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CNS and PNS Physiology
how brain and CNS and PNS work
84
Physiology
Undergraduate 4
03/13/2013

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Cards

Term
types of neurons
Definition
Afferent, Efferent, Interneuron
Term
What part of nervous system is the afferent neuron part of
Definition
afferent peripheral nervous system
Term
where does the afferent neuron conduct APs towards
Definition
Central nervous system
Term
Where is the afferent neuron cell body
Definition
outside of CNS
Term
what does afferent neuron end with
Definition
peripheral end is a sensory receptor
Term
where does efferent neuron conduct APs to
Definition
away from the CNS
Term
where are the efferent neuron cell bodies located
Definition
in the CNS
Term
what do efferent axon terminals synapse to
Definition
effectors (muscles, organs, glands)
Term
where is the interneuron located
Definition
entirely in CNS
Term
what is the role of the interneuron
Definition
integrator of afferent signals and efferent response
Term
What does the CNS consist of
Definition
Brain and spinal cord
Term
What does gray matter consist of
Definition
cell bodies and unmyelinated neurons
Term
What does white matter consist of
Definition
myelinated axons
Term
What do glial cells consist of in the CNS
Definition
ependymal cells
Term
what do ependymal cells do in the CNS
Definition
line cavities (like brain ventricles) and help form CSF
Term
What do oligodendrocytes do
Definition
form myelin
Term
what do microglia do
Definition
Phagocytosis which acts as immune defense monitoring for pathogens
Term
what do astrocytes do
Definition
help nourish neurons and help form the blood brain barrier
Term
what does the cranium do
Definition
it encases and supports the brain
Term
what does the vertebral column do
Definition
it surrounds and protects the spinal cord
Term
what do the meningeal membranes do
Definition
lie between the bone and nervous tissue
Term
what is the order of the meningeal membranes from inside to outside
Definition
Pia mater, Arachnoid mater, Dura mater
Term
what does the CSF do
Definition
it cushions the nervous tissue of brain
Term
what are some properties of the BBB
Definition
low permeability of capillaries in brain, many tight junctions between endothelial cells, lipid soluble molecs can pass through
Term
what is not protected by the BBB in the brain
Definition
the hypothalamus
Term
what must the brain have a constant supply of
Definition
oxygen and glucose
Term
what does the cerebral cortex do
Definition
sensory perception, voluntary control of move, language, personality traits, sophisticated mental events (memory, decisions, creativity, self-consciousness)
Term
what does the basal nuclei do
Definition
inhibition of muscle tone, coordination of slow sustained movements, suppression of useless patterns of movement
Term
what does the thalamus do
Definition
relay station for all synaptic input, crude awareness of sensation, some degree of consciousness, role in motor control
Term
what does the hypothalamus do
Definition
regulate many homeo static func. (temp, thirst, urine output, food intake), important link between nervous and endocrine systems, extensive involvement with emotion and basic behavioral patterns, role in sleep-wake cycle
Term
what does the cerebellum do
Definition
maintain balance, enhance muscle tone, coordinate and plan skilled voluntary muscle activity, proprioception (knowing position in space)
Term
what does brain stem do
Definition
origin of majority of peripheral cranial nerves, cardio, resp, and digestive control center, regulate muscle reflexes for equilibrium and posture, receives and integrates synaptic input from spinal cord, role in sleep-wake cycle
Term
what makes up the limbic system
Definition
parts of cerebral cortex, basal nuclei, thalamus, hypothalamus
Term
what is the major role of the hippocampus
Definition
memory
Term
what is memory
Definition
storage of info for later recall
Term
what is short-term memory
Definition
memory that lasts seconds to minutes, that is based on continuous activity of cortex synapses
Term
what is long-term memory
Definition
lasts days to years, made from growth of new connections and synapses, from protein production
Term
what is consolidation
Definition
the conversion of short-term to long-term memory
Term
how does consolidation happen
Definition
by strengthening existing synapses as a result of increasing neurotransmitter release or increasing neurotransmitter receptors
Term
what is habituation
Definition
a decreased responsiveness to repeated presentation of indifferent stimulus
Term
how does habituation occur
Definition
from repeated indifferent stimuli leading to prevention of VG Ca channels in presynaptic neurons from opening resulting in no NT being released
Term
what is sensitization
Definition
the increased responsiveness to a mild stimuli following a strong or noxious stimulus, a result of presynaptic facilitation
Term
how does sensitization occur
Definition
facilitating neuron is activated by strong or noxious stimulus, with serotonin from far neuron activating cAMP system in presynaptic axon terminal, blocking K channels in axon terminal resulting in a prolonged depolarization of the membrane
Term
what is long term potentiation
Definition
an increase the strength of existing synapses following brief periods of repetitive stimulation
Term
how does long term potentiation occur in the hippocampus
Definition
glutamate released from presyn neuron binds to AMPA and NMDA receptors, if both activate then more AMPA receptors are added
Term
how do AMPA receptors activate and what do they do when they activate
Definition
they activate by the binding of glutamate and they are gated Na/K channels that cause a Na influx (EPSP)
Term
how do NMDA receptors activate and what do they when they activate
Definition
they activate from glutamate binding and a depolarization caused by an AMPA EPSP, results in Mg ion being removed from pore and Ca influx activating 2nd messenger systems
Term
what can be found in the gray matter of the spinal cord and what is its role
Definition
the Dorsal horn (the axon terminals are afferent fibers); Ventral horn (cell bodies of efferent neurons); Lateral horn (cell binders of efferents controlling extrinsic func)
Term
how is white matter of spinal cord arranged
Definition
into ascending and descending tracts
Term
what is a reflex
Definition
a response that occurs automatically without conscious effort
Term
what is a simple reflex
Definition
an unlearned reflex that is acquired or conditioned
Term
how does the reflex arc work
Definition
sensory receptor responds to stimulus, afferent neuron conducts AP, efferent neuron responds to stimulation from interneuron, sends AP to effectors causing response
Term
what are properties of sensory receptors
Definition
specialized to respond to one type of stimulus energy, require an adequate stimulus (specific to type which it responds best to), specialized endings of afferent fiber, stimulation will cause altered membrane permeability
Term
what are the different types of sensory receptors and what is their stimulus
Definition
Photoreceptor (light); thermoreceptor (heat); osmoreceptor (osmolarity change); chemoreceptors (conc of spec chemicals); olfactory receptors (smell); taste receptors; mechanoreceptors (physical force)
Term
what are different mechanoreceptors
Definition
bororeceptors (pressure); stretch receptors; hair cells of ear (vibrations); touch receptors (physical pressure); nocireceptors (tissue damage)
Term
how do receptors work
Definition
stimulation of receptor causes altered membrane permeability (channels open), Na influx (from regions adjacent to receptor), depolarization, APs generated if enough depolarization
Term
how does a receptor work if it is a separate cell
Definition
stimulus energy causes Na influx as a result of altered permeability, VG Ca channels open, influx of Ca, exocytosis of NT, excitation of afferent neuron AP
Term
what does intensity of the stimulus affect
Definition
the greater the stimulus energy the greater the receptor potential (RP); the greater the RP the greater the freq of APs generated in afferent neurons
Term
what does and increase in area stimulated cause
Definition
results in an increased number of receptors activated resulting in an increase in intensity
Term
what is sensory adaptation
Definition
the ability to diminish depolarization despite sustained stimulus and it generates RP when a change in stimulus strength occurs
Term
what are the two types of sensory adaptative receptors and how much do they adapt
Definition
Phasic receptors (adapt easily-ex pressure receptors)
Tonic receptors(don't adapt or do so slowly ex- pain receptor)
Term
what is a receptive field
Definition
a defined region of skin in which the afferent neuron will respond to a stimulus
Term
how does receptive field compare to number of receptors
Definition
the size of the field varies inversely with number of receptors present
Term
how is the PNS divided
Definition
Autonomic Nervous System (ANS) and Somatic Nervous System
Term
what does the ANS do
Definition
it contains neurons that control involuntary responses of body (smooth, cardiac muscles, glands)
Term
how is the ANS divided
Definition
sympathetic and parasympathetic division
Term
how does the 2 neuron pathway work in the ANS
Definition
cell body of preganglionic fiber (first) is in CNS, the terminal terminate in the autonomic ganglion and synapses on cell body of post-ganglionic neuron which synapses on the effector organ
Term
what is the sympathetic action and what are the lengths of the 2 neurons in the pathway
Definition
fight or flight
short pregang, long postgang
Term
what is the parasympathetic action and what are the lengths of the 2 neurons in the pathway
Definition
rest and digest
long pregang, short postgang
Term
what does it mean that most visceral organs have dual innervation
Definition
the organs are innervated for both sympathetic and parasympathetic divisions (ex- symp increase HR, parasy decrease HR)
Term
what are the two major classes of receptors that bind Ach
Definition
Nicotinic and Muscarinic receptors
Term
what are properties of nicotinic receptors
Definition
chemically gated ion channels; Ach binds, channel opens, Na influx, depolarization, EPSP; on postgang subsynaptic membrane
Term
what are properties of muscarinic receptors
Definition
GPCR receptors; Ach binds, activates 2nd messenger system, cell response; on effector organ on site of parasymp innervations
Term
where do NE and EPI bind
Definition
to the adrenergic receptors at alpha and beta receptors
Term
what do alpha receptors have more affinity for
Definition
generally more affinity for NE than EPI
Term
what is the difference between a1 and a2 receptors
Definition
when bound to a1 usually has excitatory effect (found in arteriolar smooth muscle causes vasoconstriction) while binding to a2 is usually inhibatory
Term
what is the difference between B1 and B2 receptors
Definition
B1 has equal affinity for NE and EPI, usually excitatory (found in heart) while B2 binds with greater affinity to EPI and is usually inhibitory (arteriolar smooth muscle serves heart and skeletal muscle)
Term
where do sympathetic preganglionic neurons emerge from
Definition
thoracic and lumbar nerves
Term
where do parasympathetic pregans emerge from
Definition
cranial and sacral nerves (CN X-vagus)
Term
what does the adrenal medulla do
Definition
it produces epinephrine and norepinephrine
Term
what happens during sympathetic activation
Definition
EPI (80%) and NE (20%) are released from adrenal medulla; enters circulation as hormones; binds to adrenergic receptors throughout body
Term
what do agonists do
Definition
mimic natural ligand for receptor and brings about normal response to receptor activation
Term
what do antagonists do
Definition
compete with natural ligand for binding and when bound to receptor it blocks the normal response
Term
what do B-blockers do
Definition
they lower blood pressure (act as antagonist)
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