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Physiology

Terms in this set (54)

The Central Nervous system is made up of?
The brain and spinal cord
The peripheral Nervous system is made up of?
nerves that connect the brain or spinal cord with the body's muscles, glands, and sense organs.
Nerve cells are amitotic
do not divide
Nuclie
cluster of neuron cell bodies in the CN system
Ganglia
Cluster of neuron cell bodies in the PNS
What cells are most abundant in the CNS?
Glial cells
Glial cells are Astrocytes, which means...
support cells, control extracellular environment of neurons
Glial cells are microglia...
immune system of the CNS
Glial cells are Ependymal cells
ciliated, production and movement of of CSF
Oligodendrocytes
produce myelin sheath
Satellite cells
surround neuron bodies located in the PNS.
Schwann cells
form myelin sheaths around the larger nerve fibers.
what signals can synapses use?
Synapses can use both chemical and electrical stimuli to pass information.
Synapses can also be inhibitory or excitatory depending on the signal/ neurotransmitter being transmitted.

Synapses can also be inhibitory or excitatory depending on the signal/ neurotransmitter being transmitted.
...
when Severed axons can repair themselves and restore damage ?
damage if the damage occurs outside the CNS and the cell body is not damaged.
Remaining axon attached to the cell body...
makes a growth cone, which grows out to the effector organ so that function is sometimes restored.
Return of function is delayed because ...
axon regrowth proceeds at a rate of only 1 mm per day.
In an injury to the nervous system the myelin...
myelin coat is damaged and the axons cannot transmit information effectively.
Potential difference
difference in the amount of charge between two points
Measured in volts or millivolts (mV).
Neurons have a resting membrane potential generally in the range of
-40 to -90 mV
Changes in potential are due to
movement of ions
Depolarization
is the potential moving from RMP to less negative values.
Repolarization
is the potential moving back to the RMP.
Hyperpolarization
is the potential moving away from the RMP in a more negative direction.
Graded potentials
changes in membrane potential confined to a small region of the plasma membrane
4 major ions that are functioning in graded potential
sodium, potassium, chlorine, negatively charged proteins
Which ions are located outside the cell
sodium and chlorine
Which ions are located inside the cell
potassium and negatively charged proteins
What is an action potential
An action potential is a large change in membrane potential and is an "all or none" response.
Where are action potential possessed
Possessed by neurons, muscle cells and some other types of cells.
What channels act as a stimulus for an action potential?
Ligand-gated channels and mechanically gated channels often serve as the initial stimulus for an action potential.
The voltage-gated channels give a membrane the ability to undergo action potentials by allowing the rapid depolarization and repolarization phases of the response.
...
threshold potential
Membrane must be depolarized to a critical level to cause an action potential
Threshold potential is usually about
-55 mV
absolute refractory period
is during the action potential; a second stimulus, no matter how strong, will not produce a second action potential .
Refractory period occurs when
Occurs when the voltage-gated Na+ channels are either already open or are in inactivated state during the first action potential.
Relative refractory period
a second action potential can be produced, but only if the stimulus strength is considerably greater than usual.
limit the number of action potentials an excitable membrane can produce in a given period of time.
...
In the action potential propagtion The velocity of action potential depends upon
fiber diameter and whether or not the fiber is myelinated.
The larger the fiber diameter, the faster the action potential propagates, because a large fiber offers less resistance to local current; more ions will flow in a given time.
...
Myelin is an insulator that makes it more difficult for charge to flow between
intracellular and extracellular fluid compartments.
Action potentials occur only at the
nodes of Ranvier, where the myelin coating is interrupted and the concentration of voltage-gated Na+ channels is high.
saltatory conduction.

saltatory conduction.
Thus, action potentials jump from one node to the next as they propagate along a myelinated fiber, and for this reason such propagation
Myelin adds speed, reduces metabolic cost, and saves room in the nervous system because the axons can be thinner
...
Propagation via saltatory conduction is faster than propagation in nonmyelinated fibers of the same axon diameter.
...
Receptor potential
caused by a sensory receptor.
Synaptic potential
generated at a synapse
Pacemaker potential
spontaneous change in the membrane.
What are synapses?
Synapses are junctions between two neurons. They can be chemical or electrical.

Chemical synapses utilize neurotransmitters
Electrical synapses
Pre- and post-synaptic cells are connected by gap junctions
Chemical synapses
Pre-synaptic neurons release neurotransmitter from their axon terminals
Neurotransmitter binds to receptors on post-synaptic neurons
Neurotransmitters are produced and stored in vesicles at the axon terminal.
...
When the cell is stimulated the intracellular Ca2+ levels increase and stimulate the vesicles to translocate and bind to the plasma membrane via the SNARE proteins.
...
The neurotransmitter is then released via exocytosis.
...
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