Unit 5 - PNS Somatic Sensory Flashcards
CNS major components
brain and spinal cord
PNS major components
cranial nerves and spinal nerves
Two divisions of PNS are what?
Somatic Nervous System SNS
2 components, what are they?
Autonomic Nervous System ANS
2 components what are they?
SNS two subdivisions, what are they?
skeletal muscle control (conscious or voluntary) efferent
sensory division (afferent)
ANS two subdivisions, what are they?
sympathetic
parasympathetic
two types of neurons in this system
BOTH the SNS and ANS
use BOTH somatic sensory annnnnd somatic motor NEURONS.
what’s the difference between a somatic sensory neuron (of SNS) and a visceral sensory neuron (ANS) ?
a somatic sensory neuron conducts stimulus information
EX: tactile receptor in the skin
a vis earl sensory neuron (ANS) provides input to activate the ANS
what’s the difference between a somatic motor neuron of the SNS and a visceral motor neuron of the ANS?
a somatic motor neuron innervates skeletal muscle fibers
a visceral motor neuron innervates skeletal, cardiac, and smooth muscle, glands and adipose tissue
define a receptor
dendrites or specialized cells that transmits action potentials from the body and external environment to the CNS
sensory information coming in from
receptors
somatic senses are sometimes referred to as the
general senses
special senses are all in
in the head
photoreceptors, touch receptors, pain receptors, etc are examples of
somatic sensory neurons
skeletal muscle for the somatic motor neurons in the SNS, but there is skeletal muscle tissue innervated in the ANS TOO!! what muscle
the diaphragm, innervated by visceral motor neurons.. it is skeletal muscle
a receptor is a
dendrite
a sensation is really just an
action potential… the arriving info to CNS
somatic sense
conscious perception over
olfaction (smell) special senses
chemoreceptor - smelling a molecule
vision special senses
photoreceptor - rods and cones, cones allow u to see color.
3 types cones
red - red wavelengths
blue - blue wavelengths
green - green wavelengths
visible spectrum of light are the receptors we can
see, UV light, infrared - we don’t have those receptors
men missing two alleles that determine
color vision… that’s why men are more apt to color blindness than women. x linked recessive traits show up wayyy more than in women, because they’re missing the other piece of that chromosome - XY, vs women who have XX. In order for a boy to be colorblind, he has to get it from his mom. It means all of your daughters will carry the trait if a male has the trait. It is an X-linked trait. the severity of colorblindness in a woman if she gets it will be tend to be way worse than in a male.
can stimulate the milk line… Mary got bit! and a third nipple developed… no areola
can have a 3rd nipple
gustatory
chemoreceptors! supertasters, more hairs - wine tasters
equilibrium
MECHANORECEPTOR
function of semicircular canals, different planes of body… stimulates mechanoreceptors to tell u what plane your body is in… there is fluid in the canals that tells you your orientation.
in vestibule, tells you what position your head is in. when bend head, otaliths (crystals) slide over a mechanoreceptor signaling what position your head is in.
so, equilibrium of head and equilibrium of body
hearing
MECHANORECEPTOR
function of cochlea. cochlea, semicircular canals and ampulla all full of fluid.
fluid in cochlea moves because of sound waves.
sensory neural deafness will not be helped by a hearing aid… you need a cochlear implant. tectorial membrane is damaged.
another type of deafness but not really deaf… just arthritis in the auditory ossicles… called conduction deafness. hearing aids can easily help.
name the special senses
olfaction, vision, gustation, equilibrium, hearing
found in special sense organs
general senses
temperature
pain
touch
pressure
vibration
proprioception
scattered throughout body.
all receptors have
receptor stimulus - means they only respond to specific stimulus.
ex. chemoreceptor only responds to a specific chemical
receptive field
remember the dendrites are branching… the areas they are branching to is the receptor field.
two point discrimination - large receptive fields where if you place two fingers in one area, you will only feel one touch.
adaptation
reduction in sensitive of a constant stimulus… why you can’t smell candle after you’ve been around it for a while
your nervous system quickly adapts to stimuli that are painless and constant
(adaptation) tonic receptors
always ACTIVE.
slow to adapt
show little peripheral adaptation.
remind you of injury long after the initial damage was done.
(adaptation) phasic receptors
“they go in and out of phase”
normally inactive
become active for a short time whenever a change occurs
provide info about the intensity and rate of change of a stimulus
are fast-adapting receptors
ex: when you leave your sunglasses on the top of your head and you forget that they’re there. action potential is not being sent anymore.
lots of receptors, small receptor fields in
lips and fingertips, very small receptor fields, why they’re so sensitive
receptor activity
way of saying… “it sent that action potential”
- info arrives at receptor (binds to receptor or stimulates receptor in whatever way)
2 .sends a receptor potential (local potential)
- generator potential (achieved when local potential from previous step reaches threshold)
- transduction (transfer of the information into your primary sensory cortex)
interoreceptors
no perception over (visceral organs)
exteroreceptors
have perception over (monitor external environment)
proprioceptors
none found in the thoracic and abdominopelvic cavities… bc they’re not intended to be moving!
they monitor positions of skeletal muscles and joints
brachial plexus in left arm - referred pain
heart pain
more examples of referred pain:
pain between shoulder blades - gallbladder
pain in lower back - kidneys
groin pain - appendicitis
nociceptors
nociceptors - no pain! pain receptors
found in skin, joint capsules, blood vessel walls, periosteum around bones
sensitive to: temperature extremes, mechanical damage, chemicals….
way too cold???? A NOCICEPTOR WILL BE STIMULATED - NOT A THERMORECEPTOR**
(same for way too hot = burn, so nociceptor stimulated)
“free nerve endings”
with large receptive fields
branching tips of dendrites
not protected by accessory structures
two types of axons will transmit pain sensations: type a fibers and type C fibers
type a (myelinated) - acute, very localized (u know where its happening) sharp pain. fast, prickling pain. often trigger a somatic reflex, reach CNS quick. Relayed to primary sensory cortex and receive conscious attention. Reflex may happen first though.
type c - slow pain, dull - throbbing (“c” usually indicative of “chronic” pain). cause a generalized activation of reticular formation and thalamus. Become aware of pain but only have a general idea of the area affected.
touch something too cold???? too hot??? what kind of receptor will be stimulated?
A NOCICEPTOR WILL BE STIMULATED - NOT A THERMORECEPTOR**
thermoreceptors
two types of thermoreceptors: warm (work in a warm range until it gets too hot) cold (work in cold range until it gets too cold).
temperature sensations:
conducted along the same pathways that carry pain sensations, hence why if something is too hot it just plain hurts.
found in:
dermis
skeletal muscles
the liver
the hypothalamus
mechanoreceptors
3 CLASSES OF MECHANORECEPTORS
1. Tactile receptors
2. Baroreceptors
3. Proprioreceptors
sensitive to stimuli that distort their plasma membrane…
contain mechanically gated ion channels whose gates open or close in response to
stretching, compression, twisting, other distortions in the membrane.. 1:00:06 (3 other)
nociceptor stimulated instead if RANGE OF MOTION IS TOO MUCH***
free nerve endings, what class do they belong to and talk about them.
tonic receptors with small receptive fields… able to achieve great two point discrimination. lightly touching.. can detect!
Situated between epidermal cells
branching tips of dendrites
not protected by accessory structures
two types axons will transmit pain sensations - type A and type C fibers
root hair plexus, what class do they belong to and talk about them.
wrapped around root hair! fine touch sensations, where little hairs move on arms. are phasic, fine touch. adapt rapidly.
Monitor distortions and
movements across the
body surface wherever
hairs are located
Adapt rapidly, so are best
at detecting initial contact
and subsequent
movements
tactile discs, what class do they belong to and talk about them.
up in epidermis, called Merkel discs too. fine touch/pressure. EXTREMELY sensitive to other tonic receptors around them, can be stimulated by other receptors around them. have very small receptive fields.
tactile corpuscles or meissners, what class do they belong to and talk about them.
fine touch, pressure, low-frequency
**adapt after one second of contact
large structures
eyelids, lips, fingertips, nipples, external GENITALIA… ahem this might allude to something… hehe
*gotta change it up, otherwise no one is interested.. why it GETS BORING!!!!
lamellated corpuscles, what class do they belong to and talk about them.
pacinian corpuscles
sensitive to deep pressure
fast adapting receptors
most sensitive to high-pulsing or high-frequency vibrating stimuli
Ruffini corpuscles, what class do they belong to and talk about them.
also sensitive to pressure/distortions of skin.
located DEEEEP in the dermis. in the reticular layer of the dermis, to be exact.
tonic receptors that show little, if any adaptation.
protects collagen from tearing… which can result in stretch marks
projection
The area where the CNS makes you
perceive that the sensation started
if RANGE OF MOTION IS TOO MUCH***
nociceptor stimulated instead of mechanoreceptor
(1 of 3 categories of what)
*tactile receptors (there are many)
(1 of 3 categories of MECHANORECEPTORS)
provide sensations of touch, pressure, vibration…
free nerve endings
root hair plexus
merkel discs
meissners corpuscles
pacinina corpuscle
Ruffini receptors
ALLLLL TACTILE RECEPTORS
Provide the sensations of touch, pressure, and
vibration
–Touch sensations provide information about
shape or texture
–Pressure sensations indicate degree of
mechanical distortion
–Vibration sensations indicate pulsing or
oscillating pressure
baroreceptors (1 of 3 categories of what)
1 of 3 categories of MECHANORECEPTORS
Monitor change in pressure
Consist of free nerve endings that branch within elastic tissues - in wall of distensible organ (such as blood vessel)
Respond immediately to a change in pressure, but adapt rapidly.
all distensible organs: bladder, lungs, heart, blood vessels etc!
proprioceptors (1 of 3 categories of what)
1 OF 3 CATEGORIES OF mechanoreceptors!!!
Proprioceptors - 3 major groups…
- muscle spindles
monitor skeletal muscle length
trigger stretch reflexes.
patellar knee jerk - hitting that proprioceptor - Golgi tendon organs
located at the junction between skeletal muscle and its tendon
stimulated by tension in tendon
monitor external tension developed during muscle contraction - receptors in JOINT CAPSULES
free nerve endings detect pressure, tension, movement at the joint
Chemoreceptors, talk about them
respond only to water-soluble and lipid-soluble substances dissolved in surrounding fluid
receptors exhibit peripheral adaptation over period of seconds, central adaptation may also occur…
KEY TERMS - CENTRAL ADAPTATION - WHAT IS? Central adaptation is the ones that are inside the body that we don’t necessarily have any sensitivity too, or aren’t consciously aware of.
Chemoreceptors are located in the carotid bodies and aortic bodies. They monitor pH, carbon dioxide, and oxygen levels in arterial blood.
Somatic Sensory Pathways do what? What are 3 major somatic sensory pathways
afferent pathways, they are routes of axons basically
carry sensory info from the skin and musculature of the body wall, head, neck , and limbs
- spinothalamic pathway
- posterior column pathway - in posterior white columns so we know its sensory which means its ASCENDING!
- spinocerebellar pathway - postural, proprioception
spinothalamic pathway
don’t have good two point discrimination… provides conscious sensations of poorly localized crude touch, pressure, pain, and temp.
posterior column pathway
carries sensations of highly localized “fine” touch, pressure vibration and proprioception
*FINE TOUCH, that’s a big distinction!
Spinocerebellar pathway
cerebellum receives proprioceptive info about position of skeletal muscles, tendons, and joints
posterior column pathway consists of the fascicles gracilis and fascicles cuneatus
would go up to medulla and then to the nucleus gracilis or cuneatus (in the medulla)
corticospinal tract tells you
it went down from the cerebral cortex to the spinal cord… DESCENDING
rubrospinal tract
went from red nucleus and then went down to spine… DESCENDING
somatic sensory pathways as info travels towards brain it will…
cross over!! crossing over occurs somewhere in the spinal cord… it DESSUSSICATES!!!!!!
homunculus
little slice of a part of the cerebral cortex and what sensory areas are associated with that part of the cortex…
referred pain
when you’re getting pain from viscera and it’s traveling in same fasciculus pathway that’s out there by the skin… referred to the closest structure
phantom pain
when you lose a limb but u feel its still there… the soma up in the dorsal root ganglia is still alive… still sending impulses.
chronic pain
slow pain, type C fiber usually… hard to pinpoint… lots of time referred pain can be associated with chronic pain…
if there’s slow throbbing (chronic) pain… that means thee’s acute pain! is the opposite of chronic pain! it’s on type A fibers… stabbing sharp pain.
automatic nervous system?
autonomic nervous system!
Sympathetic division of the ANS aka
thoracocolumbar division
talk about sympathetic division
axons energy from thoracic and superior lumbar segments of spinal cord.
innervate ganglia relatively close to spinal cord
kicks in only during period of exertion, stress, or emergency.
Parasympathetic divison of ANS aka
craniosacral division!
axons energy from brain stem and sacral spinal segments
innervate ganglia very close (or within) target organs
“thanksgiving dinner”
body very very active but you become consciously tired because all the blood is shunted down to your digestive system
going to to walk after you eat really doesn’t help you out as far as speeding along digestion… don’t wanna be exercising while processing food
yin and yang systems
sympathetic and parasympathetic division
MOST OFTEN (NOT ALWAYS) these divisions have opposing effects…
if the sympathetic division causes excitation, the parasympathetic causes inhibition
2 divisions may work independently -
only one division innervates some structures… most often structures have dual innervation - the heart (acetylcholine in the body is excitatory where in the heart, acetylcholine is inhibitory - will kill you).
organ does own regulation vs external factors
intrinsic regulation… the heart does both… can generate own heartbeat also can be sped up or slowed down so extrinsic regulation too
sexual excitation
parasympathetic activation (climax is SYMPATHETIC THOUGH).
cranial nerves 3, 7, 9, 10 and sacral nerves
PARASYMPATHETIC DIVISION
autonomic ganglia - preganglionic fibers of sympathetic division are how long in comparison to postganglionic
preganglionic are short while post are long - fibers synapse relatively near spinal cord… sympathetic chain ganglia
sympathetic chain ganglia innervates
visceral effectors in thoracic cavity, hear, body, wall, and limbs
autonomic ganglia - collateral ganglia are located within
abdominopelvic cavity… includes celiac, superior, and inferior mesenteric ganglia… innervates visceral effectors in abdominopelvic cavity
autonomic ganglia - adrenal medulla
center of adrenal gland
acts of endocrine gland
targets organs and systems throughout body
adrenal medulla can produce adrenaline aka norepinephrine and release it
women lifts car up!
adrenaline needed, but to keep holding it up ADRENAL GLANDS FOR SUSTAINED ACTIVITY
autonomic ganglia - sympathetic division list of responses
typical responses -
1. heightened mental alertness
2. increased metabolic rate
3. reduced digestive/urinary functions -25% of blood being filtered by kidneys at any one time
4. activation of energy reserves - adipose tissue
5. increased respiratory rate and dilation of passageways
6. elevated heart rate and blood pressure
7. activation of sweat glands
parasympathetic division - talk about fibers and general
preganglionic fibers originate in brain stem and sacral segments spinal cord (craniosacral)
synapse in ganglia close to (or within) target organs
preganglionic fibers are long
postganglionic fibers are short
parasympathetic division stimulates visceral activity
conserves energy and promotes sedentary activities
concerned with conserving energy and replenishing nutrient stores
most active when body is at rest or digesting a meal
participates along with sympathetic division in maintaining homestasis.
parasympathetic division - 5 responses to increases parasympathetic activity
- decreased metabolic rate (muscles, for example)
- decreased heart rate and blood pressure - when sleeping, heart doesn’t need to beat so fast
- increased secretion by salivary and digestive glands
- increased motility and blood flow in digestive tract
- urination and defecation stimulation
preganglionic neuron cell bodies are housed in
different regions of the CNS
parasympathetic preganglionic neurons originate in either the
brainstem or the lateral gray matter of the S2-S4 spinal cord regions
Sympathetic preganglionic neurons originate in the
lateral horns of the T1-T2 spinal cord regions
what division is more simple (structurally)
parasympathetic more simple than sympathetic
ganglionic neurons in the parasympathetic division are found in
either terminal ganglia, which are located close to target organ OR intramural ganglia, which are located WITHIN THE WALL of target organ
75% of parasympathetic outflow
Vagus Nerve!
Numerous ____nerve branches intermingle with sympathetic fibers forming _______.
vagus, nerve plexuses
preganglionic fibers in ______ spinal cord segments form _______.
sacral, distinct pelvic nerves.
***innervate intramural ganglia in kidneys, bladder, terminal portions of large intestine, and SEX ORGANS.
Lack of what? in preganglionic axons prevents the ______ seen in the sympathetic division.
lack of extensive divergence, mass activation
effects of the parasympathetic nervous system tend to be _________.
discrete and LOCALIZED. Parasympathetic activity can affect one group of organs without necessarily having to “turn on” all other organs.
Preganglionic ______ axons travel with somatic neuron axons to exit the ________ and enter first the _______ roots and then the T1-L2 spinal nerves.
sympathetic, spinal cord, anterior roots
preganglionic sympathetic axons remain with the ________ for merely a short distance before they branch off and leave the ________.
spinal nerve, spinal nerve
immediately anterior to the paired spinal nerves are the left and right _______.
sympathetic trunks. each located immediately later to the vertebral column (looks like a pearl necklace).
fight of flight functions
may involve a single or multiple effectors
in mass activation, large # of ganglionic neurons activate many effector organs… causes a heightened sense of alertness due to stimulation of RAS
autonomic plexuses
axon bundles that innervate organs (both sympathetic and parasympathetic, remember most organs have dual innervation)
ANS - 2 neurotransmitters
acetylcholine (ACh)
norepinephrine (NE)
Neurotransmitters released by what and bind to what and has what effect?
presynaptic cell and bind to specific receptors in the postsynaptic cell membrane and binding has either excitatory or inhibitory effect - excitatory in muscle cells and inhibitory in heart, inhibited by muscarinic receptors (depending on receptor)
All about acetylcholine
secreted by preganglionic neurons in both parasympathetic and sympathetic neurons
called cholinergic fibers
*any receptor that binds Ach is called a cholinergic receptor
cholinergic receptors - how many types
two types!
- muscarinic receptors - all cardiac muscle, smooth muscle, and gland cells have a muscarinic receptor
*either excitatory or inhibitory due to subclasses of the muscarinic receptor - nicotinic receptors - on all ANS postganglionic neurons, in the adrenal medulla and at neuromuscular junctions of skeletal muscles
*excitatory when Ach binding receptors
norepinephrine, talk about … what kind of fibers
is secreted by nearly all POSTGANGLIONIC sympathetic neurons, called ADRENERGIC fibers.
several types of adrenergic receptors - alpha and beta
Autonomic neurotransmitters and receptors of sympathetic division
adrenergic receptors (bind adrenaline) located in plasma membranes of large cells, binding of E or NE activates enzymes (2nd messenger system) within cell
2 classes of adrenergic receptors of sympathetic division
1. alpha receptors (generally stimulated by NE and E)
a1 is GENERALLY excitatory (doesn’t mean always)
a2 receptors are GENERALLY (doesn’t mean always) inhibitory
2. 2nd class is beta receptors (GENERALLY, doesn’t mean always stimulated by E).
B1 receptors - cardiac muscle stimulation and increased tissue metabolism
B2 receptors - relaxation of respiratory passage and blood vessel smooth muscle
B3 receptors - release of fatty acids from adipose tissue for metabolic use in other tissues
Neurotransmitter release of sympathetic division, differences between epinephrine and norepinephrine
E and NE can be released locally, involving more NE. This effect lasts a few seconds.
Generally from adrenal medulla:
3x more E than NE
More beta receptors activated
Effects may last several minutes…
Release acetylcholine and thus are called cholinergic
Both the preganglionic and postganglionic axons in the parasympathetic division
the preganglionic axon AND A FEW postganglionic axons in the sympathetic division are ALSO cholinergic!!!
Autonomic neurotransmitters and receptors of parasympathetic division
Receptors (all bind Ach)
1. Nicotinic receptors (also bind nicotine) - located on ganglion cell surfaces - also on sympathetic ganglion cells and at SNS neuromuscular junctions. Always excitatory
- Muscarinic receptors (also bind muscarine toxin) - located at cholinergic neuromuscular and neuroglandular junctions as well as some sympathetic cholinergic junctions
can be excitatory OR inhibitory.
endometrium, perineurium, epinerium
innermost to outermost… looks like a muscle but this is the layers of nerves
one neural reflex produces
ONE MOTOR RESPONSE!
Burning your hand, what’s important
REFLEX ARC! gets the info in and out immediately, pulls the hand out without you thinking about it. negative feedback, otherwise you’d put your hand further into the fire LMAO
EXAMPLE OF FLEXOR REFLEX
really drunk person on the strip, so drunk but they still manage to keep themselves up
acquired motor reflex, this reflex involves several hundred synapses
intersegmental reflex example…
no two people TRIP the same way!! HUGELY VARIABLE IN RESPONSES
postural reflexes are
stretch reflexes, you really don’t think about them…
stepping on a pin causes EPSP and IPSP
EPSP to lift leg on the affected foot, and IPSP to keep other foot grounded so you don’t fall AKA A POLYSYNAPTIC REFLEX!!
interneurons control
MORE THAN ONE MUSCLE GROUP!
Perception occurs over our
somatic sensory, not our visceral sensory. PERCEPTION MEANS YOU HAVE CONSCIOUS AWARENESS!!!
detecting stimuli
touch receptor field, stimulates dendrites to open gates (local potential) and send local potential up to soma at dorsal root ganglia and if it reaches threshold, if will send a signal down the axon so that we can perceive that we have been touched.
adaptation doesn’t occur if the stimulus is…
PAINFUL!!! has to be constant and PAINLESS
smelling shit or olfactory sensation that you get used to is an example of a tonic or phasic receptor
PHASIC!!!
odor, touch, temperature are all phasic examples
examples of sensory tonic receptors would be
mechanoreceptors, photoreceptors
There are more cold receptors than hot receptors and the hot receptors are deeper. True or False
True
rods do what (of rods and cones)
rods provide black and white vision in low light.
nociceptor is technically what kind of receptor… and located where?
it’s a mechanoreceptor that’s been stimulated so much that bodily damage is probably going to occur…
LOCATED IN SKIN, JOINT CAPSULES, BLOOD VESSEL WALLS, PERISOSTEUM AROUND BONES
sensitive to temperature extremes, mechanical damage, chemicals
naked nerve endings are also known as
free nerve endings.. no dendrites, they have large receptor fields… can come to threshold faster without dendrites. not protected. remember type A (fastest, largest diameter, localized - u know exactly where it’s located) and type C (slowest, small diameter, not localized)
big difference between tonic and phasic signals
tonic keep sending signals (good for pain, to alert you) and phasic stop sending signals, alert for a little bit - “in and out of phase”
sacral nerves 2, 3, and 4 and cranial nerves _______.
cranial nerves 3,7, 9, and 10
innervation of parasympathetic system
2 neuron system
sympathetic and parasympathetic system
specific ganglia of sympathetic division
sympathetic chain ganglia, innervates visceral effectors in thoracic cavity, head, body wall, and limbs
collateral ganglia
located in abdominopelvic cavity… location dictates function a little bit… they innervate visceral effectors in abdominopelvic cavity.. includes celiac, superior, and inferior mesenteric ganglia
adrenal medulla acts as
ENDOCRINE GLAND. targets organs and systems throughout body.
fight or flight, pupils
DILATE!!!
ganglionic neurons in the parasympathetic division are found in either
terminal ganglia which are located close to the target organ OR intramural ganglia, which are located within the wall of the target organ
sympathetic nerve pathway
preganglionic sympathetic axons travel with somatic motor neuron axons to exit the spinal cord and enter first the anterior roots and then the T1-L2 spinal nerves. Preganglionic sympathetic axons remain with the spinal nerve for merely a short distance before they branch off and leave the spinal nerve. Then they travel immediately anterior to the paired spinal nerves to the left and right sympathetic trunks… the sympathetic trunks are those pearl necklaces that run down
