Lecture 6 Flashcards
What are the functions of the autonomic nervous system?
- Maintain homeostasis
- Respond to emergencies
What are the two divisions of the autonomic NS?
Parasympathetic (rest and digest)
Sympathetic (fight or flight)
What what type of motor neurons are part of the ANS?
INVOLUNTARY motor neurons
cardiac and smooth muscle
What type of sensory neurons are part of the ANS?
Viscerosensory
visceral afferent
Where do ANS preganglionic neurons stem from?
Lateral horn of the spinal cord
Where do pre and post-ganglionic neurons meet (synapse)?
In autonomic ganglion which are dorsal root ganglia (sympathetic ganglia and parasympathetic ganglia)
Are pre-ganglionic neurons myelinated?
YES
Are post-ganglionic neurons myelinated?
NO
What do sympathetic neurons innervate?
Nearly all body regions, if they do not directly innervate a structure, they can have an indirect effect on that organ by increasing or decreasing blood flow to it
Sympathetic neurons innervate smooth muscle in the walls of _____ and ______
arteries and veins
What is the overall effect of sympathetic neurons?
Generalized vasoconstriction
What are some specific effects of the sympathetic NS?
- Increased HR and contraction strength
- Increased diameter of bronchi and RR
- Increased BP
- Decreased digestive functions (peristalsis, enzyme secretion)
- Decreased renal function
- Pupillary dilation
- Sweating
Are parasympathetic neurons more or less specific than sympathetic?
More specific!!!
What do parasympathetic neurons NOT innervate?
Blood vessels
*Except vessels serving the genitals where they can produce vasodilation
What are some specific effects of the parasympathetic NS?
- Decreased HR and contraction strength
- Decreased diameter of bronchi and RR
- Increased digestive function
- Pupillary constriction and lens accommodation
Where on the spinal cord do sympathetic neurons come from?
- T1-T12
- L1-L2
- This is all continuous (thoracic and lumbar)
Where on the spinal cord do parasympathetic neurons come from?
- Brainstem
- S2-S4 (puedendal nerve)
What is an example of structure that has dual innervation and what does this mean?
Pupil of the eye
-Innervated by both parasympathetic and sympathetic nerves that act in opposition to one another
What is an example of a structure that is only innervated by sympathetic neurons?
Blood vessels
When vasoconstriction is needed sympathetic stimulation ______
Increases
When vasodilation is needed sympathetic stimulation _____
Decreases
Where are sympathetic ganglia (where pre and post ganglionic fibers meet and synapse) located?
- Sympathetic trunk
- Pre-aortic sympathetic ganglia
Where do sympathetic neurons that go to the head synapse and what do they follow to get there?
Cervical sympathetic trunk and they follow branches of the common carotid artery
What structures of the head are innervated by sympathetic nerves?
- Pupils (dilation)
- Walls of blood vessels (vasoconstriction)
- Salivary glands (inhibits saliva, dry mouth)
What ganglion supplies the head?
Superior cervical ganglion
How do sympathetic neurons innervate thoracic organs?
Sympathetic neurons contribute axons to two nerve plexuses that innervate thoracic organs:
- Cardiac plexus (heart)
- Pulmonary plexus (bronchiole smooth muscle)
How do sympathetic neurons innervate abdominal and pelvic organs?
They travel directly to the abdomen forming splanchnic nerves (greater, lesser, least) which then innervate blood vessels
What plexuses do splanchnic nerves form?
- Celiac plexus
- Superior mesenteric plexus
- Inferior mesenteric plexus
- Renal plexuses
What activates the release of epinephrine?
Sympathetic neurons activate the adrenal medulla to release epinephrine into the blood (this magnifies the effect of sympathetic stimulation)
Sympathetic fibers from the sympathetic trunk connect to all ________
Spinal nerves (C1-S5) ALL NERVES FROM SPINAL CORD
Sympathetic neurons travel with spinal nerves to innervate limbs and body wall structures….what are these actions
- Blood vessels to skin (vasoconstriction)
- Blood vessels to skeletal muscle (vasodilation)
- Sweat glands (sweating)
- Erector pili muscles (hair stands on end)
Every spinal nerve contains some _____ _______
Sympathetic fibers
Where are parasympathetic preganglionic neurons located?
Brain stem and S2-4
What four cranial nerves are parasympathetics part of?
3 - oculomotor
7 - facial
9 - glossopharyngeal
10 - vagus
Parasympathetics to the head are which cranial nerves?
3 - oculomotor = ciliary muscle, muscle of the lens
7 - facial = lacrimal gland, salivary glad
9 - glossopharyngeal = parotid gland
Parasympathetics to the thorax and abdomen are which cranial nerves?
10 - vagus = heart, bronchi, GI tract
What neurotransmitters do sympathetics use?
- Acetylocholine (Ach)
- Norepinephrine (NE)
What neurotransmitters do parasympathetics use?
ONLY acetylocholine
What neurotransmitters are andrenergic?
Norepinephrine (alpha and beta)
What neurotransmitters are cholergenic?
Acetylcholine
What are the 3 adrenergic receptors?
Alpha, Beta 1 and Beta 2
Where are alpha receptors located?
- Walls of arterioles (vasoconstriction)
- GI tract (decrease GI motility)
- Bladder (decreased urination)
Where are beta-1 receptors located?
- Kidney (increased renin secretion, causes increased BP)
- Heart (increases contractility, cardiac output)
Where are beta-2 receptors located?
- Bronchioles (dilate)
- Liver/pancreas (increase BG)
Where do central autonomic fibers begin?
Hypothalamus
What do central autonomic fibers connect?
The brain to the autonomic NS (regulates ANS)
Where are central autonomic fibers located?
White matter of the spinal cord
What happens in there is damage to the central autonomic fibers?
Lose connection between brain and ANS this is called Autonomic Dysreflexia
What can a person with autonomic dysreflexia not do?
- Sweat in response to heat
- Shiver in response to cold
- Regulate blood pressure in response to position
Where do viscerosensory neurons provide sensation from?
Internal organs
How do viscerosensory neurons connect to the brain?
Via spinal cord
Is the location of pain from viscerosensory neurons diffuse or precise?
Diffuse!! Vague!!
What else do viscerosensory neurons effect?
Connect to brainstem centers for responses like sweating or nausea (in response to pain)
What are the types of visceral afferent neurons?
- Baroreceptors
- Chemoreceptors
- Nocioceptors
Where are baroreceptors located?
- Detect stretch
- Carotid sinus
- Bladder wall
- GI tract
Where are chemoreceptors located?
- Detect chemicals (CO2, O2)
- Carotid body
- Medulla
Where are nociceptors located?
- Detect pain, inflammation, extreme stretching, ischemia
- Located everywhere except the brain
Connect to autonomic motor neurons which is =
Visceral reflex
What is autonomic neuropathy?
Damage to autonomic nerves (most often caused by diabetes)
