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71 Cards in this Set
- Front
- Back
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What are 3 classes of membrane lipids? |
Phospholipids Glycolipids Cholesterol |
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What 2 classes of lipids are found in the outer leaflet? |
Phospholipids Glycolipids |
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What are 2 main functions of membrane lipids? |
Impart electrical capacitance Prevent passage of ionized salts, water, water soluble molecules |
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What do head groups of outer leaflet phospholipids contain? |
Choline |
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What is the structure of a glycolipid? (3 Things) |
Glycerol Fatty Acid Phosphate w/oligosaccharide |
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What is the role of gangliosides? |
Cell recognition |
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What membrane lipid is found in the inner leaflet? |
Phospholipids (ex: Phosphatidylinositol) |
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What do head groups of inner leaflet phospholipids contain? |
Amino acids |
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What is the role of cholesterol in the membrane? |
Stabilize fluidity |
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What are the 3 main classes of membrane proteins? |
Outer Surface Proteins Transmembranal (Intrinsic) Proteins Inner Surface (Cytoplasmic) Proteins |
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What are the 2 subgroups of Outer Surface Proteins? |
Glycoproteins Proteoglycans |
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What are the 3 subgroups of Glycoproteins? |
Immunoglobulins Cadherins Integrins |
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What are Immunoglobulin proteins? (3 Things) |
Homo + Heterophillic interactions between cells Promotes neurite outgrowth (axon-target growth) |
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What are Cadherin proteins? (3 Things) |
Homophilic interactions between cells Ca2+ dependent Important for neurite outgrowth (axon-target growth) |
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What are Integrin Proteins? (2 Things) |
Heterophilic interactions with extracellular matrix glycoproteins Ca2+ dependent |
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What are Proteoglycans? (3 Things) |
Sugar chain (95%) attached to a protein Important in cell-cell recognition Attracts water to extracellular space |
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What are the 3 functions of Transmembranal (Intrinsic) Membrane Proteins? |
Contain sites for reception of neurotransmitters Contain channels for ion movement Are carriers for molecule movement |
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What are the 2 components of Inner Surface (Cytoplasmic) Membrane Proteins? |
Actin + Ankyrin Fodrin |
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What do Actin + Ankyrin do? |
Bind to transmembranal proteins to form nodal points
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What does Fodrin do? (2 Things) |
Forms links between nodes Plays a role in determining shape of axonal dendritic branches (with microfilaments) |
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What are 2 characteristics of Extracellular Matrix Glycoproteins? |
Present in intercellular space No direct membrane insertion |
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What are 2 examples of Extracellular Matrix Glycoproteins? |
Laminin Fibronectin |
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3 Functions of Laminin |
Substrate adhesion Basal lamina in PNS Has epidermal growth factor repeats for neurite outgrowth |
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3 Functions of Fibronectin |
Substrate Adhesion Neural crest migration Axonal regeneration |
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What is the Glycocalyx? (3 Things) |
A combination of all extracellular carbohydrates which surround the cell Provides structural support + cell adhesion + cell recognition Present in intercellular space |
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What are the 3 components of the Cytoskeleton? |
Microtubules Intermediate Filaments (Neurofilaments) Microfilaments |
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What are the 2 Microtubule Associated Proteins and what do they do? |
MAP2 Tau Regulate assembly and stability of microtubules |
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Where can MAP2 proteins be found? |
Dendrites + nerve cell bodies |
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Where can Tau proteins be found? |
Axons + nerve cell bodies |
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What 2 proteins can contribute to neurofibrillary tangles? (Leads to Alzheimer's) |
Tau proteins Phosphorylated Neuro/Intermediate Filaments |
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Neurofilaments (3 Things) |
Most like bones and ligaments in function Have long protein subunits unlike mt's and mf's Astrocytes are rich in neurofilaments |
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What is astrocytosis? |
Elevated GFAP, indicates impending neuropathology |
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Microfilaments |
Composed of actin 10% of total cell protein Attached just beneath membrane Interacts with fodrin to help control shape and movement. |
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Developing processes of axons and dendrites (4 Things) |
Could either become axons and dendrites Fastest growing process becomes axon GAP-43 lost from all other processes, but stays in future axon Tau appears in future axon |
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Dendrites + Soma of adult neurons |
Microtubules oriented in both directions Fewer neurofilaments and microfilaments MAP-2 |
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What are 5 ways to classify a Neuron? |
Number of Neurites Dendrites, Size + Shape of Cell Body Connections Axon Length Neurotransmitter |
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Astrocytes/Satellite Cells (4 Things) |
Envelope synaptic junctions Regulate chemical content Structural support for neuronal repair Protoplasmic + Fibrous |
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Oligodendrocytes |
Form myelin in the CNS Can accommodate more than 1 axon |
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Microglia (3 Things) |
Are Phagocytic Originate outside of CNS Derived from monocytes |
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Ependymal Cells (4 Things) |
Help make CSF (with choroid plexus) Line ventricles Direct cell migration during development Ciliated to move CSF |
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Schwann Cells |
Form myelin in the PNS Only associate with 1 axon |
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Name the 3 major proteins of Myelin |
Myelin Basic Protein (MBP) Myelin Associated Glycoprotein of the CNS (MAG) Protein Zeo of the PNS (P0) |
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What do MAG and P0 do? |
Mediate cell adhesion between layers of Schwann cell membrane |
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Resting Potential of a Nontransmitting Neuron |
-65 to -70mV |
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Sodium Concentration Outside of the Cell |
150 mM |
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Sodium Concentration Inside of the Cell |
15 mM |
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Potassium Concentration Outside of the Cell |
5 mM |
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Potassium Concentration Inside of the Cell |
100 mM |
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Calcium Concentration Outside of the Cell |
2 mM |
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Calcium Concentration Inside of the Cell |
0.0002 mM |
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Chloride Concentration Outside of the Cell |
130 mM |
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Chloride Concentration Inside of the Cell |
13 mM
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Donnan Effect Part 1 |
Because of the increased presence of nondiffusable anions inside the cell, causing an asymmetric distribution of diffusible ions, there will be an electrical difference across the membrane whose magnitude can be determined by the Nernst equation. |
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Donnan Effect Part 2 |
Because of the proteins in cells, there are more osmotically active particles in the cells than in interstitial fluid, and since animal cells don't have cell walls, osmosis would make them swell and eventually rupture if it were not for Na+/K+ ATPase pumping ions back out of the cell. |
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Donnan Effect Part 3 |
Because there are more proteins in plasma than interstitial fluid, there is a Donnan effect on ion movement across the capillary wall |
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Axons of adult neurons (4 Things) |
Outward oriented microtubules (plus out) More neurofilaments and microfilaments than dendrites or soma GAP-43 Tau |
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What is the Nernst Equation? |
Eion = (2.303)(RT/FZ){log[(CATo)/CATi)]}mV (2.303)(RT/F) = 61.54 R = Gas constant T = Absolute Temperature F = Faraday's constant Zion = Valence of the ion |
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Action Potential (4 Things) |
A rapid reversal of membrane potential in axon Also called: nerve impulse, spike or discharge Constant size and duration for given neuron, doesn't diminish “All-or-None" |
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4 Components of Measuring action potential |
Intracellular Electrode - KCL Ground - Wire in extracellular fluid Amplifier - Determines voltage b/w electrodes Oscilloscope - Displays changes in voltage |
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Voltage clamp method (4 Things) |
Inventor - Kenneth Cole Used by - Alan Hodgkin and Andrew Huxley Can clamp membrane potential at any value desired Used to determine ion conductance at any membrane potential |
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Voltage clamp method (Hodgkin + Huxley Results) (3 Things) |
Rising phase: transient increase in Na+ conductance;Na+ influx Falling phase: transient increase in K+ conductance;K+ efflux Proposed existence of voltage activated Na+ and K+ gates in axon |
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What is the Driving Force Equation? |
Vm - E-ion Vm = membrane potential (membrane voltage) Eion = ionic equilibrium potential (Nernst potential) |
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What produces the generator potential of the action potential? (2 Things) |
Ligand gated channels Physical deformations of the receptor membrane |
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What is threshold? (2 Things) |
Vm at which voltage-gated Na+ channels pop open Relative membrane ionic permeability favors Na+ over K+ |
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Rising phase (2 Things) |
Large driving force on Na+ and gNa >> 0 results in Na+ influx Rapid membrane depolarization |
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Overshoot |
Since gNa >> gK, Vm approaches ENa |
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Falling phase (3 Things) |
Voltage-gated Na+ channels inactivate Voltage-gated K+ finally pop open Large driving force on K+ and gK >> 0 results in K+ efflux |
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Undershoot |
Open K+ channels increase gK above normal, Vm approx E-K |
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What is the max rate of action potentials determined by? |
Absolute refractory period |
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Absolute Refractory Period (3 Things) |
Period during which impossible to generate action potential Approx 1 m-sec Due to Na+ inactivation gates (time necessary to de-inactivate) |
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Relative Refractory Period (3 Things) |
Current necessary to raise Vm to action potential threshold is elevated above normal Undershoot phase Stays hyperpolarized until voltage-gated K+channels close |
