Chapter 3 Flashcards
What 2 things compose the central nervous system?
- Brain
- Spinal cord
What is the term referred to as neurons responding to stimuli and converting those messages to an electrical signal?
Nerve impulse
What is the basic structural unit of the nervous system?
Neuron
The neuron has ______ major regions.
3
What are the 3 major
What are the roles of the cell body?
- Contains nucleus
- Cell processes radiate out
What are the roles of dendrites?
- Recever cell processes
- Carry impulse toward cell body
What are the jobs of the axon?
- Sender cell process
- Starts at axon hillock
- End branches
- Axon terminals
Sensory is referred to as _________ signals.
Incoming
Motor is referred to as ______ signals.
Outgoing
Somatic is referred to as ______ to skeletal muscles
Voluntary
Autonomic is referred to as _______ to viscera.
Involuntary
What are the 3 MUST’s for the electrical signal between periphery and brain?
- Must be generated by a stimulus
- Must be propagated down an axon
- Must be transmitted to next cell in line
T/F: Difference in electrical charges between outside and inside of the cell.
True
T/F: The inside of the resting membrane potential is more negative relative to the outside.
True
What is the negative charge on the inside of the cell?
-70mV
What are the two causes for the inside of the cell being more negative than the outside?
- High Na outside cell
- Medium K+ Inside cell
When charges across the membrane differ, the membrane is ______.
Polarized
RMP is maintained in what 2 ways?
- Membrane more permeable to K+ due to open K+ channels
- Na+ - K+ pump (primary mechanism)
What occurs when inside of cell becomes less negative?
Depolarization
What is the term when more Na+ channels open, and Na+ enters the cell?
Influx
What is required for nerve impulse to arise and travel?
Depolarization
What occurs when the inside of the cell becomes more negative?
Hyperpolarization
What is the term used when more K+ channels open and K+ leaves the cell?
Efflux
What makes it more difficult for nerve impulse to arise?
Hyperpolarization
What is Repolarization?
The return to RMP (Resting Membrane Potential) (-70mV)
In what 2 ways does depolarization and Hyperpolarization contribute to the nervous system function? (G, C)
- Graded Potentials
- Can excite or inhibit a neuron
What are localized changes in membrane potential?
Graded potentials (GPs)
How are Graded Potentials (GPs) generated?
Incoming signals from dendrites
How do GPs help the cell body?
Help by decking whether to pass a signal on
What happens during Excitatory postsynaptic potential (EPSP)?
- Na+ channels open = Na+ influx
- Depolarization
What happens during the inhibitory postsynaptic potential (IPSP)?
- K+ channels open = K+ efflux
- Hyperpolarization
Strong ________ will lead to an ____________.
EPSP ; Action potential
What are 4 facts along with a strong EPSP leading to an AP? (R,L,A,M)
-Rapid depolarization of neurons membrane
- Last - 1 ms
- AP will be propagated down axon & transmitted to next cell
- Must reach a threshold mV
If GP reaches _____ mV to _____ mV, ______ will occur
-55, -50, AP
What is the principle that refers to this statement:
“Threshold mV not reached, then no AP”
All-or-none principle
What keeps total of EPSPs & IPSPs?
Axon hillock
State the process/stage when given the mV:
-70 to -55mV: ____________, ________
-55 to +30mV: ____________, ________
+30 to -70mV: ____________, ________
Depolarizing GP, Na+ influx
Depolarizing AP, Na+ influx
Repolarizing AP, K+ efflux
What 2 characteristics determine propagation speed down an axon?
- Axon diameter
- Myelin
A ______ axon = a _________ propagation speed
Larger ; faster
The myelin’s fatty sheath around an axon is formed by what?
Schwann cells
Within the myelin, what are the non-continous spaces?
Nodes of ranvier
What speeds up propagation?
Saltatory conduction
What is the degeneration of myelin; loss of coordination?
Multiple sclerosis
For neurons to communicate, APs transfer form a _________ to _______ neuron.
Presynaptic ; postsynaptic
What is the site of neuron-to-neuron communication?
Synapse
T/F: AP must travel across synapse.
True
Give the pathway of transmitting AP’s.
Presynaptic axon terminal ——> synapse——> postsynaptic dendrites
T/F: signal changes form across synapse
True
T/F: the correct sequence for neuron-to-neuron communication is:
Electrical ——> chemical ——> electrical
True
AP can only move in _______ direction(s).
One
Axon terminals contain _________.
Neurotransmitters