nervous system Flashcards
Sensory system is afferent or efferent?
Afferent
What are the two types of neurotransmitters?
Ionotropics (that gate ions (Ca, K, or Cl)) and metabotropics (that act on second messengers)
How many nerve pairs are in each section of the spinal cord?
Cervical 8, thoracic 12, lumbar 5 and sacral 5
What are the differences between receptor potential and action potential?
Receptor potential can be summated, does not obey all or none rule, is in the receptor, graded and is unpropagated. Action potential is in the sensory nerve fiber, not graded, obeys all or none rule, not summated and is propagated
What type of glial cells is in the CNS and PNS?
Schwann cells in PNS and oligodendrocytes in CNS
What is the main difference between axon and dendrites?
Dendrites cannot generate action potential as they dont have Na channels
What ion is more concentrated intracelullarly than extra?
K
If positive charge is introduced in the membrane, that membrane is
Depolarized
What are the types of sensory receptors?
Mechano, thermal, chemical, electromagnetic and nociceptors
Looking from the side, What part of the brain is located in front of the central sulcus? and behind?
frontal lobe and parietal lobe
What parts of the brain are located in front and behind the central sulcus looking from above?
Pre central gyrus and post central gyrus
Low K concentration extracelularly causes:
Hypokalemia, membrane is hyperpolarized
In Hypokalemia the potential is:
Lower than the resting potential, Hyperpolarized
Hyperkalemia is when:
The K concentration extracelularly is higher than normal and so the membrane potential will be depolarized
Gray matter contains _______ and white matter contains _____
neurons and axons
An anion is an ion with a _______ charge
negative
Motor neurons leave spinal cord from _____ side
ventral
Thousands of axons form a ____in PNS and is called _____in CNS
nerve and tracts
Nernst equation is:
(EMF) = ± 61/z×log ([]inside)/([]outside)
Na has ____ channels and Ca has _____ channels
Fast and slow
What is saltatory conduction?
It’s the conduction of action potential between nodes of ranvier, where the potential is recharged at each node, since that is where the Na channels have access to the axon as these sections are not myelinated
What is absolute refractory period?
It’s the period after an action potential when another action potential cannot be created no matter the stimulus, this happens because during this period the inactivation gates of the Na channels are closed, and they can only open again when the membrane resting potential is restored.
What is relative refractory period?
It’s the period after an action potential when another potential can be created but it requires stronger stimulus, because the membrane potential is hyperpolarized thus to create a new action potential the new stimulus must overcome the hyperpolarization to reach the threshold.
Why does the action potential does not move backwards?
Because of the absolute refractory period the Na channels inactivation gates are closed and cannot be open until resting potential is returned, thus no action potential can be created in this backward direction
Explain chemical synapse:
The presynaptic terminal is close to the postsynaptic terminal and between them there is a synaptic cleft. In the presynaptic terminal there are vesicles that hold neurotransmitters and when a action potential is received the Ca channels open and these vesicles move toward the cleft and release the neurotransmitters that will be received in the postsynaptic terminal by receptor proteins, depending on the neurotransmitter this can excite or inhibit the neuron.
Also the presynaptic cleft has mitochondria that provide energy to synthesize neurotransmitters
Neurotransmitter that open cation channels are called ________ transmitters and those that open anion channels are ______ transmitters.
Excitatory and inhibitory
Electrical synapse is more common in:
Visceral, smooth and cardiac muscles
Chemical synapse move _______ and electrical synapse moves ________
in only one way, in both ways
Examples of small and fast acting Synaptic transmitters
Acetylcholine, epinephrine, dopamine, serotonin
Acetylcholine is mostly excitatory but can be inhibitory in the
peripheral parasympathetic nerve endings
Inhibitory signals open ___ channels allowing its influx and open __ channels allowing its outflux, making the membrane potential more negative
Cl, K
Presynaptic inhibition is the release of inhibitory substances _____ on the outside of presynaptic nerve, allowing Cl to enter, which will cancel some of the Na that enter when a action potential is produced
GABA
What are the main differences between spatial and temporal summation?
Spatial is the summation of stimuli from more than one terminal while temporal is the summation of stimuli of one terminal that happen multiple consecutive times rapidly
What is decremental conduction?
Is the decay of conduction of a stimuli in the dendrites, as they are not insulated and are permeable to Cl and K ions, thus signals that are farther away from the soma loose more strength and must be of greater intensity to cause a action potential or inhibition than signals close to the axon hillock
What is fatigue of a neuron?
If a stimuli is continuous the firing rate decreases with more time of excitation of a neuron because of exhaustion of the reserves of neurotransmitters in the vesicles in presynaptic terminals.
_______ increases neuronal excitability causing seizures, while _______ depresses neuronal activity and cause coma.
Alkalosis, acidosis
Caffeine is a excitatory drug that ______ the threshold for excitation of neurons
Lowers
What is the labeled line principle?
It’s how the brain interprets signals from the sensory nerves, each nerve tract terminates at a specific point in the CNS, the type of sensation felt is determined by the point in the nervous system to which the fiber leads.
What are the fastest adapting nerve endings?
Pacinian receptor, followed by hair receptors. Joint capsule and muscle spindle are slow to adapt, aka tonic
sensory info from somatic system enters the spinal cord through:
dorsal roots of the spinal nerves.
The Dorsal (or posterior) column-medial lemniscus transmits:
Faster signals, conveys light touch, proprioception and vibrations, has high fidelity of temporal and space. Has distinct orientation of nerve fibers from individual parts of the body.
The Anterolateral (or spinothalamic) system transmits:
Slower, transmits pain, thermal sensations, crude touch, tickle and itch
Cell bodies of sensory neuron is located in
dorsal root ganglia, that is outside spinal cord
Pain is transmitted through:
anterolateral system
