Studied by 3 people
Looks like no one added any tags here yet for you.
the autonomic system is also known as the
visceral motor system
the sympathetic division is
“fight or flight” responses
the parasympathetic division is
“rest and digest” responses
what does the autonomic nervous system control?
glands, cardiac muscle, and smooth muscle
what organs are innervated by the ANS?
viscera of thoracic/abdominal cavities
cutaneous blood vessels
sweat glands
piloerector muscles
the autonomic system is _____, meaning without our conscious intent or awareness
involuntary
effectors of somatic motor
skeletal muscle
effectors of autonomic motor
glands, smooth muscle, cardiac muscle
somatic motor control is
voluntary
nerve endings for somatic motor is
neuromuscular junctions
nerve endings for autonomic motor is
varicosities
neurotransmitters for somatic motor
acetylcholine (ACh)
neurotransmitters for autonomic motor is
ACh and norepinephrine
ANS pathways have
two-neuron chain with a ganglion
the preganglionic fiber is
myelinated
the postganglionic fiber is
unmyelinated
the two-neuron chain with a ganglion ends in
varicosities
what does varicosities do?
release neurotransmitters into tissue and stimulate many cells at once
visceral reflexes are
unconscious, autonomic, stereotyped responses to stimulation involving visceral receptors and effectors
what do visceral reflex arcs consist of?
receptors
afferent neurons
integrating center
efferent neurons
effectors
receptors are
nerve endings that detect stretch, tissue damage, blood chemicals, body temperature, and other internal stimuli
afferent neurons
lead to the CNS
the integrating center is
interneurons in the CNS
efferent neurons
carry motor signals away from the CNS
effectors
carry out the end response
the ANS is considered the
efferent pathway
example of visceral reflex: baroreflex
high blood pressure detected by arterial stretch receptors
afferent neuron carries signal to CNS
efferent signals on vagus nerve of ANS travel to the heart
heart then slows, reducing blood pressure
the two divisions of the ANS often
innervate the same effector, and may have cooperative or contrasting (antagonistic) effects
the sympathetic division prepares the body for
physical activity (exercise, trauma, arousal, competition, anger, or fear)
what division increases heart rate, BP, airflow, blood glucose levels, and dilates pupils?
sympathetic
the sympathetic division reduces blood flow to
the skin and digestive tract
the parasympathetic division calms many body functions by
reducing energy expenditure and assists in bodily maintenance
what division reduces heart rate, BP, airflow, and more?
parasympathetic
the parasympathetic division regulates
digestion, defecation, and urination
the sympathetic division is also known as the
thoracolumbar division
it arises from the thoracic and lumbar regions of the spinal cord
the sympathetic has __ preganglionic and ___________ postganglionic fibers
short; long
sympathetic nerve fibers are distributed
to every level of the body
what predominates in the sympathetic division?
neuronal divergence
each preganglionic cell branches and synapses on 10-20
postganglionic cells
one preganglionic neuron in the sympathetic division can
excite multiple postganglionic fibers leading to different target organs
one signal can have
widespread effects
the “fight or flight” response requires
simultaneous activation of many systems
adrenal glands are composed of
the adrenal cortex and adrenal medulla
what is essentially an extension of the sympathetic NS
the adrenal medulla
the adrenal medulla secretes a mixture of what hormones?
epinephrine (85%)
norepinephrine (15%)
adrenaline does
increases BP, HR, respiration, enlarges pupils, alters metabolism and blood flow to maximize oxygen and sugar delivery to muscles and brain
the parasympathetic division is also known as
the craniosacral division
arises from the brain/sacral regions of spinal cord
fibers travel through cranial and sacral nerves
the parasympathetic division has relatively ____ preganglionic fibers and _____ postganglionic fibers
long;short
the preganglionic fiber in PD ends in
terminal ganglia in or near target organs
the PD is relatively
selective in stimulation of target organ with very little neural divergence
most viscera receive nerve fibers from
BOTH parasympathetic and sympathetic divisions
antagonistic effect
oppose each other
example of antagonistic effect when both divisions innervate the same effector cells
heart rate decreases (parasympathetic)
heart rate increases (sympathetic)
example of antagonistic effect when each division innervate different effector cells in the same organ
pupillary dilator muscle dilates pupil (sympathetic)
constrictor pupillae constricts pupil (parasympathetic)
cooperative effect
two divisions act on different effectors to produce a unified effect
example of cooperative effect
parasympathetics increases salivary serous cell secretion
sympathetics increase salivary mucous cell secretion
both divisions do not normally
innervate on an organ equally
parasympathetics exerts more influence on
digestive organs
sympathetics have greater effects on
ventricular muscles of the heart
control without dual innervation is when
some effectors receive only sympathetic fibers
sympathetic vasomotor tone
is a baseline firing frequency of sympathetics which keeps the blood vessels in a state of partial constriction
sympathetic division acting alone can exert opposite effects on the
target organ blood vessels
an increasing in firing frequency
vasoconstriction
a decrease in firing frequency
vasodilation
nicotine
binds to nicotinic receptors
increase BP/HR
atropine
blocks muscarinic receptors
used by optometrist to dilate pupils
beta blockers
block beta receptors
used to decrease blood pressure
phenylephrine, pseudoephedrine
sympathomimetics
constrict blood vessels in nasal mucosa- decrease mucus production
Note
Flashcard