Nervous System Flashcards
What 3 functions make up the nervous system
Sensory input
Integration
Motor output
What is sensory input
On the skin is sensory receptors detect something
What is integration
Your nervous system processes that input and decides what to do about it
What is the motor output
Is the reaction that occurs when you nervous system activated certain parts of your body
What is the 2 main nervous systems
Central nervous system
Peripheral nervous system
What is the central nervous system
Is your brain and spinal cord
The main control center
It’s what decides you motor response
What is the peripheral nervous system
Is the composed of all the nerves that branch off from the brain and Solon that allow you central nervous system to communicate with the rest of your body.
Can work in both directions
Sensory division is what picks up sensory stimuli and sends it to the brain.
Motor division sends directions from your brain to the muscles and glands
Also includes voluntary nervous system that rule you skeletal muscles movement
And involuntary nervous system that keep you heart beating etc - spilt into sympathetic division which mobiles the body and vest it all fired up. / parasympathetic division relaxes the body and talks it down
What is the nervous system mainly made up of
Nervous tissue which is packed with cells
Cells like the neuron cells which respond to stimuli and transmit signals
Protected by glial cells which provide support, insulation, help with signal transmission
Central nervous systems glial cells
Astrocytes - support and regulate ions
Microglial cells - defend against invading microorganism
Ependymal cells - line cavities create and secret circulate cerebrospinal fluid
Oligodendrocytes - wrap and insulate form myelin sheath
Peripheral nervous systems glial cells
Satellite cells - surround neuron cells
Schwann cells - insulate help from myelin sheath
What is Neurons cells
Some of the longest lived cells in your body
Hey are irreplaceable
They are amitotic so they lose they ability to divide
They have huge appetites about 25% of the calories that you take in everyday are consumed by your brain activity
Structure of neurons
Cell body is the life support - nucleus, mitochondria
Dendrites pick up messages from other cells and pass it to the call body
Axon transmit electrical impulses away from the cell body to other cells.
Most common multipolar neutron
Bipolar neutron have 2 proses
Unipolar neutron have just 1
That is the neurones function
Which way an impulse travels through a neuron in relation to the brain and spine.
Sensory neurons
Pick up and transmit impulses from sensory receptors toward the central nervous system
They are mostly unipolar neutrons
Motor neurons
Transmit impulses away from the central nervous system to the rest of the body
Mostly multipolar neutrons
Interneurons
Are in the central nervous system
Move impulses between the sensory and motor neurons
Multipolar neutrons
How many signal can neutrons send and at what speed
One signal and at one speed
The frequency can change
What is action potential
The nerve impulse
What electrical change does our body’s have
Electrical neutral
Can keep positive and negative separate to build potential
What is voltage
Is the measure of potential energy generated by departed charge
Membrane potential
What is Current
The flow of electricity from one point to another
Correct = voltage / resistance
What is resistance
Whatever’s getting in the way of the current
Positive and negative in the body
Currents indicate the flow of positively or negatively charged ions across the resistance of your cells membrane.
What is a Reston neuron
Resting membrane potential - 70 mV
More negative potassium inside
Mixed with negative change protein
Outside is a bunch of positive sodium
It is polarised
What is the sodium potassium pump
Straddles the membrane of the neuron and there are tons all along the axon.
Every 2 positive potassium ions into the cell, it pumps out 3 negative sodium ions
Sodium potassium pump
Creates a difference in the concentration of sodium and potassium
Different in changes making it more positive outside the neuron
Called elecrochemical gradient
What is ion channel
Large proteins that can provide a passage across the membrane
when their respective gates are open.
This movement of ions is the key to all electrical events in neurons
Violates gated channels
Open and close in response to change in membrane potential
Sodium channels in your neurons open around -55mV
Ligand gated channels
Only open up when a neurotransmitter latches onto its receptors
Mechanically gated channels
Open in response to the physical stretching of the membrane
What is a graded potential
If only a few changes open and only a few sodium enters the cell that causes just a little change in the membrane potential in a localised part of the cell.
Inner voltage is Resting at 70mV
What is action potential
If a lot of channels open and a lot of sodium enters the cell that causes just a long change in the membrane potential in a localised part of the cell.
Bigger enough to trigger the voltage gated channels
What happens when a neuron passes messages
Inner voltage is Resting at 70mV
Then you touch something
Triggering sodium channels to open
Increasing the change inside the membrane
Has to be -55 mV
Then the voltage gated sodium channels open
Positive sodium ions rush in making the cell depolarised
Up to about 40 mV
A brief depolarisation caused by changes in current
Kick off a biological chain reaction sends that electrical signal down the axon.
Voltage gated sodium channels open its strong enough to change the voltage around
Then its repolarization kick in
Voltage gated potassium ion channels open up letting those potassium ions flow out
Voltage drops to -75mV before all the gates close and the sodium potassium pumps take over and bring things back to their resting level
What is the refractory period
It can’t respond to any other stimulus
Help stop signal from traveling down both of th actions
A myelin sheath
Axons coated in insulating myelin conduct impulse faster than non myelinated ones
A current can leap from one gap in the myelin to the next
Gaps called nodes or ranvier
Called slating conduction
Whats a synapse
The meeting point between two neurons
Tinny communication links between them
Able to change and adapt in response to neuron firing patterns
What are the to modes of transportation in the nervous system (synapses )
Electrical - immediate
Chemical - controlled, slower and more personal
Electrical synapses
Send an ion current directly from the cytoplasm of one nerve cell to another
Through small windows Calle gaps junctions
They are supper fast because the signal is never converted from its pure electrical state
One cell can trigger thousands of other cells that can all act in synchrony
Chemical synapses
Much more abundant
Slower
More precise
Uses neurotransmitters or chemical signals
Diffuse across a synaptic gap to deliver their message
They can connectivity convert the signal in steps from electrical to chemical back to electrical
At the synapses the signal can be modified, amplified or split
Chemical synapses two principles parts
The cell that sending the signal is the presynaptic neuron and it transmits through a knoblike structure called the presynaptic terminal along the axon terminal
Holding a bunch of tiny synaptic vesicles sacs each loaded with thousands of molecules of given neurotransmitter
The postsynaptic neuron and it accepts the the neurotransmitters in its receptor region
Who do the presynaptic neurons and the postsynaptic neuroses communicate
They don’t touch but there is a tinny gap called synaptic cleft between them
Come to the presynaptic terminal
Activated the voltage gated calcium channel they open and release the calcium
Into the neuron cytoplasm
This flow of positively charged calcium ions causes all those tiny synaptic vesicles to fuse with the cell membrane and purge their chemical messages
Its these neurotransmitter that act like couriers diffusing across the synaptic gap, building to receptor sites on the postsynaptic neuron
Excitatory neurotransmitters
Depolarise the postsynaptic neuron by making the inside of it more positive and bring it closer to its action potential threshold making it more likely to fire that message on to the next neuron
Inhibitory neurotransmitter
Hyperpolarizes the Postsynaptic neuron by making the inside more negative, driving its chnarge down away from its threshold.
Depends on the sum of all the excitation sand inhibitions in that area
What is serotonin
Mainly inhibitory
Role in regulating mood, appetite, circadian rhythm and sleep.
What is dopamine
Influences emotion and attention
Makes you feel good
Norepinephrine
Triggers you fight or flight
Increasing your heart rate
Priming muscles
After use what happened to the
They are diffused back across the synapse and are immediately re absorbed called reuptake
Others are broken down by enzymes in the synaptic cleft
Or sent away from the synapse by diffusion
