Neurophysiology Flashcards
3 general function of CNS?
- Collects information
- Processes evaluates information from CNS
- Initiates response
2 cell types in nervous tissue?
- Neurons (nerve cells)
- Glial (neuroglial, supporting cells)
5 characteristics of neurons?
- excitability
- conductivity
- secretion (of neurotransmitters)
- extreme longevity
- amitotic
A given neuron releases only one type of ____ with excitatory of inhibitory effect on target
neurotransmitter
Myelin sheath is composed of ____ and functions to ___ and ___ the axon, which increaes the speed of nerve impulses.
- neuroglia
- covers
- insulates
Sensory neurons have somas located outside the CNS in the _____ and have axons that synapse with ____ in CNS
- posterior ganglion root
- interneurons
what structure are most sensory neurons?
unipolar
Motor neurons receive signals from ____ and carry signals to effectors
interneurons
Most motor neurons have somas located in the ____, while its axons are located in the ____
- CNS
- PNS
____ is the thick outer layer of the nerve that provides support and protection
Epineurium
____ is the layer of the nerve that wraps bundles of axons and supports blood vessels
Perineurium
_____ is the delicate layer of the nerve that separates and electrically insulates each axon
Endoneurium
____ are the most abundant glial cells in CNS
Astrocytes
____ help form the blood-brain barrier and occupies the space of dying neurons
Astrocytes
____ are glial cells that line the ventricles of the brain and central canal of spinal cord
Ependymal cells
Ependymal cells and nearby blood vessels form the ____, which produces ____.
- Choroid plexus
- CSF
____ are the least abundant glial cells that engulf microorganisms and cell debris
Microglia
____ are glial cells that form the myelin sheath in the CNS
Oligodendrocytes
____ are glial cells that form the myelin sheath in the PNS
Schwann cells
____ are glial cells that regulate exchange of nutrients and wastes between neurons and their environment
Satellite cells
What is the most important in establishing the Resting Membrane Potential?
K+ leak channels
The RMP is ____ mV
-70 mV
The K+ leak channel allows K+ to diffuse from ____ of the cell to the ____, going ____ its concentration gradient
- diffuse from INSIDE of the cell to OUTSIDE
- DOWN its concentration gradient
____ has minor influence on the resting membrane potential
Na+ leak channel
In establishing the RMP, K+ leaves the cell creating a ____ charge outside, leaving a ____ charge inside
- POSITIVE outside
- NEGATIVE inside
In graded potentials, the permeability of a neuron membrane is determined by ____
ligand-gated K+ and Na+ channels
In action potentials, the permeability of the resting neuron membrane is determined by ____
voltage-gated Na+/K+ channels
when do voltage-gated channels open?
when the membrane is depolarized
____ is the reduction in membrane potential in which the inside of the membrane become less negative
Depolarization
____ is the increase in membrane potential in which the inside of the membrane becomes more negative
Repolarization
____ is the increase of membrane potential above RMP in which the inside of the membrane becomes more negative that the resting potential
Hyperpolarization
____ increases the probability of producing nerve impulses, whereas ____ reduces this probability
- depolarization
- hyperpolarization
____ is the propagation of action potential along the axon
Nerve impulse
When local potential first reaches threshold, ____ fully open quickly causing rapid depolarization.
voltage-gated Na+ channels
As the rising potential passes 0 mV (becoming more positive), ____ channels close.
voltage-gated Na+ channels
When the voltage peaks at +35 mV, ____ fully open quickly, resulting in rapid ____
- voltage-gated K+ channels
- repolarization
____ channels stay open longer, resulting in hyperpolarization
voltage-gated K+ channels
In the SNS, preganglionic somas are located in the ______
Lateral horn of T1-L2
In the SNS, ganglia are located ____
far from target organs
closer to vertebrae
What neurotransmitters are released by postganglionic neurons in SNS?
Ach or NE
In the PSNS, where are preganglionic neurons located?
- Brainstem (CN 3, 7, 9, 10)
- Lateral gray matter of S2-S4
True or False: No cranial nerves are sympathetic fibers
TRUE
alpha-1 receptors
- vasoconstrict blood vessels (skin, GI, kidneys)
- contract erector pili, uterus, ureters, internal, urethral sphincters
alpha-2 receptors
- inhibit insulin secretion
- contract GI sphincters
beta-1 receptors
- stimulate increased HR and contractility
- stimulate renin secretion
beta-2 receptors
- vasodilation (going to heart, liver, muscles)
- bronchodilation lungs
- relax uterus, GI, tract, bladder
which alpha-blocker causes an irreversible blockade of postganglionic synapses in exocrine glands and smooth muscle
nonselective alpa blocker
Phenoxybenzamine
alpha blockers can be either competitive at binding site or not, while beta-blockers _____
competitively bind
in the heart, what do beta blockers compete with
NE and epi
In PSNS, what do postganglionic neurons release? to what receptors on target organs
- Ach
- muscarinic receptors
In SNS, postganlionic neurons can secrete either ____ to ____ receptors -OR- ____ to _____ receptors
- ACh to muscarinic receptors
- NE to adrenergic receptors
which has higher affinity for epinephrine: alpha 1 or beta 2
beta 2
at high concentrations of epinephrine, what effect occurs
vascular smooth muscle contraction
bc more alpha-1 receptors
