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!