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BIOL 1142 - Quiz 2

neurophysiology, central nervous system, autonomic nervous system

graded potential short-distance communication; at dendrites; initiated by a stimulus that opens an ion channel (usually Na+ or K+); stronger stimulus -> stronger graded potential; lose intensity over distance; spread by passive current flow
depolarizing ions Na+, Ca2+ resting membrane potential becomes less negative, results in Excitatory Post-Synaptic Potential (EPSP) that can produce an action potential if threshold is reached
hyperpolarizing ions K+, Cl- resting membrane potential becomes more negative, results in Inhibitory Post-Synaptic Potential (IPSP) that is less likely to produce an action potential
EPSP Excitatory Post-Synaptic Potential
IPSP Inhibitory Post-Synaptic Potential
threshold what needs to be reached in order for an action potential to be generated as a result of graded potentials; for human cells, the RMP is -70, average threshold is -55.
summation of graded potentials adding up of all active synapses at one time; two types of summation: 1. spatial 2. temporal
spatial summation multiple synapses are active on different dendrites at the same time
temporal summation synapses are active over a period of time
subthreshold graded potential do not change the RMP to -55 and therefore do not result in an action potential
suprathreshold graded potential change the RMP to -55 and produce an action potential
action potential long-distance communication; initiated at the axon hillock if threshold is reached by activating voltage-gated channels; do not vary in magnitude or duration; do not degrade over distance; frequency determines strength
phases of the action potential 1. depolarization phase 2. repolarization phase 3. hyperpolarization phase
depolarization phase of an action potential voltage-gated Na+ channel is activated; phase ends when the inactivation gate closes
repolarization phase of an action potential voltage-gated K+ opens; ends when cell returns to RMP but open K+ result in hyperpolarization immediately following this stage
hyperpolarization phase of an action potential voltage-gated K+ channels are still open from previous phase; ends when cell returns to RMP and K+ gates close
resting voltage gate activation gate is closed, inactivation gate is open
open voltage gate both activation gate and inactivation gate are open
inactivated voltage gate activation gate is open, inactivation gate is closed
refractory period time at which a neuron cannot be triggered because channels are already open or inactive
absolute refractory period impossible to produce another action potential
relative refractory period possible to produce another action potential, but only with a stronger than normal stimulus
axon hillock point at which the action potential is initiated; where the first voltage-gated channels are located
axon potential speed determined by axon diameter and myelination of the axon; larger diameter -> faster travel; myelinated axons -> faster travel; action potentials can travel as fas as 120 m/s in a large, myelinated axon
saltatory conduction travel through myelinated axons, action potential "jumps" from one node of Ranvier to the next
Multiple Sclerosis affects oligodendricytes of the CNS; degradation of myelin sheath results in action potential not being able to travel entire length of the axon
Guillain-Barre Syndrome affects Schwann cells in the PNS; body attacks myelin sheaths and signal is weaker through axon
myelin protective, insulating material around the axon that prevents leakage of charge out of the axon; there are no channels under the myelin so signal can travel very quickly through this section of the axon
factors that affect neuronal signaling alteration in ion permeability; alteration in ion homeostasis; channel properties
hypernatremia too much sodium in the plasma; depolarizes; neurons are hyperexcitable
hyponatremia too little sodium in the plasma; hyperpolarizes; neurons are hypoexcitable
hyperkalemia too much potassium in the plasma; depolarizes; neurons are hyperexcitable
hypokalemia not enough potassium in the plasma; hyperpolarizes; neurons are hypoexcitable
synapse junction between two neurons, where communication between neurons occurs
electrical synapse results in voltage changes in the post-synaptic cell
chemical synapse neurotransmitters are released by the pre-synaptic cell; bind to receptors on the post-synaptic cell
termination of neurotransmission 1. diffusion 2. enzymatic inactivation within the synaptic cleft 3. active transport into pre-synaptic terminal or glial cells
acetylcholine only neurotransmitter that activates skeletal muscles
SSRI Selective Seratonin Reuptake Inhibitor; found in many anti-depressants, anxiety meds; inhibits reuptake of seratonin so that more seratonin is available to bind to receptors
acetylcholinesterase enzyme that disables acetylcholine
reuptake active transport of a neurotransmitter back to the pre-synaptic cell
brain stem medulla oblongata, pons, midbrain
medulla oblongata controls involuntary functions such as heart rate, blood pressure, blood vessel dilation/diameter
pons controls sleep/wake cycles, respiration
midbrain plays a role in cranial nerve function, especially visual and auditory
cerebellum motor control; precision and coordination of movements
diencephalon contains the thalamus and hypothalamus
thalamus sensory relay center
hypothalamus endocrine regulation; controls pituitary gland; responsible for many ANS functions
cerebrum controls voluntary actions; contains primary sensory and motor areas; divided into left and right hemispheres
hyperexcitable neuron requires less change in RMP to reach threshold because it is already depolarized due to hypernatremia or hyperkalemia
5 lobes of the brain frontal, parietal, temporal, occipital, insula (inside the brain, no cranial bone associated with it)
primary sensory/motor areas located in different lobes of the brain, each area has a specific task - ie, vision, hearing, motor function, etc.
associative areas "fine tunes" primary area functions, also involved with higher order tasks such as thinking, planning, emotional response, memory, learning, etc.
corpus callosum division between left and right hemispheres; where axons cross from one hemisphere to the other
gray matter cell bodies and dendrites
cortex sulci and fissures of the surface of the cerebrum
nuclei collections of gray matter that are located deep in the brain
white matter tracts, commissures, columns
cranium skull; protects the brain
meninges dura mater, arachnoid mater, pia mater
cerebrospinal fluid between the pia mater and arachnoid mater (subarachnoid space); protects and nourishes; 150mL volume is replaced about 3x/day
blood brain barrier prevents passage of certain types of molecules between the blood and the brain; molecules like oxygen, carbon dioxide, nicotine, alcohol can easily pass;
choroid plexus located in the ventricles of the brain; where cerebrospinal fluid is produced
ventricles of the brain fluid filled spaces in the brain; 2 lateral ventricles, third ventricle, fourth ventricle
gray matter areas of the spinal cord dorsal horn, ventral horn, lateral horn
white matter areas of the spinal cord dorsal column, ventral column, lateral column
spinal nerves nerves that carry sensory (dorsal root) or motor information (ventral root) to and from the spinal cord
dorsal horn gray matter area of the spinal cord; sensory function
ventral horn gray matter area of the spinal cord; motor function
lateral horn gray matter are of the spinal cord; contains autonomic system neurons
dorsal column white matter area of the spinal cord, carries sensory information to the brain (except pain and temperature)
ventral column white matter area of the spinal cord, carries motor information from the brain to the effectors
lateral column white matter area of the spinal cord
collateral carries sensory information to the brain after a reflex occurs; allows awareness of reflex
polysynaptic reflex arc reflex arc that involves more than two neurons (multiple synapses); involves a sensory neuron, an interneuron, and a motor neuron
monosynaptic reflex arc reflex arc that involves only two neurons (one synapse); involves only a sensory and motor neuron
upper motor neuron syndrome type of spinal cord damage that results in spastic paralysis, hypereflexia, positive Babinski test
lower motor neuron syndrome type of spinal cord damage that results in flaccid paralysis, areflexia, muscle atrophy
higher order functions for motor control 1. motivation/idea 2. planning 3. execution 4. correction
higher order functions of the limbic system 1. outputs - feeling, emotional responses 2. motivation - dopaminergic rewards
limbic system group of structures responsible for emotions and motivation
dopamine neurotransmitter that activates reward/pleasure centers; alcohol, nicotine, cocaine, amphetamines, etc. also activate the dopamine reward system
sleep active process required by all mammals; most neurons that control sleep and wake cycle are located in the pons and midbrain; sleep is restorative and may help bolster the immune system and memory function
histamine neurotransmitter that makes you wakeful
antihistamine inhibits histamine, given for inflammatory response; anti-histamines that cross the blood brain barrier (eg, Benadryl) will cause drowsiness; newer antihistamines (eg, Clartie, Zyrtec) do not cross the blood brain barrier
stages of sleep Stages 1-4, low amplitude, low frequency waves; stage 4 is deepest, happens about 2 times each night
REM sleep high frequency, low amplitude waves; stage of sleep at which dreams occur; average 4 REM periods each night; resembles brain activity when awake
types of sensations 1. conscious - somatic senses, special senses 2. subconscious - proprioception, visceral sensations
properties of sensation conscious sensations - somatic, special senses unconscious sensations - proprioception, visceral sensations
special senses vision, hearing, smell, taste
sensory receptors 1. photoreceptors 2. mechanoreceptors 3. chemoreceptors 4. thermoreceptors 5. nociceptors
photoreceptors detect light; anaxonic (no axon); constantly releasing neurotransmitters
mechanoreceptors respond to mechanical change, such as stretch, vibration, change in balance
chemoreceptors respond to taste, odor, oxygen, carbon dioxide, changes in pH level of the blood
thermoreceptors temperature, heat
nociceptors pain, detection of potentially or actually harmful stimuli
sensory transduction conversion of stimulus energy into a neuronal electrical signal; results in changes to membrane potential and possibly action potential if threshold is reached; all receptor potentials are depolarizing except photoreceptors
sensory receptor adaptation decrease over time in the magnitude of the receptor potential when there is a constant stimulus;
receptive field of sensory neurons physical location of sensory receptors; more receptors in an area results in greater sensitivity; larger fields have lower sensitivity than smaller fields; fingertips and lips are most sensitive
sensory integration 3 neuron relay 1. first order neuron (detects stimulus) 2. second order neuron (first neuron entirely in CNS, crosses the midline) 3. third order neuron (thalamus, axon goes to appropriate primary sensory cortex
CNS role in sensation processes sensory information and allows for response
tonic receptors adapt slowly to constant stimulus; examples include proprioceptors, baroreceptors (blood pressure)
phasic receptors adapt rapidly to constant stimulus
modality/labeled line coding allows for dedicated, separate pathways for different sensations that do not share neurons
lateral inhibition when an excited neuron inhibits its neighbors
nociception detection of pain; sensation of noxious stimuli
noxious stimuli chemical, mechanical or thermal stimuli that are harmful
neuropathy loss or gain of sensation; can be either loss of sensation or gain in sensation (neuropathic pain)
Adelta fibers fast transmitting, medium diameter, myelinated axons; phasic; result in sharp, intense, highly localized pain sensations
C fibers slower transmitting, small diameter, unmyelinated axons; tonic; result in more delayed and persistent pain sensation or inflammatory response
pain response 1. perception of pain 2. autonomic response (increased heart rate, sweating, blood pressure, dry mouth) 3. emotional response (fear, anxiety) 4. reflexive withdrawal
pain perception fast/Adelta fibers; slow/C fibers
algesia pain
hyperalgesia increase in pain, overactive pain system (ex - shirt on sunburned skin)
analgesia decrease in pain; can be due to natural pain suppression from periaqueductal gray, reticular formation and inhibitory interneurons or can be from a pharmaceutical analgesic
preiaqueductal gray surrounds the cerebral aqueduct and releases endorphins and other internal opiode-type molecules
reticular formation means by which pain sensations reach the cerebral cortex
referred pain pain from visceral organs that is felt in other parts of the body; internal organs do not have own pain pathways, share wtih a second order neuron that is also stimulated by a somatic nociceptor
somatic motor neurons motor neurons that are associated with voluntary actions
autonomic motor neurons neurons associated with the Sympathetic Nervous System (SNS) and Parasympathetic Nervous System (pSNS)
Sympathetic Nervous System "fight or flight" system; thoracolumbar division
Parasympathetic Nervous System "rest and digest" system; craniosacral division
craniosacral division Parasympathetic Nervous System; neurons are located in the brain stem and sacral region of the spinal cord
thoracolumbar division Sympathetic Nervous System; neurons are located in the thoracic and lumbar regions of the spinal cord
autonomic reflexes reflexes that affect internal organs; involves ganglia
ganglia collection of cell bodies outside the CNS where information is transferred
preganglionic cell body is located in the brain or spinal cord
postganglionic cell body is located outside the CNS in a ganglion
target cell that responds to a signal from a neuron; ganglion is located near the target in the pSNS, far from the target in the SNS
autonomic spinal reflexes polysynaptic; includes micturation, defecation, penile erection
visceral functions that are not under antagonistic control all under tonic control at rest; blood vessel dilation/constriction, sweat glands, liver/adipose tissue; penile erection and ejaculation is coordinated by both systems, but not antagonistic
neurotransmitters of SNS pre-ganglionic: Acetylcholine post-ganglionic: Norepinephrine
neurotransmitters of pSNS pre-ganglionic: Acetlycholine post-ganglionic: Acetlycholine
effectors of the autonomic nervous system smooth muscle, cardiac muscle, exocrine glands, some endocrine glands, lymphoid tissue, adipose tissue
norepinephrine released by postganglionic SNS neurons
adrengenic receptors receptors that bind to epinephrine and norepinephrine; two types: alpha and beta
alpha receptors type of adrenergic receptor (epinephrine or norepinephrine); broadly distributed in the body
beta receptors type of adrenergic receptor (epinephrine or norepinephrine); not broadly distributed in the body; beta1 - heart, beta2 - respiratory system, bronchioles, beta3 - adipose tissue
examples of pharamcological substances that act as agonists for beta receptors albuterol, isoproterenol
examples of pharamcological substances that act as antagonists for beta receptors propranolol, metropolol
adrenal gland located on the kidney; releases epinephrine when stimulated by a preganglionic sympathetic neuron
epinephrine adrenaline
muscarinic receptor type of cholinergic receptor (for Acetylcholine) that is found only in the pSNS; used by the target cell
variscosities swellings of an axon that contain neurotransmitters; like beads on a string
hypoexcitable neuron a hyperpolarized neuron that will require more than normal change to the resting membrane potential to reach threshold; due to hyponatremia nad hypokalemia
nicotinic receptor type of cholinergic receptor (for Acetylcholine) that is found in both pSNS and SNS; used by the postganglionic neuron
examples of pharmacological substance that acts as an antagonist for a muscarinic cholinergic receptor atropine
Created by: pinklrt98 on 2011-02-26

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