Chapter 9 - Autonomic Nervous System Flashcards
T/F - Somatic Motor Neurons send impulses away from the CNS to a smooth muscles
False - Somatic motor neurons sen impulses away from the CNS to a voluntary muscle
Where can you find a somatic motor neurons cell body?
CNS
Autonomic motor neurons are composed of 2 neurons. Where is the first neurons cell body located, and what is this neuron called?
1) gray matter of Brain/Spinal Cord
2) preganglionic Neuron
What is the second neuron in an autonomic motor neuron called?
Postganglionic Neuron
Where are the 3 areas that preganglionic neurons originate from?
Midbrain
Hindbrain
Upper thoracic to the fourth sacral levels of spinal cord
Where are autonomic ganglia found in the body?
- Chains on the right and left of the spinal cord
- head
- neck
- abdomen
How do skeletal muscles undergo denervation hypersensitivity?
- Skeletal muscles do not undergo denervation hypersensitivity. Smooth muscles do!
- It is when a smooth muscle gets denervated, it actuals stays toned and functions. In fact it is more sensitive than normal to stimulating agents.
T/F - Without innervation, smooth muscles and the heart would stop and kill the person…
- False - the muscles can contract rhythmically in response to electrical waves of depolarization caused by the cells themselves.
- Autonomic innervation simply increases or decreases this intrinsic activity
1 function of the Vagus nerve is to supply inhibitory fibers to the heart…what if the Vagus nerves activity is increased?
The heart beat will slow sense more inhibitory fibers will be activated.
The thorocolumbar division of the autonomic nervous system is also called….
Sympathetic Division
Where exactly do the preganglionic fibers of the sympathetic division exit the spinal cord?
Ventral Roots from the first Thoracic (T1) - to the seoncd Lumbar (L2)
Where are the sympathetic ganglia found? What are these ganglions name?
- Located on either side of the spinal cord - interconnected forming a sympathetic chain of ganglia that parallels the spinal cord on each lateral side
- paravertebral ganglia
Sympathetic Postganglionic neurons follow spinal nerves for what purpose?
To innervate blood vessels and other involuntary effectors aournd muscles and kin.
What is another name for the unmyelinated postganglionic neurons?
gray rami communicantes
Preganglionic fibers that exit the spinal cord, but do not synapse with sympathetic ganglia form what type of nerve?
Splanchnic nerves
Splanchnic nerves synapse in [] or [] ganglia. Name these 3 ganglia -
- Collateral or prevertebral
- Celiac, superior mesenteric, inferior mesenteric
What do postganglionic fibers arising from collateral ganglia innervate?
Organs of digestive, urinary, and reproductive systems
Why is the adrenal medulla consider part of the “sympathoadrenal system?”
- The adrenal medulla acts almost like a sympathetic ganglion in that it is innervated by preganglionic sympathetic fibers
- The adrenal medulla also secrete epinephrine which is complementary to norepinephrine - which is released from post ganglionic sympathetic nerve endings.
This nervous system divsion is named [] because its preganglionic fibers originate in the midbrain, pons, and medulla, as well as the 2nd - 4th sacral levels of spinal column…..
Craniosacral division - parasympathetic division
Where do the cranialsacral neurons synapse with their ganglia?
- The parasympathetich ganglia are located right next to - or actually within - the organs innervated
What neuron innervates the effector organ/cell in the parasympathetic division?
The terminal ganglia synapse with effector cells
Which Cranial Nerves are mixed nerves (both sensory axons and parasympathetic motor axons)?
IX (glossopharyngeal and X (Vagus)
The Vagus nerve synapses with ganglia outside of the head - name some of the locations that these terminal ganaglia reside…..(there are alot)
- Lungs
- Heart
- Liver and gallbladder
- spleen
- Stomach
- Pancreas
- Large Intestine
- Small Intestine
- Adrenal Gland and Kidney
Where do parasympathetic pregagnlionic fibers from teh sacral level of the spinal cord innervate?
- Lower half of large intestine
- Rectum
- Urinary and reproductive system
Why are somatic motor neurons only activated during fight-or-flight situations?
- They aren’t. Sympathetic neurons are continually firing…or they are in a tonic state.
What is the neurotransmitter of all preganglionic axons, both sympathetic and parasympathetic?
Acetylcholine (ACh)
Cholinergic synapses can be found where?
- All preganglionic synapse
- Some parasympathetic postganglionic synapses and thei effector cell
Most sympathetic postganglionic synapses are adrenergic. Which neurotransmitter do they use?
Norepinephrine
What is a “synapses en passant?”
- When autonomic psotganglionic neurons enter an organ, they have a bunch of swellings, varicosities, that contain neurotransmitters.
- The swelling are considered the synapse in passant, since since the neurotransmitters can be released along the length of an axon instead of only at the terminal portion.
Adrenergic stimulation - by epinephrine in the blood and by norepinephrine released from sympathetic nerve ending - has both [] and [] effects?
Excitatory and inhibitory - depending on the organ and the receptor proteins.
What are the 4 “known” adrenergic receptor proteins?
Alpha 1
Alpha 2
Beta 1
Beta 2
How do all subtypes of the Beta adrenergic receptors produce their effects?
Stimulate the production of cAMP within the target cell.
The most medically important alphat 2-adrenergic receptor is found where, and what stimualtes it to lower blood pressure by activation of sympathoadrenal system?
Found in the brain
Stimulate by the drug - clonidine
Vasoconstricter effect of sympathetic nerves always results from the acitvation of [] [] receptors
Alpha-adrenergic receptors
The effect of beta-adrenergic activation is more diverse…what are some effects?
relaxation of smooth muscles (in digestive tract, bronchioles, and uterus)
Increase force of contraction of cardiac muscle and icreased cardiac rate.
The alpha-adrenergic receptors are more sensitive to…[] ?
norepinephrine
The beta-adrenergic receptors are more sensitive to… [] ?
epinephrine relesed from adrenal medulla into blood
What can happen if you stimulate an alpha 1 -adrenergic receptor?
vasoconstriction in viscera and skin
What can happen if you stimulate a Beta 1 - adrenergic receptor?
Increased heart rate and contractility
What can happen if you stimulate a Beta 2 - adrenergic receptor?
dilation of bronchioles and blood vessels.
What do the following use as their neurotransmitter?
- somatic motor neurons
- All preganglionic neurons
- most postganglionic parasympathtetic neurons
Acetlycholine - they are cholinergic
The effects of parasympathetic innervation are [] to the effects of sympathetic innervation
opposite
Nme three places you can find nicotinic cholinergic receptors?
- CNS
- Neuromuscular junction of skeletal muscle
- Autonomic ganglia
These receptors are stimulated by ACh releseased by postganglionic parasympathetic axons to produce a parasympathetic effect.
Muscarinic Receptors
- This drug blocks the nicotinic ACh receptors
- This drug blocks the muscarinic ACh receptors
Curare
Atropine
Why are nicotinic receptors always excitatory?
- They always open a Na/K cotransport channel. The sodium gradient is steeper so the net charge is a (+) going inside the cell = depolarization
Which organs do Muscarainic cholinergic receptors produce parasympathetic nerve effects in?
Heart
Smooth Muscle
Glands
What “neurotransmitter” - adrenergic or cholinergic - causes the penis to erect?
- It does not invovle cholinergic or adrenergic receptors because it is caused by NO , Nitric Oxide. It causes smooth muscle of the dick to relax and cause dilation of blood vessels = erection!
What is the best example for antagonist dual intervention using the autonomic system?
- Pacemaker cells in the heart
- The adrenergic stimulation from sympathetic fibers increases heart rate
- The cholinergic stimulation from parasympathetic fibers decreases heart rate
The effects of sympathetic and parasympathetic stimulation on salivary gland secretion are []?
complementary
How is the salivary gland activity controlled by complementary innervation?
- parasympathetic innervation stimulates a watery saliva
- Sympathetic stimulation constricts blood vessesl thoughout the digestive trac
This leads to a decrease in blood flow to the salivary glands and causes the production of a thicker, more viscous saliva.
What are the 5 organs that do not receive dual innervation from ANS - only receive sympathetic stimulation?
- Blood Vessels
- Sweat Glands in skin
- Adrenal Medulla
- Arrector pili muscles in skin
- Salivary Glands
This receptor inhibits adenylcyclase to decrease [] levels. This receptor is really only found in 1 place and produces [] inhibition
cAMP
Presynaptic Inhibition
T/F - the sweat glands respond to adrenergic stimulation?
False - they respond to cholinergic stimulation
A Fall in cyclic AMP within the target cell occurs when norepinephrine binds to which of adrenergic receptor?
Alpha 2
