nervous system overview Flashcards
functions of nervous system
send and receive signals within body (from brain to rest of body and from body to brain)
CNS vs PNS
CNS acts as control center in receiving information and generates response to stimuli (made of brain and spinal cord)
PNS sends information to CNS and carries out action
(made of nerves and ganglia)
motor (efferent) vs sensory (afferent)
motor travels away from brain (action)
sensory travels towards the brain (stimulus)
describe nervous system as a control system
sensory receptors detect a stimulus –> afferent pathways bring signal to control center –> control center decides on a response –> efferent pathways bring response signal to target where action occurs
somatic motor vs autonomic motor divisions
somatic = voluntary control of muscles
autonomic = signals to involuntary tissue (organs, glands, etc)
somatic vs visceral sensory divisions
somatic = receives signals from skin, muscle, and joint receptors
visceral = receives signals from organs
composition and arrangement of gray vs white matter
gray matter = cell bodies, dendrites and axon terminals
white matter = myelinated axons (think communication)
structure of typical nerves
cell body (soma) which contains nucleus and nucleolus
dendrites branch off cell body
axon hillock and trigger zone connects to axon
dendrites vs axon
dendrites –> receive information
axon –> sends impulses
structure and location of nucleus vs ganglion
nucleus are found in CNS
ganglion are found in PNS
structure and location of tract vs nerve
tracts are found in CNS
nerves are found in PNS
different structural types of neurons
multipolar –> 1 axon and many dendrites
bipolar –> 1 axon and 1 dendrite
unipolar –> axon and dendrite on same process (cell body on the side)
3 different functional types of neurons
sensory –> receive information from receptors
interneurons –> in CNS and connect sensory and motor neurons (allows for communication)
motor –> sends response to stimulus
oligodendrocytes
branched structure that connects to multiple axons forms myelin sheath
–> found in CNS
ependymal cell
produces CSF
–> found in ventricles and central canal
microglia
acts as macrophages
–> in brain and spinal cord
astrocyte
provides supportive framework
(most abundant and looks like star)
–> in CNS
schwann cell
wraps PNS and forms myelin sheath
–> found in PNS
satellite cell
surrounds PNS cell bodies
–> found in PNS
myelination function
allows electrical impulses to transmit quickly
myelination in CNS vs PNS
CNS: oligodendrocytes produce myelin sheath but do not wrap around axon, instead it pushes new under old (centripetal)
PNS: schwann cells produce myelin sheath and wrap around axon (centrifugal)
role of sodium potassium pump in maintaining the resting membrane potential
for every 3 sodium ions out, two potassium ions are brought in maintaining negative potential
depolarization
brings sodium in the cell to turn resting membrane potential positive
repolarization
releases potassium out of the cell to bring membrane potential back to negative
hyperpolarization
moves past the membrane potential
threshold
minimum level of depolarization that triggers an action potential
–> once hit fires at max to depolarize
—> if not hit it returns back to resting membrane potential
graded vs action potentials location and ions/ion channels
graded: temporary, decremental (gets weaker), and reversible
–> ligand gated channel
action: all or nothing (threshold), nondecremental (gets stronger), and irreversible
–> voltage gated and leakage channel
importance of voltage-gated channels in the conduction (propagation) of an action potential
depolarization caused by opening of voltage gated channels acts as dominos sequentially opening sodium channels of different axons
how do axon diameter and myelination affect conduction velocity
myelination allows for a domino effect
–> faster more efficient movement of signals
role of myelin in saltatory conduction
propagation instead of moving channel to channel nodes of ranvier (voltage gated channel) allows signal to jump node to node
action potential conduction in unmyelinated vs myelinated axon
unmyelinated: move down axon
myelinated: jump from node to node
