Anatomy Exam 2

CNS makes up the…

brain and spinal cord

PNS makes up…

beyond brain and spinal cord (ganglion, nerves)

3 terms unique to the CNS

nucleus, tract, neurons

nucleus

group of neural cell bodies (CNS)

tract

bundle of axons (CNS)

2 terms unique to PNS

ganglio, nerves

ganglion

group of neuron cell bodies (PNS), enlargements

nerve

bundle of axons

white matter has regions with many

axons

gray matter has regions with many

cell bodies (somas) & dendrites

white matter is deep & internal in ____ and periphery in _____

deep in brain, periphery in spinal cord

gray matter is deep & internal in ____ and periphery in _____

deep in spinal cord, periphery in brain

why is white matter white?

because of the fatty myelin surrounding axons

composition of myelin

80% fat, 20% protein

what part of a multipolar neuron receives signals from other neurons?

dendrites

where do dendrites of one neuron make contact to receive singals from another neuron?

synapse

beginning of the axon

axon hillock/initial segment

end of the axon

axon terminal

what is the axon hillock’s function?

gatekeeper, trigger zone

what part of the neuron makes the connection with the target cell to transmit information?

synaptic end bulbs

what are the 3 universal properties of neurons?

excitability, conductivity, and secretion

what are the 3 types of neurons?

unipolar, dipolar, multipolar

physical characteristics of a unipolar neuron

only one process emerging from the cell, or one axon that splits (pseduopolar)

which neuron type is only for sensory neurons?

unipolar

physical characteristics of a bipolar neuron

2 processes that extend in opposite ways from the soma; axon and dendrite

where are bipolar neurons found?

in the eye

physical characteristics of a multipolar neuron

axon and dendrites

what are most neurons classified as?

multipolar

glial cells in the CNS

astrocytes, oligodendrite, microglia, ependymal cell

glial cells in the PNS

satellite cell, schwann cell

astrocyte functions

support: establishes the Blood Brain Barrier (BBB), removes excess signaling molecules, reacts to tissue damage, maintains concentration of chemicals in extracellular space

astrocyte unique feature

star shaped

oligodendrite functions

insulation, myelination, provides myelin for multiple axon segments (wraps out to in)

oligodendrite unique feature

cell of a few branches

microglia functions

immune surveillance, phagocytosis of cells/pathogens that cause disease

microglia unique feature

smaller than most glial cells

ependymal cell functions

filters blood to create CSF by breaking down BBB

ependymal unique feature

similar to epithelial cells (single layer, little space between, tight connections between), cilia on apical surface

satellite cell functions

support, surround neurons, NOT BBB

schwann cell functions

insulation, myelination (wraps around portion of one axon segment only)

steps of a spinal reflex arc

receptors receive stimulus, afferent signal (sensory neuron) sends to CNS, integration center (interneuron) integrates to CNS gray matter, efferent signal (motor neuron) sends to target, effectors cause response

what contributes to resting membrane potential?

ion channels are closed, NA+ greater outside cell, K+ greater inside cell, large negative anions inside, leakage channels, NA+/K+ pump

what is the value of the resting membrane potential?

-70 mV

what prevents resting membrane potential voltage from being lower?

leakage channels allowing NA+ to slowly move into cell or K+ to slowly move out, and NA+/K+ pump restoring them

what is the outside of the cell assumed to be when measuring membrane potential?

0 mV

leakage channels allow ___ to slowly move out and ___ to slowly move in

NA+ out, K+ in

what happens during depolarization?

Na+ channels open, Na+ rushes into cell, charge increases to +30mV, K+ will begin to open

what happens during repolarization?

NA+ channels close, K+ channel fully opens and K+ leave the cell, charge decreases

what happens during hyperpolarization?

K+ channels delayed in closing, overshoots to be too negative

what is the threshold value in the action potential?

-55 mV

action potential characteristics

all or none, non decremental, irreversible

what does nondecremental mean?

action potential doesn’t get weaker with distance along the axon

what are local potential characteristics?

graded (local) changes in membrane charge, decremental, reversible

what does decremental mean in local potentials?

local potentials are _____ on the strength of the stimulus

dependent

action potentials are _____ on the strength of the stimulus

not dependent

what are depolarizing graded potentials caused by?

Na+ or Ca2+ entering the cell

Na+ and Ca2+ have higher concentrations _____ the cell

outside

hyperpolarizing graded potentials are caused by

K+ leaving the cell or Cl- entering the cell

graded potentials develop in the dendrites in unipolar cells of sensory neurons, influencing generation of an action potential. this potential is called…

generator potential

graded potentials in sensory receptor cells result in the release of neurotransmitters at synapses with sensory neurons. this potential is called…

receptor potential

the graded potential in the dendrites of a neuron that is receiving synapses from other cells

postsynaptic potential (PSP)

PSP can be _____ or _____

depolarizing or hyperpolarizing

Depolarization in a postsynaptic potential is called

excitatory PSP

excitatory PSP causes the membrane potential to move ______ threshold

toward

Hyperpolarization in a postsynaptic potential is

inhibitory PSP

inhibitory PSP causes the membrane potential to move _____ threshold

away from

in action potential, does myelination or size have a greater impact on propagation speed?

myelination

will a larger or smaller axon diameter result in faster propagation?

larger

will the presence or absence of myelin increase propagation speed?

presence

why does axon diameter influence propagation speed?

larger axons have more surface area & can conduct signals faster

why does threshold not matter for receptor potentials?

the change in membrane potential for receptor cells directly causes neurotransmitter release

associating the activity of multiple inputs to a neuron with each other; result of multiple graded potentials at different locations on the neuron

spatial summation

relationship of multiple action potentials from a single cell resulting in a significant change in the membrane potential; result of multiple graded potentials all at the same place but separated in time

temporal summation

a chemical signal—namely, a neurotransmitter—is released from one cell and it affects the other cell

chemical synapse

direct connection between the two cells so that ions can pass directly from one cell to the next

electrical synapse

steps of neurotransmitter release

action potential reaches axon terminals causing depolarization of the neuron, voltage gated Ca2+ channels in synaptic end bulb open, Ca2+ enters the cell, Ca2+ associates with proteins of neurotransmitter vesicles, Ca2+ allows vesicles to merge with presynaptic membrane, neurotransmitters released into synaptic cleft, neurotransmitters diffuse to postsynaptic membrane & interacts with specific receptors

cerebrum functions

controls memory, emotion, consciousness

what is the cerebrum made up of?

gray matter

what is the cerebral cortex?

thin, continuous layer of gray matter wrapping around the cerebrum

temporal lobe functions

memory and hearing

where is Wernicke’s area found?

in the temporal lobe

what are the functions of Wernicke’s area?

language comprehension

what are the functions of the parietal lobe?

somatosensation (general body sensations), proprioception, kinesthesia

what is proprioception?

awareness of body position

what is kinesthesia?

awareness of movement

where is the somatosensory cortex found?

in the parietal lobe

what does the somatosensory cortex do?

sensory system for touch, pressure, pain, proprioception

what lobe is the postcentral gyrus found in?

in the parietal lobe

what are the frontal lobe functions?

motor functions, planned movements, personality, short-term memory, consciousness

where is broca’s area found?

in the frontal lobe

what does broca’s area do?

language production

where is the primary motor cortex found?

in the frontal lobe

what does the primary motor cortex do?

movement

what are the functions of the occipital lobe?

visual processing

where are the subcortical structures?

beneath the cerebral cortex

what 3 things make up the subcortical structures?

basal forebrain, limbic structures, basal nuclei

what 4 structures make up the diancephalon?

thalamus, hypothalamus, epithalamus, subthalamus

what is the function of the diancephalon?

nervous system (brain, spinal cord, PNS) sends info to the cerebrum through this structure

what are the functions of the thalamus?

communication center; all sensory information (except smell) passes through here before cortical processing; cerebrum communicates motor commands here