Lecture 17 > Flashcards
Lecture 1: Membranes, ions & potentials
Objectives:
- Review the generation of the resting membrane potential
- Review the generation of the action potential
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Membrane ion pumps generate an .. … and a …. …. across the membrane
Excitable cells, including neurons, can rapidly change this … …. and thus use it to carry information
Membrane ion pumps generate an ION GRADIENT and a VOLTAGE DIFFERENCE across the membrane
Excitable cells, including neurons, can rapidly change this MEMBRANE POTENTIAL and thus use it to carry information
The resting membrane potential
- Membrane pumps set up .. ….
- The membrane has .. & … channels
- Most Na+ channels are … at rest
- Specific K+ channels (leak channels) remain … at rest
- K+ ions flow … of the cell
The resting membrane potential
- Membrane pumps set up ION GRADIENTS
- The membrane has Na+ & K+ channels
- Most Na+ channels are CLOSED at rest
- Specific K+ channels (leak channels) remain OPEN at rest
- K+ ions flow OUT of the cell
The resting membrane potential
- K+ equilibrium reach when … gradient drive …. is balanced by … drive ….
- This equilibrium potential for K+ is about ..mV
The resting membrane potential
- K+ equilibrium reach when CHEMICAL gradient drive OUT is balanced by ELECTRICAL drive IN
- This equilibrium potential for K+ is about -80mV
During the rising phase … enters - cell membrane rapidly …..
Membrane potential becomes …. because Na+ conductance exceeds that of K+
During the rising phase Na+ enters - cell membrane rapidly DEPOLARIZED
Membrane potential becomes POSITIVE because Na+ conductance exceeds that of K+
During the falling phase the voltage-gated Na+ channels have …
Delayed voltage gated K+ channels …
K+ leaves the cell causing …
During the falling phase the voltage-gated Na+ channels have CLOSED
Delayed voltage gated K+ channels OPEN
K+ leaves the cell causing RE-POLARIZATION
Undershoot because K+ conductance is …. membrane potential towards (-80mV) membrane becomes …. …. due to …..
Undershoot because K+ conductance is INCREASED membrane potential towards (-80mV) membrane becomes RELATIVE REFRACTORY due to HYPERPOLARIZATION
Na+ channels open upon depolarization but close again despite continued depolarization referred to as …. ….
Provides a period of … ….
Cannot be activated until …. to … ….
Na+ channels open upon depolarization but close again despite continued depolarization referred to as CHANNEL INACTIVATION
Provides a period of ABSOLUTE REFRACTION
Cannot be activated until RETURNED to RESTING POTENTIAL
Molecular analysis of the Na+ channels provides a model to describe its properties
Gate prevents Na+ flux at … … …
Gate opens upon …. (to -40mV)
… enters cell
Channel inactivated when …. portion of channel swings into pore
“plug” removed upon return to .. … …
Molecular analysis of the Na+ channels provides a model to describe its properties
Gate prevents Na+ flux at RESTING MEMBRANE POTENTIAL
Gate opens upon DEPOLARIZATION (to -40mV)
Na+ enters cell
Channel inactivated when GLOBULAR portion of channel swings into pore
“plug” removed upon return to RESTING MEMBRANE POTENTIAL
…. Binds to the outside of the channel and prevents it ….
TETRODOTOXIN Binds to the outside of the channel and prevents it OPENING
Lecture: Membranes, ions & potentials
Objectives
- What is a neurotransmitter vesicle and how is it handles at the synapse?
- What are the difference b/w SSV and LDCV?
- What are the roles of vesicle-associated proteins?
- What are mechanisms of neurotransmitter release?
- How does neurotransmitter release alter changes in stimulation strength?
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Presynaptic events
Summation may be …
- Multiple input neurons activated
Summation may be …
- Input neuron strongly activated
Presynaptic events
Summation may be SPATIAL
- Multiple input neurons activated
Summation may be TEMPORAL
- Input neuron strongly activated
Nerve terminals often contain two types of synaptic vesicle
- …. & ….
Nerve terminals often contain two types of synaptic vesicle
- SSV (small synaptic vesicles) & LDCV (secretory vesicles)
SSV contain … neurotransmitters (NT)
LDCV also contain …. NT an ….
LDCV more frequent in …. neurons or …. cells
SSV contain CLASSICAL neurotransmitters (NT)
LDCV also contain CLASSICAL NT an NEUROPEPTIDES
LDCV more frequent in NEUROSECRETORY neurons or NEUROENDOCRINE cells
LDCV
… precursors synthesized by …
packaged into vesicles by …
Delivered to nerve terminal by … …
… process en route
Vesicles position at …. release sites
LDCV
NEUROPEPTIDE precursors synthesized by ER
packaged into vesicles by GOLGI
Delivered to nerve terminal by AXONAL TRANSPORT
PEPTIDES process en route
Vesicles position at EXTRASYNAPTIC release sites
SSV
Vesicles synthesized by …
Delivered to nerve terminal by … …
enter … …
Become filled w/ .. …
SSV
Vesicles synthesized by GOLGI
Delivered to nerve terminal by AXONAL TRANSPORT
enter VESICLE CYCLE
Become filled w/ CLASSICAL NT
SSV
- may enter one of two … ….
- A reserve pool associated w/ …
A readily releasable or docked pool at … site
SSV
- may enter one of two VESICLE POOLS
- A reserve pool associated w/ CYTOSKELETON
A readily releasable or docked pool at ACTIVE site
SSV
Ca+ … through voltage-gated Ca2+ channels triggers … …
SSV membrane recycled by … to … or … … …
SSV
Ca+ INFLUX through voltage-gated Ca2+ channels triggers VESICLE EXOCYTOSIS
SSV membrane recycled by ENDOCYTOSIS to ENDOSOME or RESERVE VESICLE POOL
SSV
- Pumps to generate … gradients
- Used to power transporters to … ….
SSV
- Pumps to generate H+ gradients
- Used to power transporters to LOAD NEUROTRANSMITTERS
SSV
Small … binding proteins
Assist in vesicle … & …
Provide an on (..) or off (…) indicator of vesicle location
SSV
Small GTP binding proteins
Assist in vesicle TARGETING & DOCKING
Provide an on (GTP) or off (GDP) indicator of vesicle location
SSV
- …. proteins (synaptobrevin)
Bind to complementary …. on synaptic membrane
Assist in … vesicles and priming for …
SSV
- v-SNARE proteins (synaptobrevin)
Bind to complementary t-SNARES on synaptic membrane
Assist in DOCKING vesicles and priming for RELEASE
SSV
- Proteins comprising the … machine
- … sensor (synaptotagmin)
SSV
- Proteins comprising the EXOCYTOTIC machine
- … sensor (synaptotagmin)
SSV
- Proteins involved in endocytosis (…)
- And formation of coated pits (…)
SSV
- Proteins involved in endocytosis (DYNAMIN)
- And formation of coated pits (CLATHRIN)
SSV docking
As noted earlier requires interaction … proteins
…. involved in vesicle trafficking throughout the cell
But specific v-SNARE and t-SNARE pairs mediate … … …
SSV docking
As noted earlier requires interaction SNARE proteins
SNARE involved in vesicle trafficking throughout the cell
But specific v-SNARE and t-SNARE pairs mediate mediate SYNAPTIC VESICLE DOCKING
SSV docking
v-SNARE = …
t- SNARE = … & …
SSV docking
v-SNARE = SYNAPTOBREVIN
t- SNARE = SYNATAXIN & SNAP25
Synaptic vesicle fusion with membrane promoted by …. “….”
L2&3, page 35-37
Synaptic vesicle fusion with membrane promoted by SNARE “ZIPPING”
Vesicle protein … provides a mechanism for Ca2+ regulation
Vesicle protein SYNAPTOTAGMIN provides a mechanism for Ca2+ regulation
L2&3, page 47
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a-latrotoxin from the black widow spider interacts with a synaptic protein called …
Causes massive release of ….
but not …
a-latrotoxin from the black widow spider interacts with a synaptic protein called Neurexin
Causes massive release of SSV
but not LDCV
Objectives
- What is a neurotransmitter?
- How are neurotransmitters classified?
- How are neurotransmitter receptors classified
- How do neurotransmitters work?
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Classification of Neurotransmitters
Type I: … ….
- Glutamate (excitatory)
- Glycine and GABA (inhibitory)
Type II: … & ….
- Acetylcholine
- Catecholamines (noradrenaline & dopamine)
- ATP
- Histamine
Type III: - ….
- Opioids, substance P, vasoactive intestinal peptide
Type IV: - ….
- NO, CO
Classification of Neurotransmitters
Type I: AMINO ACIDS
- Glutamate (excitatory)
- Glycine and GABA (inhibitory)
Type II: AMINES & PURINES
- Acetylcholine
- Catecholamines (noradrenaline & dopamine)
- ATP
- Histamine
Type III: - NEUROPEPTIDES
- Opioids, substance P, vasoactive intestinal peptide
Type IV: - GASES
- NO, CO