Neurophys part 1 Flashcards
What does the PNS split into
Sensory (afferent) and Motor division (efferent)
What is the CNS made of
Brain and spinal cord
What is in PNS
Cranial and spinal nerves
What does the motor system break into
Somatic (voluntary movement of skeletal muscle)
Autonomic (visceral motor, involuntary)
What does Autonomic system split into
Sympathetic and Parasympathetic (also enteric)
What is the recieving region of the neuron
Soma and dendrites
Where does the action potential start, and why there
Axon Hillock- have large concentration of NA/K VG channels
Where is the signal propegated on the neuron
the axon
What is the nerve ending on the neuron
Terminal Buttons
What is neuron RMP
-70 Mv
What are the 3 things that maintain the RMP
- Na/K pumps
- Negatively charged proteins in the cell
- K and Na leak channels
Which channels have inactivation gate
Na has inactivation gate, NOT K
What is the thing that causes hyperpolarization
potassium leaving, and then when the AP gets more positive, K closes
What causes the absolute refractory period
the Na channels are inactivated with the inactivation gate, so cannot open because they haven’t been reset yet
What channels are open during resting phase
none
What channels are open during depolarization
Na channel
What channels are open during repolarization
K channels open
What channels open during hyperpolarization
K open in hyperpolarization until back at RMP
Describe saltatory transduction
- When we have myelinated axons, we need to recharge the nodes of ranvier only to transduce AP. Signal jumps from one node to next
Which parts of axon have highest Na channel density
node of ranvier
Is myelin a good or bad insulator
Myelin is made of cell membrane of schwann cells, and is a good insulator (keeps signal in). Lipid layer
Lipids vs water as conductors and insulators
Lipid: bad conductor, good insulator
Water: good conductor, bad insulator
Why can AP only move one way
the Na channels are inactivated behind, so signal must continue moving in one direction
What are the factors that dictate transmission speed
- Diameter of axon
- Degree of myelination
Fastest neuron fibers
A alpha- somatic motor, proprioception
268mph
Slowest nerve fibers
C fibers, temperature/ sympathetic
1mph
What direction does orthograde transport go
Move things from cell body down to axon
Proteins, vesicles, neuropeptides move this way
what direction does retrograde transport go and what goes that way
from axon terminal to cell body
viruses, nerve growth factors
Function of astrocytes
anchor neurons to blood vessils, ergulate extracellular envrionment, repair damaged tissue
Function of oligodendrocytes
myelinate axons in CNS
COPS- Central=oligodendrocytes, Peripheral=schwann
Function of microglial cells
act as phagocytes
Macrophages are also phagocytes and start with an M, so microglial are like macrophages (they phagocotyze)
Function of ependymal cells
line cavities, cillia circulate fluid
Function of schwann cells
myelinate axons in pns
COPS- CNS=oligodendrocytes, PNS=schwann
function of satellite cells
sourround and support cell bodies
Which cells make CSF
Endothelial cells, made of epithelial tissue (Choroid plexus)
Where is CSF found
-in subarachnoid space and ventricles
- Central canal of spinal cord
Purpose of CSF
- Nutriant rich fluid
- Shock absorbtion/buoyancy to help float the brain
What is Hydrocephalus and what is the primary cause of it
-Too much CSF
-Most common cuase is blockage of cerebral aqueduct
Which cells create the blood brain barrier
Endothelial cells
What passes through blood brain barrier
O2, CO2, Water, steroid hormoes
What needs help getting through bbb
Glucose
What is tightly regulated by BBB
pH changers
What does p-glycoprotein do
Pump things out of the brain that pass through the BBB. Use ATP.
- Example is chemo drugs- bad that it does, but it does. If chemo drug gets in brain, p-glycprotein pumps back out (bad <:()
Functions of BBB
- Ion balance
- Keep NT’s in brain
- Protect from toxins/pathogens
What are circumventricular organs
parts of the brain outside of BBB
- Most have functions next to the blood or needing to interact w blood
Examples of circumventricular organs
- Area of postrema (Contain chemoreceptors, trigger vommiting)
- Posterior Pituitary(- Neurohypothesis- release hormones to put them directly into blood)
Why is constant blood pressure important in the brain
-Perfusion of brain tissue
What is a gap junction/signficance
Neurons directly touch one another with gap junction- electrical synapse, rarer
Most common type of synapse
chemical
What is found in post synaptic densities
Neurotransmitter receptors
What is found in presynaptic terminal
Vesicles of NT
What do dendritic spines do
Motivation, learning, memory,
lots of ribosomes and RNA to grow spines
Grow and solidify connections between 2 neurons
Botulinum A vs B
A: cleaves SNAP-25, which is needed for ACch to bind to membrane for exocytosis
B: cleaves synaptobrevin–>blocks AcH release completely
How many axons do oligodendrocites connect to
many axons
How many axons do schwann cells connect to
only 1 axon
What are EPSPs and ISPSs classified as
graded potentials
What does teatnus do
blocks inhibitory signals so muscles contract out of control
What ion currents cause depolarizing GP’s
NA+ or Ca2+ influx
What causes ion currents causing hyperpolarizing GP’s
K+ efflux or Cl- influx
Most common inhibitory NT’s
GABA or glycine
Most common excitatory NTs
Glutamate or Serotonin
What is a renshaw cell
inhibitory interneuron that inhibits same motor neuron it is stimulated by
-Called presynaptic inhibition
Describe stretch reflex
EPSP in quad causes contraction, IPSP in hamsting causes relaxation at same time
give example of post synaptic inhibition
in stretch reflex, the inhibitory interneuron ensures hamstring doesn’t contract
Describe wallerian degeneration
Axon damage leads to degeneration of axon from injury site to terminal
Describe denervation hypersensitivity
muscle cell upregulates nicotinic Ach Receptors
What is the action of a NT the result of
Not of the neurotransmitter itself, but of the receptor
What are ionotropic receptors
ligand gated ion channels
Receptor is also channel
What are metabotropic receptors
GPCRs that lead to multiple effects
Receptor for NT is not also the channel
Monosynaptic vs polysynaptic
Mono- only one synapse
poly- interneuron in chain between pre/postsynaptic
Describe the components of muscle spindle
-Intrafusal fibers have contractile ends and noncontractile center
-Small diameter efferent neurons for end
-Extrafusal fibers are parallel to intrafusals
- Static portion sense length
- Dynamic portion senses speed of movement
What do static vs dynamic portions of muscle spindles sense
-Static: length
- Dynamic: speed of movement
How many synaptic knobs does the motor neuron have
average is 10,000
What is the inverse stretch reflex also known as
golgi tendon reflex
Ganglion
collection of cell bodies of neuron
In what parts of the nervous system are parasympathetic vs sympathetic
Parasympathetic is only in cranial and sacral nerves
sympathetic is in thoracic nerves
Compare pre and post ganglionic lengths in sympathetic vs parasympathetic
Parasympathetic: Long pre ganglionic, short post ganglionic
Sympathetic: Short pre ganglionic, Long post ganglionic
