Chapter 48 - Electrical Signal in Animals Flashcards
Axon hillock
connects end of nerve body to axon
- place where summation occurs
- cone shaped
3 types of neurons
- Sensory neuron : receive sensory information
- Interneuron (relay) : CNS, non-myelinated
- Motor neuron : transfer to effector cell.
Membrane potential
concentration gradient of electrochemical ion across the membrane
Resting potential
- membrane potential of resting cell (non-excitable neuron) that does not send electrical signals
- 70mV (internal environment of cell is more negative than outside)
-membrane potential maintained by Na+/K+ pump and leaky K+ channel
(3 Na+ moves out, 2K+ moves in)
Action potential
- electrical signal (impulse) that moves along the membrane of the neuron
- must reach thresh hold (-35mv) before action potential
- huge change in membrane voltage (caused by depolarization)
- Na+ channels open - Na+ influx
-all-or-non response - occurs in non-graded depolarization manner
+30mV
Acetylcholine
- neurotransmitter that is both excitatory and inhibitory
* but in scull contraction, works as an excitatory neurotransmitter
Movement of Na+ and K+
2 K+ in
3 Na+ out
Depolarization
opens Na+ channels
Na+ moves into the axons
Repolarization
Opens K+ channels
K+ moves out of axons
sensory neuron
cell body in the middle of the neuron
interneuron
no myelin sheath in CNS
ganglia
cluster of neuron’s cell bodies found in PNS
Myelin sheath
made by glial cells
insulates neurons
Schwann cell
type of glial cell in PNS
Oligodendrocyte
type of glial cell in CNS
speed of conducting electrical signal
1) axon diameter
- bigger the diameter, faster the transmission
2) myelin sheath
- accelerates transmission speed - saltatory conduction
Excitatory neurotransmitter
Na+ channel receptor
Inhibitory neurotransmitter
K+ channel receptor
Types of summation
1) Temporal summation
- adds postsynaptic potentials that are generated at a single synapse
2) Spatial summation
- adds postsynaptic potentials that are produced simultaneously by different synapses on the same postsynaptic neuron
Chemical classes of neurotransmitters
1) Acetylcholine
-use inotropic & metabotropic receptor
-acts as excitatory NT in skeletal muscle
-acts as inhibitory NT in brain
2) Amino acids
e.g. GABA (IPSP in brain - causes anxiety), glutamate, glycine
3) Biogenic amines
e.g. Norepinephrine
-synthesized from amino acid
-when working as hormone, produced in adrenal medulla
other examples: dopamine, serotonin
4) Neuropeptides
e.g. Endorphin - natural analgesics
morphine - structural mimics of endorphin
5) Gases
e.g. nitric oxide - causes vasodilation in penis
Acetylcholine
class of neurotransmitters
- use inotropic & metabotropic receptor
- acts as excitatory NT in skeletal muscle
- acts as inhibitory NT in brain
GABA
Gamma amino-butyric acid
type of amino acid neurotransmitter
-IPSP in brain - causes anxiety
Norepinephrine
type of biogenic amine
- synthesized from amino acid
- hydrophilic
- when working as hormone, produced in adrenal medulla
Serotonin
type of biogenic amine
- depression
- treated with Prozac which inhibits reuptake of serotonin
Dopamine
type of biogenic amine
-lack of dopamine secretion causes Parkinson’s disease
Endorphin
type of neuropeptide
Morphine
type of neuropeptide
-structural mimic of endorphin
Nitric oxide
type of gas neurotransmitter
-causes vasodilation of penis
Sarin
nervous toxic gas
- noncompetitive inhibitor for acetylcholinesterase (which breaks down EACh)
- this causes irreversible inhibition of EACh breakdown
- causes paralysis
Botulism
food poisoning
- inhibits release of EACh that produces EPSP in skeletal muscle
- botox
