Transcript Pre AP Biology

Nervous Systems
Part 3
RA # 4.3
What is a synapse?
Gaps between neurons or between
neurons
and effectors
Nerve Impulse is approaching the axon terminal by
Saltatory Conduction
Schwann cell
Depolarized region
(node of Ranvier)
Cell body
Myelin
sheath
Axon
Explain the steps of nerve impulse conversion
Presynaptic
cell
Postsynaptic cell
Synaptic vesicles
containing
neurotransmitter
Na+
K+
Presynaptic
membrane
Neurotransmitter
Postsynaptic
membrane
Ligandgated
ion channel
Voltage-gated
Ca2+ channel
Postsynaptic
membrane
Ca2+
Synaptic cleft
Ligand-gated
ion channels
Post synaptic membrane
Na+
Na+
Na+
Na+
K+
K+
Rising phase of the action potential
Falling phase of the action potential
Na+
Na+
Membrane potential
(mV)
+50
0
–50
K+
Action
potential
–100
Threshold
Resting potential
Time
Depolarization
Na+
Na+
Extracellular fluid
Na+
Potassium
channel
Activation
gates
K+
Plasma membrane
Cytosol
Resting state
Undershoot
Sodium
channel
K+
Inactivation
gate
COMPARE EPSP’s TO IPSP’s.
 The ability of the postsynaptic membrane to
either turn on (EPSP) or turn off (IPSP) a
nerve impulse.
Spinal cord
Motor
unit 1
Explain the
purpose of
summation
Motor
unit 2
Synaptic terminals
Nerve
Motor neuron
cell body
Motor neuron
axon
Muscle
Muscle fibers
Tendon
To reach
threshold
more
quickly
What is the most common neurotransmitter in the
human body?
 Acetylcholine
What is the “sleep” neurotransmitter?
 Serotonin
What neurotransmitter relays pain?
 Substance P
Which gas is AKA “laughing gas?”
 Nitric oxide
What do GABA’s do?
 Inhibit transmission
Which neurotransmitters create the “fight or flight”
response?
 Epinephrine and norepinephrine
Which neurotransmitter is the “happy” neurotransmitter?
 Dopamine
What affect does carbon monoxide have on nerve
transmission?
 Inhibits
What do endorphins do?
 Block Substance P