Physiology Exam 2
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Physiology Exam 2
Structure of neurons include...(5)
Nodes of Ranvier (Ron-Vee-Ay)
Body of perikaryon
Conducts nerve impulses away from soma
Never more than one axon per neuron(some have none)
receive impulses from other neurons
Myelin Sheath (4)
Insulating layer (mostly lipid) around nerve fibers, which are formed by
neuroglia cells(Schwann Cells in PNS & Oligodendrocytes in CNS).
Not all nerve fibers are myelinated.
Myelinated comprise the white matter.
Unmyelinated comprise the gray matter.
Nodes of Ranvier (2)
Myelinated nerve fibers
Ions can be exchanged with the ECF only with this...
Types of Neurons (4)
Conduct impulses toward the CNS
Interneurons (association neurons) (2)
Entirely within the CNS
Conduct impulses from sensory neurons to motor neurons.
Conduct impulses away from the CNS and to the effectors (muscles or glands).
Reflex Ark is an arrangement of...(3)
Functions of Neurons (3)
Secretion of neurontransmitters
Nervous Tissue is specialized for...by? (2)Consists of? (2)
Communication, by means of electrical or chemical signs
neurons (nerve cells)
neuroglia (glial cells)
Interior of nerve cell or any cell is...? Relative to ECF. (3)
The charge differences across the plasma membrane is...? which is about...?
Resting Membrane Potential (RMP)
The...charge of the ion in cell.
Large anions that cannot escape cell Na+ is ...x higher concentration outside. K+ is ...x higher concentration inside.
Uneven distribution of Na+ & K+ on ... of plasma membrane pertains only to thin film of ions adjacent to the membrane surface.
Electrical events involves ions adjacent to membrane in...?
Local Potentials (3)
Influx of Na+ diffuse for a short distance along the inside of plasma membrane
Produce a current that travels from point of stimulation toward the cell's trigger zone; short range change
High need of glucose and ATP energy
Characteristics of Local Potentials
Stimulation of neuron by chemical, light, heat, mechanical distortion.
Stimulation alters permeability of various ions thus leading to a change in resting membrane potential
Action Potential (2)
Occur where there is high density of voltage gated channels, ex
: trigger zone has 350 to 500 channels/μm2.
Generated if local potential spreads all the way tot he trigger zone and is still strong, it can open these channels.
The action potential changes the membrane potential from -70mV (resting) to 35mV & back again to the resting membrane potential. (7)
The action potential arrives at the axon hillock, depolarizes the membrane at that point.
This local potential must rise to a critical voltage called threshold ~ -55mV.
The neuron now produces an action potential.
As potential passes 0mV the Na+ channel closes, the voltage peaks @ +35mV, as the voltage peaks the K+ channels open K+ ions exit the cell.
Their outflow repolarizes the membrane.
Hyperpolarization, membrane voltage drops 1 or 2mV more negative because K+ channels stay open longer than Na+ channels, so more K+ leaves the cell than the amount of Na+ entered.
Refractory Period, for a short time, few milliseconds, after action potential, it is impossible to stimulate that region of a neuron to fire again; This is the period of resistance to restimulate.
All or Nothing Law
Action Potentials are non decremental
There are 2000 to 12000 voltage gated ion channels/μm2 at...?
The node of ranvier
In..., ions can be exchanged with the ECF only at the Nodes of Ranvier.
Myelinated nerve fibers
Impulses jumping from node to node.
(Filled w/neurotransmitters) in the pre-synaptic neuron
In the post-synaptic membrane
Cessation of signal at the synapse (3)
Re uptake of the neurotransmitter by the pre-synaptic neuron
Diffusion of the neurotransmitter into the extracellular fluid, where astrocytes absorb it.
Degradation of the neurotransmitter in the synaptic cleft.
Muscle contraction (3)
Molecular processes involving muscle contraction
General structure & functions of different muscle cells
Smooth Muscles (4)
Cardiac Muscles (5)
Skeletal Muscles (3)
Striated Cylindrical Fiber
Myosin (thick) filaments
Actin (thin) filaments, tropomyosin & troponin are associated w/thin filaments
Titin (elastic) filaments
Spinal Cord, motor neuron 1, motor neuron 2
Skeletal Muscle Fibers