Bootcamp.com - Nervous System (11)

a _____ is the basic functional unit of the nervous system

neuron

what are the three main parts of neuron?

cell body (soma); dendrites; axon

what is the name for the cell body of a neuron, and what organelle does it contain?

soma; nucleus

_____ are processes that receive signals from previous neurons

dendrites

_____ are long processes that transduce signals to the next neuron

axons

graded potential summation occurs at the _____, which connects the soma to the axon

axon hillock

what will happen if a summation is more positive than the threshold potential?

an action potential will fire

_____ is a fatty insulation of the axon, which helps for faster axon conduction

myelin sheath

which cells produce the myelin sheath in the central nervous system?

oligodendrocytes

which cells produce the myelin sheath in the peripheral nervous system?

schwann cells

_____ are gaps between myelin sheath of the axon

Nodes of Ranvier

what is saltatory propagation?

the action potential "jumps" from one node of Ranvier to the next

what is the benefit of saltatory propagation?

it provides faster conduction than propagating the signal down the entire axon

what is the resting potential for a typical neuronal cell?

-70 mV

a cell's resting potential is maintained by _____

Na+/K+ ATPases

more Na+ is _____ the neuron at the resting state

outside

more K+ is _____ the neuron during the resting state

inside

the Na+/K+ ATPase (pump) exchanges _____ out of a cell for _____ into the cell, and it consumes _____ to do so

3 Na+; 2 K+; 1 ATP

the Na+/K+ pump maintains a (positive/negative) charge in the neuron

negative

(extracellular environment is more positive)

what happens when a neuron is stimulated by an excitatory potential?

depolarization

(membrane potential is made less negative)

gated Na+ channels open/close when a neuron is depolarizing

open

Na+ flows in/out of a neuron during depolarization

in

what is the threshold potential of a neuron?

minimum potential for an action potential

(typically -55 mV)

after a neuron reaches threshold, it will experience an action potential that is always the same size - what is the typical charge of an action potential?

+30 mV

what happens at +30 mV (peak action potential)?

repolarization

(membrane potential becomes more negative)

Na+ channels (open/close), while K+ channels (open/close) to initiate repolarization

close; open

K+ flows (in/out) of the neuron during repolarization

out

eventually, a neuronal cell will _____, meaning the membrane potential falls below the normal resting potential of -70 mV

hyper-polarize

what is the typical charge of a hyperpolarized neuronal cell?

-90 mV

a neuron's refractory period occurs during _____ & _____, and it extends into _____

action potential; repolarization; hyperpolarization

what are the two stages of the refractory period?

absolute; relative

a second stimulus cannot generate another action potential during the _____ of an action potential/repolarization

absolute refractory period

describe Na+ and K+ channels during the absolute refractory period?

gated Na+ channels are open until peak action potential, then they close

K+ channels open at peak action potential until the end of repolarization

a second stimulus can stimulate an action potential if it is strong enough during a _____

relative refractory period

the relative refractory period occurs after the _____

absolute refractory period

(or onset of hyperpolarization)

describe Na+ and K+ channels during the relative refractory period:

the Na+ channels remain closed

the K+ channels remain open until the resting potential is acheived

neurons are _____ during the relative refractory period

hyperpolarized

a _____ is the space between two neurons

synapse (synaptic cleft)

the _____ neuron releases neurotransmitters into the synapse

presynaptic

the _____ neuron receives neurotransmitters that cross the synapse

postsynaptic

what happens when an action potential reaches the end of the presynaptic axon?

voltage-gated Ca2+ channels open, allowing Ca2+ to flow into the neuron

what happens when voltage-gated Ca2+ channels open to allow Ca2+ influx into the presynaptic neuron?

synaptic vesicles release neurotransmitters into the synapse by exocytosis

postsynaptic graded potentials can be _____ or _____ depending on the neurotransmitter

excitatory; inhibitory

excitatory postsynaptic potentials (EPSPs) occur when the neuron _____ due to _____ that open

depolarizes; Na+ gates

Na+ flows (into/out of) the cell during an excitatory postsynaptic potential (EPSP)

into

excitatory postsynaptic potentials (EPSPs) bring the neuron _____ to the threshold

closer

inhibitory postsynaptic potentials (IPSPs) occur when the neuron _____ due to _____ & _____ channels that open

hyperpolarizes; Cl-; K+

in which directions do Cl- and K+ flow during an inhibitory postsynaptic potential (IPSP)?

Cl- = into the cell

K+ = out of the cell

inhibitory postsynaptic potentials (IPSPs) bring the neuron _____ from the threshold

further away

graded potentials vary in _____ and _____ (EPSP v. IPSP)

magnitude; direction

_____ occurs when all graded potentials (EPSPs and IPSPs) are added together at the _____

summation; axon hillock

an _____ and ensuing _____ occur if the sum of EPSPs and IPSPs is higher than the threshold

action potential; refractory period

there will not be an action potential (or refractory periods) if the sum of EPSPs and IPSPs is _____

below threshold

what are neurotransmitters?

chemical messengers used during chemical neurotransmission

what is the main excitatory neurotransmitter of the vertebrate central nervous system?

glutamate

which category of neurotransmitter does glutamate fall into?

amino acid neurotransmitter

gamma-aminobutyric acid (GABA) is a(n) _____ (class of neurotransmitter), and it is an inhibitory/excitatory neurotransmitter of the brain

amino acid neurotransmitter; inhibitory

glycine is a(n) _____ (class of neurotransmitter), and it is an inhibitory/excitatory neurotransmitter of the spinal cord, brainstem, retina

amino acid neurotransmitter; inhibitory

epinephrine and norepinephrine are _____ (class of neurotransmitter)

amino acid-derived

epinephrine and norepinephrine are _____ postsynaptic neurotransmitters of the _____

excitatory; SNS

another name for epinephrine and norepinephrine is _____ and _____

adrenaline; noradrenaline

dopamine is a(n) _____ (class of neurotransmitter), and it is an _____ neurotransmitter of the brain

amino acid-derived; excitatory

_____ is an amino acid-derived neurotransmitter that is responsible for reward-motivated behavior

dopamine

serotonin is a(n) _____ (class of neurotransmitter), and it is an inhibitory/excitatory neurotransmitter of the brain

amino acid-derived neurotransmitter; inhibitory

for which bodily functions is serotonin responsible?

mood, appetite, sleep, and learning

serotonin increases/decreases contraction of the GI tract in response to food intake

increases

which category of neurotransmitter is involved in diverse roles for many brain functions?

short chain amino acid neurotransmitters (neuropeptides)

what is a common example of a short chain amino acid neurotransmitter?

substance P

_____ is a gaseous neurotransmitter (gasotransmitter)

nitric oxide

nitric oxide gasotransmitter causes relaxation of the smooth muscle in blood vessels (_____)

vasodilation

nitric oxide gasotransmitter is synthesized and released _____

on demand

what is the excitatory neurotransmitter of a neuromuscular junction?

acetylcholine

acetylcholine is the presynaptic/postsynaptic neurotransmitter of the sympathetic and parasympathetic nervous systems

presynaptic

What is the postsynaptic neurotransmitter of the parasympathetic nervous system?

acetylcholine

_____ are non-neuronal cells that nourish, support, and protect neurons

glial cells

what are the two subcategories of glial cells?

microglia; macroglia (various types)

_____ are specialized macrophages that protect the CNS

microglia

what are the various types of macroglial cells?

schwann cells; oligodendrocytes; astrocytes; satellite cells; ependymal cells

_____ form the myelin sheath in the peripheral nervous system

schwann cells

_____ form the myelin sheath in the central nervous system

oligodendrocytes

what is the most abundant type of CNS neuroglia?

hint: it is a type of macroglial cell

astrocytes

astrocytes provide blood to _____ neurons and help form the _____

CNS; blood brain barrier

_____ are macroglia that recycle neurotransmitters and maintain ion levels

astrocytes

satellite cells ensheathe the _____ of central/peripheral nerves

soma; peripheral

_____ are similar to astrocytes; however, they function in the peripheral nervous system

satellite cells

ependymal cells are macroglia that create the _____

cerebrospinal fluid

what are the major components of the central nervous system (CNS)?

the brain and spinal cord

what are the major components of the peripheral nervous system?

all the nerves that branch off the CNS

what are the three areas of the brain seen during embryonic development?

forebrain; midbrain; hindbrain

what does the forebrain develop into?

telencephalon and the diencephalon

the telencephalon gives rise to the _____

cerebrum

the _____ gives rise to the thalamus, hypothalamus, pineal gland, and retina

diencephalon

what does the midbrain develop into?

mesencephalon

the mesencephalon gives rise to the _____

midbrain

what does the hindbrain develop into?

metencephalon and the myelencephalon

the metencephalon gives rise to the _____ & _____

pons, cerebellum

the myelencephalon gives rise to the _____

medulla oblongata

the _____ is the brain cortex, which has two hemispheres and is involved in higher cognitive functions

cerebrum

what are the four lobes of the cerebrum?

frontal; temporal; occipital; parietal

where is the cerebellum located?

under the occipital lobe of the cerebrum