Nerve Physio Flashcards
Main genetic and metabolic center of the neuron.
Cell body/ Soma
Contains the nucleus and nucleolus of the cell
Cell body/ soma
Also a region in which the neuron receives synaptic input
Cell body/ soma
The rough ER, called Nissl substance, and neurofibrils are abundant
Cell body/soma
The main direct recipients of signals from other neurons
Dendrites
Conduct nerve impulse toward the cell body
Dendrites
Longest process in the body
Axon
Longest process in the body
Axon
The initial segment is usually the site where action potentials (spikes) that are propagated down the axon are initiated
Axon Hillock
Most excitable part
Axon Hillock
Whitish fatty material
Myelin sheath
Protects and insulates the fibers and increases the transmission rate of nerve impulses
Myelin sheat
facilitate faster impulse conduction, oligodendrocytes and schwann cells
Myelin sheats
where ions still can flow with ease through the axon mem-
brane between the extracellular fluid and intracellular fluid
inside the axon. This area is called the
Nodes of ranvier
where ions still can flow with ease through the axon mem-
brane between the extracellular fluid and intracellular fluid
inside the axon. This area is called the
Nodes of ranvier
contains membranous sacs that contain chemicals called neurotransmitters
Axon terminal
where multiple local potential changes generated by synaptic connections are integrated
Receptor or dendritic zone
where action potentials cause the release of synaptic transmitters
Nerve endings
that transmits propagated impulses to the nerve endings
Axonal process
carrying impulses from the sensory receptors
Sensory afferent
detect amount of stretch or tension, in skeletal muscles, their tendons and joints
Proprioreceptors
neurons carrying impulses from the CNS to the viscera or muscles
Efferent neurons
connect the motor and sensory neurons in neural pathways
Interneurons or association neurons
• Several neurons
• Most common type
Multipolar neuron
Two processes, an axon and a dendrite; rare in adults (eye, nose)
Bipolar neuron
• Axons conduct nerve impulses both toward and away from the cell body (sensory neurons in the PNS)
Unipolar neuron
• Single process emerging from the cell body
Unipolar neuron
*Most synapses occur on
- In the cerebral and cerebellar cortex, endings are commonly located on
Axodendritic
but some presynaptic nerves terminate on the
Axosomatic synapse
is a specialized type of synapse where one neuron’s axon terminal forms a connection with another neuron’s axon
Axoaxonic
is a junction between the axon terminal of one neuron and the dendrite of another neuron
Axodendritic
is a junction between the axon terminal of one neuron and the soma (cell body) of another neuron.
Axosomatic
Wheretwoneuronscomeinto close proximity and functional interneuronal communication occurs
Synapses
Communication at a _______, under physiologic conditions, takes place in one direction only
Synapse
the neurotransmitter, passes across the narrow space between the cells and becomes attached to a protein molecule in the postsynaptic membrane called _____
Receptor
The vesicles fuse with the ___________and discharge the neurotransmitter(s) into the _________ by a process of exocytosis
Presynaptic membrane, synaptic cleft
containing channels that extend from the cytoplasm of the presynaptic neuron to that of the postsynaptic neuron
Gap junctions
Rare in the human central nervous system
Electrical synapse
Gap junctions containing channels that extend from the cytoplasm of the presynaptic neuron to that of the postsynaptic neuron
Electrical synapse
The bridging channels permit ionic current flow to take place from one cell to the other with a minimum of delay.
Electrical synapse
In ________ ,the rapid spread of activity from one neuron to another ensures that a group of neurons performing an identical function act together.
Electrical synapse
___________ also have the advantage that they are bidirectional; ____________ are not.
Electrical synapses, chemical synapses
release of neurotransmitter substances at synapses
Presynaptic vesicles and mitochondria
Most ______ produce and release only one principal transmitter at all their nerve endings.
Neurons
is widely used as a transmitter by different neurons in the central and peripheral parts of the nervous system
Acetylcholine
Star-shaped cells that account for nearly half of the neural tissue.
Astrocytes
Their numerous projections have swollen ends that cling to neuron, bracing them and anchoring them to their nutrient supply lines, the blood capillaries.
Astrocytes
Form a living barrier between capillaries and neurons and play a role in making exchanges between the two.
Astrocytes
spider-like phagocytes that dispose debris, including dead brain cells and bacteria
Microglia
line the central cavities of the brain and SC
Ependymal cells
The beating of their cilia helps to circulate the Cerebrospinal fluid (CSF) that fills those cavities and forms a cushion around the CNS.
Ependymal cells
Glia that wrap their flat extensions tightly around the nerve fibers,
Oligodendrocytes
producing fatty insulating coverings called
Myelin sheats
are transmitted by
ACTION POTENTIAL GENERATION
action potentials, which are rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane
Nerve signals
Each action potential begins with a sudden change from the normal resting _______ membrane potential to a _______ potential and then ends with an almost equally rapid change back to the ________potential
Negative,positive,negative again
membrane potential is at -70mV
Resting stage
membrane suddenly becomes permeable to sodium ions, allowing tremendous numbers of positively charged sodium ions to diffuse to the interior of the axon. (40 mV)
Depolarization stage
The normal “polarized” state of_________ is immediately neutralized by the inflowing positively charged sodium ions, with the potential rising rapidly in the positive direction
-90 millivolts
The sodium channels begin to close and the potassium channels open more than normal.
Repolarization stage
rapid diffusion of ______ to the exterior re-establishes the normal negative resting membrane potential
Potassium ions
Different types of _______excite ________ to become active and generate impulse
Stimuli,neurons
Most neurons in the body are excited by
Neurotransmitters
Normally, _________cannot diffuse through the plasma membrane, but when the neuron is stimulated, the “gates” of sodium channels in the membrane open
Sodium ions
Higher to lower concentration what law is this
Law of diffusion on sodium
Duration of non-excitable state
REFRACTORY PERIOD
Controls the maximum frequency that the action potentials can
be conducted along the plasma membrane
REFRACTORY PERIOD
________ in myelinated axons jumps from one node of Ranvier to the next
Depolarization
In the__________ state, the gates of the _________ are ________ than those of the sodium channels, which are nearly closed.
Nonstimulated, potassium channels, open wider
In the ________state, the gates of the sodium channels are at first _________ ; then, the gates of the ________ are opened, and the gates of the sodium channels are nearly closed again.
Stimulated channels, open wider, potassium channels
It is the opening and closing of the sodium and potassium channels that is thought to produce the _______ and_________ of the plasma membrane.
Depolarization and repolarization
occurs at the onset of the action potential when a second stimulus is unable to produce a further electrical change. It is thought to be due to the inability to get the sodium channels open
Absolute refractory period
when a very strong stimulus can produce an action potential, presumably the sodium channels are opened.
Relative refractory period
Anautoimmunediseasethataffectsover3 million people worldwide, usually striking be- tween the ages of 20 and 50 and affecting women about twice as often as men.
Multiple sclerosis
The cause of ______appears to include both genetic and environmental factors.
Multiple sclerosis
_________,antibodiesandwhitebloodcellsinthe immune system attack myelin, causing inflammation and injury to the sheath and eventually the nerves that it surrounds.
Multiple schlerosis
Loss of ____leads to leakage of ____through voltage- gated channels, hyperpolarization, and failure to conduct action potentials
Myelin, k+
