Ch. 2: Physical and Electrical Properties of Cells in the Nervous System Flashcards
On a neuron:
What is the cell body called?
Soma
On a neuron:
What is the “reciving” antenna called?
Dendrite
On a neuron:
Where are new action potentials generated?
Axon Hilock
On a neuron:
What is the “transmitting antenna?”
Axon
On a neuron:
Where do parts of two neourns come together?
Synapse
On a neuron:
What is the end of an axon called when it connects with the next neuron?
Presynaptic Terminal
On a neuron:
What is the space called where chemical signaling occurs?
Synaptic Cleft
On a neuron:
What is the dendrite called that recieves chemical signals?
Postsynaptic membrane
What are the 4 general functions of nerve cells?
- Reception: receive signals
- Integration: gather many inputs and boil down to a majority opinion.
- Transmission: Transmit new signals electrically and chemically to other cells
- Transfer: transfer messages to other neurons across the synapse
What is the name of this neuron?
Bipolar
What is the name of this neuron?
Pseudo-Unipolar
(sensory neurons of the peripheral nervous system)
What is the name of this neuron?
Multipolar
(motor)
Transmission of info ALONG one neuron is _______
electrical
(within)
Transmission of info BETWEEN neurons _______
Chemical and electrical
(between)
What is a Nongated channel?
- structural gate that it always open
- Always leaking ions depending on relative concentrations or charge gradient
What is a Modality-Gated channel:
- Touch or temperature
- Primary modalities that cause them to open
- @ distal end of sensory neurons
What is a Ligand-Gated channel?
- “Protein”
- Ligands that open these channels are neurotransmitters
- On dendrites & bodies of nerve cells
What is a Voltage-Gated channel?
- Responds to charge in membrane voltage
- When -70mV changes it allows these gates to open
- @ axon hilock of multipolar celss (most often) & near distal end of puedo-unipolar cells
What must exsit across cell membranes to create an “excitable” cell?
Potential Difference
(difference in charge)
What factors maintain “resting potential” across a membrane?
- Na+/K+ (3 Na+ out for every 2 K+ in)
- Large negative molecules trapped in soma
- Passive diffusion through non-gated channels
What is Depolarization?
Cell becomes:
- Less negative
- More excited
- More likely to create action potential
What is Hyperpolarization?
Cell becomes
- More negative
- More Inhibited
- Less likely to create an action potential
What characterizes a local (change in) potential?
- Modality and Ligand-Gated channels
- “Receptor” and “Synaptic”
- Small changes in polarity
- Graded (can sum)
- Larger stimulus or more transmitter equals bigger change in polarity
- Depolarizing or hyperpolarizing
- “Passive” propagation
- Travel short distances
- “Do I want to send a message or not?”
What characterizes an action potential?
- Voltage-Gated channels
- “Action”
- Large changes in polarity
- All or none (can’t sum)
- Larger stimulus or more transmitter equals more frequent action potentials
- Depolarizing
- “Passive” and “Active” propagation
- Travel long distances
- Message is sent
What is a Receptor (change in) potential?
Generated by modality-gated channels at distal end of sensory neurons
What is a Synaptic (change in) potnetials?
Generated by ligand-gated channels on post-synaptic membrane
What is a Temporal Summation?
- Repetitive opening of a channel
- Open gate over and over, ions will spill, change in potential gets bigger
What is a Spatial Summation
What is the sequence from local potential to action potential?
- Local potential (receptor or synaptic) reaches area with large #’s of voltage-gated channels
- trigger zone - receptor potentials
- Axon hillock - synaptic potentials
- “Threshold” depolarization -> open voltage-gated channels
- Action potential -> full depolarization - repolarization
- Refractory period (temporary hyperpolarization)
- Propagation
What is passive propagation?
spilling of ions
What is active propogation?
regeneration
opening of new voltage gated channel downt he membrane
(How action potentials travel)
What prevents an action potential from moving backwards?
Refractory period
What is saltatory conduction?
Action potential jumps from one Node of Ranvier to the next (space between Schwann Cells)
What is the diameter and myelination needed for fast conduction?
Large diameter
Heavily myelinated
What is the diameter and myelination needed for slow conduction?
Small diameter
Less myelinated
What is divergence?
One axon slplits into many terminal branches
What is convergence?
axons from many cells come together
(Heart of integration)
What is the function of Glia cells?
- Support cells of NS (pitt crew)
- Structure
- Transmission (Assist with)
- Pathogenesis (Possible role)
What are the 3 kinds of macroglia (big support cells)?
- Astrocytes
- Oligodendrocytes
- Schwann Cells
What are the functions of Astrocytes?
- Direct role in cell signaling
- calcium waves
- release glutamate
- inc/dec communication between neurons
- Scavenger - restor AP
- Connect neurons & capillaries (part of blood brain barrier)
- Scaffold - Pathway for migrating neurons
What are the functions of Oligodendrocytes?
- Protective insulation of the CNS
- Insulates several neurons
What are the functions of Schwann Cells?
- Myelin of PNS
- one neuron → wrapped coverings (“myelinated”)
- many neurons → simple covering (“unmyelinated”)
- Phagocytic function in injury: eat cell debris (vacuum cleaner of PNS)
What is the function of Microglia?
- Eat cell debris when there is damage in CNS
- eats aging neurons
- abnormal activation → may contribute to brain disease
What is Guillain-Barré?
- Auto-immune attack on Schwann cells (peripheral myelin)
- weakness and sensory loss
- typically myelin regenerates - EXCELLENT recovery
What is Multiple Sclerosis?
- Auto-immune attack of oligodendrocytes
- signs/symptoms: depneds on location of demyelination
- pattern is random
- Can get better and worse
- inflammation squeezese neurons - fall to sleep - inflammation goes down - function comes back.
- typically remyelination does not occur
- signs/symptoms: depneds on location of demyelination
What is the most common tumor of the CNS?
What is its most commong location in the brain?
Astrocytoma
Frontal lobe
(Sx: headache, speech and motor loss, trouble planning, goal setting, organizing)
What are three attributes for primitive neural stem cells?
- Self-renew
- Differentiate - can change
- Populate
