Nervous system Flashcards
Why does the presynaptic knob contain many mitochondria?
energy from ATP is requirerd to generate neurotransmitters and to actively transport calcium ions out of the presynaptic knob.
What are the products from each hydrolysis of ACH by acetylcoholinesterase?
ethanaic acid and choline
What does undirectionalability in a synapse mean?
Synapses can only pass impulses in one direction that transmitter is only released by the presynaptic knob and receptors are found only on the post synaptic knob. In this way syanapses act like valves.
What do dendrites do?
from connections (synapses) with neurons which make up the CNS. One motor neuron may connect with many different neurons in the brain or spinal cord.
What does the nucleus do?
Contains the DNA of the neuron
What is depolarisation?
A temporary reversal of the normal electrical chgarge between the inside and outside of the cells.
What are nerve impulses?
Waves of depolarisation that moves along the axon.
What happens at rest in the nerve cell?
Inside is negative compared to the outside
What is the nodes of Ranvier?
gaps between Schwann cells. the combination of the myelin sheath and the nodes mean impulses can travel down a motor neurone much quicker than if they weren’t presnt.
What is a reflex?
A rapid short-lived involuntary reponse to a specific stimulus.
Why are simple reflexes important?
-involuntary actions, do not involve decision making areas of the brain.
-rapid, fast electrical impulses and short neurone pathways.
-control of continuous and repetiticve actions e.g. breathing
Describe the reflex arc process
SRSRMER
-First a stimulus is detected such a a hot plate by a receptor and thsi generates an inpulse in a sneosry neurone.
-sensory neurone impulse diffuses to relay neurone, then diffuses to motor neurone (by synapses)
-Motor neurone carries impulse to effector (muscle glands) which produces a response
What does the axon terminals do?
the end of the axon splits inot the axon terminals, connecvting with the effector. The ends of the terminals swell into the synaptic end bulbs.
What does the myelin sheath do?
A lipid coat that covers most of the axon. Individual sections of the sheath are sperate cells known as schwan cells which wrap around the axon.
Label the structure of a motor neuron
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What is a reflex arc?
The shortest pathway taken by impulses in a simple reflex
Label the reflex arc
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What 2 sections is the nervous system divided into?
central NS: The brain and spinal cord
perpheral NS: the sensory and motor nerves.
What do sensory neurones do?
carry nerve impulsews from receptors towards the CNS.
What do motor neurons do?
carry nerve impulses away from the CNS to the effectors.
What do sensory neurons do? (detail)
transmit inbfo from snes organs and receptors found around the body to the CNS. The CNS processes the info and coordinates the repsinse. the respinbse is sent down motor neurons to an effector like a muscle or gland to carry out the repsonse
What does the cell body do?
Contains most of the cell organelles.
what does the axon do?
the fibre of the neurone stretches from the CNS to the effector
What is a neuromuscular junction?
A synapse between a motor neurone and a muscle. the post-synaptic membrane is the self membrane of the msucle cell.
What happens when the nerve cell is negative?
When stimulated by a synapse or receptor, the charge changes from N to P. This chnage in the charge of bthe neurone is passed along the axon in a wave with one part of the neurone chnaging to + being the stimulus to change to the next part to positive. This wave travels along the axon until it reaches a synapse.
Draw an example of nerve impulses with depolarisation
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What is the CNS composed of?
brain, spinal cord
What does the CNS contain (neurons)?
relay neurons (interneurons)
What is the peripheral nervous system composed of?
cranial nerves, spinal nerves, peripheral nerves.
What does the PNS contain?
Sensory neurons, motor neurons.
What is the proces of transmission across a synapse (6 steps)?
.
What is one of the most common neurotransmitters in humans?
Acetylcholine (ACH)
What is ACH made up of?
ethanoic acid and choline
What are the synapses called that use ACH as transmitter?
cholinergic synapses
Where are cholinergenic synapses found?
In the CNS at the neuromuscular junction.
Why are neurons with a myelin sheath more efficent?
Only the sections between the schwann cells (nodes of ranvier) become depolarised, so the impulse ‘jumps’ along the axon.
What are the group of chemical involed in communication between neurons at synapses called?
neurotransmitters
What is the function of the synapse?
To allow sensory impulses to travel in one direction and to ensure that each impulse remails individual and doesn’t merge together with…
What is a synaptic cleft?
neurons are seperated from each other from this.
What is the presynaptic neurone?
The neurone which releases the transmitter
What is a synaptic knob?
the end of the axon swells to form this. The knob contains mitochondria.
What is the synaptic vesicles?
This is where the transmitter is stored
What is the presynaptic membrane?
When the synaptic vesicles is stimulated this will fuse the membrane and relaease the neurotranmitter into the cleft.
What is the postsynaptic neurone?
once the neurotransmitter is released into the cleft it will diffuse to this which has specific receptor molecules to bind to transmitter.
Label the synapse
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How could some drugs stimulate the nervous system by creating impulses in postsynaptic neurons?
-mimic the neurotransmitter
-cause the release of excess neurotransmitters
-reducing the activity of the enzyme which breaks it down.
How could a drug inhibit the nervous sytem?
By causing fewer impulses in the psotsynaptic membrane.
How can you monitor the nervous system?
electroencephalograms
how do electroenccephalograms work?
electrodes are placed on the scalp. These detect the tiny changes in charges of the neurone in the brain. This is then recorded as a wave on a ECG trace.
