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Nervous System bio 12

Terms in this set (100)

What are the 3 functions of the nervous system?
sensory input, integration, motor output
What is sensory input
Ex
conduction of signals from sensory receptors
Ex. 5 senses
What is integration of the NS
Info is interpreted by the interneurons from sensory receptors and creates a response by the CNS
What is motor output
CNS signals are sent to effector cells and carry out the response (action) by a motor neuron
What are effector cells
muscle or gland cells
What 2 types of cells are located in nervous system
Neutrons and gillia cells
What are neutrons ?
Nerve cells, transmit electrical messages in form of impulses
What is a Gillia cell? Aka?
Ex
Supporting cell
Provide structure, insulation, protections and nourishment to neutrons
Schwann cells
What is function of supporting cells?
What is an example
Provide structure, protection, nourishment, insultation to neutrons

Schwann cells
What are the 3 parts that make up a neuron
Dendrites
Axon
Cell body
What is the dendrite function?
Structure?
Receives and conducts an impulse towards the cell body
Usually branched extension projections
What is the cell body function of a neuron
Contains a nucleus and carries out regular cell activity
What is the axon of a neuron?
Structure
Conducts an impulse away from the cell body
Long single projection
What are the 3 types of neurons
Where do they function
sensory neurons in sensory input
internerouns in integration
motor neurone in motor output
What do the 3 types of neurons together create
A reflex arc
What is a reflex arc?
How is it record?
Automatic response to large stimulation that has immediate response w/o waiting for brain to recognize it

What the stimulus exceeds threshold
What is the pathway of how stimulus is received and carried out from the body? (Neurons and cells)

What is the reflex arc pathway?
Stimulus occurs
Goes to receptor cell
Then to the sensory neuron
Then to interneoron in CNS
And to the brain (end)
OR
from the interneuron to the motorneuron
To the effector cell
Leading to an immediate reaction to stimuli
(Reflex arc first goes here then to brain)
What is a receptor?
Detects stimuli and goes over the minimum threshold

Initiated impulse in the sensory neuron
What are examples of receptors
Stretch receptors in aveoli of lungs
Pain receptors on skin
Photoreceptors of eyes
Chemoreceptors in heart and brain
What is the function of a sensory neuron?
Where is the neuron found?
Structure?
Takes sensory info from sensory receptors to cell body
Dorsal root ganglion of CNS
long dendrite, short axon
What is the function of an interneuron?
Where is it found?
Structure?
takes sensory neuron info into correct motor neuron for a response
Fully in spinal cord or CNS
short dendrite, short/or long axon
What is the function of the Motor Neurone?
Where is it found?
Structure?
Takes impulses to an effector cell
Dendrite is in the CNS, axon is outside the spinal cord
Short dendrite, long axon
What is the difference when an effector cell stimulates a muscle vs gland
Muscle- will contract
Gland- will release a hormone
What is a nerve bundle?
group of nerves of long neuron fibres
What a neuron fibres covered in?
What is the material of this?
Myelin Sheath
fatty layer
What cell is the Myelin Sheath made up of? aka
Where is the myelin sheath located?
Schwann cells (neuroglia cell)
Wraps around neuron fibres of the axon
What 2 functions does the myelin Sheath layer have?
insulates neurons as they pass each other through a nerve

Speeds up an electric impulse
How does the Myelin sheath speed up impulse rates?
Inbetween each layer of the Schwann cells (myelin sheath) there are empty points called
NODES OF RAVIER

The sheath layer, allows for impulses to go directly from one node to another and perform its ACTION PE
What is a threshold?
What needs to occur for a neuron to fire?

How is this minimum threshold amount determined by the neuron?
amount of stimuli needed to make an impulse

The threshold minimum has to be passed

all causing and preventative electric signals on the dendrites are added up by the neuron

(to see if its enough or not for min threshold)
What kind of force is created when an impulse travels down a neuron?

measured in?

does this make the neuron fibre charged? (the axon)
wave of ionic charge

millivolts (mV)

Yes, small electrical charge
What are the 4 steps to action potential?
Resting PE
Depolarization
Repolarization
Refractory Period
What molecules are inside the neuron vs outside
Inside the neuron is (POTASSIUM) K+ and electrically charged ions-

Outside the neuron are Na+ (SODIUM)
what occurs at resting PE?

Where is the neuron more positive?

mV?
membrane is not permable because gates to Na+ or K+ are closed
(they dont move in or out)

Outside of the neuron is slightly more POSITIVE

mV at -70mV
What occurs in depolarization?

what is the minimum threshold value?
stimulus exceeds minimum threshold of -40mV

Sodium gates Na+ open, becomes permeable and Na+ goes into the axon
What occurs in repolarization?

what voltage must be reached for this to occur?

what voltage is reached by the end of this phase? what is restored?
+40mV peak is reached
POTASSIUM gates open and it flows outside the axon
SODIUM gates begin to close

they are in inverse positions than resting PE

back to -70mV , same charge is restored
What occurs during the refractory period?
What is required for this to occur?
-70mV, Na+ and K+ gates are closed

The pump starts to pump out the Na+ back out and K+ back into the axon

ATP
Why is the refractory period important?
So the Na+ and K+ can be restored into original positions as its resting PE phase

So a new impulse can be created, travelling in one direction
What is the ALL OR NOTHING response?
What voltage must be reached for this to occur?
-40mV threshold of stimulus

a stimulus to become an impulse has to exceed the threshold
are each impulse equal ?
What does it mean if there is a "strong impulse"
Yes
Not a bigger impulse, but a larger quantity of impulses

-more nerves involved or one nerve sending many impulses
Where does action potential occur?
why?
Nodes of Ranvier

b/c myelin sheath layer creates insulation allowing the neurones to not get lost
Why does PE act so effectively?
each node of ranvier, has PE occurring, when one is done it will cause the next one to move and so on
What occurs to an impulse when it reaches the end of a neuron? (the axon)
it goes through synaptic transmissions with another neurone or an effector cell
Do neurons phycially connect to each other when sending impulses?

How do they communicate then?
no

There is a space, that allows the impulse to cross and reach a new neuron
What is the space inbetween neurons called?
Synaptic gap or Cleft
What is a presynaptic neuron?

What is it filled with?

Where is the presynaptic membrane found?
conducts impulses toward the synaptic gap

Synaptic vesicles, with neurotransmitters

At the end of the axon, they are the end bulbs
What is a neurotransmitter?
chemical message created by the axon
What is a postsynaptic neuron?

What is found alone the postsynaptic membrane?
transmits impulses away from the synaptic gap

protein receptor sites that allow specific neurotransmitters to pass
What is synaptic transmission?

How does synaptic transmission begin?
The movement of the neurotransmitter (impulse) from neuron to neuron or to effector cells through the synaptic gap

impulse arrives at the end of an axon
What is step one and two of synaptic transmission?
when do they occur?

IS this apart of the postsynaptic or presynaptic neutron?
same time

1- impulse arrives at the end of the axon (at the bulbs)
Sodium Na+ (SODIUM) and Ca+ (CALCIUM) gates
open
moving into the axon bulb of the axon of the PRESYNAPTIC NEURON
What is step 3 of synaptic transmission?

What is triggered? What is required for this to occur?
Ca+ binds to the contracticle proteins of the vessicles

Forcing them to move down towards the presynaptic membrane

Exocytosis, ATP
In the vessicles, found in the presynatpic neuron. What are the vessicles filling with?
Neurotransmitters recieved from the axon impulse
What is step 4 of synaptic transmission?What is released? Where?
Vessiles are found at the bottom of the presynaptic membrane of axon bulbs

Exocytosis occurs

Neurotransmitters difuse accros the synaptic gap
What is step 5 of synaptic transmission?
Neurotransmitters bond to receptor sites of POSTSYNAPTIC membranne
What are the 2 types of neurotransmitters?
What do each trigger
Excitatory nt- triggering depolarization (threshold is reached, higher mV)

Inhibitory nt- Hyper polarization occurs lower mV, makes it harder for threshold to be reached (relaxed)
What occurs in step 6 of synaptic transmission IF

Excitatory neurotransmitters vs Inhibitory neurotransmitters
bond to postsynaptic receptors?
Excitatory nt- changes voltage of postsynaptic membrane to higher voltage, Sodium gates open allowing Na+ to flood into postsynaptic membrane

Depolarization occurs

Inhibitory nt- hyperpolarization, threshold is harder to be reached, voltage is lowered of postsynaptic membrane around -70mV to -90mV
What 3 options can the postsynaptic membrane be ?

If this is step 7 of synaptic transmission, what will occur if an impulse travels through the synaptic gap to each?
A new dendrite of another neurone
A muscle cell, causing contractions
A gland cell, releasing hormones
What is found in the synaptic gap?

What is step 8 of synaptic transmission? What is restored?
Enzymes that destroy neurotransmitters if they are there for too long

Enzymes destroy nt found in the synaptic gap that haven't been bonded to postsynaptic receptors

regular conditions restored of gap
What is the final step (9) of synaptic transmission?
How?
Ca+ ions return to synaptic gap by active transport
Where are neurotransmitters stored?

Where are postsynaptic receptors found?
vesicles found in axon bulbs

dendrite receptors
Synaptic transmission occurs in______ direction
one direction axon to dendrite, muscle cell or gland
Where does energy for synaptic transmission come from?
Vesicles
what is an example of an inhibitory neurotransmitter?

What is an example of an exhibitory neurotransmitter?
in- Acetylcholine

ex- Noradrenaline
What is the purpose of acetylcholine?

which muslce does it control?

Which enzyme destroys this neurotransmitter in synapse?
inhibitory, relaxed state of mind
skeletal muscle

acetylcholine sterase
What is the purpose of noradrenalin neurotransmitter?

When is this nt activated? state is aka?

Which enzyme destroys it in synapse?
excitatory, increases activity of receiving
cell/tissue/organ

when we are stressed
"flight or flight mode"

monoamine oxidase (MAO)
What are the 5 affects drugs can affect our synapse?
1) Hold receptors open for longer
2)Block enzyme to destroy excess nt
3) Increase amounts of released nt
4)Some can imitate nt and bond to the receptors
5) Stop nt from joining receptors
What drug makes receptors open for longer?
How?
Alchol
makes GABA nt work for longer, so brain gets more relaxed
What occurs to your serotonin levels and why when your depressed?

What drug contracts this?
serotonin is reabsorbed before it can make you happy

Prozac makes seratonin stay in the synapse for regular amount to bind to receptorss
What drugs increase the amount of neurotransmitters being absorbed?

Which neruotansmitters do they increase? WHat is the affect of this?
cocaine- dopamine increases, causing pleasure sensation
ecstasy- seratonin increases, sexual feeling, no anxiety/fear
What 3 drugs take the place of other nt during synapse to the receptors?

Which ones do they replace? Affects of this?
caffein- causes alterness

nicotine- acetylcholine, arousal/rewardal

morphine- replaces endorphins, increases "runners high" feeling
What drug causes nt to stop binding to receptors?

Why would this be used?
Painkillers- stops pain transmission between nerve cells
Why are neurotransmitters recycled?
so receptors arent constantly using energy
What affect does cocaine have on the nt in the synapse?
bind to nt
causing them to stay in the synapse
depolarization rate increases (higher voltage)
What affect does cocaine have on the receptors of the postsynatic membrane ?
receptor proteins decrease
What occurs to the amount of nt and receptors on the postsynaptic membrane when cocaine is removed?
the amount of nt goes back to normal but receptors do not regenerate (stay the same)
what affect does cocaine use have on the body?
less receptors, harder to depolarize neurones (harder high)

Withdrawal symptoms b/c you crave it
What are the 3 embryonic brain regions?
HindBrain
MidBrain
ForeBrain
Where is the Hindbrain located? What is it made up of?

What is another word for Hindbrain?
connects to the spinal cord
to the midbrain, pons, medulla oblongata to spinal cord

Brain Stem
Which region of the brain is the oldest and smallest, and most primitive?
Hindbrain
What is the Mendula oblongata purpose to the Hindbrain?

Where is it found?

Is it controlled by us?
regulates heartbeat, breathing, BP (vasoconstriction)

closest to spinal cord

no, cant be controlled
What is the function of pons in the hindbrain?

AKA?
sends activities from medulla to rest of the body

Bridge
What is the Midbrain ? What does it carry?

What is in the Midbrain structure?
connects midbrain and forebrain

carries reflex centres, visions, hearing and touch

Cerebellum
What is the cerebellum function? Location? Structure?
responsible for muscle contraction, movements , posture, balance (motor control)

Cauliflower, leafy, near brain stem, back of brain
What is the cerebrum divided into?
What is the structure of the cerebrum? Why?
left and right hemispheres

wrinkled to increase SA for neuron transmission
What is the left vs right cerebral hemisphere function?
What connects these 2 sides?
left(verbal)
Right(visual)

Corpos Callosum
What covers the left and right hemisphere?
What is this layer for?
thin layer aka Cerebral Cortex
triggers intelligence
What does the cerebrum control?
coordinates sensory data, voluntary motor functions (we control, PNH), conscious decisions, stores memory, personality, learning
What is the cerebrum made up of?
Mostly?

What is grey vs white matter
white(mostly) myelinated axons
and
gray matter- cell bodies, dendrites, unmyelinated axons
What 4 lobes make up the Cerebrum?

How are they grouped?

Do these lobes work together or alone?
frontal, parietal, temporal, occipital

function

together, with separate functions
What is the occipital lobe responsible for?
receiving and processing visual info
What is the temporal lobe responsible for?
hearing, smell, proccessing language and word meanings
What is the parietal lobe responsible for?
sensations, language, perception of hot/cold and pain/pressure, body awareness, attention
What 3 functions does the frontal lobe do?
Motor control, speech production, though proccess
What is the corpus callosum?
dense tissue that separates cerebral hemispheres

allows impluses from one side to go to otherside of the brain
What is the thallmus purpose?
recieves impulses from the spinal cord
directs it into either of the 4 cerebrum lobes

filters out pointless/low stimulus
What is the hypothalamus?

where is it located

What is its connection to the pituitary gland?
connects the NS to endocrine system
maintains homeostasis
regulates thirst, hunger, BP, body temperature

controls the internal organs by telling the Pituitary glands to release hormones

under the thalmus
How does the hypothalamus connect to the pituitary gland?
it will recieve a sample of blood, and it will either send an impulse or release hormones
What is the pituitary gland separated into?

What is the main function of the pituary gland? AKA?
2 lobes: posterier gland and anterior gland

Master gland

will release hormones that are necessary for other glands to function
What is the posterior gland function?

what hormones are released?
releases hormones made by the hypothallmus

oxytocin
What is the anterior pituitary?

How is it connected to the phyiscally to the hypothalmus and posterior gland?

Ex of a hormone produced here?
makes hormones when the hypothlamus tells it to

by blood

Human Growth Hormone, prolactin
What 2 ways are hormones controlled?
Describe how these 2 processes of hormone regulation work
Negative feedback (self regulating)- releases until correct level is reached then stops

Other hormones- until hormone is released to counteract it
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