Neurons do not undergo mitosis The Nervous System can transmit impulses as fast as 100 meters per second If we lined up all the neurons in our body it would be around 600 miles long ID: 492724
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Slide1
Did you know?
Neurons
do
not
undergo mitosis!
The
Nervous System can transmit impulses as fast as 100 meters per
second!
If
we lined up all the neurons in our body it would be around 600 miles
long!
A
newborn baby's brain grows almost 3
times larger
during the course of its first
year!Slide2
Neurotransmitters & Synapses
ARE YOU READY TO RUMBLEEEEEE!?Slide3
Please Mr. Byrnes, I’m dying to know.. just what is a synapse?
Synapses are the areas where impulses are sent from one neuron to another
Remember that an nerve impulse travels down the axon as a result of depolarizing electrochemical gradientsSlide4
The space between the synaptic knob of one neuron and the dendrite of another
A
nerve impulse reaching synaptic knobs triggers release of chemical signals called
neurotransmittersSlide5
Synapses
Several impulses over a short period of time cause neurotransmitters to accumulate in the synapse
S
pecific levels of neurotransmitter will stimulate the post-synaptic neuron to conduct the impulse
Neurotransmitters are decomposed by enzymes, clearing the synapse for the next impulseSlide6
Synapses
Some neurons and their transmissions are excitatory & some are inhibitory.
Excitatory
: make the postsynaptic membrane more permeable to sodium & create “normal” action potentialSlide7
Synapses
Some neurons and their transmissions are excitatory & some are inhibitory.
Inhibitory
: make the postsynaptic membrane more permeable to potassium & prevent neurons from becoming activeSlide8
Neurotransmitters:
c
hemicals that transmit signals from a neuron to a target cell across a synapseSlide9
Neurotransmitters
All listed below are classified as monoamines:
Acetylcholine
: major excitatory neurotransmitter in the brain; makes post-synaptic membranes more permeable to Na
+
ions; destroyed by cholinesterase enzyme
Adenosine
: inhibitory; promotes sleepSlide10
Neurotransmitters
All listed below are classified as monoamines:
Dopamine
: involved in motor systems and emotional behaviour; increases heart rate and blood pressure
Serotonin
: involved in sleep regulation, appetite, mood; has multiple receptors body-wideSlide11Slide12
Drugs Effects
Agonists & Antagonists
: either mimic or block neurotransmitters
morphine is an endorphin agonist
amphetamines are monoamine agonists
LSD is a serotonin antagonist; caffeine is an adenosine antagonistSlide13
Drug Effects
Monoamine
oxidase
(MAO) inhibitors: block re-absorption of neurotransmitters so that they stay in the synapse and continually bind to the post-synaptic membrane
cocaine blocks dopamine re-absorption, resulting in reduction of the number of dopamine receptorsSlide14
Drug Effects
Stimulants & Depressants
: change the rate of transmission of neurotransmitter across the synapse
caffeine & diazepam are stimulants
aspirin & strychnine are depressantsSlide15
Nervous System Disorders
Epilepsy
syndrome characterized by episodic abnormal electrical activity in the brain (seizures)
caused by genetic default or trauma
triggers include lack of sleep, flashing lights, low blood sugar, alcohol
genetic mechanisms include defective ion channels that make neurons hyper-excitable, or an over-abundance of excitatory neurotransmittersSlide16
Nervous System Disorders
Alzheimer's
deterioration of memory and mental capacity
related to decreased production of acetylcholine
Parkinson's
characterized by involuntary muscle contractions and tremors
caused by inadequate production of dopamineSlide17
Nervous System Disorders
Botulism
paralytic illness caused by poisoning from toxins produced by the bacterium
Clostridium
botulinum
blocks release of acetylcholine at synapses
death occurs due to respiratory failure