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74 Cards in this Set
- Front
- Back
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somatic and autonomic which is conscious and which is unconsciousess |
somatic - consc auto - unconsc |
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structure of afferent neuron |
-single long dendrite -short axon -smooth rounded cell body
-the dendrite is strucurally and functionally similar to axon |
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4 receptors of somatosensory |
-chemo -thermo -photo -mechano |
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visceral afferent |
incoming afferent pathway from organs (viscera) -mostly subconscious but pain receptors can make u become aware |
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somatic sensations vs special senses |
somatic - somaesthetic, proprioception
special - hearing, smelling, seeing, taste, equilibrium |
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perceptions dont replicate reality |
- different receptors result in diff perceptions, other species with diff receptors perceiev different |
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somatosensory vs specal senses receptors |
somato - ex. free nerve endings consist of neuron with exposed receptor
special - ex.turn mechanical stimulation into neural by synapsing on a sensory neuron |
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trasduction |
mechanical or chemical stimulation converted into electrical signal thru changes in ion permeability at controlled ion channels |
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4 properties allwoing CNS to differentiate between incoming stimuli |
modality, location, intensity, duration |
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modality |
the type of receptor, sent to cerebral cortex |
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generator potential |
same as receptor potential but ending of an afferent neuron |
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photoreceptors are hyperpolarized upon stimulation |
yes |
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duration |
graded potential last longer with stronger stimulus |
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seperate receptor |
chemicals will travel to afferent and open ion channels for action potential |
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magnitude |
greater stimulus, more frequent action potential |
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adaptation |
stimuli can diminish extent of depolarization despite sustained stimulus strength |
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tonic receptors |
dont or hardly adapt - imprt in situations where valuable to maintain info about stimulus -ex. -muscle stretch, and joint proprioceptors -constantly need infor to monitor |
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phasic receptors |
rapidly adapting - no longer responds to maintained stimulus but when stimulus removed receptor slightly depolarizes and is called off response
-useful to signal change in stimulus -ex.tactile (touch) receptors in skin signalling pressure - not consciouss continually of wearing clothes but when some new comes on u become accustomed, when taking offf u aware of removal because of off response |
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order sensory neurons |
order of neurons from afferent receptor up to brain |
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labelled lines |
since stimulus seems same to brain, labelled lines relay specific, location, and type etc |
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phantom pain |
pain percieved as orginating from somewhere but it is just the neural pathway this would take being falsely stimulated
-person feels foot pain but leg was amputated, free nerve endings falsely doin it doe
-brain attempt at remapping when limb severed could lead to signal of pain misinterpretation |
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receptive field |
each neuron hs region of skin surface of receptors it responds too, small field = more receptors = more senstiive (greater acuity and discriminative ability) |
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lateral inhibition |
-pencial prick on finger, region around the point feels slight stimulation, lateral inhibition blocks these from sending action potentials so brain can pinpoint exact spot |
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mechanoreceptors (5) |
pressure,strech, vibration, acceleration sound |
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receptor location |
sent to corresponding somatosensory cortex pathway |
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pacnian corpuscles |
-touch and deep pressure -detect moderately rough/rougher surfaces -very sensitive to vibration -350 per fingy - 800 in palm -phasic tactile mechanoreceptor -onion like connective tissue layers at end of myelinated axon -to adapt, as stimuli continues pressure energy dissapates as layers slip like onion |
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meissners corpuscles |
phasic tactile myelinated mechanoreceptors - nerve endings in skin - light touch -encapsulated nerve endings surrounded by connective tissue capsule -fingers lips nipples, light touch, low frequency vibration threshold |
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merkels discs |
most senstive mechanoreceptor - slowly adapting type 1 myelinted -superficial layers of skin and mucosa -clustered beneath ridgs of fingertips making up fingerprint -mammary glands -merkels nerve endings are clustered into specialized epethelial structues called touch domes or hair discs |
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ruffini corpuscles |
-myelinated, encapsulated, slow adapting nerve endings found in deep layers of skin & joints - tied into collagen matrix -respond to stretch & torque -register mechanical deformation within joints and continuous pressure |
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free nerve endings |
skin,hair roots, eyes, other tissues - myelin/unmyelinated - most abundant skin receptors - touch & pressure & temp & nociception - tickling an itching (unmyelinated slow fibres)
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neurotransmitters used by effector neurons (2) |
acetylcholine & norepinephrine |
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where do sympathtic nerve fibres originate |
thoracic & lumbar regions of spinal cord |
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some preganglionic fibres pass thru ganglion chain w/o synapsing instead they end later in sympathetic colateral ganglia (halfway between CNA and effector) and post ganglionics take from here |
euuss |
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where do parasympathtic preganglioncs originate from |
braina nd sacral ares , very long cause terminate at terminal ganglia which are close to effector |
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what neurotransmitters do pre/post ganglioncs mau for sympa/parasympa |
both pres release acetylcholine
sympa - noradrenaline (adrenergic fibres)
parasympa - acetylcholine (cholnergic fibres) |
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postganglionic varicosities |
many swellings that release neurotransmitter over large area of innervated organ
-allows autonomics to influence whole organs |
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times of sympathetic dominance |
- fight or flight - digestion and urination arent essential functions at this time so they are inhibited |
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times of parasympathetis dominance |
-quiet restful circumstances - digestion/urination -no need for heart beat rapid in tranquil setting |
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advantages of dual autonomic innervation |
- accelerator and brake system in automobile -antagonistic, one can slow while other fires |
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tonic control |
one autonomic system controls |
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exceptions to dual innervation |
most innervated blood vessels - sympathetic most sweat glands - sympathetic salivary glands - both, not at same time |
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adrenal medulla |
modified sympathetic ganglion that doesnt give rise to postganglionic fibres - on stimulation from preganglionic it secretes hormones into blood -nor/epinephrine and reinforce sympathetic activity |
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cholinergic receptors (2) |
nitotinic and muscarininc |
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nicotinic receptors |
activated by nicotine - postganglionic cell bodies in all autonomic ganglia -binding of actylclne opens cation channels in postganglionic cell (Na and K) |
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muscarinic receptors |
effector cell membranes (parasympathetic) - bind with actyclne released from para post ganglionic, 5 subtypes all linked to G proteins for 2nd messenger systems |
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adrenergenic receptors (5) |
a1,a2,b1,b2,b3
- 2nd messenger G proteins |
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b2 receptors |
- epinephrine -cAMP -inhibitory - respiratory airway dilation |
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b1 reeptors |
nor/epinephrine - cAMP - heart - excitatory response, increased rate and force of cardiac contraction |
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a1 receptors |
norepinephrine -Ca2+ 2nd messenger -excitatory response -most sympathetic target tissues |
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a2 receptors |
norepinephrine -inhibits cyclic AMP production -inhibitory response to effector organ -decreased smooth muscle contraction in digestive tract |
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b3 receptors |
rare but found in adipose tissue, stimulates adipose to break down along with a2 |
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agonists |
drugs that bind to same receptor as neurotransmitter and mimics |
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antagonists |
drugs that bind w/receptor and block neurotransmitter response
- can use to block out para or sympa use of NT but keep other free of inhibition |
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medulla most responsible for? |
autonomic output -centres for cardio, respiratory and digestive are here |
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hypothalamus integrates what 3 systems |
autonomic somatic and endocrine for emotional response |
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some autonomic reflexes (urination, defecation, erection) are integrated mostly where |
spinal cord |
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emotional expresson nd characteristics are integrated by what? |
pre-frontal associatoon cortex and responses can take place thru hypothalmic-medullary pathways |
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cell bodies of motor neurons supplying muscles of head located where? |
brain stem |
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motor neuron axon terminals release_______ |
acetychlone |
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can motor neurons stimulate an dinhibt muscle cells |
only stimulate, inhibition must block synaptic input to dendrites and cell body |
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poliovirus |
destroys cell bodies of motor neurons - paralysis of affected neurons |
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ALS |
pathological changes in neurofilaments that -block axonal transport of crucial materials -accumulation of toxic levels glutamate - mitochondiral dysfunction - reduced energy -aggreation of misfolded proteins |
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End-plate potential (EPP) |
- graded potential similar to EPSP but much larger - more NT released from terminal button than presynaptic knob - motor end plate has bigger surface area for greater density of receptors -more ion channels open -creates the larger depolarization |
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where does neuromuscular juction hit muscle fibre and how is whole muscle contracted thru action potential |
middle and spreads both ways allowing contraction |
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higher centres involved in ANS |
- spinal cord - medulla - hypothalamus - pre-frontal associatio cortex |
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higher centres involved in SNS |
- spinal cord - motor cortex - basal ganglia - cerebellum - brain stem |
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where is site of action potential initiation of afferent neuron |
first excitbale portion of membrane adjacent to receptor |
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AChE |
destroys acetylcholine in synaptic cleft and parts can be reuptaken by synaptic vesicles |
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black widow spider venom |
explosive release of ACh at all cholinergic sites causimng prolonged depolarizaton which keeps diaphragm contracted and stopping the in and out of breathng and death |
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botulinim toxin |
blocking release of ACh from button - causes botulism (form of food poisoning) which prevents muscles from responding to nerve impulses - death due to respiratory failure because diaphragm cant contract - one of most lethal poisons |
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curare |
reversibly binds to ACh receptors on motor end plate - paralysis ensues, inability to contract diaphrgam causes death |
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OP's |
binds to AChE so acetylcholine isn't destoryed -death cause diaphragm cant repolarize and get phresh air |
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myasthenia gravis |
autoimmune body produces antibodies against own ACh receptors, not enough receptors to bind to causing weakness |
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treatment of myasthenia gravis |
drug neostigmine inhibits AChE giving chance for ACh to find receptor, instead of OP which irreversiblly bind to AChE |
