nervous system (10-pager and action potentials) Flashcards by Jacey Chen

the Central Nervous System consists of…

brain and spinal cord

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what are sensory (afferent) neurons responsible for?

sending impulses from the senses to the central nervous system (CNS)

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cranial and spinal nerves make up the…

peripheral nervous system (PNS)

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what are motor (efferent) neurons responsible for?

transmitting impulses from the central nervous system (CNS) to the muscles and glands

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aside from involuntary muscle control, name THIS nervous system division and 3 things it’s responsible for:

system: autonomic nervous system
3 things: breathing, chewing, fight/flight response (all under the ‘survival skills’ umbrella )

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voluntary muscle control is controlled by THIS nervous system division:

somatic nervous system

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true or false? the parasympathetic and sympathetic NS can run at the same time

FALSE!

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which NS division is used in emergency situations? name that division and give 1 example of something it regulates

name: sympathetic division
function: fight/flight/freeze/fawn

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which NS division is NOT used in emergency situations? name that division and 2 of its functions

name: parasympathetic division
function: reduces sympathetic response and provides resting functions like digestion and urination

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what is the function of the NS? which other system has the same function?

function: communication and control
name of other system: endocrine

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the nervous system is the ______ _______ ______ of the body.

master control center

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the 3 things the nervous system uses/relies on to do its job properly are:

sensory input (detects changes/stimulus from inside and outside the body)
integrations/processing (processing and interpreting info)
response (activation of muscles or glands)

so really it’s just sense -> process -> respond

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name the 2 major types of nerve cells and their functions:

neurons: make up ~10% of nerve cells, conduct impulses around the body
neuroglia: make up ~90% of nerve cells; they support, insulate and protect neurons

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what is the structure of a neuron?

they all possess:
- a main cell body (containing nucleus, cytoplasm and organelles) w/ outward extending processes

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how many parts are processes divided into and what are they?

dendrites (receive signals/impulses from other neurons)
axons (send impulses away from cell body)
axon terminals (release neurotransmitters to pass impulses to the next neuron)

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how are neurons classified? name all the possibilities within the 2 classification categories

the # of processes extending from cell body + function
- by process: unipolar, bipolar, multipolar
- by function: afferent, efferent, interneuron

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what is the myelin sheath and how is it formed?

is the cell’s waxy insulation
schwann cell (type of neuroglia) wraps itself around axon like a coil
all “lumps” on axon (myelin wrapping) tgt form the myelin sheath

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name the outer layer of the schwann cell

neurilemma

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what is the function of myelin?

help nerve impulses travel quicker

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what are the names of the gaps between the myelin “lumps”?

nodes of ranvier

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which type(s) of neuroglia are found in the CNS? which type(s) are found in the PNS?

CNS:
- astrocytes
- microglia
- ependymal cells
- oligodendrocytes
PNS:
- satellite cells
- schwann cells

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define nerve impulses and describe why/how it occurs

electrical signal that travels along the neuron.
occurs bc ion movement causes a change in electric charges

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at rest, a neuron’s intercellular space is __________ charged and the extracellular space is __________ charged

negatively, postively

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when the neuron is _______, either by the ___________ or _______ ______, ______ (element) rushes into it and reverses the charges. the charges being reversed is called ______________ and it’s also known as the ______ _________.

stimulated, environment, another neuron, sodium, depolarization, action potential

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name the 5 steps of an action potential (do NOT name the functions yet, that's for another deck)

1. resting potential 2. threshold 3. depolarization 4. repolarization 5. hyperpolarization

define resting potential and its voltage (intro 1/5)

neuron not transmitting any impulses. voltage: -70 mV

describe resting potential (3 points; detailed 1/5)

- the neuron is not transmitting any impulses. - outside of (currently polarized because inside and outside regions have opposite charges) neuron is (+) charged, inside is (—) charged. - voltage: -70 mV

describe threshold and its voltage (intro 2/5)

stimulus triggers influx of Na+ ions; voltage is -55 mV

describe threshold (3 points; detailed 2/5)

- action potential gets triggered when stimulus alters resting potential - stimulus opens stimulus-gated Na+ channels, and ion channels which lets Na+ ions rush in - sudden surge of Na+ ions cause a rise in voltage; it is -55mV

describe depolarization and its voltage (intro 3/5)

threshold opens nearby Na+ channels, voltage surges and becomes +35 mV

describe depolarization (3 points; detailed 3/5)

- nearby voltage gated Na+ channels open once threshold voltage is reached. - even more Na+ ions enter cell - action potential triggers depolarization in each area

describe repolarization and its voltage (intro 4/5)

membrane repolarizes due to exiting of K+ ions. voltage: -70 mV

describe repolarization (3 points; detailed 4/5)

- membrane repolarizes as action potential moves down axon - all Na+ channels close and K+ channels open - large outflux of (-) ions cause drop in voltage, it's now -70 mv

describe hyperpolarization (intro 5/5)

K+ channels stay open longer than needed; voltage: -75 mV

describe hyperpolarization (4 points; detailed 5/5)

- K+ channels stay open longer than needed - voltage falls briefly to -75 mV - Na/K pump must move more Na+ ions outside cell and more K+ inside cell - resting potential reached, neuron fires again

what is a synapse? do neurons touch?

synapse: junction between 2 neurons where nerve impulses/action potentials are transmitted through neurontransmitters. and no, neurons don't touch.

space between neurons is called the...

synaptic cleft

because there's a synaptic cleft between neurons, impulses can't get across directly. how are impulses transmitted, then?

- via neurotransmitters - they bridge the gap and conduct the impulse in the next neuron bonus: - nerve impulse reaches knob-like extensions called synaptic bulbs and it triggers the release of neurotransmitters.

what are the 5 steps of synaptic transmission? (no functions just yet)

1. action potential arrives at presynaptic terminal 2. Ca2+ channels open 3. Synaptic vesicles release neurotransmitters 4. neurotransmitters bind to receptors on post-synaptic neuron 5. Na+ channels open on the postsynaptic neuron (6. impulse continues)

what is the refractory period?

the amount of time after an action potential when a neuron can't fire again.

what types of refractory periods are there?

1. absolute refractory period 2. relative refractory period

differentiate between absolute and relative refractory period

absolute: - neuron cannot trigger another action potential - due to inactive Na+ channels - lasts 1 ms relative: - neuron CAN trigger action potential but w/ larger stimulus - due to K+ channels still open - lasts 3 ms

define the all-or-none rule

actions potentials either occur fully or not at all; larger stimuli do not result in larger action potentials. the FREQUENCY OF POTENTIALS is what determines how a stimulus is perceived by the CNS. small stimuli: - lower freq. of action potentials - perceived by CNS as less intense large stimuli: - higher freq. of action potentials - perceived by CNS as more intense

3 layers of __________ ______ protects the CNS

connective tissue

name the 3 layers of tissue that protect the CNS from superficial to deep and describe them briefly

- dura mater: thick, tough layer - arachnoid mater: thin, cobweb-like layer - pia mater: thin layer w lots of blood vessels

what is found between the arachnoid layer and pia mater? what does it do?

cerebrospinal fluid. it protects the brain by stopping it from hitting the skull and maintains the blood-brain barrier (maintains homeostasis and fights infections)

where is cerebrospinal fluid (CSF) produced?

ventricles

how many ventricles does the brain have? name them

4 in total: L, R, (lateral) 3rd and 4th

what connects the latter ventricles (L+R) to the 3rd ventricle?

intraventricular foramen/foramen of monro

what secretes CSF and where are they found?

capillary clusters called choroid plexus; found in ventricles

what part of the NS controls the R side of the body

L hemisphere

which chemical substances assist with carrying a message to the next neuron?

neurotransmitters

define homeostasis

body's ability to maintain stability/equilibrium

which part of the brain is largest and controls thinking, reasoning and memory?

cerebrum

subdivision of NS that brings info to CNS

peripheral NS

system made of brain, spinal cord and nerves:

nervous system

contains the midbrain, pons, and medulla oblongata

brainstem

darker tissue of brain and spinal cord, mainly made of nerve cells and dendrites

grey matter

message travelling from dendrites to axon

impulse

part of CNS linking brain to rest of the body

spinal cord

extensions of a neuron that receive message and conduct impulses toward the cell

dendrites

subdivision of PNS that controls voluntary activities

somatic NS

controls thirst, hunger and body temperature

hypothalamus

rapid response to protect from danger that takes place without thinking about it

reflex

part of NS and consists of brain and spinal cord

CNS

type of neuron carrying messages w sense information

sensory neuron

responsible for balance, coordination and routine movement

cerebellum

controls L side of body

R hemisphere

part of NS that controls involuntary mvt and responses

autonomic NS

paler tissue of the brain and spinal cord, made mainly of myelin sheaths

white matter

define axon

long nerve fibre that conducts away from the body of the neuron

changes in the environment that cause a response

stimuli

folds in the brain that allow for greater surface area

cortical folds

backbones that protect the spinal cord

vertebrae

insulating layer along the axon of nerve cell made mainly of fat and protein

myelin sheath

reflex arc is....

the nerve pathway involved in a reflex action

the type of neuron carrying msgs telling muscles and glands to move are...

motor (efferent) neurons

a synapse is...

the junction between two neurons where neutrotransmitters are released to transmit nerve impulses

basic building block of the nervous system is...

neuron

stores long-term memory

hippocampus

nervous system (10-pager and action potentials) Flashcards

know the nervous system material inside and out