACh-gated ion channel.
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ACh receptor structure
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transmembrane protein, 5 subunits each with multiple transmembrane segments.
2 identical alpha-subunits which contain the ACh binding site, taking 2 ACh molecules to open the channel. Fetal: alpha,alpha,beta,gamma,delta Adult: alpha,alpha,beta,epsilon,delta Fetal has long openings w/ small amplitudes Adult has short openings w/ large amplitudes |
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Types of glutamate receptors
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AMPA, kainate, NMDA
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Non-NMDA channels are
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non-selective cation channels similar to the ACh channel. Pass Na and K, 0mV reversal potential. EXCITATORY.
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NMDA channels are
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non-selective cation channels that pass Na, K, and Ca. Binding of glutamate and glycine required. Blocked by zinc. If opened @ a negative potential, Mg blocks the channel. Therefore, Na and K move out, and Ca moves in @ +70mV. Excess glutamate is CYTOTOXIC because it will cause an increase in intracellular Ca and cause cell death.
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Made up of 4 subunits. Can be homomer, or heteromer
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glutamate receptors
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Competitive antagonist of AMPA receptors
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NBQX
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Competitive antagonists of NMDA receptors
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D-AP5 and D-AP7
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Non-competitive antagonists of NMDA receptor
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Ketamine and MK-801
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GABA receptors
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post-synaptic, Cl- ion channel, INHIBITORY, 5 subunits, subunits encoded by multiple genes = diversity.
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Allosteric potentiators of GABA (increase the effect of GABA)
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Benzodiazepines (anti-anxiety) and barbituates (sedatives).
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Blockers of GABA receptor
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Cause excessive neuronal excitation, which lead to seizures. Picrotoxin (non-competitive antagonist) and bicuculline (competitive antagonist)
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Only glial cells in the PNS
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Schwann cells
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Multipolar neurons
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3 or more processes (one of which is axon) Cell bodies in CNS and in autonomic ganglia.
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Bipolar neurons
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2 processes (2 axons). Cell bodies in retina, and vestibular and acoustic ganglia.
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Unipolar (pseudounipolar) neurons
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Derived from bipolar neurons during development. 1 process (axon) which bifurcates. Soma in DRG and sensory ganglia of certain CNs.
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Three types of neurons
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Sensor, motor, Interneurons (interconnectors - usually in CNS)
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Neural tube derived cells
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soma inside CNS
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Neural crest derived cells
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soma outside CNS
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Only stem cells in the PNS
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bipolar olfactory neurons within the olfactory epithelium
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Nissl bodies are
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basophilic clumps of RER and polysomes in perikaryon
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Dendrites carry
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graded potentials (EPSP, IPSP) to the cell body (decremental conduction).
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Axon contains
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neurofilaments, microtubules, actin filaments, mitochondria and various vesicles. NO Nissl bodies in the axon or hillock.
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Axon hillock
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contains microtubule bundles, trigger zone, carry action potentials away from soma. Axon branches (rare) occur @ only right angles and only nodes of ranvier.
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Slow axon transport (1-5mm/day)
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unidirectional waves of material with defined composition, providing growth and maintenance (actin, tubulin, neurofilament proteins, metabolic enzymes. Regeneration.
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Fast axon transport (100-500mm/day)
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Bidirectional. ATP dependent. Dyenin and Kinesin (microtubules).
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Neuronal signaling involves
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Ion pumps, voltage-gated Na and K channels, voltage-gated Ca channels, ligand-gated channels (neurotransmitters)
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Unmyelinated axon Na channels
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are uniformly distribuand few in numberted
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Myelinated axon Na channels
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clustered at nodes of Ranvier.
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Only type of glial cell in PNS, neural crest derivatives, surrounded by external lamina, contain GFAP IFs.
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Schwann cells
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Schwann cells around a soma is called
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satellite cells
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Schwann cells around axons are called
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Schwann sheath
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Schwann cells around 1 axon
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myelinated axon
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Schwann cell around many axons
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unmyelinated axon
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Axon hillock...Myelinated or unmyelinated?
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Unmyelinated
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Neurilemma is always known as
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Schwann sheath
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