Nervous System Flashcards
– serves as a shuttles for messages going toward and away from the brain
spinal cord
spinal cord also acts as a – that can process certain incoming messages and provide an autonomic response without processing by the brain
reflex center
– is a set of neurons that consists of a receptor, a sensory neuron, an interneuron, a motor neuron, and an effector
reflex arc
– transmits a message to a sensory neuron
receptor
– routes the message to an interneuron located in the spinal cord
sensory neuron
– processes the message in the spinal cord and sends a response out through the motor neuron
interneuron
– passes the message to an effector
motor neuron
– carries out the appropriate response
effector
peripheral nervous system is composed of pairs of nerves that are bundles of –
axons
there are – pairs of cranial nerves branching off the brain
12
there are – pairs of spinal nerves branching off the spinal cord
31
nerves that exist in the – are categorized in to the somatic or autonomic nervous system
PNS
– nervous system controls conscious functions within the body such as sensory perception and voluntary movement due to innervation of skeletal muscle
somatic
– nervous system controls the activity of involuntary function within the body to maintain homeostasis
autonomic
– system is further divided into the sympathetic and parasympathetic divisions
autonomic
T/F: most internal organs are innervated by both sympathetic and parasympathetic divisions
true
when activated, the sympathetic branch produces the – in which heart rate, ventilation, blood pressure increases while digestion decreases
fight-or-flight response
– is the primary regulator for the fight-or-flight response
acetylcholine
largest portion of the brain
cerebrum
– is the outer tissue of the cerebrum
cerebral cortex
cerebellum is located at the – of the brain
base
– responsible for sensorimotor coordination for complex muscle movement patterns and balance
cerebellum
connects the brain to the spinal cord
brain stem
– connects the spinal cord and cerebellum to the cerebrum and diencephalon
pons
– has reflex centers for vital function such as regulation of breathing, heart rate, and blood pressure
medulla oblongata
messages entering the brain from the spinal cord must pass through the –
medulla
– is a tract of neurons that runs through the medulla into the cerebrum
reticular activating system (RAS)
RAS acts as a – to prevent the processing of repetitive stimuli
filter
RAS is also an – center for the cerebrum
activating
when RAS is not activated, – occurs
sleep
hypothalamus and thalamus make up the
diencephalon
– used to regulate the activity of the pituitary gland in the endocrine system
hypothalamus
T/F: hypothalamus regulates such as thirst, hunger, sex drive, and temperature
true
thalamus serves as a – center for sensory info entering the cerebrum as it routes incoming info to the proper parts of the cerebrum
relay
– side of the brain tends to specialize in spatial and pattern perception
right
– side of the brain tends to specialize in analytical processing and language
left
connection between the two hemisphere
corpus callosum
composed of the brain and spinal cord
central nervous system
composed of any nervous tissue located outside of the brain and spinal cord
peripheral nervous system
– are the primary structures within the PNS
nerves
– exists in the PNS and direct their messages toward the CNS
sensory (afferent) neurons
– exist in the PNS and direct the messages away from the CNS
motor (efferent) neurons
interneurons are only found in the –
CNS
provide support to neurons and are capable of mitosis unlike mature neurons
glial cells
projections that pick up incoming messages
dendrites
processes messages and contains the nucleus and other typical cell organelles
cell body
carries electrical messages down its length
axon
occur at the ends of an axon where electrical impulses are converted to chemical messages in the form of neurotransmitters
synaptic terminals
myelin sheath produced by – in the PNS
Schwann cells
myelin sheath produced by – in CNS
oligodendrocytes
surrounds the axons of some neurons
myelin sheath
gaps between myelin sheath
nodes of Ranvier
space between the synaptic terminal of one neuron and the dendrites of another neuron
synapse
state of neurons when they re not generating messages
resting potentials
resting potential requires the maintenance of an – balance of ions on either side of the membrane to keep the membrane polarized
unequal
T/F: resting potential requires a great deal of ATP to maintain
true
during resting potential, – pumps within the membrane of the axon are used to actively transport ions into and out of the axon
sodium-potassium
Na+/K+ pumps bring – into the axon while sending out three Na+ ions
two K+ ions
because 3 Na+ are pumped out and only 2 K+ are pumped in, the membrane potential of the cell becomes more – with each cycle of the Na+/K+ pump
negative
there are also many – such as proteins within the neuron so that ultimately the inside of the neuron is more negative than the outside
negatively charged molecules
resting potential has a voltage of
-70 mV
in order to transmit a message, the resting potential of the neuron must be disrupted and - so that the inside of the cell becomes less negative
depolarized
in order for depolarization to occur, a threshold voltage of about – must be achieved
-55mV
once the action potential has initiated, – in the membrane of the axon will open
voltage-gated channels
Na+ channels open, allowing Na+ to flow – across the membrane into the axon
passively
a local flow of NA+ causes the next voltage-gated Na+ channel to open since this also also become depolarized; this continues down the length of the axon towards the synaptic terminals like a –
wave
while the speed of the action potential can vary depending on the axon diameter and myelination, its – cannot
strength
action potentials are an – event
all-or-nothing
most voltage-gated Na+ channels are – while the neuron is at rest
closed
when a stimulus arrives that cause the membrane to depolarize, voltage-gated Na+ channels in the area of depolarization open allowing for an –
influx of Na+
influx of Na+ further depolarizes the membrane, causing more voltage-gated Na+ channels to open as the membrane approaches the –
threshold voltage
if the original – was strong enough, it generates an action potential
stimulus
after voltage-gated Na+ channels open, they rapidly change conformation into an – state which will proven any additional Na+ from entering the cell
inactivated
voltage-gated K+ channels also open causing K+ to leave the cell as they flow down their electrochemical gradients, thereby making the membrane potential more – as the positively K+ ions leave
negative
T/F: if a second stimulus, capable of causing depolarization arrives at an inactivated Na+ channel, it will not be able to generate a second action potential
true
when neuron cannot generate a second action potential
refractory period
a mother consequence of the inactivation of voltage-gated Na+ channels is that action potentials are transmitted in only – direction
one
only the membrane – of the action potential can be depolarized
ahead
each neuron specializes in specific types of neurotransmitters and contains – full of them within its synaptic terminals
vesicles
when an action potential reaches the synaptic terminals, the membrane in the area is depolarized, causing the opening of voltage-gated – channels
Ca2+
influx of Ca2+ causes the synaptic vesicles to fuse with the membrane and release the neurotransmitters they contained by – into the synapse
exocytosis
neurotransmitters will diffuse through the – until they reach the neighboring neuron’s dendrites
synaptic cleft
neurotransmitters will bind to – gated channels which will open and allow for an influx of ions
ligand
– within the brain and spinal cord consists of myelinated axons
white matter
– consists of clusters of cell bodies of neurons
gray matter
cranial bones and vertebrae protect the CNS as do protective membranes called the –
meninges
between the meninges, and within the cavities of the brain, there is –
cerebrospinal fluid
cerebrospinal fluid provide nutrients, removes waste and provides – and support for the brain
cushioning
