KAAP 309 Exam 2 (Nervous System)

CNS

brain and spinal cord

PNS

somatic, autonomic (sympathetic, parasympathetic)

divisions of PNS

somatic sensory division

receptors in the skin, muscles, bones, and joints

visceral sensory division

receptors of the organs of the thorax, abdomen, and pelvis

somatic motor division

signals to skeletal muscle

visceral motor division

signs to cardiac muscle, smooth muscle, and glands (ANS)

group of cell bodies in CNS

nucleus

group of cell bodies in PNS

ganglia

group of axons in CNS

tract

group of axons in PNS

nerve

multipolar neuron

many processes extend from cell body

most are interneurons, some are motor neurons

medium receptive region, large-ish conducting region

bipolar neuron

one axon and one dendrite

almost all are sensory neurons

large receptive region, small conducting region

unipolar neuron

one process extends from cell (peripheral and central process)

primary/first order sensory neurons

small receptive region, largest conducting region

sensory neurons

conducts signals from receptors to CNS

interneuron

integration in CNS

motor neuron

conducts signals from CNS to effectors

neuroglia of CNS

astrocytes, microglia, ependymal cells, oligodendrocytes

neuroglia of PNS

schwann cells, satellite cells

oligodendrocytes

branching cells

wrap around axons of CNS neurons, create myelin sheath

ependymal cells

line cavities of brain and spinal cord

circulate CSF

create permeable barrier

microglia

small, ovoid shape

monitor health of neurons and transform to macrophages

astrocytes

function: everything

exchanges between capillaries and neurons

control chemical environment around neurons (leaked k+)

satellite cells

astrocytes of PNS

schwann cells

oligodendrocytes of PNS

myelin

fatty; protein-lipid

insulation and increase speed of electrical impulse

myelin in pns

formed by Schwann cells, one segment of an axon

myelin in cns

oligodendrocytes, multiple axons

nodes of ranvier

gaps between myelin sheaths

first gap is known as initial segment

largest diameter/thick myelin sheaths

fastest propagation speed

sensory and motor fibers for skin, muscles, joints

intermediate diameter/lightly myelinated

smallest diameter/nonmyelinated

ANS and pain

voltage-gated ion channels

na leaks in while k leaks out

pump compensates

working constantly

ligand gated channel

ligand binds to receptor

channel opens and na floods into neuron

shifts membrane to depolarization

mechanically gated channels

open under mechanical stress

shearing, compression, tension, vibration, swelling

local potentials

produced by gated channels on dendrites and nerve cell body

depolarizing or hyperpolaring

graded

reversible

short distance

decremental

action potentials

produced by voltage-gated channels on trigger zone and axon

depolarization always

all or none

irreversible

self-propagating

nondecremental

step 1 of ap

a local current arrives at axon hillock, depolarizing the area

step 2 of ap

minimum threshold (critical voltage) of -50 mv must be reached

step 3 of ap

voltage gated channels open (na fast, k slower) na channels continue to open

step 4 of ap

at 0 mv the na channels close and final voltage peaks between 35-50 mV

step 5 of ap

at peak, k gates are open and k floods out of cell

step 6 of ap

k channels stay open, resulting in more k leaving than na entering

voltage is 1-2 mv more negative than rmp

step 7 of ap

na begins to re-enter cell, returning to normal rmp

four primary regions of brain

cerebrum, diencephalon, brainstem, cerebellum

white matter

internal, myelinated neurons

gray matter

external, short nonmyelinated neurons

ventricles

lateral, third, cerebral aqueduct, fourth

primary motor cortex

majority of motor movement

premotor cortex

movement planning

broca's area

speech production

basal nuclei

control of movement (start and stop)

caudate, putamen, globus pallidus

subthalamic nuclei, substansia nigra

neurotransmitters of basal nuclei

GABA, dopamine, glutamate

parkinsons disease

degeneration of dopamine-releasing neurons of substansia nigra

become overactive, results in tremors and slow initiation of movement

segments of diencephalon

thalamus, hypothalamus, epithalamus

thalamus

sensory relay center, where info is sorted

hypothalamus

vital for homeostasis

control ANS, response to emotion, body temp, food intake, thirst, sleep/wake, endocrine functions

epithalamus

visible as pineal gland

secretes melatonin

segments of brain stem

midbrain, pons, medulla

(ANS)

midbrain

superior cerebellar peduncles, superior colliculi, inferior colliculi, substansia nigra, red nuclei

pons

composed mainly of tracts (longitudinal and transverse)

longitudinal tract of pons

brain to spinal cord

transverse tract of pons

pons to cerebellum

medulla

crucial for ANS

cardiac center, respiratory center, cochlear nuclei

site of decussation

inferior cerebellar peduncle

cerebellum

provides precise timing and appropriate patterns of muscle contractions (subconscious)

ipsilateral

cerebellar processing 1

motor cortex relays their intention for movement to cerebellum

cerebellar processing 2

cerebellum is simultaneously receiving info from proprioceptors

cerebellar processing 3

cerebellum calculates the best way to coordinate force, direction, and extent of muscle contraction

cerebellar processing 4

cerebellum dispatches a blue print of movement to cerebrum

dura mater

fibrous connective tissue (periosteal and meningeal layers)

encloses dural venous sinuses (blood)

dural folding (falx cerebri, falx cerebelli, tentorium cerebelli)

arachnoid

fine, elastic ct

pia mater

direct contact w brain tissue

meningeal spaces

epidural, dura, subdural, arachnoid, subarachnoid, pia

epidural space

potential or real

subdural space

potential space

subarachnoid space

real space (CSF)

CSF is formed by

appendemal cells in choroid plexus

CSF circulation 1

choroid plexus of each ventricle produces CSF

CSF circulation 2

CSF flows through ventricles and into subarachnoid space via median/lateral apertures

CSF circulation 3

CSF flows through the subarachnoid space

CSF circulation 4

CSF is absorbed into the dural venous sinuses via the arachnoid granulations

limbic system

emotional-visceral brain

amygdala, cingulate gyrus, hypothalamus, hippocampus

spinal cord anatomy

from foramen magnum to l1/l2

cervical and lumbar enlargements

conus medullaris, filum terminale, cauda equina

gray matter of spinal cord

dorsal horn, ventral horn, lateral horn (t1-l2)

white matter of spinal cord

funiculi

roots of spinal cord

ventral - motor (out)

dorsal - sensory (in)

how many pairs of spinal nerves are there

31

cervical spinal nerves

c1-c8

thoracic spinal nerves

t1-t12

lumbar spinal nerves

l1-l5

sacral spinal nerves

s1-s5

coccygeal spinal nerves

Co1

brachial plexus

C5-T1

provides all nerves for upper extremity

musculocutaneous n, axillary n, radial n, median n, ulnar n

brachial plexus image

lumbar plexus

L1-L4

provides nerves for lower abdomen, anterior and medial thigh

femoral n, obturator n

sacral plexus

L4-S5

provides nerves for pelvis, posterior thigh, and all of leg and foot

emerges through pelvis (inferior to piriformis m.)

sciatic n, tibial n, common fibular n, deep fibular n, superficial fibular n

chemical synapse 1

action potential arrives at axon terminal

chemical synapse 2

voltage gates Ca channels open

chemical synapse 3

Ca entry causes synaptic vesicles to release neurotransmitters

chemical synapse 4

neurotransmitters diffuse across synaptic cleft and bind to receptors on postsynaptic membrane

chemical synapse 5

binding of neurotransmitters opens ion channels, creating graded potentials