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Physiology Nervous System 8
Chapter 8
85
Physiology
09/29/2012

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Term
Action Potiental
Synonym
Definition
AP, Spike,nervous impulse, conduction signal
Term
Autonomic nervous system
synonym
Definition
Visceral nervous system
Term
Axon
synonym
Definition
nerve fiber
Term
Axon terminal
synonym
Definition
synaptic knob,synaptic bouton, presynaptic terminal
Term
Cell body
synonym
Definition
Cell soma, nerve cell body
Term
cell membrane of an axon
synonym
Definition
axolemina
Term
what Glial cell in the central nervous system nerve cells act like scavengers
Definition
microglia
Term
What do ependymal cells do?
Definition
Create compartments, produce stem cells
Term
WHAT DO OLIGODENDROCYTES CELLS DO?
Definition
wrap around axons to form myelin sheaths and secrete neurotropic factors
Term
What do Astrocytes do?
Definition
take up neurotransmitters, secrete neurotropic factors, form the blood brain barrier and provide substrates for ATP production
Term
List cells of central nervous system
Definition
Microglia
ependymal cells
oligodendrocyte
astrocytes
Term
WHAT GLIAL CELLS ARE IN THE PERIPHERAL NERVOUS SYSTEM
Definition
Satellite cells
schwann cells
Term
In the nervous system which cells are more abundent?
Glial or neuron
Definition
Glial
Term
Describe the cerebrospinal fluid?
Definition
Fluid in the centralnervous system. Circulates and distributes nutrients and picks up waste products
Term
What does the peripheral nervous system include
Definition
all neural tissue outside the brain and spinal cord.
Term
Function of the satellite cells
Definition
support the cell bodies of neurons
Term
what do the schwann cells so?
Definition
wrap around axons to form myelin sheaths and secrete neurotropic factors
Term
What is the synapse
Definition
the region where an axon terminal communicates with a postsynaptic target cell
Term
What ate the p4 parts of a neuron
Definition
Dendrite
cell body
axon
synaptic terminal
Term
List the 6 steps for neurons to send mesages
Definition
1. peptides are synthesized on rough ER and packaged by the golgi apparaus
2. fast axonal transport walskvesicles and mitochondria along microtubule network
3. Vessel contents are released by exocytosis
4. synaptic vesicle recycling
5. retrograge fast axonal transport
6. Old membrane components digested in lysomomes
Term
Describe properties of graded potentials-
Definition
-can be produced by all cells
produced in dendrites and cell bodies ofneuronsmagnitude strength can vary
magnitude decreases with distance from intial site
no minimum voltage change required to intiate (no threshold)
two graded potientals can sum togethercaused by opening of ion channels
Term
what does myelin consists of?
Definition
multiple layers of cell membrane
Term
What is node of ranier
Definition
is a section of unmyelinated axon membrane between two schwann cells
Term
where are action potientals regeneragted?
Definition
at each node of ranier along the axon
Term
the resting membrane potiental of living cells is primarily determined by?
Definition
K+ concentration gradient and the resting cells permability to Na+; K=and Cl-
Term
Must have GP's to generate?
Definition
AP's
Term
Graded potientals -amplitude decrease with
Definition
distance. The stronger the initial stimulus, the further the signal will travel
Term
Graded potiental are?
Definition
type of electrical signal and are a result of neurotransmitter binding to a receptor which causes ion channels to open.
Term
What ion movement causes depolarizing?
Definition
Na+ entry
Ca2+ entry
Term
What ion movement causes hyperpolarizing
Definition
Cl- entry
K+ exit
Term
During repolarization of a nerve fiber what happens to potassium?
Definition
potassium ion leaves the cell
Term
The conduction of an action potiental along an axonoccurs at what kind of velocity?
Definition
Constant
Term
Whithout much moreinformation, which of the following would be most likely to be discrupted by a lower than normal ca2+ avaiability?
a. fast axonal transport
b. absolute refractory period'
c. threshold voltage
d. Neurotransmitter release
Definition
D. neurotransmitter release
Term
A geneticmutation has resulted in a neuron whose voltage-gated Na+ channels are missing their inactivation gates. The mutation has nott affected the activation gates what observation do you expect to see.
Definition
a. APs will lose strength along the length onf the axon.
b. APs will fire erractically or be conducted in both directions along the axon
c. THere will be no termination of depollarization after the intial trigger event
Term
what reasons might you suggest to explain why stretching the nerve dissrupts its function?
Definition
stretching could distroy the integrity of the cell membrane or could pop open channels that would allow ions to move between cell and the exracellular fluid.
Term
What are the 3 motor efferent pathways?
Definition
Autonomic
smooth/cardiac muscle
somatic
Term
What are the 2 autonomic motor (efferent pathways)
Definition
Sympathetic
Parasympathetic
Term
Describe autonomic sympathetic pathway?
Definition
fight or flight
increase heart rate
decrease digestive activities
Term
Desce=ribe autonomic parasympathetic pathway?
Definition
rest/digest
decrease heart rate
increase digestive activies
Term
Describe somatic motor efferent pathway
Definition
somatic- controls sketal muscle by releasing actycholine onto nicotinic receptors
Term
Describe graded potiental?
type of signal
occurs where
types of gated ion channels involved
type of signal
strength of signal
what intiates signal
Definition
type of signal? input signal
Occurs? usually in dendrites and cell body
Types of gated ion channels involved? Mechanically, chemically or voltage gated channels involved
ions involved? Na+, Cl-, Ca2+
Tpes of signals? depolarizing(Na+) or hyperpolarizing (Cl-)
Strength of signal? depends on intial stimulus can be summed
What intiates signal? Entry of ions through gated channels
Term
Describe action potiental?
type of signal
occurs where
types of gated ion channels involved
type of signal
strength of signal
what intiates signal
Definition
type of signal? regenerating conduction signal
occurs where? Trigger zone through axon
types of gated ion channels involved? voltage gated channels
type of signal? Depolarizing
strength of signal? all or none cannot be summed
what intiates signal? above threshold graded potiental at the trigger zone opens ion channels
Term
Unique characteristics of graded potiental?
Definition
-no minimum level required to intiate
-two signals coming close together in time will sum
-intial stimulus strength is indicated by frequency of a series of action potientals
Term
Unique characteristics of action potiental?
Definition
threshold stimulus required to intiate

-refactory period: two signals too close together in time cannot sum
Term
Describe properties of action potientals?
Threshold stimulus?
Produced by?
Produced in?
Magnitutude?
Can sum together?
Causedby what?
Definition
Threshold stimulus? (to-50mV) required to intiate
Produced by? axons in the neurons
Produced in? axons of neurons
Magnitutude? all or none
Can sum together? CANNOT SUM together
Causedby what? opening of voltage-gated channels
Term
Graded potiental brings Vm to?
Definition
-50mV
Term
Describe depolarization phase of action potiental?
Definition
Due to Na+ entry when Vg Na+ channels is open->+30mV
Term
K+
extracellular fluid range
intracellular fluid
Definition
K+
extracellular fluid range-5mM (normal range 3.5-5)

intracellular fluid (mM) 150mM
Term
Na+
extracellular fluid range
intracellular fluid
Definition
Na+
extracellular fluid range 145mM (normal range 135-145)
intracellular fluid mM (15mM)
Term
The voltage gated Na+ Channel
When does it open? Closes?
Definition
The vooltage-gated Na+ channel has a fast activation gate that opens -50mV. There is also a slow inactivation gate that closes the channel around +30 mV
Term
A fast action gate does what to the channel?
Definition
opens the channel
Term
A slow inactavation gate does what to the channel?
Definition
Closes the channel
Term
At what mV are the fast activation and slow inactivation gates triggered?
Definition
50mV
Term
At the hyperpolarization phase the Vm gets more negative than?
Definition
-70mV
Term
Describe the positive feedback of the sodium channel.
Definition
The opening of some voltage-gated Na+ channels causes the membrane to depolarize, which then cause the opening of more voltage-gated channels
Term
What are refractory periods?
Definition
refractory periods are times when the membrane is less sensitive to depolarizing stimuli
Term
What cannot be reproduced in an absolute refractory period?
Definition
In the absolute refractory period, noother AP can be produced. because Na+ channels are not in the resting state some are inactive.
Term
In the relative refactory period can you generate AP?
Definition
It might be possible to generate another AP because some Na+ channels are back in the resting state.
Term
How do you know if you are touching something warm versus something hot?
Definition
Larger GPs lead the membrane being at or above the threshold voltage for longer, so more AP's are produced. More neurotransmitters are released
Term
Describe the conductionof action potiental 5 steps
Definition
1. a graded potiental above threshold reaches the trigger zone
2. voltage gated Na+ channels open, and Na+ enter the axon
3. positive charge flows into adjacent sections of the axon by local current flow.
4. Local current flow from the active region causes new sections of the membrane to depolarize
5. The refractory period prevents backward conduction. Loss of K+ from the cytoplasm repolarizes the membrane.
Term
What disease leads to the loss of myelin?
Definition
Multiple sclerosis
Term
Electrical signals are regenerated where?
Definition
At the nodes of Ranvier
Term
Increase ECK+=
Definition
Hyperexcitable cells depolarize resting Vm
Term
Decrease ECK+=
Definition
Decrease in excitiability of cells hyperpolized resting Vm
Term
What enzyme is considered "stop signal"
Definition
Acetylocholinesterase (AChE)
Term
Desribe 5 steps to neurotransmitter release
Definition
1. an action potiental depolarizes the axon ternminal
2. The depolarization opens voltage-gated Ca2+channels, and Ca2+ enters the cell
3. Calcium entry triggers exocytosis of synaptic vesicle contents
4. Neurotransmitter diffuses actros the synaptic cleft and binds with the receptors of the postynaptic cell
5. Neurotransmitter binding intiates a response in the postsynaptic cell
Term
What is neurotransmitter release
Definition
cell to cell communication uses chemical and electrical signaling to coordinate function and maintain homestasis
Term
What are two types of cholinergic receptors
Definition
1. Nicotinic receptor
2. Muscarinic Receptor
Term
Describe the 4 steps of Enzymatic degradation and re-uptake of ACH
Definition
1. Acetylcholine (ACh)is made from choline and acetyl CoA
2. In the synaptic cleft ACh is rapidly broken down by the enzyme acetylcholinesterase
3. Choline is transported back into the axon terminal by cotansport with Na+
4. Recycle choline is used to make more ACh
Term
If the ion channel that is opend depolarizes the membrane (ex Na+) it is called the ?
Definition
excitatory post-synaptic potiental (EPSP)
Term
while the ion channel is open that hyperpolarize the membrane (K+) is called
Definition
inhibitory post-synaptic potiental (IPSP)
Term
Define neurotansmitter termination
Definition
Neurotransmitter action terminates when the chemicals are broken down, are taken up into cells, or diffuse away from the synapse
Term
Describe the 3 steps of neurotransmitter termination
Definition
1. Neurotransmitters can be returned to axon terminals for reuse or transported into glial cells
2. Enzymes inactivate neurotransmitters
3. Neutransmitters can diffuse out of the synaptic cleft.
Term
Describe synaptic connectivity
Definition
-the activity of each neuron is controlled by the activity of all the neurons that synapse with it. '-each neuron only makes and releases one kind of neurotransmitter (NT)
-Some NT's are excitedatory while others are inhibited
Excitatory NTs increase the chance that the post-synaptic neurons has AP while inhibitory NT decrease the chances of an AP
Term
spatial summation
Definition
all 3 pre-synaptic neurons produce EPSPs and, if they all fire at the same time, their EPSP will sum to produce a larger membrane potiental change. If the change hits threshold (-50nV) at the trigger zone an AP will occur in the post-synaptic neuron
Term
Spatial summation-EPSP and IPSP
Definition
1 IPSP and 2 EPSP will sum, but if they total voltage changes does not hit threshold, then the post-synaptic neuron will not produce AP
Term
Describe 3 steps of presynaptic inhibition
Definition
1. An excitatory neuron fires
2. An action potiental is generated
3. An inhibitory neuron fires, blocking neurotransmitter release one synapse.
Term
Describe 4 steps of postsynaptic inhibition
Definition
1. One excitatory and one inhibitory presynaptic neuron fire
2. modified signal in postsynaptic neuron below threshold
3. Action potiental intiated at trigger zone
4. No reponse in any target cell
Term
Acetycholine (ACh)
receptor
type
rectptor location
Definition
Recptor-
1. Cholinergic
2. Nicotinic- type ICR (Na+; K+) Location Sketal muscles, autonomic neurons, CNS
3. Muscarinic Type: GPCR; Location Smooth cardiac muscles; endocrine and exocrine glans, CNS
Term
Norepinephrine
receptor
Type
Location
Definition
receptor-Adrenergic
Type: GPCR
Location: Smooth and cardiac muscle, glands, CNS
Term
Dopamine:
receptor
Type
Location
Definition
receptor: dopamine
Type: GPCR
Location: CNS
Term
Serotonin (amine)
receptor
Type
Location
Definition
receptor: Serotonergic
Type: ICR (Na+; K+) GPCR
Location: CNS
Term
Amino Acid
Glutamate:
Type
Location
Definition
Type: Na+, K+, Ca2+
Location: CNS
Term
Amino Acid:
GABA

Type
Locationr
Definition
Type: ICR (Cl-), GPCR
Location: CNS
Term
Glycine:

Type
Location
Definition
Type: ICR
LocationCNS