The Nervous System Flashcards
Ependymal cells
Line the ventricles of the brain and produce cerebrospinal fluid
Microglia
A phagocyte that ingest and break down waste products and pathogens in the CNS
Oligodendrocytes and Schwann cells
Myelinating cells in the CNS and PNS respectively
Voltage of the resting potential
-70 mV
How the negative potential inside the membrane during the resting phase is set
Na+/K+ active pump
Greater permeability of K+ channels, making K+ leave the membrane
Approximate threshold voltage for an action potential
-40 mV
Na+ Voltage gated channel opening frame
Very short
Open at the threshold and then close around +35 mV which is the point when K+ channel slowly opens to rush out
During an action potential, is it electrically and chemically favorable for the Na+ to rush into the membrane?
YES, electrically excess positive charge built up outside the membrane are attracted to the negative inside the cell.
Chemically, there is a higher concentration of Na+ outside the cell than the inside.
What’s the purpose of action potential moving down the axon in wave-like fashion with a refractory period preceding the activated segment?
Allows the impulse to propagate in one direction
What is the speed of the conduction dependent on?
Resistance increase with Length and decrease in Cross Sectional AREA (REPLAY)
How does one increase the action potential?
Increase the frequency not the intensity
How are are the NT’s in the vesicles of a pre synaptic cell released?
Ca2+ binding stimulates exocytosis
What are some post synaptic responses?
Ligand gated cell that causes depolarization or hyper polarization
G-coupled protein receptor: change in cAMP concentration or influx of Ca2+
Ways NT’s are cleared in the synapse
1) enzyme inhibitor
2) transporter channel back into the pre synaptic cell
3) diffuse out of the synaptic cleft (nitrous oxide is a good example that causes this)
Inter neurons
Reflexive behaviors
Reflex
Only at the level of the spinal cord not the brain
Spinal cord: white and grey matter composition
White matter outside and grey matter inside
Brain: White and grey matter composition
Grey matter outside, white matter inside
Preganglionic and postganglionic neurons
Neurons working together just outside the spinal cord to convey the message to the effector cells
NT’s used in parasympathetic and sympathetic nervous system
Parasympathetic: ACh only
Sympathetic: ACh and NE in the postganglionic
Monosynaptic reflex
Directly from sensory to motor neuron
Simple sense and react mechanism - knee jerk
Polysynaptic reflex
Sensory -> inter neuron -> motor
Interneuron synapses with other motor neurons for additional function.
For example, maintaining balance during the reflexive behavior.
Astrocyte
Star shaped cell that reaches across all neurons with his legs and nourish them, and form the blood-brain barrier
