lecture 7 part 1 Flashcards
the nervous system is divided into….
peripheral nervous system and central nervous syste,
classify the peripheral nervous system
autonomic and somatic
autonomic can be vided into sympathetic NS and parasympathetic NS
what can the CNS be divided into
brain and spinal cord
true or false
all glands are under the control of the parasympathetic nervous system
FALSE
all glands except sweat glands
the ANS is largely _______
what does this mean?
independent
its activities are not under our direct conscious control
the ANS controls _____ functions like cardiac output, blood flow distribution, and digestion
visceral
true or false
both the autonomic and somatic nervous system have important afferent (sensory) inputs
TRUE
these give information about the internal/external environment and modify motor output
explain what afferent neurons are
run from the periphery to the INTEGRATING CENTERS. this includes the enteric plexus in the gut, the autonomic ganglia, and the CNS (BRAIN/SPINAL CORD)
TRUE OR DALSE
afferent neurons go away from the brain/spinal cord
false – approach the brain/spinal cord with sensory information
true or false
efferent neurons are motor neurons
true
give 3 types of efferent neurons
sympathetic neurons
parasympathetic neurons
enteric neurons
explain what the somatic nervous system controls
CONSCIOUS AND SUBCONSCIOUS control of SKELETAL MUSCLES
give the pathway of the somatic nervous system
an upper motor neuron and a lower motor neuron
the lower motor neuron may be controlled by REFLEXES based in the brain or spinal cord
the upper motor neurons are located in the nuclei of the brain or the primary motor cortex
true or false
the upper motor neurons of the somatic nervous system may be controlled by reflexes based in the brain/spinal cord
FALSE - this is true for lower motor neuron
upper motor neurons are either located in the nuclei of the brain or the primary motor cortex
what does the autonomic nervous system control?
visceral functions, MOSTLY outside of our awareness
where are the integrative centers of the autonomic nervous system located?
in the hypothalamus
explain the neurons of the autonomic nervous system
2 motor neurons are in sequence to control the visceral effectors
preganglionic neurons are embedded in the brain stem/spinal cord
ganglionic neurons go inside the organ
where are the cell bodies of preganglionic neurons located?
in the brain stem and spinal cord
where are the cell bodies of ganglionic neurons located?
in the peripheral autonomic ganglia
name some visceral effectors that ganglionic neurons innervate
cardiac muscle
smooth muscle
glands
adipose tissue
what are the “visceral motor neurons”
ganglionic neurons
___ neurons are part of visceral reflex arcs
preganglionic
most activities of these neurons represent direct reflex responses
preganglionic neurons
what is the neurotransmitter(s) released for the somatic nervous system
acetylcholine only
what are the neurotransmitters for the autonomic nervous system?
sympathetic: preganglionic neuron releases acetylcholine and postganglionic neuron releases norepinephrine
parasympathetic: preganglionic AND postganglionic releases acetylcholine
what is norepinephrine
a neurotransmitter AND hormone
travels in neurons AND the bloodstream
what is the effect of acetylcholine
activates the parasympathetic nervous system (“rest and digest”)
what is the effect of norepinephrine
activates the sympathetic nervous system (“fight or flight”)
true or false
when a neuron of the somatic nervous system releases acetylcholine, the effect is always stimulatory on skeletal muscle
true
which has neurons with HEAVILY myelinated axons — somatic nervous system or autonomic nervous system?
somatic
what causes the adrenal medulla to secrete epinephrine and noepinephrine?
the preganglionic neuron of the sympathetic nervous system releases acetylcholine to the adrenal medulla which stimulates it to secrete epinephrine and norepinephrine
what are the major divisions of the autonomic nervous system
sympathetic and parasympathetic division
true or false
the sympathetic and parasympathetic divisions always have opposing effects and are dependent on one another
FALSE
they may work independently, and some structures may only be innervated by one division
USUALLY THO, they do have opposing effects. Sometimes they work together in complex processes too
the sympathetic and parasympathetic divisions both influence what?
the 3rd autonomic division called the ENTERIC NERVOUS SYSTEM
In general, when is the sympathetic division active?
during exertion, stress or emergency
the sympathetic division is also called….
the thoracolumbar division
where on the spinal cord does the sympathetic division start and end?
starts at T1 and ends at L2
an epidural injection is given where?
to L3 or L4 (BELOW the sympathetic division)
how many cranial nerves are part of the parasympathetic division?
name them
4:
III, VII, IX, and X
ocularmotor, facial, glossopharyngeal, vagus
besides the cranial nerves, what other nerves carry parasympathetic fibers?
sacral nerves S2, S3, and S4
the parasympathetic division is also called….
the craniosacral division
when does the parasympathetic division predominate?
under resting conditions
which preganglionic fibers are longer – sympathetic or parasympathetic?
parasympathetic bc they have to go all the way from the brain/sacral regions of the spinal cord to the target organs
true or false
the enteric nervous system is its own system apart from the parasympathetic and sympathetic divisions
true, but those divisions do influence it
define the ENS (enteric nervous system)
an extensive network of neurons and nerve networks in the walls of the digestive tract
is there any CNS input in the enteric nervous system?
NO
what does the ENS (enteric nervous system) do?
initiate and coordinate many complex local visceral reflexes with NO CNS INPUT
how many neurons are part of the ENS?
~100 million
-At least as many as the spinal cord
true or false
the ENS has different neurotransmitters than the brain
false - the same
true or false
the ENS functions in a fully autonomous manner
FALSE – semi autonomous
it receives input from the outflow of the autonomic nervous system to modulate GI activity
also, it sends sensory information back to the CNS
True or false
the ENS has no relation to the CNS
FALSE
it gets no input from the CNS, but it does send sensory info back to it
what ensures the forward propulsion of gut contents, and the relaxation of sphincters when the gut wall contracts?
the enteric nervous system
what plays a modulatory role for the enteric nervous system?
the parasympathetic and sympathetic fibers that synapse on the enteric plexus neurons
explain most neuron-neuron synapses in mammals
the neuromuscular junction is relatively “tight” meaning that the nerve ends very close to where the tissue is innervated.
therefore, the diffusion path from the nerve terminal to the postsynaptic receptors is very short AND EFFECTS ARE RELATIVELY RAPID AND LOCALIZED
as mentioned, classic synapses like the mammalian neuromuscular junction have very rapid and localized effects.
what junctions have slower onset?
junctions between autonomic neuron terminals and effector cells (smooth muscle, cardiac muscle, glands)
the discharge of a single motor fiber often activates many effector cells
_______ preganglionic fibers are long
parasympathetic
POSTGANGLIONIC ARE SHORT
postganglionic ______ fibers are long
sympathetic
where is acetylcholine released?
it is a primary excitatory neurotransmitter for what?
at ANS ganglia
at somatic NMJ
at PARASYMPATHETIC POSTGANGLIONIC NERVE ENDINGS
a primary excitatory neurotransmitter to SMOOTH MUSCLE CELLS and SECRETORY CELLS IN THE ENS
true or false
acetylcholine is the primary inhibitory neurotransmitter to smooth muscle cells and secretory cells in the ENS
FALSE - excitatory
what is the primary neurotransmitter at most sympathetic postganglionic nerve endings?
norepinephrine
what is 5-HT
serotonin
where is serotonin an important neurotransmitter?
at excitatory neuron-neuron junctions in the ENS
where is dopamine important?
a modulatory neurotransmitter in some ganglia and in the ENS
(possibly a postganglionic sympathetic transmitter in renal blood vessels)
what does VIP stand for
vasoactive intestinal peptide
explain what VIP (vasoactive intestinal peptide) does
a vasodilator and cardiac stimulant
excitatory secretomotor transmitter in the ENS
explain what substance P is
a sensory neurotransmitter in the ENS and elsewhere
related tachykinins are excitatory neurotransmitters with acetylcholine at ENS neuromuscular junctions
SUBSTANCE P IS A VASODILATOR
true or false
substance P is a vasodilator
true
true or false
ATP is a neurotransmitter
TRUE
acts as a transmitter or cotransmitter at many ANS-effector synapses
what does CGRP stand for
calcitonin gene related peptide
what does calcitonin gene related peptide (CGRP) do?
a neurotransmitter
found with substance P in cardiovascular sensory nerve fibers and some secretomotor ENS neurons
A CARDIAC STIMULANT
Name 2 cardiac stimulant neurotransmitters
VIP
CGRP
