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

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