Topic 1 Nervous system Flashcards
The nervous system works in conjunction with
endocrine system
the nerves and endocrine system respond to both internal and external environment changes to maintain
homeostasis (balance) within the body
nerves are made up of
neurons
The nervous system responds via ____ messengers relayed ___
electrochemical,
from the brain
The endocrine system responds via ___ messengers relayed ___
chemical
through the bloodstream (hormones)
Two main types of nerve cells found in the nervous system :
Glial cells and neurons
Glial cells are used for
structural and nutritional support
Neurons do what
conduct nerve impulses throughout the body and are supported by glial cells
basic unit of nervous system is
neurons
Dendrites are
starting point with nucleus and branches which accept nerve impulses from other neurons and carry them twoards the cell body
Axons are
longer branches which carry nerve impulses away from the cell body
Myelin sheath
fat surrounding each axom , insulating the neuron , speeding up the rate of impulse transmission
Schwann cells are
a type of glial cell, responsible for producing the myelin around each axom
node of ranvier are
gaps between schwann cells, electrical impulses jump from node to node
no myesin
saltatory coduction
action potentials and electrical impulses that jump from node to node
this is the jumping
axom terminal
the ending of the neuron where electrical signals go to be passed to dendrites and adjoining neurons
myelinated neurons are vital for
vital for proper signal transduction within the nervous system
myelinated neurons are
can they regenerate after injury
the fatty part that makes up the white matter of your brain responsible for conducting nerve impulses,
can regenerate after injury
unmeyelinated neurons make up the
can it regenerate?
grey matter of your brain responsible for processing information and generating nerve impulses
cannot regenerate
three main types of neurons
sensory neurons, internerouns, motor neurons
sensory neurons do what
gather information from sensory receptors and transmit these impulses to the brain
(sensory receptors are touch,taste,sight and sound)
interneurons do what
process and integrate incoming sensory information from sensory neurons and relay info to motor neurons
motor neurons do what
transmit information from the brain to muscles glands and organs
which neurons are responsible for what?
takung in processing and taking out
Sensory take info from sensory receptors in to the brain
Interneurons process information
Motor neurons transmit information back out of brain to muscles and organs
CNS is
central nervous system or brain
the pathways / order of type of neurons
Sensory > Interneurons > Motor neurons
reflex arc is
a neural circuit that passes through interneurons in the spinal cord for immediate response
- simplest nerve pathway
the reflex arc reflexs are
involuntary and unconscious ( no brain coordination)
5 essential components for reflex arc in order
1- Receptor
2- Sensory neuron
3- Interneuron ( spinal cord)
4- motor neuron
5 - effector
the speed of an impulse is dependent on
Myelin ( fatty) axons as the send information faster than non fatty ones
Diameter of axons = bigger = faster
conduction of nerve impulses is a
electrochemical impulse and electrical event
the stages of nerve impulses are
1- Polarized / resting state
2- Depolarization
3- Repolarization
4- Refractory period
Resting state of nerve impulses is when
the inside of a neuron has a slight negative charge at rest and outside slight positive resulting in resting potential-70 mV
No message is being recived
What happens during resting phase w sodium potassium pump
Sodium Na ions are found mostly outside and Potassium K ions within the axon along with other latge molecules that cant pass through the membrane, but membrane is slightly permable for K ions and they leak out = more positive outside and repative negative inside
ENDS UP WITH MORE POSITIVE OUTSIDE AND -70 inside
3 Na out 2 K in
Resting state resting potential is
-70 mV
Depolarization occurs when
action potential occur when neurons are stimulated by an electrical impulse and reaches -55mV
What happens during depolarization period
an electrical impulse causes sodium Na gates to open letting them into the membrane so its slightly more positive on inside relative to the outside
-70 mV turns to 40 mV membrane is depolarized
Once Na reaches equalibrium the gates close
threshold potential is a
all or none event must reach -55 mV to work , increasing the stimulus strenght dose not increase impulse strenght it will just fire or not fire
tge intensity of a stimulus increase when
increased frequency of nerve impulses
Repolarization is when
once action potential is peaked Na+ gates close and K+ gates open letting it out of axon
Repolarization process
K ions leave out axon restoring initial -70mV
(reversed as compared to resting state when Na leaves )
So Na is higher inside membrane
Refractory period or hyperpolarization is when
during repolarization so much K ions rush in tk membrane overshooting the -70mV potential instead is at like -90 mV becoming hyperpolarized and so the sodium potassium pump restores mV back to -70 but until it can do that the membrane cannot be made permable to Na
all or nothing stage is
when the na rushes out before depolarization but if dosent reach -55 then no tepolarization occurs
signal transduction across synapse is a
chemical event when axon terminal is in close contact with another neurons dendrites and the signal must cross the space between the synapse or synaptic cleft
synapse or synaptic cleft is
the space between the axon terminal and dentrites of subsequent cell
Neurotransmitters are required for
helping carry the electric impulse from one neuron to the next
the way of signal transduction across synapses
- action potential reaches axon terminal of one neuron
- Calcium channels gates within axon terminal open, calcium ions flow into cell triggering movement of neurotransmitter vesicles twoards the presynaptic membrane
- Vesicles fuse to the membrane and neurotransmitters are released into synapses
- They defuse across synaptic cleft to post synaptic membrane
- they bind with receptors
- binding induces or inhibits action potential in corresponding neuron
- neurotransmetteurs are released by receptors and either return or are broken down by enzymes but dont go into membrane
Neurotransmitters types
Excitatory or inhabitory
Excilatory neurotransmitters
cause Na channels to open resulting in depolarization and continuing action potential
acetylcholine is a
excitatory neurotransmitter found in muscle cells causing contractions of muscle celks
chlinsterase is
the enzyme required to bteak down acetylcholine qfter action potential has occurred
what causes miucles to remain in constant contraction state
insecticide and netve gas block the release of cholinesterase
inhabitory neurotransmission
triggers K channels to open , K flows out and lowers membrane potential leading to hyperpolarization difficult to grnerate action potential
GABA
gamma aminobutyric acid associated either epilepsy or hunters disease
type of inhabitory neurotransmitter
Norepinephrine
produced by adrenal glands during flight or flight response can be exicibitory or inhabitory increases blood glucose levels, decreases digestion rate
summation
effect produced by accumulation of neurotransmitters from
two or more neurons on the second neuron
excitatory transmission + excitatory transmission
= action potential
inhabitory transmission + excitatory transmission
= balance so nothing happens
