150 terms

Central Nervous System, Sensory Systems, Efferent Systems of the Peripheral Nervous System

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acetylcholine (ACh)
- neurotransmitter released from all autonomic preganglionic fibers, parasympathetic postganglionic fibers, and motor neurongs
vitreous humor
- jelly-like substance in the posterior cavity of the eye between the lens and retina
stereocilia
- auditory and vestibular hair cells that transduce mechanical movements into electrical signals
Sensory/Motor maps
- different regions of the body are represented differently in the brain
- certain regions take up much larger space in brain
association cortex
- involved in higher levels of processing
glial cells
- support neurons physically and metabolically; astrocytes, oligodendrocytes, microglia, ependymal cells
- brain tumors are a result of improper division
cerebrospinal fluid (CSF)
- bathe the brain and spinal cord
- made up of astrocytes that limits the exchange of materials which forms the blood-brain barrier
3 types of memory
- short-term
- long-term
- working
spinal reflexes
- information does not need to reach cortex (reflex arc)
receptors
- pick up sensations from the environment
transduction
- change of physical parameter into membrane voltage; causes receptor potentials and initiates APs
sensory pathway
receptor -> transduction -> receptor potential
receptive fields
- smaller fields lead to greater acuity
- discriminative ability to discern between two different points of stimulation
labeled line of sensory system
- receptors transmit signals to specific region of the cortex
types of pain receptors
- bony nerve endings called nociceptors; mechanical, thermal, polymodal
types of axon fibers in pain
A-delta fibers
- small, myelinated fibers; fast pain (prick)
C fibers
- unmyelinated fibers; slow pain (dull)
rods
- work in low light levels and gray-scale; high surface area
cones
- work in high light levels; small surface area
short wavelength - blue
middle wavelength - green
long wavelength - red
determination of color by cones
- each type of cone has a different absorption spectrum
magnocellular parallel pathway
- big cells
- fast processing (shape, motion, big picture)
- retina feeds into it
parvocellular parallel pathway
- small cells
- detail (color, texture)
- retina feeds into it
crossing of visual information
- left visual field projects to right side of the brain; right to left side
- crossing occurs at optic chiasm above the thalamus
receptive fields of retinal ganglion cells
on-center
off-surround
receptive fields of visual cortex
simple cells: on-middle, off sides
complex cells: on, off-each side; edge detector
depth perception
- in focus image lies on same points in both retinas
- when further or closer than focal plane, there is disparity in position of object between two retinas
middle ear
- transmits sound from eardrum to inner ear
middle ear bones (ossicles)
- malleus (hammer)
- incus (anvil)
- stapes (stirrup)
oval window - connection between middle/inner ear
discrimination of pitch/amplitude
- different portions of cochlea vibrate in response to different frequencies (low further from oval window)
- amplitude determined by the amount of vibrations coming through
detection of rotational acceleration in head
3 semicircular canals
- filled with fluid that move
- detected by hair cells embedded in cupula in ampulla
chemical sense detect presence of odorants/tastants
taste buds
- taste pore that allows entrance of testant molecule
- receptor cells respond to a single taste
odorants
- different receptor for every smell
info sent to cortical gustatory area in parietal lobe of cortex
organophosphates
- inhibits acetylcholinesterase activity
curare
- blocks ACh receptors
botulism toxin
- inhibits ACh release (relaxes muscles)
black widow spider toxin
- causes massive release of ACh from NMJ (muscle contraction)
Sympathetic/Parasympathetic
Positions where fibers emerge from spinal cord
Symp - nerves exit middle of spinal cord
Para - nerves exit from top/bottom of spinal cord
Sympathetic/Parasympathetic
Situations in which they are active
Symp - "Fight or flight" responses
Para - relaxed situations
Sympathetic/Parasympathetic
Effects on Organs
Symp - increase HR, BP, release of glucose from stores; decrease digestive/urinary function
Para - opposite effects of sympathetic system
Autonomic Nervous System
- controls most involuntary organ activities; sympathetic and parasympathetic
Output Organs for the PNS
Movement - muscle
Secretion - exocrine/endocrine glands
rhodopsin
- photopigment in rods
slow pain pathway
- impulses from polymodal receptors that respond to chemical receptors are carried by small, unmyelinated C fibers
tastant
- taste-provoking chemical
taste buds
- 50 long, spindle-shaped taste receptor cells packaged with supporting cells
taste pore
- small opening in taste bud through which fluids in the mouth come in contact with the surface of its receptor cells
tone
- pitch of sound
NMJ
- juncture between a motor neuron and a skeletal muscle fiber
motor end plate
- part of a skeletal muscle fiber that lies beneath the terminal button of the motor neuron and has receptor sites for binding ACh
agonists
- substance that binds to a neurotransmitter's receptors and mimics the neurotransmitters response
end-plate potential
- graded receptor potential that occurs at the motor end plate of a skeletal muscle fiber in response to binding with ACh
cholinergic fibers
- nerve fibers that release ACh as their neurotransmitter
adrenergic fibers
- nerve fibers that release norepinephrine as their neurotransmitter
somatic sensation
- sensory information arising form the body surface; somesthetic and proprioceptive input
Steps of Phototransduction
1. light hits rhodopsin
2. conformation change 11-cis retinal to all trans-retinal
3. all-trans retinal activates transducin
4. transducin causes activation of a PDE
5. PDE cleaves cGMP
6. cGMP-gated Na+ channels close due to lack of cGMP
7. photoreceptor hyperpolarizes
8. photoreceptor decreases release of glutamate from synaptic terminal
sclera
- visible, white, outer layer of the eye
otoliths
- sense organs in the inner ear that provide information about rotational changes in head movement; utricle and saccule
organ of Corti
- sense organ of hearing within the inner ear
chemoreceptors
- sensory receptor sensitive to specific chemicals
somatosensory cortex
- site of initial processing of somesthetic and proprioceptive input
somatic nervous system
- innervates skeletal muscles; consists of axonal fibers of alpha motor neurons
hippocampus
- portion of the temporal lobe that is crucial for forming long-term memories
frontal lobes
- responsible for voluntary motor output, speaking ability, and elaboration of thought
kinocilium
- the one cilium in a vestibular hair cell
Wernicke's area
- concerned with language comprehension
epilepsy
- large number of neurons undergo abnormal, synchronous APs that produce involuntary spasms
dorsal root
- where afferent fibers carrying incoming signals from peripheral receptors enter the spinal cord
dorsal horn
- contains cell bodies of interneurons on which afferent neurons terminate
consolidation
- process of transferring and fixing short-term memory traces into long-term stores
amygdala
- processes inputs that five rise to the sensation of fear
sensory afferent
- pathway into the CNS carrying information that reaches the level of consciousness
retina
- innermost layer in the posterior region of the eye that contains photoreceptors (rods/cones)
photoreception
- sensory reception response to light
perception
- conscious interpretation of the external world created by the brain from a pattern of nerve impulses
oval window
- membrane covered opening separating the middle ear from the inner ear
optic nerve head
- nerve fibers leaving the retina that relay information about visual input
lateral inhibition
- most strongly activated signal pathway originating from the center of a stimulus area inhibits the less excited pathways from the fringe areas
cochlea
- snail-shaped portion of the inner ear that houses the receptors for sound
analgesic systems
- pain relieving
temporal lobes
- process auditory input
somatic cells
- body cells
reflex
- response that occurs automatically without conscious effort
PNS
- nerve fibers that carry information between CNS and other parts of the body
parietal lobes
- contain somatosensory cortex
occipital lobes
- process visual input
nerve
- bundle of peripheral neuronal axons, afferent and efferent
dorsal root ganglion
- cluster of afferent neuronal cell bodies adjacent to the spinal cord
effector organs
- muscles or glands innervated by the nervous system that carry out the nervous system's orders to bring about a desired effect
efferent division
- portion of the PNS that carries out instructions to effector organs from the CNS
cognition
- act of "knowing"; awareness and judgement
CNS
- brain and spinal cord
amnesia
- lack of memory that involves whole portions of time; retrograde (past events) and anterograde (inability to consolidate information for long-term use)
emotion
- encompasses subjective emotional feelings and moods
morphine
- powerful analgesic; part of the opium poppy
fast pain pathway
- small, myelinated A-delta fibers that carry pain signals
working memory
- briefly holds and processes data for immediate use (both new and old information)
neuroendocrinology
- study of relationships between the nervous and endocrine systems
motor neurons
- innervate skeletal muscle and their axons constitute the somatic nervous system
sympathetic ganglion chain
- located along either side of the spinal cord and is location of postganglionic neurons
visual system functioning as a 10 log-unit range
- changes visual sensitivity to prevent response saturation while keeping contrast sensitivity constant
Sympathetic/Parasympathetic
Neurotransmitters Used
Symp - preganglionic - Acetylcholine, postganglionic - Norepinephrine
Para - pregangionic/postganglionic - Acetylcholine
Sympathetic/Parasympathetic
Types of Receptors Triggered
Symp - alpha1/beta1 - excitatory, alpha2/beta2 - inhibitory
Para - nicotinic, muscarinic
Sympathetic/Parasympathetic
Location of Ganglia
Symp - collateral ganglia - halfway between CNS and innervated organs
Para - terminal ganglia - in or near effector organs
Steps by which activation of somatic nervous system leads to muscle contraction
1. Motor neuron axons terminals release ACh
2. Excitation/contraction of innervated muscles
3. Motor neurons can only stimulate skeletal muscles
corpus callosum
- thick band of nerve fibers that connects the two cerebral hemispheres structurally and functionally
efferent neurons
- found in PNS and originate from the CNS
afferent neurons
- found in PNS and send sensory information to the brain
Hemispheres
left - detail stuff
right - big picture stuff
Cerebral Cortex Layers
Upper - gray matter
Lower - white matter
Cerebral Cortex Neuron types
stellate cells - small dendritic and axonal fields
pyramidal cells - longer axons, send information out of cortical column
Cerebral Cortex Lobes
occipital - primary visual cortex
temporal - primary auditory cortex
parietal - primary somatosensory cortex
frontal - primary motor cortex
hair cells of cochlea transduce information
- when hair cells bend to stereocilium, mechanically gated channels are opened causing inflow of K+
outer ear
- pinna
- ear canal
- tympanic membrane (eardrum)
phasic receptors
- rapidly adapting response
tonic receptors
- slowly adapting response
primary cortex
- responsible for voluntary motor ouptut
Aplysia
habituation - tune out working stimulus
sensitization - respond quicker 2nd time
cerebral cortex language ability
Broca's - speaking ability
Wernicke's - comprehension
acquisition of memory
- consolidation
- change in synaptic efficiency - short term
- change in synaptic connections - long term
limbic system
- controls behavior, motivation
amygdala - fear
astrocytes role in blood-brain barrier
- surround blood vessels in bran and limit exchange of materials
ependymal cells
- stem cells; new glia and neurons, active in hippocampus
microglia
- immune cells of brain
astrocytes
- hold neurons in proper spatial relationship
- guide neurons during development
- form blood-brain barrier
- repair injuries
interneurons
- lie between efferent and afferent neurons and important in integration/processing of life
pons
- relays signals from the forebrain to the cerebellum
midbrain
- associated with vision, hearing, motor control
aphasia
- language disorder caused by damage to cortical areas
capsaicin
- activates peripheral receptors of afferent C fibers
mitral cells
- in olfactory pathway
myopia
- nearsightedness
diencephalons
- consists of thalamus and hypothalamus
proprioception
- awareness of position of body parts in relation to one another and surroundings
accomodation
- ability to adjust the strength of the lens in the eye so that both near and far sources can be focused on retina
basilar membrane
- forms the floor of the middle compartment of the cochlea and bears the organ of Corti
receptor potential
- graded potential change that occurs in a sensory receptor in response to a stimulus
acetylcholinesterase (AChE)
- enzyme that inactivates ACh
adrenal medulla
- secretes hormones epinephrine/norepinephrine into the blood in response to sympathetic stimulation
inner ear
cochlea
- scala tympani - outside of coil
- scala vestibuli - inside of coil
- cochlear duct
pain neurotransmitters
- substance P
- glutamate
cerebellum components
vestibulocerebellum - balance
spinocerebellum - coordination of complex movements
cerebrocerebellum - planning movements
thalamus
- relay/integratoin station for sensory inputs
- controls attentions
oligodendrocytes
- form myelin
meninges
three membranes that wrap CNS
- dura mater
- arachnoid mater
- pia mater
prostaglandins
- local chemical mediators
memory mediated by...
- hippocampus, cerebellum, prefrontal cortex
hypothalamus
- regulates internal environment; homeostasis
brain stem
- centers for life support systems
cerebrum
- consists of basal nuclei and cerebral cortex
medulla
- deals with involuntary functions
subcortical structures
- basal nuclei, thalamus, hypothalamus
basal nuclei
- motor control
opiate receptors
- inhibitory interneurons release enkaphalin at the pain-fiber terminal and bind with these