Ch # 16 Autonomic Nervous system & higher order functions Flashcards
What neuron runs from the CNS to the autonomic ganglion?
preganglionic neuron
Autonomic nervous system
=>We have three neurons
one descend from primary motor cortex to the spinal cord then second go to postganglionic neuron as preganglionic
=> effectors
Glands, smooth muscle and adipose.
=> Response to neurotransmitter
structural comparison helps us understand
how visceral reflex arcs differ from somatic reflex arcs
-short reflex includes two neurons as somatic
- long reflex arc includes three neurons as visceral
Efferent pathway for SNA
Lower motor neurons has cell body in brainstem or spinal cord, axon leaves and synapses with the effector (skeletal muscle)
efferent pathway for ANS
two neurons chain starting at brianstem
or spinal cord
preganglionic neuron with cell body in CNS, axon leaves
ganglionic (postganglionic) neuron with cell body in ganglia
NTs for SNS
Ach always has excitatory effect on the skeletal muscle. Ach degrades quickly from synapses and it is short-lived.
NTs for ANS of sympathetic
Norepinephrine (NE) - this is present at level where ganglionic neurons acts on effector
Ach - present at the end of preganglionic neuron
NE is longer-lived than Ach
NTs for ANS of parasympathetic
Ach
excitatory or inhibitory depending on receptor at both ends of pre and post ganglionic neuron
SNS vs ANS regarding conduction velocity
SNS are fast and have more myelination than ANS
ANS dual innervation
Para & sympathetic have opposing effect on visceral at the same time with one exerting primary control
it made continuous adjustment => dynamic
which structure only innervated by sympathetic division
Arrector pili muscles and sweet glands of skin: smooth muscles of most blood vessels
Why will it be important for both divisions to always remain active
(even if it is at low levels)?
on/off of system takes time and extra energy.
Short-term stress: hypothalamus activates adrenal medulla via neural stimuli
- AP triggered hypo. to activate Sympathetic
- AP travel to pregang. to adrenal medulla
- adrenal sceretes amino: Epi. 80% and NE 20%
- Epi & NE reinforce sympathetic response for exertion
fight/ flight response
Cardiovascular–> increase HR % BP and flow away from nonessential organs like stomach and urinary
Metobolic –> Liver converts glycogen to glucose & more energy & more metabolic rate
Respiratory–> Bronchioles dilate to facilitate airflow in%out of lungs and more O2
Preganglionic neurons of the autonomic nervous system are located in
both the brainstem and the lateral gray horns of the spinal cord.
the brain.
The parasympathetic nervous system is especially active during which physiological state?
Digestion
Sympathetic nerve activity would cause all of the following responses EXCEPT
increased stomach motility
What is the effect of neurotransmitters released at the area in the adrenal medulla of sympathetic?
They are released into the blood and produce long-lasting and widespread effects in the body.
Which of the following effectors is innervated by neurons that synapse in the collateral ganglia?
abdominopelvic cavity => intestine
Visceral motor neuron nuclei are located in which part of the brain?
hypothalamus
where is the cell body for Parasympathetic
pre-gang => brainstem or sacral region of SC
Post-gang => near or in organ
where is the cell body for sympathetic
pre-gang => lateral horn of spinal cord (thoracic & lumber)
post-gang => ganglia of 1. sympathetic chain.
2. collateral. 3. adrenal medulla
explain sympathetic neurons
- Preganglionic neurons have cell bodies in lateral horns
- Axons pass through rami communicans (pl. rami
communicantes) - May synapse at sympathetic chain ganglia or pass through them
Where do pre-ganglionic and
ganglionic neurons synapse in sympathetic?
- Synapse at same level of
sympathetic chain ganglia - Synapse at a higher or lower level
of sympathetic chain ganglia - Synapse in a distant ganglia (emerges
from chain ganglia without synapsing)
collateral ganglia
innervates visceral organs in abdominopelvic cavity
it has cell body in distant ganglia
sympathetic chain ganglia
it has two types
1. pass through anterior
2.knlnbh
the adrenal medulla division
secrete NTs into the general circulation
What is the benefit of releasing neurotransmitters into the blood?
- travel far distance through blood
- long lasting effect as clearing out will take time
parasympathetic divisions
they are associated with the cranial and sacral region of spinal cord
oculomotor (3)
- intrinsic eye muscle
- shape of lens and diameter of pupil
Facial nerve (7) & Glossopharyngeal nerve (9)
- increase of salivary glands
vagus nerve (10)
90 % neurons goes through
Sympathetic nerves contain postganglionic fibers that innervate organs in which cavity?
thoracic
A pedestrian narrowly avoids being hit by an oncoming car. He notices that it takes a little while for his heart rate and respiratory rate to return to normal. This is likely because
sympathetic activation of the adrenal medulla has released epinephrine and norepinephrine into the bloodstream.
Sympathetic preganglionic fibers are ________ and have ________ axons.
short; myelinated
In what part of the given pathway is norepinephrine secreted?
from the varicosities of the postganglionic fiber
Which of the following is not controlled by the ANS?
skeletal muscle system
In which system are the ganglia in or near the target organ?
parasympathetic division of the ANS
Sympathetic preganglionic neurons are located in the __________ horn of the __________ cord.
lateral gray, thoracic and lumbar spinal
The ________ nervous system stimulates the arrector pili muscles and gives you “goosebumps.”
sympathetic
Specialized ganglionic sympathetic neurons that release hormones into the bloodstream are found within the
adrenal medullae
define consciousness
Consciousness is associated with perception of sensation, ability to voluntarily initiate control movement, higher mental functions.
