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What are the two divisions of the peripheral nervous system?
Somatic and autonomic
What are the two divisions of the autonomic nervous system?
Sympathetic and parasympathetic
Which nervous system controls voluntary muscles and is based on external stimuli?
Somatic nervous system
Which nervous system controls visceral bodily functions and is based on internal stimuli?
Autonomic nervous system
Which nervous system is known as the fight or flight system?
Sympathetic nervous system
Which nervous system is known as the rest and digest system?
Parasympathetic nervous system
Describe myelination in the pre and post ganglionic nerves in both divisions of the autonomic system
Preganglionic fibers are myelinated while postganglionic fibers are unmyelinated in both
Describe the length of pre and post ganglionic fibers in the sympathetic division
Pre - short
Post - long
Describe the length of pre and post ganglionic fibers in the parasympathetic division
Pre - long
Post - short
T/F Both symp and parasymp divisions release ach from the preganglionic fiber into nicotinic receptors
True
What is released from the postganglionic fibers in the sympathetic division?
Norepinephrine
What is released from the postganglionic fibers in the parasympathetic division?
Ach
What is released when ach is released into the adrenal medulla, and where?
Norepinephrine and epinephrine into the blood vessels
What kind of neuron is the preganglionic neuron in the sympathetic pathway? Parasympathetic pathway?
Both are cholinergic (releases ach)
What kind of receptor is the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?
Both are nicotinic receptors
What kind of neuron is the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?
Sympathetic - adrenergic neuron
Parasympathetic - cholinergic neuron
What is released by the postganglionic neuron in the sympathetic pathway? Parasympathetic pathway?
Sympathetic - norepinephrine
Parasympathetic - ach
What kind of receptor is in the target tissue in the sympathetic pathway? Parasympathetic pathway?
Sympathetic - adrenergic receptor
Parasympathetic - cholinergic receptor (muscarinic)
What is divergence?
When there are more postganglionic fibers than preganglionic fibers or when there is one stimuli and many responses
T/F Tracks in the CNS are the same as nerves in the PNS
True
What are afferent nerves? Efferent nerves?
Afferent nerves - conduct signals from sensory neurons to the CNS
Efferent nerves - conduct signals from CNS to motor neurons
What is a cluster of soma and dendritic structures bundled and connected together?
A ganglia
Name the sections of the spinal cord (31)
Cervical (8)
Thoracic (12)
Lumbar (5)
Sacral (5)
Coccygeal (1)
What does posterior or dorsal mean?
Towards the back
What does anterior or ventral mean?
Towards the front
Where are the cell bodies of each preganglionic neuron going to be located?
In the intermediolateral horn of the grey matter
What is another name for the sympathetic division and why?
Thoracolumbar division, connections are made in the thoracic and lumbar sections of the spinal cord
What is another name for the parasympathetic division and why?
Craniosacral division, connections are made in the cranial and sacral sections of the spinal cord
What are ganglia located close to in the sympathetic division?
Spinal cord
What are ganglia located close to in the parasympathetic division?
Target organs (aka intraneural ganglia)
What cranial nerves are a part of the parasympathetic division?
Cranial nerves 3, 7, 9, and 10
What are the three locations for ganglionic neurons of the sympathetic division?
Sympathetic chain ganglia
Collateral ganglia
Adrenal medulla
What is another name for the sympathetic chain ganglia and where are they located?
Paravertebral ganglia
Located very close to the spinal cord, on both sides
What does the sympathetic chain ganglia innervate?
The head and limbs
What is another name for the collateral ganglia and where are they located?
Prevertebral ganglia
Located close to spinal cord, more anterior
What does the collateral ganglia innervate?
Mostly abdominopelvic tissues and organs
What is another name for the adrenal medulla and where are they located?
Suprarenal medulla
Located near kidney
What is special about the preganglionic fibers that go to the adrenal medulla?
They bypass the intermediolateral horn in spinal cord and ganglia and go straight for the adrenal medulla
The postganglionic fibers from the adrenal medulla are short or long?
Very short
What is the effect of adrenal medulla receiving stimuli?
NE and E are released into bloodstream and act as hormones
Why are NE and E described to be acting as hormones?
Because they enter the bloodstream and affect target cells throughout the body
Preganglionic fibers travel through what structure after the intermediolateral horn to get to the ganglion?
The ventral root
Which cranial nerve accounts for ~80% of parasympathetic nerve cell connections?
Cranial nerve x (vagus)
What are the sacral connections of the parasympathetic division mainly for?
Sexual reflexes and bladder
Cholinergic fibers secrete what?
Ach
Adrenergic fibers secrete what?
NE
Which ganglionic neurons would be excited by Ach or Ach-like drugs?
Both symp. and parasymp. postganglionic neurons bc those are the parts that have receptors
Almost all of the postganglionic neurons of the parasym. system are cholinergic except in the?
Genitals (they secrete nitric oxide)
Why are sweat glands an exception?
Because they are controlled by sympathetic division but have the anatomy of parasympathetic division
Pregang = ach nicotinic receptors
Postgang = ach muscarinic receptors
Most of the postganglionic neurons of the parasym. system are? Sympathetic system? What is the exception?
Para = cholinergic
Symp = adrenergic
Exception - sweat glands
How do ach and NE from postganglionic nerve ending get secreted to the target organs?
By varicosities that synthesize and store NTs
How are varicosities able to synthesize and store so much NTs?
Because they have a lot of mitochondria that make a lot of ATP
Describe the process of NT release starting from stimulation.
Stimuli
Membrane depolarization
Calcium enters
Varicosities empty NTs
NTs react with receptors
NTs get reabsorbed or degraded
Are most NTs reabsorbed or degraded?
Reabsorbed to varicosities (50-80%)
How are NTs degraded?
By MAO or COMT enzymes
Why do NTs that are released in the blood last longer, and which NTs would this be?
NE and E, and because the breakdown enzymes have to follow them to the target to break them down
Answer for cholinergic neurons
NT released: _______
Synthesized from: ___________
Duration of action: ____________
Removed by: _________
NT released: Acetylcholine
Synthesized from: Acetyl CoA + Choline
Duration of action: Few seconds
Removed by: Acetylcholinesterase degradation into Acetate + Choline
Answer for adrenergic neurons
NT released: _______
Synthesized from: ___________
Duration of action: ____________
Removed by: _________
NT released: Norepinephrine
Synthesized from: Dopamine
Duration of action: Few seconds - 1 min
Removed by: Neuronal uptake, diffusion into blood to tissue, or degradation by MAO and COMT
What amino acid is NE derived from, and what enzyme converts dopamine to NE?
Tyrosine
Dopamine beta-hydroxylase
What enzyme converts NE to E, and where does this happen?
PNMT (Phenylethanolamine-N-methyltransferase), in the adrenal medulla
What is a plexus?
Interconnected ganglia; a branching network of nerves or vessels
What is the name, type, and function for cranial nerve III?
Name: Oculomotor
Type: Motor
Function: Moves exterior eye muscles
What is the name, type, and function for cranial nerve VII?
Name: Facial
Type: Mixed sensory and motor
Function: Facial muscles, taste, saliva secretion
What is the name, type, and function for cranial nerve IX?
Name: Glossopharyngeal
Type: Mixed sensory and motor
Function: Taste, gag reflex, swallowing, salivation
What is the name, type, and function for cranial nerve X?
Name: Vagus
Type: Mixed sensory and motor
Function: Swallowing, outer ear sensation, cardiac activity
What kind of receptors are ion channels?
Ionotropic receptors
What kind of receptors are GPCR?
Metabotropic receptors
Describe the process of ionotropic receptors
NT binds to binding site
Conformational change happens
Ions come through
Describe the process of metabotropic receptors
NT stim receptor
G-protein activates
Adenylate cyclase is activated with ATP to form cAMP (2nd messenger)
Enzymes that change cell metab are activated
Acetylcholine receptors are also called?
Cholinergic receptors
What are the types of cholinergic receptors? How are they different?
Muscarinic (M) is activated by muscarin and Nicotinic (N) is activated by nicotine
What kind of receptors are muscarinic receptors? And where are they found and stimulated by?
Metabotropic receptors
Found in all effector cells and stimulated by postganglionic neurons in either symp or parasymp (except sweat glands)
What kind of receptors are nicotinic receptors? And where are they found and stimulated by?
Ionotropic receptors
Found in autonomic ganglia at synapses of both symp and parasymp
What does M1 receptor innervate?
Neural, CNS, gastric mucosa
What does M2 receptor innervate?
Cardiac, inhibitory action on heart
What does M3 receptor innervate?
Glands and smooth muscles, secretions
What does M4 and M5 receptors innervate?
Unknown
What is N1 or Nm receptors and where is it found?
Muscle type receptors and found in motor end plate of neuromuscular junctions
What is N2 or Nn receptors?
Ganglion type
What are receptors for NE and E called? What kind of receptors are they?
Adrenoreceptors or adrenoceptors
GPCR metabotropic receptors but act thru different G-proteins
What is the most common metabotropic receptor, and what does it innervate?
Alpha-1, excites smooth muscle
What does alpha-2 metabotropic receptor innervate?
Inhibits GI
What does beta-1 metabotropic receptor innervate?
Stimulates heart (ex. heart rate)
What does beta-2 metabotropic receptor innervate?
Inhibits smooth muscle, causes smooth muscle relaxation
What does beta-3 metabotropic receptor innervate?
Lipolysis in adipocytes
Which NT affects both alpha and beta metabotropic receptors? Which NT affects one type more, and which one?
Epinephrine affects both
Norepinephrine affects alpha receptors more
What receptors are targeted by asthma medications, and why?
Beta-2 receptors to dilate the lung bronchi
Stimulation of which adrenoreceptor causes the following?
Smooth muscle contraction
GI smooth muscle relaxation
Pupil dilation
Saliva secretion
Pilomotor hair erection
Bladder sphincter contraction
Worsened asthma symptoms
Alpha-1 receptors
Stimulation of which adrenoreceptor causes the following?
Inhibition of NT release in presynaptic terminals
Inhibition of lipolysis in adipocytes
Alpha-2 receptors
Stimulation of which adrenoreceptor causes the following?
Increased heart rate and force of contraction
Beta-1 receptors
Stimulation of which adrenoreceptor causes the following?
Inhibition/relaxation of vascular smooth muscle
Inhibition/relaxation of bronchial smooth muscle
Glycogenolysis in liver and skeletal muscle
Beta-2 receptors
Stimulation of which adrenoreceptor causes the following?
Lipolysis stimulation in adipocytes
Beta-3 receptors
What is dual innervation?
When an organ is innervated by both the sympathetic and parasympathetic division
Describe the dual innervation opposing effects in the…
Digestive tract
Heart
Lungs
Eye
Digestive tract - inhibited (symp), stimulated (para)
Heart - stimulated (symp), slowed (para)
Lungs - stimulated (symp), slowed (para)
Eye - dilated pupil/contracted eye muscle (symp), constricted pupil/dilated eye muscle (para)
What is the complementary effect of dual innervation in the glands?
Both increase secretion, but symp increases mucus (dry mouth) while parasymp increases saliva (digestion)
What is the complementary effect of dual innervation in the reproductive system?
Erection (point) - parasymp
Ejaculation (shoot) - symp
What is autonomic tone and what is it caused by?
Normal basal rate activity of an organ caused by basal NT secretion
Which type of tone
maintains smooth muscle tone in intestines
holds resting heart rate
stimulates digestive function
stimulates urinary function
Parasympathetic tone
Which type of tone
keeps most blood vessels partially constricted
maintains bp
excites heart
inhibits digestive function
inhibits urinary function
Sympathetic tone
What is denervation and its effect on its organ?
Cutting a nerve, organ loses its autonomic tone