Term
| what are the excitable tissues? |
|
Definition
| nerve, muscle, and endocrine |
|
|
Term
| what is the axon hillock? |
|
Definition
| its where the action potential starts. it has the most voltage gated sodium channels. |
|
|
Term
| what is the synaptic terminal? terminal? axon terminal? |
|
Definition
|
|
Term
| what are the four membrane electrical states? define them. |
|
Definition
Polarization -Any state when the membrane is other than 0mV
Depolarization -Membrane less polarized than resting potential
Repolarization -Membrane returns to resting potential after
having been depolarized
Hyperpolarization- Membrane becomes more polarized than at
resting potentia |
|
|
Term
| what are the two kinds of potential change? |
|
Definition
| graded potentials and action potentials. |
|
|
Term
| what are leak channels? what are some types of gated channels? |
|
Definition
leak channels are open all the time. gated channels include
Voltage gated channels
Chemically (ligand) gated channels
Mechanically gated channels
Thermally gated channel |
|
|
Term
| what triggers a voltage gated potassium channel? |
|
Definition
| a depolarization of the membrane. |
|
|
Term
| what is a graded potential? |
|
Definition
ocal changes in membrane potential
Occur in varying grades or degrees of magnitude
(strength).
-70mV to -60mV is a 10mV graded potential
The stronger the trigger, the larger the
graded potential
Trigger will open an ion channel in a small,
specialized region of the membrane |
|
|
Term
| how do graded potentials die over short distances? |
|
Definition
| K+ leaks out of the membrane |
|
|
Term
| if a graded potential is strong enough, what can be triggered? |
|
Definition
|
|
Term
| what is an action potential? |
|
Definition
Brief, rapid, large (100mV) changes in
membrane potential: potential actually
reverses
Involves only a small portion of the
total excitable cell membrane
All or nothing
Conduction without decrement |
|
|
Term
| what causes the rising phase of the action potential? the falling phase? |
|
Definition
| influx of Na+ (permeability of Na+ is increased). then, at the peak, the permeabilities switch, so Perm Na+ decreases, and perm K+ increases. This allows K+ to flow out, causing the membrane potential to fall. |
|
|
Term
| at peak membrane potential what happens to voltage gated sodium and potassium channels? |
|
Definition
| Na+ channels close, K+ channels open |
|
|
Term
| what causes the after hyperpolarization? |
|
Definition
| potassium channels stay open, causing a bit of an imbalance. |
|
|
Term
| what are some typical values of an action potential in terms of milivolts? |
|
Definition
Flow of sodium ions into the ICF reverses the
membrane potential from -70 mV to +30 mV |
|
|
Term
| what are some additional characteristics of action potentials? |
|
Definition
Sodium channels open during depolarization by
positive feedback.
When the sodium channels become inactive, the
channels for potassium open. This repolarizes the
membrane.
An action potential at one point in the plasma
membrane regenerates an identical action
potential at the next point in the membrane.
Therefore, it travels along the plasma membrane
undiminished. |
|
|
Term
| How do Na+/K+ pump restore concentration gradients |
|
Definition
Sodium is pumped into the ECF
Potassium is pumped into the ICF |
|
|
Term
| what are the two types of propagation? |
|
Definition
| contiguous conduction and saltatory conduction |
|
|
Term
| what is contiguous conduction? |
|
Definition
Conduction in unmyelinated fibers
Action potential spreads along every portion of the
membrane |
|
|
Term
| what is saltatory conduction? |
|
Definition
Rapid conduction in myelinated fibers
Impulse jumps over sections of the fiber covered
with insulating myelin |
|
|
Term
| what is the area called in myelinated fibers where there is no myelin, the axoin is exposed, and there is a high # of Na+ voltage gated channels? |
|
Definition
|
|
Term
|
Definition
| myelin creating cells in the peripheral nervous system. a schwann cell myelinates 1 mm of 1 axon by wrapping round and round it, electrically insulating it |
|
|
Term
| what is an oligodendrocyte? |
|
Definition
| myelin producing cells in the brain and CNS |
|
|
Term
| does the action potential have to be regenerated in myelinated sections of axon? |
|
Definition
|
|
Term
| how much faster are myelinated fibers at conduction? |
|
Definition
| about 50 times faster than an unmyelinated axoin of comparable size |
|
|
Term
|
Definition
Primarily composed of lipids
Formed by oligodendrocytes in CNS
Formed bySchwann cells in PNS |
|
|
Term
| what is a disease of the myelin sheath? |
|
Definition
| multiple sclerosis is a disease of oligodendrocytes. people with MS have trouble conducting signals from their CNS |
|
|
Term
| what are the absolute and relative refractory periods of an action potential? |
|
Definition
absolute:Membrane cannot produce
another AP because Na+ channels are inactivated
relative:occurs when VG K+
channels are open, making it harder to
depolarize to threshold |
|
|
Term
| how is frequency related to information coding? |
|
Definition
| different frequencies can encode different information, like the strength of the signal |
|
|
Term
|
Definition
unction between two neurons
Primary means by which one neuron directly interacts
with another neuron (muscle cells or glands as well) |
|
|
Term
| what is the anatomy of a synapse? |
|
Definition
resynaptic neuron – conducts action potential toward
synapse
Synaptic knob – contains synaptic vesicles
Synaptic vesicles – stores neurotransmitter (carries
signal across a synapse)
Postsynaptic neuron – neuron whose action potentials
are propagated away from the synapse
Synaptic cleft – space between the presynaptic and
postsynaptic neurons |
|
|
Term
| what are some common neurotransmitters? |
|
Definition
| acetylcholine, dopomine, norepinephrine, epinephrine, serotonin, histamin, glycine, glutamate, apartate, GABA |
|
|
Term
| what are some differences between classical neurotransmitters and neuropeptides? |
|
Definition
| this is on two separate slides in the notes. its too much for one card, but it is important. bring up the notes and look at the chart of differences now. |
|
|
Term
| when the action potential reaches the synapse, what happens? |
|
Definition
| it triggers voltage gated channels for calcium which enter the synaptic knob. this calcium triggers a lot of enzymatic cascades which cause the vesicles sitting in the knob to migrate to the snyaptic cleft and empty their contents. |
|
|
Term
| what is the difference between an excitatory synapse, and an inhibitory synapse |
|
Definition
| excitatory synapses typically cause a depolarization (EPSP) by allowing influx of Na+ (acetylcholine). inhibitory synapses will cause a hyperpolaization (IPSP) (glycine or GABA) |
|
|
Term
|
Definition
Large molecules consisting of from 2 to
40 amino acids
Synthesized in neuronal cell body in the
endoplasmic reticulum and Golgi
complex
Packaged in large, dense-core vesicles
present in axon terminal |
|
|
Term
| what is an axoaxonic synapse? |
|
Definition
| a synapse in which the axon of one neuron comes in contact with the axon of another neuron |
|
|
Term
| how can an inhibitory axoaxonic synapse stop a graded potential from happening? |
|
Definition
| it interferes with repolarization/depolarization, and makes it so the calcium ion voltage gated channels do not open up |
|
|
Term
|
Definition
| A gap junction or nexus is a specialized intercellular connection between a multitude of animal cell-types.[1][2][3] It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells |
|
|
Term
|
Definition
| One gap junction channel is composed of two connexons (or hemichannels) which connect across the intercellular space |
|
|
Term
| what do cells use most often for intercellular communication? |
|
Definition
|
|
Term
| how do ligand receptors work for signaling? |
|
Definition
Cell surface proteins bind
to each other
Cells release chemical
which bind to surface
proteins of other cells (paracrine, neurotransmission) |
|
|
Term
| how do endocrine systems work? |
|
Definition
Multiple agents act at
multiple sites through
endocrine mechanism
• direct release to
circulation
• “spillover” from
nervous system
ex: adrenal gland/ PNS secretion of Norepinephrine, epinephrine. |
|
|
Term
| how does a G protein system work? |
|
Definition
| g protein receptor on the surface binds to its signal molecule, causing a conformational change that causes the g protein to release GTP on the inside of the cell. METABOTROPIC |
|
|
Term
| what is the integrin system? |
|
Definition
| ligand binding to integrin receptors alters the cytoskeleton |
|
|
Term
| how does the g protein coupled system work? |
|
Definition
Ligand binding induces change in
protein configuration (change enzymatic
activity)
Energy-carrying phosphates (guanosine
triphosphate - GTP)
Alpha (active), beta and gamma subunit
Transformation of GDP to GTP (alpha)
upon activation
G-alpha unit activates membrane bound
enzymes
-and/or- Soluble chemicals generated, increased
levels trigger other reaction |
|
|
Term
|
Definition
| Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3'-5'-cyclic adenosine monophosphate) is a second messenger important in many biological processes. cAMP is derived from adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms, conveying the cAMP-dependent pathway. METABOTROPIC |
|
|
Term
|
Definition
| it phosphorylates some enzyme or compound. |
|
|
Term
| where is calcium stored in the cell? |
|
Definition
|
|
Term
| where is calcium stored in muscle cells? |
|
Definition
|
|
Term
| what is metabotropic modulation? |
|
Definition
Phosphorylation of proteins
occurs in secs to mins, last mins to hours
binding of phosphate molecule on proteins
change configuration/activity of proteins |
|
|
Term
| what are some possible results of the phosphorylation of a protein? |
|
Definition
modulate ionic channels
change resting and action potential generation
modulate ionotropic transmission
change metabolism
trigger division/cell death
change protein synthesis (hours to days) |
|
|
Term
| what is the difference between ionotropic modulation and metabotropic modulation? |
|
Definition
Ionotropic communication
Uses small amino acids/amines
Ligand binds to ligand-gated channel – changes protein
conformation (i.e., increases conductance to ionic flow)
Very rapid onset (milliseconds)
very rapid offset
Usually 3-10 ms
Special case - longest possible is 250 ms
Metabotropic communication (i.e., modulation)
Usually larger peptides (this is a lie)
Ligand binds to cell-surfce proteins – activate intracellular
enzyme cascade (G-protein, tyrosine kinase)
occurs in secs to mins, last mins to hours
Examples of ionotropic vs.
metabotropic ligands
Ionotropic ligands
Excitatory
Depolarization/EPSP -allow Na influx/K efflux
glutamate,
acetylcholine
Inhibitory
Hyperpolarization/IPSP
-allow Cl influx
GABA, glycine
Metabotropic ligands
All except glycine
Action depends on:
Receptor types
Activation of
intracellular
messenger system
Examples
Ionotropic vs. metabotropic
examples
Acetylcholine
Nicotinic receptor
ionotropic
neuromuscular junction, spinal cord
Muscarinic receptor
metabotropic
CNS, parasympathetic responses at peripheral tissues
Glutamate
Ionotropic
AMPA receptor - basic Na/K flow; what you already know
NMDA – Na/K and Ca flow; don’t worry about it yet
Metabotropic - GluM receptor, everywhere in CNS/spinal cord
GABA
Ionotropic – GABA
A
receptor – opens Cl channels (IPSP)
Metabotropic – GABAB
receptor – opens K chan |
|
|
Term
| what are some excitatory and inhibitory ionotropic ligands. |
|
Definition
Excitatory
Depolarization/EPSP -allow Na influx/K efflux
glutamate,
acetylcholine
Inhibitory
Hyperpolarization/IPSP
-allow Cl influx
GABA, glycine |
|
|
Term
| what are some metabotropic ligands? |
|
Definition
All except glycine
Action depends on:
Receptor types
Activation of
intracellular
messenger system
Examples |
|
|
Term
| acetylcholine - how is it both iontropic and metabotropic? |
|
Definition
Nicotinic receptor
ionotropic
neuromuscular junction, spinal cord
Muscarinic receptor
metabotropic
CNS, parasympathetic responses at peripheral tissue |
|
|
Term
| How is glutamate both iontropic and metabotropic? |
|
Definition
Ionotropic
AMPA receptor - basic Na/K flow; what you already know
NMDA – Na/K and Ca flow; don’t worry about it yet
Metabotropic - GluM receptor, everywhere in CNS/spinal cord |
|
|
Term
| how is gaba both ionotropic and metabotropic? |
|
Definition
Ionotropic – GABA
A
receptor – opens Cl channels (IPSP)
Metabotropic – GABAB
receptor – opens K channels over a long term
(really, really slow and long lasting IPSP) |
|
|
Term
| what is the time frame for an ionotropic response vs a metabotropic response? |
|
Definition
| ionotropic takes place in about 10 milliseconds. that same chemical, if being used metabotropically, would elicit a response over 20 seconds. huge time difference. slower acting, longer lasting |
|
|
Term
| what are some other mainly metabotropic ligands? |
|
Definition
Dopamine, Norepinephrine,
Serotonin, Histamine, Epinephrine
Neuroactive Peptides - partial
list!!
Bradykinin
beta-endorphin
bombesin
calcitonin
cholecystokinin
enkephalin
dynorphin insulin
gastrin
substance P
neurotensin
glucagon
secretin
somatostatin
motilin
Soluble Gases
Nitric Oxide (NO), Carbon Monoxide
vasopressin
oxytocin
prolactin
thyrotropin
angiotensin II
sleep peptides
galanin
neuropeptide Y
thyrotropin-releasing hormone (TRH)
gonadotropnin-releasing hormone
growth hormone-releasing hormone
luteinizing hormone
vasoactive intestinal peptide |
|
|
Term
| initiation of protein synthesis slide |
|
Definition
|
|
Term
| how can metabotropic modulation help stroke patients? |
|
Definition
| when we are trying to teach someone to reuse their left hand, it is through metabotropic changes that increase the sensitivty and excitability of ion channels in that arm, strengthening synaptic connections. |
|
|
Term
| What do C 3, 4 , and 5 do? |
|
Definition
| keep the diaphragm alive. |
|
|
Term
| what is the phrenic nerve? |
|
Definition
| main nerve that innervated the diaphragm to elicit a muscle contraction |
|
|
Term
| what is electromyography? |
|
Definition
| Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG |
|
|
