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PERIPHERAL SYSTEM :information_desk_person: (SOMATIC SENSORY SYSTEM :nose:…
PERIPHERAL SYSTEM :information_desk_person:
SOMATIC SENSORY SYSTEM :nose:
STIMULUS :fire:
DURATION
tonic
slowly adapting
firing action potential thru out the duration of the stimulus application
action potential fire for so long that the frequency actually go down
ex: wearing a shirt
phasic
tell the somasomactic system
fire at onset and offset of the stimulus
= rapidly adapting
definition: how long the stimulation is applied
LOCATION
RECEPTIVE FIELD
LATERAL INHIBITION
increases the
difference/ contras
t in magnitude tonic level in the frequency of action potentials
frequency of AP of A and C go way down , B is the same
This is to help us identify the location of the stimulus much more accurately
CONVERGENCE
many sensory cells sending signal to one secondary neuron
receptive field large
discrimination low
def: stimulate anywhere in the receptive field would activate the second order neuron /
region of sensory space that will elicit an action potential
MODALITY
some area of the of the periphery send more innervation to the cortex
lips, tongue
eye
hand
leg, feet
homunculus
some area send less innervation to the brain
evolutionary question
INTENSITY
receptors :arrow_forward: graded potential
in response to stimulii
encoded by number of action potentials generated
MECHANORECEPTORS
response to physical deformation of the cell
so if you touch your skin really lightly, you will not feel it
because the graded potential is sub-maximal, not enough to explicit an action potential
between the mechanicoreceptor, there's a trigger zone that convert mechanic energy to electrical energy
SOMATOSENSORY NERVE FIBERS/
predict their speed of conductivity
C adelta abeta aalpha
A BETA
large
myelinated
mechanical stimuli
A DELTA
small
myelinated
cold, fast pain, mechanical stimulii
C
small
unmyelinated
slow pain
heat/ cold / throbbing pain :cold_sweat:
mechanical stimulii
A ALPHA
large
myelinated
motor effrerent :muscle:
MOTOR SYSTEM :slot_machine:
AUTOMATED NERVOUS SYSTEM
PARASYMPATHETIC :slightly_smiling_face:
characterisitc
relaxation
digest food
eating
lead to
:arrow_down: heart rate :<3:
:arrow_up: GI motility
:eyes: constrict pupil
constricts bronchioles
innvervation location in spinal cord
brain stem
cranial nerve VII
cranial nerve IX
carnial nerve X
cranial nerve III
sacral
length of axon
preganglionic long
postganglionic short
ganglia
exist!
very close to target organs
NEUROTRANSMITTER
preganglionic
secrete Ach
post-ganglionic
nicotinic receptor
secrete Ach
target tissue
muscarinic receptor
SYMPATHETIC :scream:
characteristics
ready to be active
respond to stress
low blood pressure
lead to
:arrow_up: heart rate :two_hearts:
:arrow_down: GI motility
:eye: dilate pupil
dilate bronchioles (smooth muscle)
innervation location in spinal cord
from thorac T1
to lumbar L2
GANGLIA
preganglionic short
note: cell body is in the spinal cord
postganglionic is long
every organ above the diaphragm, cell body is in the
paraverterbral
ganglia
below diaphragm cell body is in
prevertebral
ganglia
ADRENAL MEDULLA
spinal cord innervate pre-ganglionic neuron
activate adrenal medulla
secrete
epi
into blood vessel
slow response, because it takes time to travel in the blood
termination of Epi
active transported
back into axon varicosity
broken down MAO in the axon varivosity
some diffuse away
NEUROTRANSMITTERS
pre-ganglionic
secrete Ach
post-ganglionic
nicotinic receptor
called autonomic ganglion
secret NE
target tissue
adrenergic receptor
beta 2
mechanism ex
cAMP
relaxation
Gs
location: smooth muscle
blood vessels
bronchioles
uterus
effect
vasoliation :relaxed:
bronchodilation :wind_blowing_face:
uterine relaxation
prefer E >> NE
alpha 1 - adrenergic receptor
mechanism ex
PLC
muscle contraction
Gq
location
blood vessels
pupils
effect of stimulation
vasocontraction
:eye:pupil dilation
picky with neurotransmitter: NE> E
beta 1
Gs
effect
:arrow_up: heart rate :<3:
force of contraction
location
heart
kidney
like NE = E
SKELETAL MUSCLE
internal organization
sacrolemma = cell membrane
sacroplasm = cytoplasm
myofibril
composed of sarcomere
thin filament
I band
= only thin filament with no overlap of thick
actin
thick filament
A band
= the whole length of thick filament
H band
= thick without the overlap of the thin
M line
= the line where thin filament eventually crash in when they pull thick filament
aka. anchor point for the thick filamnet
myosin
sacrcomere go from Z line to Z line
aka anchor point for the think filament
sarcoplasmic reticulum
contain lots of calcium
T tubule
close to SR
VG Na allows action potential to travel
how it works
ACTIN
note
: has tropomyosin wrapping around and covering the spot where myosin has high affinity to attach
troponin bind to Ca
:arrow_right: pull tropomyosin away
:arrow_right: expose the affinty site on actin
EXCITATION - CONTRACTION COUPLING
Ach released from the somatic motor neuron
VG Na channels open :arrow_right: muscle action potential down the T-tubule
DHP (L-type Ca channel) receptor opens RyR (Ca releasing channel)
release Ca from SR into the sacroplasm
MYOSIN
note
: myosin head is ATPase
crossbridge formation
myosin head bind to the exposed site
kicks off Phosphate group
powerstroke: thick filament grab on thin filament and pull it to M line :arrow_right: sarcomere shorten
kicks off ADP group
myosin only detach from actin :arrow_left: new ATP bind
myosin high energy state :arrow_left: ATP hydrolyzed
myosin head has stronger affinity to actin than tropomyosin,
so without ATP it won't detach :arrow_right: rigor
SERCA
transporter channel between the sarcoplasm and SR
vacuum Ca back into SR
transporter uses ATP
EXTRA DETAILS
SARCOMERE LENGTH
too short sarcomere
lots of crossbridges formation
but, actin already pushes on the M line, no room to shorten
less tension
too long sarcomere
no myosin and actin overlap
no crossbridges
no contraction
crossbridges formation overtime
one crossbridges formed at first
over time, more crossbridges formed :arrow_right: tension :arrow_up:
TWITCH
single muscle fiber contraction
the cause of the delay
notes
when stimulus introduced, there's 3 ms delay before tension :arrow_up:
EPP to cause AP
AP cause Ca to release
Ca binds to tryponin and move trypomyosin away
relaxation
Ca is sequested into SR
crossbridges become undone
SUMMATION
scenario: increase tension produced in the whole muscle/ independent of stimulus
engage more muscle cells
at different frequency
underlying concept for one muscle cell : more Ca = more crossbridges = more tension
if really high frequency, muscle cell generate maximum amount of tension and doesn't relax
FREQUENCY
frequency of stimulation decide the force generated
after each stimulus, muscle recover
unless, high frequency of stimulation :arrow_right: high force :arrow_right: tentanus (muscle cell no relax)
RECRUITMENT
motor unit
all fibers innvervated by a motor neuron
increase stimulus :arrow_right: increase motor unit responds :arrow_right: increase tension
maximal stimulus :arrow_right: all motor units respond :arrow_right: max tension
supramaximal stimuli :arrow_right:
cannot
generate any higher tension 'cause all of motor already responded
SUSTAINED SUB-MAXIMAL TENSION
motor units recycle so that muscle can keep sub-maximal tension for a long period of time
ASYNCHRONOUS MOTOR UNIT SUMMATION
each motor unit get to recover before it's stimulated again
'cause different motor units back each other up!
TYPES OF CONTRACTION
ISOTONIC
muscle contract, shorten
to generate force to move the load
ISOMETRIC
generate force but not change in length
force cannot move load
aka, you carry a load but you stay stationary
some elements
ELASTIC PROPERTY
how it works
ISOTONIC
elastic element contract
sarcomere shorten
ISOMETRIC
: elastic element stretches
every isotonic begin with an isometric
components
myofibrils : titin
connective tissue: tendons
stretch during contraction
CONTRACTILE PROPERTY
thick and thin filaments
crossbridges
powerstroke
things that contract
MUSCLE TYPES
TYPE 1
metabolic
slow oxidative
glycolysis
oxidative phosphorylation
color
red
many capillaries
more myoglobin
many mitochondria
more myoglobin = darker muscle
duration of contraction
prolonged sustained contraction
sustained
slow ATPase
slow rate of contraction
few number of muscle fibers innervated by a single axon
fatigue resistant
yes
long duration of twitches
TYPES 2
TYPE 2A
resistance to fatigue
intermediate rate of contraction
sustained
repetitive movement
metabolic
glycolysis
oxidative phosphorylation
fast-oxidative fatigue resistant
color
red
many capillaries
many mitochondria
more myoglobin
the more myoglobin, the darker the muscle
duration of contraction
generate large amount of force for an intermediate period
in-between number of muscle fibers innervated by a single axon
fast ATPase
short duration of switches
TYPE 2x
metabolic
more glycolysis
little oxidative phosphorylation
color
white
few capillaries around the muscle
few mitochondria
duration of contraction
fast rate of contraction
fast ATPase
short twitch
resistance to fatigue
no
short bursts of extreme forces
