ch4: nervous system

Question 1

Neurons

Answer 1

highly specialized cells responsible for the conduction of impulses

communicate using both electrical and chemical forms of communication

electrical: occurs via ion exchange and the generation of membrane potentials doewn the length of the axon
chemical: occurs via neurotransmitter release form the presynaptic cell and the binding of these neurotransmitters to theist synaptic cell

Question 2

neurons consist of

Answer 2

dendrites, soma, axon hillock, axon, nerve terminal/synaptic bouton, nodes of ranvier, synapse, synaptic cleft

Question 3

dendrites

Answer 3

appendages of neurons that receive signals form other cells and direct them to the soma

Question 4

soma

Answer 4

cell body of neuron

location of the nucleus as well as organelles such as the ER and ribosomes

Question 5

axon hillock

Answer 5

where the cell body of the neuron transitions into the axon, and where the action potentials are initiated

integrates excitatory and inhibitory signals form the dendrites and fires an action potential if the excitatory signals are strong enough to reach threshold.

Question 6

axon

Answer 6

long appendage on neuron down which the action potential travels

Question 7

nerve terminal/synaptic bouton

Answer 7

the end of the axon from which the neurotransmitters are released

transmits an electrical signal (the action potential) form the soma to the synaptic knob.

Question 8

Nodes of Ranvier

Answer 8

exposed areas of myelinated axons that permit saltatory conduction (the signal hopping form note to node since myelin insulation is so effective that the membrane is only permeable to ion movement at the nodes of ranvier)

small breaks in the myelin sheath with exposed areas of the axon membrane along the axon

critical for rapid signal conduction

Question 9

synapse

Answer 9

consists of the nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell, and the space between the two, called the synaptic cleft

Question 10

myelin

Answer 10

an insulating substance that prevents signal loss

many axons are coated in this

increases the speed of conduction in the axon of nerve impulses

creates the nodes of ranvier bc it forms gaps along the axon (saltatory conduction: signal jumping)

created by oligodendrocytes in the CNS and Schwann cells in the peripheral NS

prevents dissipation of the neural impulse and crossing of neural impulses from adjacent neurons

myelin sheath: maintains the electric signal within one neuron

Question 11

individual axons are bundled into ___ or ___

Answer 11

nerves or tracts

Question 12

tracts vs nerves

Answer 12

tracts contain only one type of info
tracts are collections neurons in the CNS and contain cell bodies in NUCLEI

nerves may carry multiple types of information, including sensory, motor, or both
nerves are collections of neurons in the CNS
contain cell bodies in GANGLIA

Question 13

ganglia

Answer 13

cell bodies of neurons of the same type with in a nerve cluster are within this in the peripheral NS

collection of cell bodies in the PNS

Question 14

nuclei

Answer 14

cell bodies of individual neurons within a tract cluster in this in the central nervous system

collection of cell bodies in the CNS

Question 15

Neuroglia/ Glial Cells

Answer 15

other cells within the NS in addition to neurons

astrocytes, ependymal cells, microglia, oligodendrocytes and Schwann cells

Question 16

astrocytes

Answer 16

nourish neurons and form the blood brain barrier, which controls the transmission of solutes form the bloodstream into nervous tissue

Question 17

ependymal cells

Answer 17

line the ventricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as shock absorber

Question 18

microglia

Answer 18

phagocytic cells that ingest and break down waste products and pathogens in the CNS

Question 19

Oligodendrocytes (in the CNS) and Schwann cells (in the PNS) produce…

Answer 19

myelin around axons

Question 20

resting membrane potential

Answer 20

all neurons exhibit this at approximately -70mV

maintained using selective permeability of ions as well as the NA+/K+ ATPase

depends on differential distribution of ions across the axon membrane and active transport of ions across the membrane

Question 21

The Na+/K+ ATPase

Answer 21

pumps three sodium ions out of the cell for ever two potassium ions pumped in

brings the neuron back to the resting potential and restores the sodium and potassium gradients

Question 22

excitatory signal

Answer 22

a type of incoming signal

cause DEpolarization of the neuron

Question 23

inhibitory signal

Answer 23

a type of incoming signal

cause hyperpolarizaiton of the neuron

Question 24

temporal summation

Answer 24

the addition of multiple signals near each other in time

Question 25

Spatial summation

Answer 25

addition of multiple signals near each other in space

Question 26

action potential

Answer 26

used to propagate signals down the axon

impulse propagates down the length of the axon because of the influx of sodium in one segment of the axon brings the subsequent segment of the axon to threshold. the fact that the preceding segment fo the axon is int its refractory period means that the acting potential can only travel in one direction

“all or nothing messages” used by neurons

rely electrical impulses down the axon to the synaptic bouton

Question 27

when enough excitatory stimulation occurs, the cell is ______ to the _____ and the voltage gated sodium channels open

Answer 27

when enough excitatory stimulation occurs, the cell is DEPOLARIZED to the THRESHOLD VOLTAGE and the voltage gated sodium channels open

Question 28

electrochemical gradient

Answer 28

sodium flows into the neuron due to its strong electrochemical graduate, which continues depolarizing the nueron

Question 29

action potentials peak:

Answer 29

+35 mV

sodium channels are inactivated and potassium channels open

Question 30

potassium glows out the of the neuron due to its strong electrochemical gradient, ____ the cell

Answer 30

potassium glows out the of the neuron due to its strong electrochemical gradient, REPOLARIZING the cell

potassium channels stay open long enough to overshoot the action potential, resulting in a hyper polarized neuron; then the potassium channels close

Question 31

refractory period

Answer 31

while the Xon is hyper polarized, it is in its refractory period.

during the absolute refractory period, the cell is unable to fire another action potential.

during the relative refractory period, the cell requires a larger than normal stimulus to fire an action potential

Question 32

the process of nerotransmitters being released into the synapse at the nerve terminal

Answer 32

when the action potential arrives at the nerve terminal voltage gated calcium channels open

the influx of calcium causes fusion of vesicles filled with neurotransmitter with the presynaptic membrane, resulting in exocytosis of neurotransmitter into the synaptic cleft

the neurotransmitters bind to the receptors on the postsynaptic cell, which may be ligand gated ion channels or G protein coupled receptors

Question 33

postsynaptic cells

Answer 33

must clear the neurotransmitters to stop the propagation of the signal

Question 34

neurotransmitter

Answer 34

can be enzymatically broken down (by the post synaptic receptors)

can be absorbed back into the presynaptic cell by REUPTAKE CHANNELS

the neurotransmitter can diffuse out of the synaptic cleft

Question 35

equilibrium potential of potassium

Answer 35

around -90mV

negative sign is due to potassium (pos) leaving the cell

this is that potential difference that is caused when potassium has left the cell and there is no more net movement of the ion

cell is slightly more permeable to potassium than sodium so the balance of the two effects is around -70mV for an average enrobe cell

Question 36

equilibrium potential of sodium

Answer 36

around 60 mV

moving in to the cell

Question 37

When when the membrane potential Vm approaches +35 mV, the sodium channels are

Answer 37

inactivated and will aha etc be brought back near the rising potential to be deinactivated

Question 38

sodium channels can exist in three states:

Answer 38

closed: before the cell reaches threshold, and after the inactivation step has been reversed
open: from threshold to approximately +35mV
inactive: from approx +35 mV to resting potential

Question 39

repolarizaiton

Answer 39

a restoration of the negative membrane potential as positively changed potassium cations are driven out of the cell

the efflux of the cations causes an overshoot of the resting membrane potential, hyperolarizing the neuron, which serves an important function of making the neuron refractory to further action potentials

Question 40

impulse proporations

Answer 40

action potential traveling down the axon and initiating neurotransmitter release, causes it to flow in one direction

increased lengths of the axon result sin high resistance and slower conduction. greater cross sectional areas allowed for faster proapgation due to decreased resistance.

the effect of the cross sectional area is more sig than effect of length!

Question 41

if the neurotransmitter receptor is a G protein coupled receptor…

Answer 41

it will cause either change in the levels of cAMP or an influx of calcium

Question 42

if the neurotransmitter receptor is a ligand gated ion channel…

Answer 42

the postynaptic cell will either be depolarized or hyperpolarized

Question 43

regulation of neurotransmission and neurotransmitters

Answer 43

can be broken down by enzymatic reacionts

can be brought back into the presynaptic neuron using reuptake

neurotransmitters may simply diffuse out of the synaptic cleft

Question 44

neutotransmitters

Answer 44

acetylcholine (ACh), serotonin(5-HT), Dopamine (DA) and norepinephrine (NE) Nitric oxide (NO)

Question 45

serotonin(5-HT), Dopamine (DA) and norepinephrine (NE) are all explampes of

Answer 45

reuptake carriers as a form of neurotransmission regulation

Question 46

Nitric oxide (NO)

Answer 46

a gaseous signaling molecule

regulation by simply diffuse out of the synaptic cleft

Question 47

what neural structure initiates the action potential

Answer 47

axon hillock

Question 48

what entity maintains the resting membrane potential and what is the approx voltage of the resting gmemebrane potential

Answer 48

the resting membrane potential is maintained by the Na+/K+ ATPase at approx -70mV

Question 49

temporal vs spatial summation

Answer 49

temporal summation is the integration of multiple signals close to eachother in time TT

spacial summations the integration of multiple signals close to each other in space
SS

Question 50

During the action potential, which ion channel opens first? How is this ion channel regulated? What effect down the opening of this channel hav eont depolarization of the cell

Answer 50

the sodium channel opens first at threshold (-50mV) and regulated by inactivation (occurs at _35mV) which can only be reversed by repolarizing the cell. The opening of the sodium cannel causes depolarization

Question 51

During the action potential, which ion channel opens first? How is this ion channel regulated? What effect down the opening of this channel hav eont depolarization of the cell

Answer 51

the potassium channel opens second at +35 mV and is regulated by closing at low potentials (belowish -70mV) and the opening of the potassium channel causes repolarization and eventually hyperpolaizaiotn

Question 52

absolute vs. relative refractory period

Answer 52

during the absolute refractory period, the cell is unable to fire an action potential regardless of the intensity of a stimulus. during the relative refractory period, the cell can fire an action potential only with a stimulus that is stronger than normal

Question 53

what ion is primarily responsible fo sth effusion of neurotransmitter containing vesicles with the nerve terminal membrane

Answer 53

calcium is responsible for fusion of neurotransmitter vesicles with then nerve terminal membrane

Question 54

three main methods why which a neurotransmitters action can be stopped

Answer 54

enzyme degradation, reuptake, diffusion

Question 55

motor neurons

Answer 55

efferent

Exersize: motor idk

Question 56

sensory neurons

Answer 56

afferent
enter spinal cord on the dorsal side

AAAwww- im sensing sadness
Aflec ben- wow… idk

Question 57

white matter

Answer 57

in the CNS

consists of myelinated axons

lies on the outside of the cord

in the brain, white matter is deeper than grey matter
in the spinal cord, grey matter is deeper than white matter

Question 58

grey matter

Answer 58

in the CNS

consists of unmylinated cell bodies and dendrites.

in the brain, white matter is deeper than grey matter
in the spinal cord, grey matter is deeper than white matter

Question 59

somatic NS

Answer 59

voluntary

part of the PNS

Question 60

autonomic NS

Answer 60

automatic actions

kinda self explanatory

Question 61

autonomic nervous system is further divided into

Answer 61

parasympathetic NS (rest and digest):

sympathetic (fight or flight) NS

usually when you SYMPathize with someone, they are explaining a fight or flight scenario
and usually when ur PARAchuting its kinda quiet up there so u might as well take a nap while u think about ur digestion

Question 62

spinal cord 4 divisions:

Answer 62

cervical, thoracic, lumbar, and sacral

all fo the structures below the neck receive sensory and motor innervitation form the spinal cord.

the spinal cord is protected by the vertebral column, which transmits nerves at the space between the adjacent vertebrae

Question 63

dorsal root ganglia

Answer 63

contain the cell bodies of the sensory neurons (bringing info in form the periphery and enter the dorsal (back) side of the spinal cord)

sensation

Question 64

PNS

Answer 64

made up of nerve tissue and fibers outside the brain and spinal cord, including all 31 pairs of spinal nerve and 10 of the 12 pairs of cranial nerves (the olfactory and optic nerves are technically outgrowths of the CNS)

connects the CNS to the rest of the body and can itself be divided

Question 65

in the autonomic nervous system, two neurons work in series to transmit messages from the spinal cord. they are

Answer 65

preganglionic neuron- in the CNS and its axon travel s to a ganglion the PNS

post ganglionic neuron: in the PNS preganglionic neuron synapses on this cell body, which then affects the target tissue

Question 66

monosynaptic reflex arc

Answer 66

a single synapse between the sensory neuron that receives the stimulus and the motor neuron that responds to it.

knee jerk reflex

Question 67

polysynaptic reflex arc

Answer 67

there is at least one interneuron between the sensory and motor neurons.

withdrawal reflex: stepping on a nail

different form the monosynaptic reflex arc becuase not only does it do all that the monosynaptic reflex arc does, but it also triggers and stimulates other motor neuron other actions, like balancing, shifting weight

interneurons in the spinal cord profile the connections form tehincoming sensory information to the motor neurons in the supporting limb

SIMPLY PUT: a sensory neuron may fire directly onto a m motor neuron, bu t interneurons are used as well, which fire onto other motor neurons

Question 68

voltage gated calcium channels are important in the …

Answer 68

nerve terminal, where the influx of calcium triggers the fusion of vesicles containing neurotransmitter with the membrane. it has nothin to do with maintaining resting membrane potential

Question 69

t/f neuronal info is coded by the frequency and number of action potentials, and not the “size” fo the action potential

Answer 69

TRUE

once an action potential is triggers, an impulse of a given magnitude and speed is produced

Question 70

when a sensory neuron receive a stimulus that brings it to threshold it will

Answer 70

become depolarized, allowing it to traduce the stimulus to an action potential, which will then be carried by sensory neurons to the CNS where the cell will release neurotransmitters. if a receptor is stimulated, it will promote the bread of the action potential to postsynaptic sensory neurons int eh spinal cord, which can send the signal toward the brain

Question 71

hyperpolarization

Answer 71

when the potential across the axon membrane is more negative than the normal resting potential

occurs right after an action potential and is caused by EXCESS POTASSIUM EXITING THE NEURON

Question 72

reflective arcs

Answer 72

monosynaptic and polysynaptic

reflexive responses to certian stimuli that involve only a sensory and a motor neuron, which synapse in the spinal cord and do not require signaling form the brain. (The pathways of the somatic division can involve two three or more neurons, depending on the type of signal)

Question 73

acetylcholine

Answer 73

neurotransmitter released by the preganglionic neuron in both the sympathetic and parasympathetic nervous systems. the postganglionic neuron in the sympathetic nervous system usually releases norepinephrine, while the postganglionic neuron int he parasympathetic nervous system releases acetylcholine

so acetylcholine is used in the ganglia of both the parasympathetic and sympathetic NSs

Question 74

voltage gated calcium channels…

Answer 74

open when the nerves terminal depolarizes, allowing an influx of calcium, which triggers the fusion of synaptic vesicles containing neurotransmitters with the membrane of the neuron at the nerve terminal, allowing for exocytosis of the neurotransmitters into the synapse.

a blocking of the influx of calcium could cause flaccid paralysis because there would be no release of neurotransmitters, so the neuron cannot send excitatory signals to the muscle

Question 75

summation

Answer 75

a pattern of excitation in which some neurons require multiple instances of excitatory signals/transmission to be brought to threshold.

These excitatory signals may be close to each other in time (temporal) or int space (spatial).