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nervous system by monika


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what are the two main nervous system divisions?
Centeral and Peripheral Nervous Sytems
what is the Centeral Nervous stem control?
spinal cord and brain
what does the peripheral nervous system contain?
rest of body.
what is the Pheripheral divided to?
Autonomic and somatic nervous system
what is the atononomic nervous system?
connects to smooth (involuntary) muscles.
what does the somatic nervous system contain?
skletal muscles
what doed the autonomic nervous system further divide into ?
Sympathetic and parasympathetic.
what is the sympathetic nervous system?
usually causes effects with emergancy situations
what is the parasympathetic Nervous system?
activites at normal state
what do dendrites do?
conduct nerve impulses towards the cell body.
what do axons do?
nerve impulses away from the cell body.
what are dendrites and axons sometimes called?
what are most long fibers covered with?
myelin sheath
what are the nodes of ranriver?
the sheaths spaces that expose the axons
what does each node of ranvier have?
schwann cells.
what does the sensory neuron do?
takes a message from a sense organ to cns.
what is the description of the sensory nueron?
long dendrite and shot axon.
what is the motor neuron?
takes message away from cns to a mucle fiber or gland.
how does the motor neuron look?
short dendrites, long axon.
What is the interneuron?
conveys message between parts of the system.
description of internuron?
dendrites axons maybe long or short
what is a nerve conduction?
an electrochemical change that moves in one direction along the length of a nerve fiber.
why is it electrochemical?
it involves changes in voltage as well as concentration of ions.
what is a oscilloscope?
a volotometer shows a graph of voltage changes to measure potential differences
what are the three phases in the nerve impulse along an axon?
resting action recovery
what is the resting phase?
potential difference across membrane of axon when not conducting an impulse.
what is the number and why is it negative ?
-60 its negative because of the presence of large organic negative ions in the axoplasm
what occurs during resting potential?
Na+ ions are more concentrated on outside of membrane then inside and k+ are more concentrated on inside of axon.
what is the uneven Na+ and K+ maintained by?
active transport across pumps they operate when neuron is not conducting impulse.
what is action potential?
a nerve being stimulated by electrical shock, ph change, mechanical stimulation, a nerve impulse is generated and a change in potential
What is the upswing ?
(-60mV to 40+mV) membrane becomes peremable to Na+ ions.and Na+ ions move to inside of axon.
what is the downswing?
(+40mV to -60mV) membrane becomes peramble to k+. K+ moves from outside to inside of axon.
what is the recovery phase?
between transmissions K_ ions are returned to inside of axon, Na+ to outside. done actively.
how does the Potassium and sodium channels work?
!:sodium moves in - sodium channels open Na+ ions diffuse into axon 2: depolarization _the inside of axon becomes positive in that region 3. Na+ channels close, K+ open - potassium channels open K+ ions diffuse out of axon 4. Repolarization - the movement of K+ ions counters depolarization. The voltage difference across the membrane returns to the resting potential level (-60mV) 5. Recovery phase -Na+ and K+ actively transport back across membrane until disturubeted to same concentration before impulse 6. Depolarization of adjacent part of axon. - sodium channels open Na+ ions diffuse into axon.
why is the speed quit rapid in nerve impulses ?
structure of nerves
what is the mylein sheath?
sheath formed by tightly packed spirals of cell membrane of schwan cells.
what gives the nerves a white apperance?
mylein sheath.
what is the speed of the transmission?
-200m/sin myelinated fibers and 0.5 m/s in non-myelinatedfibers.
why is the speed transmission less in myelinated fibers than non-mylenated?
nerve impulses jump from node to non in mylinated non-mylinated they depolarize and repolarize each point along the nerve fiber
what is a synapse?
the region between end of an axon and the cell body or dendrite to which is attached.
synaptic ending?
swollen terminal knobs on the ends of axon terminal branches.
define presynaptic membrane?
the membrane of the axon synaptic ending.
postsynaptic membrane ?
the membrane of the next neuron just beyond the axons synaptic membrane.
synaptic cleft?
the space between the presynaptic and postynaptic membrane.
Neurotransmitter substance?
chemicals that transmit the nerve impulses across a synaptic cleft.
synaptic vesicles?
contain neurotransmitters. contain near surface of synaptic endings.
what are the four important neurotransmitters?
acetylcholine Noradrenalin Serotonin Adrealin
why is the transmission across a synapse flow in one way?
the ends of axons have synaptic vesicles that are able to release neurotransmitters to affect the potential of the net neurons.
what types of impulses do synapse have?
inhibotary and stimulaory impulses.
what is the summary effect?
whaether or not the neuron they are attached to fires.
what happens if the when the excitaory nerutransmitter is sufficent to overcome the amount of inhibatory? and if it doesnt overcome?
the neuron fires, local exitation
what is the first event that happens in transmission of impulse acros synapse?
nerve impulses travel along axon to reah a synaptic ending
what is the second event that happens in transmission of impulse acros synapse?
arrival of nerve impulse at synaptic ending changes membrane ca ++ flows into ending
what is the third event that happens in transmission of impulse acros synapse?
ca++ ions cause contractile protein to pull synaptic vesicles to inner surface of the presynaptic membrane
what is the fourth event that happens in transmission of impulse acros synapse?
vesicle fuses with presynaptic membrane, releasing neurotransmitters into synapse
what is the fifth event that happens in transmission of impulse acros synapse?
Neurotransmitters diffuse across synaptic cleft to receptors on postsynaptic membrane. The receptors control selective ion channels: binding of a neurotransmitter to its specific receptor opens the ion channels.
what is the six event that happens in transmission of impulse acros synapse?
the resulting ion flux changes the voltage of the postsynaptic membrane. this eaither moves the membrane voltage closer to threshold voltage required for action pontential or hyperpolarizes the membrane. the neurotransmitter receptor causes nerve impulses to be transmitted down dendrite of second neuron.
what is the seventh event that happens in transmission of impulse acros synapse?
neuotransmitters deactivate to prevent them from continually acting on postsynaptic membrane. By : 1. neurotransmitters degrading by enzymes 2. synaptic ending reobsorbs neurotransmitter.
where do nerves take nerve impulses?
across synapse
what are neurotransmitters?
small molleculles eaither single amino acids, dervites of protein, short chains of amino acids
what do the proper brain and nervous funtcions depend on?
the proper balance of excitaory and inhibatory synaptic transmitters.
what do exitatory transmitters include?
acetylcholine adrealin noradrenalin serotonin dopamine
What does the inhibatory transmitter include?
Gaba glycine serotonin
what do nurotransmitters include?
endorphins enkephalins which are 5 amino acid chains that function as neutral pain reliver in the brain.
what mimics the action of endorphins and enkepalins.
opium and heroin.
where do neurons recieve information from?
thousands of neurons through thousand synapse.
what does excitatory mean?
tell neroun to fire
what is inhibatory?
neroun not to fire
what does instant depend on?
ability to integrate thease multiple positive and negative inputs.
what kinds of nerves does it contain?
long dendrites and or long axons.
where are the peripheral neuron bodies found?
brain,spinal cord and Ganglia(the collections of cell bodies)
what are the three types of nerves?
sensory motor mixed
what is the characteristic of sensory nerves?
contain only long dendrites of sensory nurons
what is the characteristic of motor nerves?
have only long axons of motor nurons
what is the characteristics of mixed nerves?
contain both long dendrites of snsory neurons and long axons fo motor nurons
how many pairs of cranial nerves are attached to the brain?
what are cranial nerves part of
what do the cranial nerves serve?
head, neck, and face regions except for the vagus nerve which branches to internal organs.
how many spinal nerves do humans have?
what type of nerves are spinal nerves?
mixed nerves
where are spinal nerves located?
leaving the spinal cord by two short branches called roots which lay within the vertebral column
how is the dorsal root indentified?
by the presence of an enlargement called the dorsal root galigon.
what does the dorsal root galigon contain?
the cell bodies of sensory nurons whose dendrites conduct impulses toward the cord.
what is the ventral root?
each spinal cord contains axons of motor nurons that condut impulses away from the cord.
whaere does the venteral and dorsal root join?
the join just before the spinal nerve leaves the vertebal column.
what are reflexes?
automatic, involuntary responses to changes occuring outside of the body. It can involve the brain.
what is the refex arc?
it allows us to react to internal and external stimuli.
what is a receptor?
allows to generate a nerve impulse.
what is a sensory nuron?
takes message to cns. impulses move along dendrite proceed to cell body and then go from cell body to axon in gray matter of cord.
what is a internuron?
passes messages to motor nuron
what is motor nuron?
takes message away from cns to axon of spinal nerve
what is an effector?
revieves nerve impulses and reacts: gland secrete amd mucles contract.
what is the autonomic nervous system made up of?
motor nurons
what do motor nurons do in ans?
control internal organs automaticaly
what are the autonomic system divided into?
sympathetic and parasympathetic
how do the autonomic nervous system function?
unconconciaously on internal organs and utilize two motor nurons and one ganglion for each nerve impulse.
when is sympathetic nervous system important?
during emergancy situations and is associated with fight or flight
what happens during an emergancy situation?
-energy directed away from digestion -pupils dilate -heart rate increases -perseption increases -salivation decreases -breathing rate increases
what is the postganglonic axon of the sympathetic nervous system?
what is noradrenalin releases by?
postganglionic axon --------> heart rate accelerates
fibers for the sympathetic nervous system arise from where?
middle part (thoracic-lumbar) of the spinal cord.
where do the fibers for the sympathetic system arise from?
middle part (thoraic-lumbar) of the spinal cord.
what type of fibers do preganglionic have?
what is the size of postganglionic fibers?
what does the parasymphathetic system promote?
all internal responses asociated with relaxed state.
what oes the parasympathetic nervous system conduct in the body?
puplis to contract energy diverted for digestion of food heart rate slows
what is the important neurotransmitter in the parasympathetic system?
where do these fibers arise from? for the parasymphathetic system/
arise from upper and lower part of spinal cord.
in the parasympathetic system what is the sze of the pregongalic fiber and postgangolic fiber?
pre-long post-short
what does the centeral nervous system contain?
brain and spinal cord.
where is the centeral nervous system located?
in the mid-line of the body
what happens in thecenteral nervous system?
sensory infromation is recieved and motorcontrol is initated.
what is the centeral nervous system protected by/
wht is the centeral nervous system wrapped up by what does it do?
meninges and it is a protective membranous covering .
what are the spaces between the manings filled with what is the point of this fluid?
cerebrospinal fluid for cushoning and protection
what does the spinal cord contain?
centeral canal filled with cerebrospinal fluid.
what does the gray matter contain?
cell bodies of nurons and short fibers.
what do dorsal cll bodies function as in the grey matter?
to recieve sensory infromation and venteral cell bodies send along primarly motor information.
what does white matter contain?
long fibers of internuron that run together in bundles called tracts that connect the cord to the brain.
in white matter where do ascending and decending take information?
ascending- to the brain decending-in the venteral part carry information down from the brain.
where is the mudulla oblongata located ?
closest to spinal cord
what does the mudulla oblangata do?
controls heart rate, breathing, blood pressure and reflex reactions such as coughing, sneezing, vomiting, hiccouphing and swallowing.
what happens in the thalamus?
recieves sensory information from all parts of the body and channels them to cerebrum.
what is the last part of the brain before the cerbrum to recieve sensory input?
What does the thalmus recieve from all parts of the body and what happens when the thalamus recieves this?
it recieves sensory infromation and channels them to the cerebrum.
what is the last part of the brain to recieve sensory input before the cerebrum?
what does the thalamus serve?
it serves as a centeral relay station for sensory impulses comming up from spinal cord and other parts of the cerebrum
what also happens in thalamus?
recieves sensory impulses and sends them to cortex.
what system is the thalamus a part of?
reticular activity system
what is the reticular activity system?
sorts out incoming stimuli passing on to cerebrum
Reticular activity system extands from?
medulla oblongata to thalamus.
what is cerebellum?
controls balance and complex muscular movement.
what is the cerebellum function?
muscle coordination and make sure skeletal muscles work together smoothly.
what is the crebellum responsible for ?
maintaining normal musle tone , posture and balance.
where does the creebellum recive sensory infromation?
inner ear.
what is the hypothalmus a site for ?
what does the hypothalmus controL?
HUNGER, SLEEP thirst body temp water balance and blood pressure.
what is the function of the pitutary gland?
serves as a link between nervous and endocrine system.
what does the hypothlamus play ar ole in?
sexual response and mating behaviour and the flight to flight response
where is the corpus collosum located?
horizontaly connecting piece between two hemispheres of the brain.
what side does the left hemisphere control what side does the right side?
opposite sides left heisphere right side of body.
What is the frontal lobe?
it has activites for concioiusness, thought, movement and intellectual processes
What is the temporal lobe?
activites for hearing smell, interpertation experiences, memory of visual senses, music and complex sensory patterns.
what is the occipitial lobe?
vision compling, visual experiences with sensory experiences
what is the parietal lobe?
speech production and snsation
what is the cerebrum?
concioussness/intellect/ learning/ memory/ sensation.
what is the cortex?
outer layer of cerebrum
what are the 4 main lobes?
frontal partiel temporal occipital
what do all the frontal lobes have and what are they associated with?
association areas they are concerned with intellect, artistic and creative abilites, learning and memory.
what is extrapyramidal system?
masses of white matter that belong to decending tracts
what does the extrapyramidal system control?
body movement and posture
where does the extrapyramidial system pass into?
basal nuclei.
what is basal nuclei?
masses of grey matter that lie deep within each hemisphere of the cerebrum.
what system are basal nuclei a part of ?
limbic system
what does the limbic system do ?
connects portions of the frontal lobes, temporal lobes, thalamus, amygdala and hypothalamus
what is the limbic system involved in/
emotion memory and learning .
why is the limbic sometimes called the emotional brain?
it controls emotions: pain, pleasure, rage , affection, sexual interest, fear and sorrow.
where are memorys sotred and what part of the brain concentrates on it?
all over the body but the limbic system concentrates on it
what is the limbic system essential for ?
short term and long term memory.
what does long term memory involve and what might it include/
it involves protein synthesis and may include formation of new connections between neurons .
where do impulses move at first?
limbic circuit
where do basal nuclei transmit the nurotransmitter ach?
to the sensory areas where memories are stored.
what does the limbic system explain?
why emotional - charged events result in the most vivid memories.
what does the limbic system communicatye with?
sensory areas for touch, smell, vision, hearing and taste.
what do mood drugs affect?
Ras and limbic system
what do mood drugs either promote or decrease?
the action of particular neurotransmitters
what are the five ways drugs act?
1. stimulating the release of neurotransmitter 2. by blocking relese of nurotransmitter 4. mimicing neurotransmitter 5. by blocking receptor so nurotransmitter can't be recieved.
how do drugs promotote or decrease neurotransmitters?
by stimulationg or inhibiting the action of excititory transmitters or inhibitory transmitters.
what do stimulants do?
eaither enhance excitiory transmitters or block the action of inhibitory transmitters.
what do depressants do ?
either enhance the action of an inhibitory transmitter or block the action of excitiory transmitter.
When u have depression what kind of nurotransmitter is being used and what is the drug action?
excitory and blocks nurotransmitter

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