Autonomic Nervous System Flashcards
Responsible for ensuring homeostasis, respond to internal and external stimuli to ensure a stable environment
Autonomic nervous system
Two neuron chain in the ANS
Pre synaptic and post synaptic
Where does parasympathetic neurons synapse
Close to organ
Where do sympathetic synaps
In chain
What does ANS control
Everything except skeletal muscles
Two divisions of ANS
Sympathetic and parasympathetic
What division is the sympathetic nervous system
Thoracocolumbar
-presynaptic fibers leave spine at the level of the thoracic vertebrae and upper lumbar
Where do symp nervous systme synapse
In the paravertebral chain
Length of pre synaptic in sympathetic
Short
What does the sympathetic nervous system innervate
Wall of organs, glands, and smooth muscles
Which division is fight or flight
Sympathetic nervous system
What is the sympathetic nervous system mediated through
Mostly epi and norepi release on target organs
What is the crnaiosacral division of the ANS
Parasympathetic nervous system
Where do pre synaptic fibers leave parasympathetic
At the level of cranial nerves and sacrum
What ar the parasympathetic CN
3,7,9,10
Where do parasympathetic synapse
In or near target organ
Length of parasympathetic pre synaptic
Long
What does parasympathetic innervate
Walls of organs glands and smooth muscles
What kind od effect does parasympathetic have
Discrete
What is rest anddigest
Parasympathetic
What is parasympathetic mediated through
Ach release on target organs
What kind of effect is sympathetic
Diffuse
What does not have dual innervation of ANS?
Sweat glands
Adrenal glands
Lacrimal glands
Parotid glands
Which glands are sympathetic
Sweat glands and adrenal glands
Which glands are parasympathetic
Lacrimal glands and parotid glands
What does sympathetic increase?
- heart rate
- BP
- sphincter tone of bladder
What does sympathetic decrease
- motility
- relaxes lungs *bronchodilation)
- dilation of pupils
What does parasympathetic decrease
-HR
-BP
_bladder
What does parasympathetic increase
Bowel motility
Bronchoconstriction
Pupil constriction
A 52 year old woman present to the emergency department with recurrent episodes of chest and abdominal pain, dyspnea, palpitations and diaphoresis. On arrival she is asymptomatic. BP was 143/86 mmHg, pulse was 88bpm. Physical exam was normal. The patietns electrocardiograph and chest X-ray were both normal. Initial blood tests reveal nothing out of ordinary. Dysregulation of which nervous system division is most likely causing her symptoms?
Sympathetic
All presynaptic s are _____ in ANS everywhere
Ach
What is released during parasympathetic innervation and what is the receptor
- Ach
- muscarinic receptor
What is the sympathetic NT 99% of the time and what is the receptor
- epi or norepi
- a1 and B1 receptors
What kind of NT in post synaptic cleft of liver
Dopamine
Sympathetic
What is the NT for sweat glands and the receptor
- Ach
- muscarinic
Sympathetic, one of those occasions where it is not epi or norepi
What is different about the NT in the adrenal glands?
It dumps epi and norepi into the blood, this is an example of NT acting as a hormone
Sympathetic
Where is the nicotinic receptor in PNS
On post synapse
Where is the muscarinic receptor in PNS
On target organ
In the SNS, what is the presynaptic NT?
Ach
In the SNS what is the post synaptic NT
Norepinephrine
What are the NT for pre and post synaptic clefts in PNS
Ach for both
What is usually the NT in the post synaptic cleft?
Norepinephrine
What is the post synaptic NT for eccrine sweat glands (sympathetic)
Ach
What is the post synaptic NT for kidney (sympathetic)
Dopamine
What does the adrenal medulla function as
Post synaptic neuron
ANS ganglia form __________ where NTs are formed
Varicosities
Where are NTs stored
In large vesicles with other neuromodulators (ATP, VIP, etc)
Where is NT released onto smooth muscle
- autonomic control
- several places
A 52 year old woman present to the emergency department with recurrent episodes of chest and abdominal pain, dyspnea, palpitations and diaphoresis. On arrival she is asymptomatic. BP was 143/86 mmHg, pulse was 88bpm. Physical exam was normal. The patietns electrocardiograph and chest X-ray were both normal. Initial blood tests reveal nothing out of ordinary. You suspect she has pheochromocytoma. You order blood draw looking for neurotransmitter metabolism by products. You also order imaging to confirm diagnosis. Elevated levels of which metabolite would be expected?
Modified frullic acid
What is pheocytoma
Tumor in adrenal glands that secretes epi and norepi in blood when it wants
What kind of receptors are on the target organs in PNS
Muscarinic receptors
-M2 and M3
What is M2 (muscarinic in PNS) coupled to?
I (inhibitory)
What is M3 (muscarinic, PNS) coupled to
Q (calcium comes in, contractions iris)
What type of receptors are usually on target organs in SNS
Adrenergic
a1, a2, B1, B2
What happens when nicotinic receptors open
Na+ enters cell, cause excitatory response
What is the G subunit associated with a1
GQ
- calcium
- vasc smooth muscle
What G subunit is associated with a2
GI
- presynaptic inhibitor
- stop release of NT
Where are B1
Heart
Where are B2 receptors
Lungs
What G subunit is associated with B2 adrenergic receptors
Gs
CAMP
Usually regulate release of epi and norepi and modulates sympathetic response via negative feedback
Alpha 2 adrenergic receptor
Mechanism of alpha 2 adrenergic receptor
Regulate cAMP, flow of Ca2+ in cell
Maximal effect of ANS
Requires full stimulation by one and a full stop of stimulation by other
In most organs resting tone from _________ predominates
PNS
Heart will beat faster if vagus N is cut
What are some organs that have only SNS innervation
- sweat glands
- most vascular smooth muscle
- liver
- adipose
- kidney
What is an example of dual innervation of ANS
Pupillary light reflex is controlled by the ANS
Also accommodation
Bladder filling and emptying
What is the dilator muscle of the iris controlled by
SNS
What is the constrictor muscle of the iris innervated by
PNS
Too much light strikes retina, _____ activates
PNS
If not enough light strikes the retina, _____ activates
SNS
A 52 year old woman present to the emergency department with recurrent episodes of chest and abdominal pain, dyspnea, palpitations and diaphoresis. On arrival she is asymptomatic. BP was 143/86 mmHg, pulse was 88bpm. Physical exam was normal. The patietns electrocardiograph and chest X-ray were both normal. Initial blood tests reveal nothing out of ordinary. Which nervous system division is most likely trying to correct the changes caused by her condition
Parasympathetic
What is generally activated as an entire system
Sympathetic
What does sympathetic system increase
HR BP BG Airway and pupil diameter Sweating
What does sympathetic decrease
Blood flow to gut
Absorption and secretions
SNS increases total what
Body energy production
What ANS system is activated on specific organs, targeted effect
Parasympathetic because of short post synaptic
What does PNS increase
Blood flow to gut, absorption, and secretions
What does PNS decrease
HR
BP
Pupil diameter
What division of ANS is the body usually controlled under
PNS (tonic)
_________ sensory nerves carry information to appropriate region of brain stem or hypothalamus
Afferent
Responses are carried to target organs by the _______ on efferent nerves
Efferent ANS neurons
Can higher level input affect ANS?
Yes
Change in heart rate when thinking about block exam
Sense a drop in blood pressure
Baroreceptors
How do baroreceptors inform brain
Via afferent sensory nerves. Info processed in cardio center in medulla
Baroreceptors and PNS
Efferent response carried along vagus, reduce PNS tone on SA node, increased HR
SNS and baroreceptors
SNS efferent response carried along thoracic nerves
- increase SNS tone on heart, increased HR and force
- increase adrenal release, increase HR and force
Baroreceptors as a balancing act
PNS and SNS both act on heart to increase heart race no force to normalize blood pressure
A 52 year old woman present to the emergency department with recurrent episodes of chest and abdominal pain, dyspnea, palpitations and diaphoresis. On arrival she is asymptomatic. BP was 143/86 mmHg, pulse was 88bpm. Physical exam was normal. The patietns electrocardiograph and chest X-ray were both normal. Initial blood tests reveal nothing out of ordinary.
Diagnosis is pheocromocytoma, a NE producing tumor in adrenal glands. Uses blood draw or urine analysis for metabolites of adrenergic
What drug could you use?
SNS blocker (a1, a2. B1, B2)
