nervous system Flashcards
central nervous system
brain and spinal cord
peripheral nervous system
all nerves and nervous tissue outside the cns
where is CSF
around brain and spinal cord in CNS
afferent nerves
nerves of pns that bring info to the CNS from periphery
efferent nerves
nerves of pns that take info from the cns to periphery
ganglia
cells with clusters of cell bodies in the PNS
major divisions of the pns
somatic and autonomic
proencephalon
forebrain
mesencephalon
midbrain
rhombencephalon
hindbrain
forebrain function
behavior and personality
what does the forebrain divide into
the diencephalon and telencephalon
diencephalon contains
contains the thalamus, hypothalamus, pineal gland and posterior pituitary
thalamus
relay sensory and motor signal and regulates sleep
hypothalamus
mediates homeostasis and communicates between nervous and endocrine systems
what does the telencephalon contain
cerebrum (largest and most important brain structure)
cerebral cortex
thin outer lauer
limbic system contains
hippocampus, basal ganglia, amygdala, olfactory bulb
function of limbic system
structures involved in emotion, motivation, and memory
cortex lobes
parietal, occipital, frontal, temporal
frontal lobe function
higher level cognition and executive function
parietal lobe
sensory processing
temporal lobe
sound and language processing
occipital lobe
primary visual cortex
hindbrain
basic functions that are conserved through evolution
cerebellum
fine motor skills and balence
medulla oblongata
autonomic function control like breathing and heart rate
pons
relay station for signals to pass between medulla, cerebellum and rest of brain
- also deals with sleep, respiration, swallowing, bladder control
midbrain
central region of brain that is important for motor control, sleep, and homeostatic regulation
structures of midbrain
superior and inferior colliculi, substantia nigra
substantia nigra
control coordination of voluntary movement and domaine production (AD) `
brain stem
midbrain + hindbrain
- midbrain, medulla, pons
inferior colliculi
structure of midbrain that processes auditory signals and sends them to the thalamus
superior colliculi
structure of midbrain that processes visual signals
basal ganglia
structure of forebrain that particpates in motivation, eye movement, and decision making
pineal gland
forbrain structure that controls sleep and makes melatonin
posterior pituitary
projection through which hypothalamus secretes oxytocin and vasopressin
septal nuclei
reward pathway
cervical spine
top of the spine
7 vertebrae
c1-c7
thoracic spine
12 vertebrae
t1-t12
lumbar spine
5 vertebrae
L1-L5
sacral spine
5 vertebraw
s1-s5
somatic nervous system
controls voluntary muscle movement
autonomic nervous system
controls involuntary movement
- sympathetic and nonsympathetic nervous systems
sympathetic nervous system
fight or flight
parasympathetic nervous system
rest and digest
functions of sympathetic nervous syste
mobilizes body systems to respond to acute stressors. increases heart rate, dialates pupils
function of pns
deescalates body
preganglionic neurob
synapses on post ganglionic neuron near the target organ
length of preganglionic neurons in pns
long and synapse on ganglia near or on the target organ
length of preganglionic neurons in sympathetic nervous system
shorter and synapse on sympathetic trunk
what is the primary neurotransmitter of the autonomic nervous system for preganglionic neurons
AcH
primary neurotransmitter of the ans for postganglionic neurons
norepinephrine
enteric nervous system
complex autonomic nervous system that regulates digestive activity
where are afferent nerves located
pns and send info to the cns to be processed
somatosensation
touch
where does the planning of motor control being
premotor cortex
where in the brain is motor control executed
primary motor cortex
neurotransmitter involved in coordination
dopamine
efferent fibers
transverse spinal cord before exiting the vertebral column at the level of muscles
glutamate
excitatory neurotransmitter
- responsible for neuron depolarization
GABA
inhibitory neuron
- repolarization
where do efferent neurons binds to effector organs
neuromuscular junction
neuron
non-dividing highly specialized cell
glial cells
provide nutients structure insulation and defense from pathogens
regulate growth and pruning of neurons
- many subtypes
Blood Brain Barrier
epithelial barrier
oligodendrocytes
myelin of central nervous system
schwann cells
myelin of PNS
can regenerate
nodes of ranvier
saltatory conduction, between mylein to speed up conduction
microglia
first line of defense against invaders of cns
- similar to macrophages
oligodendrocytes
provide mylination of CNS
schwann cells
provide mylination of PNS
astrocytes
provide various support functions to neurons in the CNS
ependymal cells
produce and circulates CSF in the CNS
satellite cells
control the microenvironment around cell bodies in ganglia in the PNS
microglia
macrophages that clean out microbes and debris in the CNS
dendrites
recieve input
soma
cell body of a neuron
axon
long structure that carriers the action potential
synaptic cleft
small gap between 2 neurons
graded potential
variable strength signals that are conveyed a small distance, determine wheather or not an action potential is generated
action potential
constant strength signal conveyed over a long distance
Na+/K+
transmembrane protein can regyulate the entry and exit of specific ions in the presense of a membrane potential
negative membrane potential
more positive charges on the outside of the cell than inside
is the cl- concentration higher on the inside of a cell or outside
outside
is extracellular or intracellular calcium more highly concentrated
extracellular
what is the intracellular envirnment rich in
K
what is the intracellular envirnment poor in
na, cl, ca
na/k atpase
enzyme that hydrolyzes atp to pump 3 sodium ions out of the cell and brings 2 k in
why is the work of atpase sometimes undone
membrane is permiable to K so it flows out as K+ is being pumped back in through transmembrane protein
resting membrane potential
-70 mV
depolarization
cell becomes more positive and reaches 0 mV
hyperpolarization
move more negative than -70 mV
what ion channels are closed during resting potential
most k and all na channels
what happens to ion channels during hyperpolarization
na is closed and k is open
k leaves the cell and membrane becomes more negative
where are neurotransmitters released
synaptic cleft
most graded potentials are …
excitatory (raise the potential to become more positive)
Excitatory postsynaptic potentials
graded potential that makes potential more positive
inhibitory postsynaptic potential
graded potential that makes potential more negative
spatial summation
simultaneous signals coming from multiple presynaptic neurons being received by a single postsynaptic neuron
temporal summation
rapid series of weak pulses from a single source into one large signal`
what is found in high concentrations at the axon hillock
voltage gated sodium channels
what do voltage gated ion channels open and close in response to
membrane potential changes
depolarization
rapid opening of Na+ ion channels along the axon toward the terminal
repolarization starts when
voltage gated k+ channels are opened via the positive membrane potential from previous influx of na
what potential causes na channels to close and begin repolarization
+35 mV
hyperpolarization
after na channels are closed, k+ still leaves the cell and overshoots membrane resting potential and na/k atpase will reestablish membrane potential
where are k and na concentrated in a resting neuron
na is higher outside
k is higher inside
-70 mV
what are k and na concentrations in a neuron that is initiating action potential
open na+ channels to flood into cell
inside becomes more positive
movement of action potential, what happens to channels
na+ are continuing to open and k+ opens after sodium ones
absolute refractory period
+40 mV
when sodium channels are closed and cannot open again
relative refractory period
na channels begin to open again but membrane is still hyperpolarized
- depolarization possible but not likely
voltage gated ca channels
at the end of the axon
open in response to change in membrane potential and depolarization
- cause influx of ca2+ into terminal buttons and cause exocytosis of neurotransmitters
function of calcium in action potential
enters terminal bouton and causes exocytosis of neurotransmitters which bind to postsynaptic cell and depolarize that one
what happens to excess neurotransmitters in the synapse
either degrade or reuptake
degredation
hydrolytic enzymes break neurotransmitters apart
what enzyme degrades ach
acetylcholinesterase
reuptake
neurotransmitters are moved out of synaptic cleft and prevented from bninding
function of acetylcholine
activates muscle contractions at NMJ
used in all autonomic outputs of brain to ganglia
dopamine function
used in reward and motor pathways
- parkinsons is loss of dopaminergic neurons in substantia nigra
where are dopaminergic neurons formed
substantia nigra
endorphins
pain supression and produce euphoria
epinephrine
nt that stimulates fight or flight response in sympathetic nervous system
GABA
inhibitory neuron that hyperpolarizes cells to reduce action potential firing
- alcohol intoxication
glutamate
excitatory neurotransmitter (90%) of neurons
glycine
inhibitory nt of spinal cord and brainstem
- works with gaba
norepinephrine
used in post ganglionic connections of sympathetic division of ANS
- increase arousal, alertness, focus
serotonin
regulates intenstinal movement in GI tract and regulates mood appetite and sleep in the brain
gap junctions
allow ions to fuse between two neurons enabling the membrane potential of one to directly and immediately influence another
capacitance
ability to store charge
cell membranes of neurons posess what
capacitance and resistance
membrane resistance
reflects the ability of a membrane to effectively seperate charge
- high membrane resistance = more effective transmission of AP
membrane capacitance
charge stored across membrane
cytoplasmic resistance
opposition to flow of ions through cytoplasm
myleination
increases membrane resistance, and increases action potential speed
- conduction is more rapid
nodes of ranvier
short unmyleinated regions of axon where na+ k+ and Na/k+ atpases are concentrated
- action potentials jump from nodes –> saltatory conduction
Nerst equation
standard cell potential = cell potential of cathode - cell potential of anode
= 0 as a concentration cell
nerst eqn
cell potential = standard cell potential - RT/nF * lnQ
- n is moles of electrons
concentration cell
electrochemical cells that consist of two half-cells wherein the electrodes are the same, but they vary in concentration.
