Neuro Flashcards
3 Fxns of Nervous System
- Detect: changes from stimuli in the internal and external environment
- maintains homeostasus and flags when things change - Evaluate: the level and type of stimuli
- CNS evaluates info received - Respond: by initiating changes in muscles or glands or not initiating change
CNS vs PNS
CNS = brain and spinal corf
PNS = cranial nerves (12), spinal nerves (31), pathyways (afferent/sensory/to CNS, efferent/motor/away CNS)
SAID: sensory afferent in dorsally
MOVE: motor ventrally, efferent
cells of nervous system
Neuron: carrie electrical impulses
- dendrites: receptor arms of the neuron
- axon: delivery arm of the neuron
GLia (Glial Cells): support and facilitate neurons
- supportive cells to neurons
Neurons
Three Components:
- cell body/SOma
- mainly in CNS
- densely packed in CNS - Nuclei
- densly packed in PNS - ganglia - Dendrite:
- receptive portion of neuron - Axon:
- carries nerve impulse away from the cell body
- one per neuron
axon hillock
- all or nothing response
- “gatekeeper” - tells neurons to go or not go
- action potential starts here
myelin
- insulating layer of wrapped lipids
- increase speed of conduction
- schwam sites and oligodenrisites
neuron functions
- sensory: external and internal environment changes
- receptors to CNS
- afferent - Associateional: CNS evaluation
- interneurons
- sensory to motor - Motor
- from CNS to efferent organ
- efferent
Neuroglia
support cells: 50% brain and spinal column volume: 5-10 times more numerous than neurons
- glial cells, helper supporting cells
- oligodendrocytes: CNS neurons only
- Schwann Cells: peripheral nervous system. myelinate peripheral neurons
- Ependymal Cells: gives brain all good blood, CNS only, cored plexus
- Astrocytes: blood brain barrier
- microglia: macrophages of the CNS
- only immune cell that interacts with nervous system
blood brain barrier
- selectivity for brain exposure to blood
- tight web of astrocytes around the brain capillaries that form the BBB
- Tight junctions
- selectivity
oligodendrocytes
create myelin sheath around neurons
Action Potential
- sodium and potassium pups don’t need ATP to work = facilitated
- the sodium/potassium pump needs ATP
- cell = Na+ outside and K+ inside
- Resting membrane potential = positive outside and negative inside = at rest = negative overall
Action potential steps
- resting membrane potential = -70 (overall negative)
- Threshold = reach stimulus, Na+ pumps open (~-50ish)
- depolarization = lots of Na+ comes in cell and inside of cell becomes positive and outside becomes negative (overall positive)
- repolarization: K+ leaves cell via K+ pump
- hyperpolarization: too much k+ leaves, drops below -70 and cell reaches
6 refractory period (cannot start another impulse) - Back to positive outside and negative inside via the sodium/potassium pump
propigation
an impusle can only move forward, not back
myelination
makes action potentials a lot quicker
- saltatory conduction
- hops between nodes of rondier
resting electric potential
- more K+ inside cell
- more NA+ outside cell
- more Ca2+ outside cell
= overall negative inside, positive outside - calcium important in cardiac muscle cells and drives initial depolarization event
- low Ca+ levels decreases heart rate, weak heart rate = anorexic people
action potential of NERVE cell
- resting phase (-60 to -70)
- threshold (-45 to -55)
- rising phase = depolarization ( facilitated transport of Na+ in)
- falling phase = depolarization (facilitated transport of K+ out)
- refractory period = hyper polarization (na/K ATPase)
ion pumps
- active transport pumps to set the cells back up to “resting potential”
1. na/k atpase (3na OUT, 2 k in)
2. Ca ATPase (ca OUT)
3. Na/Ca exchanger (3na in, 1 ca out)
synapses
- neurons are not physically continuous with each other
- region between adjacent neurons = synapse
- impulses are transmitted across the synapse by neurotransmitters
synaptic cleft
= electrochemical regulation of neurotransmitter release
1. electricity - change in charge of nerve
2. open or closed gate
3. release of messenger
4. messenger received
5. new message delivered
“chemical intersection”
synaptic bouton
- vesicles containing neurotransmitters
- more than 30 different neurotransmitter substances
- excitatory
- inhibatory
- the receptor on the 2nd cells tells it to excite or inhibit, NOT neurotransmitters
- ca = neurotransmitter release signal
neuomuscular junction
motor unit = neuron and all the units it acts on - neuron and skeletal muscle = acetocholine (binds to neuro receptor)
- junction = neuron axon and plasma membrane of muscle
- small things like writing and surgery = minor units of neurons/muscles
- big things like lifting = big motor units
Meninges
protective membrane structures surround the brain and spinal cord
- dura matter - outer covering, tough. subdural space = veins
- arachnoid matter - CSF in subarachnoid space
- pia matter = attached to the brained, cellophaned on, cannot be removed
CSF, cerebral spinal fluid
CSF = clearn, colorless similar to blood plasma and interstitial fluid
- 125-150 ml in body
- produced by choroid plexus (ependymal cells) within the ventricles (lateral, 3rd, 4th)
- reabsorbed through the arachnoid villi
ventricles of the brain
open space in middle of brain filled with CSF
giri
bumps of brain
grooves
sulci, fissure (bigger sulk)
central fissue
separates sensory in front and motor in back of brain
corpus collosum
separates right and left sides of brain
cerebellum
balance and coordination
thalamus
sensor info passes through the thalamus and prioritizes info and sends to proper areas of brain
frontal lobe
memory and movement
parietal lobe
language and reading
occipital lobe
vision
brain stem
blood pressure, breathing, consciousness, heartbeat, swallowing, coughing, sneezing, vomiting
temporal lobe
hearing, speech
cranial nerevs
- OOO to touch and feel virgin girls’ vaginas and humans
- some say marry money but my brother says big boobs matter most
olfactory i optic ii oculomotor iii trochlear iV trigeminal V abducens VI facial VII vestibulocochlear VIII Glossopharyngeal IX vagus X accessory XI hypoglossal XII
cranial nerve i
Olfactory
- sensory
- smell
cranial nerve ii
optic
- sensory
- vision
cranial nerve iii
oculomotor
- motor
- move muscles of eye
cranial nerve IV
trochlear
- motor
- move muscles of eye = superior oblique muscle
cranial nerve V
trigeminal
- sensory and motor
- sensory of face
- motor or chewing, mastication
cranial nerve VI
abducens
- motor
- move muscles of eye = external rectus
cranial nerve Vii
facial
- sensory and motor
- taste sensory (anterior 2/3s tongue)
- facial motor = facial expression
cranial nerve Viii
vestibulochoclear
- sensory
- ear, hearing, balance, equilibrium
cranial nerve IX
glossopharengeal
- sensory and motor
- last 1/3 of tongue sensory
- motor swallowing (deglutition)
cranial nerve X
vagus
- sensory and motor
- “wanderer”
- visceral organs both sensory and motor
- parastalsis, secretion, pressure, pain
- autonomic
cranial nerve Xi
accessory
- motor
- shrug musscles (traps, levator scapuli)
cranial nerve xii
hypoglossal
- motor
- command of tongue and muscles underneath
cranial nerves for the eye
- optic II - sensory vision
- oculomotor iii - motor control superior, medial, inferior rectus, inferior oblique, pupil constriction
- trochlear iv - motor control superior oblique
- abducens vi - motor control lateral rectus
spinal cord
- spinal nerves = both sensory and motor
grey vs white matter: - grey inside
- white outside: info highway, up and down and left and right. impulses carrying info
reflex
- receptor - temp, pain, presure
- afferent sensory neurons (behind) - carry to spinal cord
- interneuron in spinal cord
- efferent motor neuron (front) - carry away to affected object
- effector - muscle gland where the motor neuron lands
* dorsal root ganglion = sensory
* motor neuron cell body is in spinal cord and is interneuron - the axon travels ALL the way to the affected muscle
vertebrae
- 7 cervicle
- 12 thoracic
- 5 lumbar
- 4-5 sacrum
- 3-4 coccyx
spinal nerves
- 8 cerv nerves
- 12 thoracic nerves
- 5 lumbar
- 5 sacral
- 1 coccyx
total = 31 - dorsal root –> localized/specific cord level afferent sensation (dermatomes
- ventral root –> localized/specific cord level efferent motor control (myotomes)
MYOtomes: relationship b/n spinal nerve and muscle (motor)
DERAtomes: relationship b/n spinal nerve and skin (sensory)
CNS vs PNS
CNS = two components, brain and spinal cord
PNS = all the rest!
- autonomic - involuntary heart beat
- somatic - voluntary skeletal muscle
- sensory nerves
PNS Autonomic Nervous system
part of PNS
- involuntary control of nerves
1. sympathetic NS - fight or flight
2. Parasympathetic NS - rest and digest - controls everything we take for granted
PNS autonomic nervous system - sympathetic
fight or flight
chain of sympathetic ganglia (cell to cell communication)
- accelerates heart rate
- constricts blood vessels to smooth muscle (away from digestion and to skeletal muscles)
- dilates blood vessels to skeletal muscles
- decreases GI movement
- dilation of pupil - see more mydriasis
- effects glands: increase epinephrine, sweat secretion, decrease digestive secretion
PNS autonomic nervous system - parasympathetic
rest and digest, homeostasis
- slows heart beat
- no effect on blood vessels to smooth muscle
- no effect on blood vessels to skeletal muscle
- increase peristalsis
- contract pupils Miosis
- effects on glands: no effect on adrenal or sweat glands, but increase secretion of digestive enzymes
PNS differences b/n SNS and PNS
SNS (QUICK)
- fight or flight
- short preganglionic fibers
- cholinergeic (ACH releases)
- long post ganglionic fibers
- adrenergic (norepinephrine signal)
PNS (not so quick)
- rest and digest
- long periganglionic fibers
- cholinergic (ACH)
- short post ganglionic fibers
- cholinergic (ACH)
somatic vs autonomic
somatic = one long axon autonomic = lots of axons in a row. pre ganglia and post ganglia
PNS somatic nervous system
- voluntary control of motor nerves
ACH release - musculoskeletal control
nerve injury and regeneration
only myleniated axons
- only PNS, schwann cells
CNS minited by increase in scar formation and different type of melin (oligodendrytes)
- repair depents on location, type of injury (crush or cut), inflammatory response and scan tissue formation
The senses
- Eye - photoregeptor - vision
- Ear - mechanoreceptor - hearing
- Inner Ear - mechanoreceptor - balance
- nose - chemoreceptor - smell
- taste buds - chemoreceptor - taste
- peripheral NS - nocireceptors - pain
- hypothalamu - osmoreeptor - thirst
- muscle/tendons - proprioreceptors - proprioception
vision
rods = black and white, calrity and precision
cones = color
RETINA
more rods that cones in humans
