Exam 4: Nervous System Flashcards
what is white matter made of
bundles of myelinated axons
neural tracts
-propagation of action potential from one area to the next
what is gray matter made of
bundles of unmyelinated axons
neuron cell bodies & dendrites
-integration and relaying of signals
what is a synapse
junction between two cells in the nervous system
what are the different components of synapses
neuron and effector synapse (muscle or gland)
neuron and neuron synapse
what do pre-synaptic neurons do
send signals (away from CNS)
what do post-synaptic neurons do
receive signals (to CNS)
what are the types of synapses
electrical synapses
chemical synapses
What are electrical synapses
pass electrical signal directly from cytoplasm of one cell to another via gap junctions
-allows rapid bidirectional signal conduction (especially important in the heart)
what are chemical synapses
conducts signals via neurotransmitters
-very common (nervous system uses this communication the most)
Steps of neurotransmitter release
Same as acetylcholine release EXCEPT:
-neurotransmitter binds to receptors on post-synaptic neuron’s dendrite (instead of muscle fiber)
-axon terminal of pre-synaptic neuron synapses to post-synaptic neuron
what do neurotransmitters effect
effects are on target cells (like neurons or muscles) via receptors
how are neurotransmitters classified
based on structure
-except acetylcholine - its in its own category
Describe acetylcholine
neurotransmitter that effects skeletal muscle, autonomic nervous system, smooth & cardiac muscle
-within the CNS
what is acetylcholine secreted by
cholinergic neurons
what does acetylcholine bind to
cholinergic receptors
what are the different neurotransmitters
acetylcholine
monoamines
amino acids
purines
neuropeptides
gases
what are the 2 types of monoamine neurotransmitters
catecholamines
indolamines
what are catecholamines
epinephrine, norepinephrine, dopamine
what are indolamines
serotonin, melatonin
what is a specific amino acid neurotransmitter
GABA - inhibitory (inhibits things)
what is a specific gas neurotransmitter
nitric oxide
what are the responses to neurotransmitters
response of post-synaptic neuron to a neurotransmitter can vary:
-excitatory and inhibitory responses can occur
what does an excitatory post-synaptic potential (EPSP) result in
depolarization (+ charge) of post-synaptic neuron
-due to Na+ (sodium) influx
what does an inhibitory post-synaptic potential (IPSP) result in
hyperpolarization (- charge) of post-synaptic neuron
-due to Cl- (Chloride) influx or excessive K+ (potassium) efflux (leaving cell)
describe summation
-signals from other neurons occur at dendrites
-these are graded potentials (weak stimulus produces a weak response, strong stimulus produces strong response)
-graded potentials summate (total up) at trigger zone
-If threshold (-55 mV) is reached, an action potential will be produced and propagated along axon to axon terminals
——> leads to something like neurotransmitter release
How many major regions exist in the adult brain
4
what are the 4 major regions of the adult brain
- Cerebrum
- Diencephalon
- Brainstem
- Cerebellum
what does each region of the brain contain
nuclei
-clusters of neuron cell bodies in the Central Nervous System (CNS)
what is the cerebrum responsible for
higher brain functions
what does the cerebrum contain
cerebral cortex - layer of gray matter surrounding cerebrum
left & right cerebral hemispheres - separated by longitudinal fissure
how does communication across hemispheres of cerebrum occur
through commissures
-connections across hemispheres
-corpus callosum - biggest commissure
what is the left hemisphere of the brain responsible for
language function
what is the right hemisphere of the brain responsible for
spatial perception, nonverbal reasoning
True or False
-myth of lateralization is oversimplified
true
what are the cortical lobes of the brain
frontal lobe
prefrontal cortex
parietal lobe
occipital lobe
temporal lobe
what are the functions of the frontal lobe
-motor functions
-planning movements and executing movements
what are the functions of the prefrontal cortex
-most anterior portion of the frontal lobe
-associated with personality
-regulation of emotional behavior & mood
-motor decision making
what is the function of the parietal lobe
processing of somatic sensations from body
what is the function of the occipital lobe
visual processing
what are the functions of the temporal lobe
-auditory processing
-regions for memory formation
what are the special functions of the cerebral cortex
-speech
-memory
what is speech
integration of sensory information and generation of words
what areas of the brain make speech possible
Wernicke’s area
-language development
Broca’s area
-word formation
Arcuate Fasiculus
-connects Wernicke’s & Broca’s areas
what is memory
storage of knowledge
what are the different kinds of memory
working memory
short-term memory
long term memory
describe working memory
transient (shorter than short-term memory)
-task associated
describe short-term memory
lasts minutes to day
-susceptible to trauma
describe long-term memory
lasts for years or more
-consolidation (transfer of short-term to long-term memory)
-strengthening of synaptic connections
how are synaptic connections strengthened in long-term memory
-cAMP responsive transcription factor activates transcription for proteins
-dendritic spines - more/stronger synaptic connections
what are the types of long-term memory
declarative
procedural
what is declarative long-term memory
retention of facts
-hippocampus=facts
-amygdala=associated emotions
what is procedural long-term memory
skills
cerebellum and premotor area
what makes up the limbic system
olfactory cortex, deep cortical regions
what does the limbic system effect
-mood (production)
-emotions/visceral responses to emotions (production)
-motivation
how is there a close relationship between hippocampus & limbic system
evolutionary adaptation
what makes up the diencephalon
-thalamus
-hypothalamus & pituitary
what is the function of the thalamus
relay between cerebrum and rest of nervous system
what is the function of the hypothalamus & pituitary
-homeostatic regulation
-signal for regulatory mechanisms
-endocrine function
what makes up the brainstem
-midbrain (superior)
-pons
-medulla (inferior)
The location of nuclei of most cranial nerves
brainstem
what functions are regulated by the brainstem
-respiration
-cardiac rhythm
-eye movements
-chewing (mastication)
-communication
what is the function of the cerebellum
balance and coordination
how does the cerebellum work
using the cerebellar comparator function
describe the cerebellar comparator function
-receives output from cerebrum to spinal cord
-compares with sensory input from environment
-sends information to correct motor commands for coordination
what is the function of the autonomic nervous system
unconscious/involuntary control of organ functions
Examples:
-GI Function
-Heart Rate
-Blood Pressure
-Stress Response
-diameter of airways
-pupil dilation/constriction, etc.
what are the 2 branches of the autonomic nervous system
sympathetic
parasympathetic
What is the sympathetic branch of the ANS responsible for
“fight-or-flight” response
-physical activity & stress
Ex. increase Heart Rate, blood pressure, respiration
what is the parasympathetic branch of the ANS responsible for
“Rest-and-digest” response
-slow functions like digestion
-Vagus nerve stimulation (Cranial Nerve X (10))
Ex. decrease heart rate, blood pressure, respiration
Describe the 2 neuron series of the ANS
preganglionic neuron
-cell body located within the CNS
postganglionic neuron
-cell body located within an autonomic ganglia
*sympathetic chain ganglia (sympathetic branch)
*terminal ganglia, near or on surface of effector (parasympathetic branch)
True or false
-autonomic neurons secrete neurotransmitters
True
what in the ANS is based on the type of neurotransmitter that is released
neuron type
what do cholinergic neurons secrete
acetylcholine neurotransmitter
what do adrenergic neurons secrete
norepinephrine neurotransmitter
what neurotransmitter do cholinergic receptors bind to
acetylcholine
what are the 2 subtypes of cholinergic receptors
nicotinic receptors
muscarinic receptors
where are nicotinic receptors found
on all postganglionic neurons of the ANS
-both sympathetic and parasympathetic branches
where are muscarinic receptors found
on effectors of the parasympathetic branch of ANS
what neurotransmitter do adrenergic receptors bind to
norepinephrine and epinephrine
where are adrenergic receptors found
on effectors of the sympathetic branch of ANS
what are the 2 subtypes of adrenergic receptors
alpha adrenergic receptors
-respond more to norepinephrine than epinephrine
Beta adrenergic receptors
-respond equally to norepinephrine & epinephrine
function of preganglionic neurons
secrete neurotransmitter that exerts its effects on postganglionic neurons
function of postganglionic neurons
secrete neurotransmitters that exert their effects on effector organs
where do many effector organs have input from
sympathetic and parasympathetic branches of the autonomic nervous system
-often antagonistic effects (opposite) of one another
describe the response to stress
fast acting response (within seconds) resulting in mass activity by sympathetic branch of ANS:
-activates adaptations to escape stressor
*increase HR, BP, blood flow to muscles, respirations
*inhibits non-essential activities like digestion, reproduction
-sympathetic preganglionic neurons innervate adrenal medulla
-adrenal medulla secretes epinephrine
-epinephrine travels to multiple effectors in the body via the bloodstream
——-> Results in widespread effects
Describe ANS activity of the Eyes
sympathetic: pupil dilation
parasympathetic: pupil constriction
Describe ANS activity of the GI Tract
sympathetic: decrease digestive activity
parasympathetic: increase digestive activity
Describe ANS activity of the heart
sympathetic: increase heart activity
parasympathetic: decrease heart activity
Describe ANS activity of the blood vessels
sympathetic: mostly vasoconstriction (alpha adrenergic receptors) - increases BP
*some vasodilation (beta adrenergic receptors)
parasympathetic: vasodilation of some blood vessels
what are receptor agonists
drugs/medications that mimic the natural effects of neurotransmitters
sympathetic drug example: epi pen
parasympathetic drug example: diuretics
what are receptor antagonists
drugs/medications that block the natural effects of neurotransmitters
ex. anticholinergics (block acetylcholine)
what are special senses
those that use a specific sensory organ:
-vision (the eye)
-hearing and balance (the ear, which includes the auditory system and vestibular system)
-smell (the nose)
-Taste (the tongue)
what are general senses
those that are detected across the body
-includes visceral senses (organs)
-includes somatic senses (5)
*touch
*pressure
*temperature
*pain
*proprioception (awareness of body position)
what are the different sensory receptors
-mechanoreceptors
-chemoreceptors
-thermoreceptors
-nociceptors
what do mechanoreceptors detect
mechanical stimuli
-vibration
-touch
-pressure
what do chemoreceptors detect
chemical stimuli
what do thermoreceptors detect
temperature
what do nociceptors detect
pain
what is receptor potential
graded potential due to sensory detection
what do primary receptors do
conduct action potentials in response to sensory stimulus
what do secondary receptors do
have no axons
-release of neurotransmitters to trigger action potential in adjacent neuron
what properties of a stimulus must the Central Nervous system distinguish
modality
-what kind of stimulus (touch, temp, pain, etc.) depending on the type of receptor activated
location
-where the stimulus is, based on topographical organization of receptors
*lateral inhibition=strong contrast between activated and inactive neurons (helps isolate location of stimulus)
Intensity
-strength of signal, based on Action potential frequency
Duration
-length of signal, based on duration of series of action potentials
*adaptation=decreased sensitivity to continuous stimulation
why does rate of adaptation vary
due to different adaptation receptor types
what are slow adapting receptors
Tonic Receptors
-generate signal as long as stimulus is present
Ex. baroreceptors, irritant receptors (things that should be monitored continuously)
what are fast adapting receptors
phasic receptors
-reduced signal with continued stimulus
Ex. long, non-painful touch - adapting filters out extra information such as wearing glasses or a bracelet
how does adaptation occur
K+ (potassium) channels opening, causing repolarization
Na+ (sodium) channels inactivating
what are the components of the special sense vision
-eyes
-accessory structures:
*eyebrows, eyelashes - protection
*eyelids, lacrimal glands - lubrication & antimicrobial properties via tears
*extrinsic eye muscles - movement of the eye
-Optic nerves and other nervous system components
*results in transmission & reception of signals
anatomy of the eye
sclera - whites of eyes
cornea - allows light to refract (bend)
iris - colored portion
pupil - lets light in
lens - flat or round in shape depending on how closely you are looking at an object
retina
optic disk
blind spot
describe the eye focusing system
-light rays are refracted by the eye
-focal point where light rays converge
-projection of object image at retina
distant object (>20 feet)
-parallel light rays
-in focus when lens is flatter in shape
near object (<20 feet)
-light rays come in at oblique angles
-in focus when lens in rounder in shape
What is accommodation when referring to vision
keeping objects in focus via lens changing shape (use of ciliary muscle)
Distant objects:
-ciliary muscles relax, there is ligament tension on lens —->flatter lens shape
Near objects:
-ciliary muscles contract, less ligament tension on lens —->rounder lens shape
*as we age, lose ability to accommodate lens for vision
-can also be genetic (why people need glasses)
Are images inverted at the retina
yes
what are the components of the retina
neurons
-photoreceptors (rods & cones)
-bipolar cells
-ganglion cells (axons form optic nerve)
retinal pigment epithelium (RPE)
-dark epithelium that absorbs light & reduces scatter
what are photoreceptors
rods and cones
what are rod photoreceptors
responsible for non-color, & low-light vision
-most numerous photoreceptor, distributed over most of the retina
what are cone photoreceptors
responsible for color vision & visual acuity
-less numerous
-concentrated at fovea (fovea centralis)
describe photoreceptor structure
-visual pigments (of both rods and cones) bound to disk membranes in outer segments
-ion channels
what is the rods pigment
rhodopsin
-purple pigment
-opsin bound to 11-cis-retinal
what are the cones pigments
three photopsins
-analogous to rhodopsin
-have color-sensitive pigments that are sensitive to different wavelengths of light
describe process of phototransduction in the dark
-11-cis retinal is bound to opsin (keeps ion channels open)
-photoreceptors continuously depolarize
-causes continuous release of glutamate (neurotransmitter)
-glutamate binds to receptors on bipolar cells
Effects on bipolar cells:
ON bipolar cells
-glutamate binds to receptors, ion channels close
-ON bipolar cells hyperpolarize (inhibited)
OFF bipolar cells
-glutamate binds to receptors, influx of ions
-OFF bipolar cells depolarize (excited/active)
describe the process of phototransduction in the light
-11-cis retinal changes shape
-opsin converts from dark to light state
-biochemical pathway leads to hyperpolarization of photoreceptor
-inhibition of glutamate release
Effects on bipolar cells:
ON bipolar cells depolarize (active)
OFF bipolar cells hyperpolarize (inhibited)
How does the optic nerve carry signals to the brain
-bipolar cells synapse with ganglion cells
-ganglion cell axons are what create optic nerve
describe the visual pathway
-visual field: temporal and nasal halves
-each half projects on opposite side of retina
-optic chiasm
*nasal part of optic nerve crosses over
*temporal part of optic nerve does not cross
-axons synapse in thalamus
-project to visual cortex in occipital lobe
what is the human visible spectrum
400 - 700 nanometers
Explain human trichromatism
humans have 3 types of cones
-short, medium, long wavelength cones
-each opsin is color sensitive
*short=blue, medium=green, long=red
what does tetrachromatic mean
something has 4 types of cones
-gives ability to see in ultraviolet (UV) spectrum
-like constantly viewing things under a black light
birds are tetrachromatic
what does dichromatic mean
something has 2 cones
-see more diluted colors like yellows, blues, grays
dogs are dichromatic
