Neuro week 1 - Nervous system overview

the master control and communicating system of the body

nervous system

the nervous system is classified based on

structure and function

organs of the central nervous system

brain, spinal cord

integration and command center of the body

central nervous system

organs of the peripheral nervous system

spinal nerves, cranial nerves

what nerves carry impulses to and from the spinal cord

spinal nerves

what nerves carry impulses to and from the brain

cranial nerves

major communication lines among sensory organs, brain and spinal cord, and effectors

parasympathetic nervous system

what nerve fibers in the PNS carry information TO the central nervous system

sensory (afferent) fibers

what nerve fibers in the PNS carry impulses AWAY FROM the CNS

motor (efferent) fibers

subdivisions of the motor (efferent) division of the PNS

somatic nervous system, autonomic nervous system

true or false: the somatic nervous system is involuntary

false

true or false: the autonomic nervous system is involuntary

true

what nervous system division controls conscious movement of skeletal muscles

somatic nervous system

what nervous system division controls automatic movement of smooth and cardiac muscles / glands

autonomic nervous system

subdivision of the autonomic nervous system

sympathetic, parasympathetic nervous system

what autonomic motor fiber causes fight or flight effects on smooth and cardiac muscles and glands

sympathetic fibers

what autonomic motor fibers trigger rest and digest effects on smooth and cardiac muscles and glands

parasympathetic fibers

support cells in the CNS and PNS are grouped together as ____

neuroglial (glial cells)

general functions of neuroglia / glial cells

support, insulate, and protect neurons

what best describes astrocytes

most abundant and versatile neuroglia, star shaped

primary function of astrocytes

control chemical environment of the brain; form barrier between capillary and neurons

what best describes microglia

spiderlike phagocytes that reside in the brain

primary function of ependymal cells

cilia assist with circulation of cerebrospinal fluid; line cavities of brain and spinal cord; help produce CSF

primary function of oligodendrocytes

produce myelin sheaths around nerve fibers in the CNS

what are the support cells of the CNS

astrocyte, oligodendrocyte, ependymal, microglia

what is another term for support cells

glial cells

what are the support cells of the PNS

satellite, Schwann

primary function of satellite cells

protect neuron cell bodies in the PNS

primary function of Schwann cells

form myelin sheath in PNS

true or false: Schwann cells wrap around one neuron at once and none exist in the CNS

true

true or false: deterioration of myelin sheaths in the CNS is a causative factor of multiple sclerosis

true

what best describes neurons

nerve cells specialized to transmit messages

the nucleus and metabolic center of a neuron

cell body

fibers that extend from the cell body of neurons are called

processes

feature of neuron cell bodies that has a specialized rough endoplasmic reticulum

Nissl bodies

major structures of the cell body

Nissl bodies, neurofibrils, nucleus

axons end in _____

axon terminals

axon terminals contain _____ with neurotransmitters

vesicles

what are the two types of gaps that separate axon terminals from adjacent neurons

synaptic cleft, synapse

a synaptic cleft is

gap between adjacent neurons

a synapse is

junction between nerves

the whiteish, fatty material covering axons

myelin sheath

gaps in myelin sheath along the axon

nodes of Ranvier

primary function of myelin sheaths

speed the nerve impulse transmission

what cells are responsible for producing myelin in the PNS and CNS

Schwann cells, oligodendrocytes

where are MOST neuron cell bodies found

central nervous system

what is gray matter composed of

dense collection of neuron cell bodies, unmyelinated fibers

clusters of cell bodies within the white matter of the CNS

nuclei

collections of cell bodies outside the CNS best describes what

ganglia

bundles of nerve fibers in the CNS

tracts

bundles of nerve fibers in the PNS

nerves

collections of myelinated fibers (tracts) in the CNS

white matter

what creates white matter

myelinated axons

where is grey and white matter found within the brain

cerebral cortex, nuclei

where is grey and white matter found within the spinal cord

grey matter central, white matter superficial

what neurons carry impulses from the sensory receptors to the CNS

sensory (afferent)

where are sensory (afferent) neurons found

cutaneous sense organs, proprioceptors

what neurons carry impulses from the CNS to viscera, muscles, glands

motor (efferent)

neurons found in neural pathways in the CNS that connect sensory and motor neurons

interneurons (association neurons)

what property best describes the ability to respond to a stimulus and convert it to a nerve impulse

irritability

what property best describes the ability to transmit a nerve impulse to other neurons, muscles, or glands

conductivity

what is the fundamental neuronal process that underlies all aspects of brain function

electrical signaling

true or false: neurons are intrinsically efficient generators of electricity

false

what are electrical signals based on

flow of ions across neuronal plasma membrane

what is approximate neuron resting membrane potential

-70mV

a state where inside of the neuron membrane is more negative than the outside

polarization (resting potential)

a state where inside of the neuron membrane becomes more positive than the outside

depolarization

the state where the inside of the neuron membrane becomes more negative. return to resting potential.

repolarization

a state where inside of the neuron membrane becomes more negative than resting potential. temporary decrease below -70mV

hyperpolarization

excitatory neurotransmitters bind to receptors at the start of the neuron, triggering the opening of _______ and the inflow of Na+ into the neuron

chemical gated sodium channels

the small shifts in potential that occur at the start of the neuron in response to the binding of neurotransmitters and subsequent opening of ion channels are referred to as

graded potentials

if a graded potential causes the neuron to move closer to threshold potential, it is referred to as

excitatory graded potential (EPSP)

if a graded potential causes the neuron to move farther from threshold potential, it is referred to as

inhibitory graded potential

if a neuron receives enough excitatory stimuli, its potential will rise to threshold (-55mV), triggering what

action potential

what is threshold potential

-55mV

where do action potentials begin

axon hillock (trigger zone)

how far do action potentials travel

along the entire axon to the axon end bulbs

what happens when an action potential reaches the end bulbs

triggers neurotransmitter release

are action potentials stoppable once triggered

no - they are all-or-none

what channels open when the neuron reaches threshold

voltage-gated sodium channels

what is the effect of opening voltage-gated sodium channels

sodium floods into the neuron, causing depolarization

during depolarization, what does the membrane potential rise to

+30 mV

what does the sudden rise in membrane potential during depolarization trigger

propagation (next section of axon reaches threshold and opens sodium channels), repolarization (voltage-gated potassium channels open)

what channels open to start repolarization

voltage-gated potassium channels

what happens during repolarization

potassium flows out, dropping membrane potential back to -70mV

why does the action potential move down the axon in a wave

each depolarized segment triggers the next segment to reach threshold and open its sodium channels

what happens when the action potential reaches the axon terminal

the electrical charge opens calcium channels

what molecule causes axon vesicles containing neurotransmitter chemical to fuse with the axonal membrane

calcium

how do neurotransmitters travel to bind to receptors

diffuse across the synapse

true or false: transmission down a neuron is electrical, transmission to next neuron is chemical

true

are amino acids excitatory or inhibitory

glutamate is excitatory, GABA and glycine are inhibitory

are amines are excitatory, inhibitory, or modulatory

can be any depending on receptor and location

primary function of peptides

pain modulation, stress and reward response

primary function of purines

often modulatory, involved in energy transfer and signal transduction

primary function of acetylcholine

a quaternary amine, involved in muscle activation and PNS functions

primary function of excitatory neurotransmitters

promote the generations of an action potential

what is the primary function of inhibitory neurotransmitters

inhibit the generation of an action potential

primary function of modulatory neurotransmitters (neuromodulators)

modulate the effects of other neurotransmitters

acetylcholine acts at what two classes of receptor

nicotinic, muscarinic