ANS and Hypothalamus Flashcards
function of the ANS
the 2 efferent divisions
maintains homeostasis
(regulate digestive/urinary systems, visceral fx)
involuntary
Sympathetic (SNS) – “fight or flight”
Parasympathetic (PNS) – “rest and digest”
what are the three afferents that stimulate ANS responses
- General sensations – such as pain, temp., and touch
- Special senses – such as vision or hearing
- Visceral afferents – sensation from organs communicated via solitary nucleus tract and visceral afferent nucleus in SC
which type of muscle receives NO innervation from the ANS
Skeletal muscle receives no direct innervation from the ANS
The ANS does innervate smooth muscle, cardiac muscle, glands, and organs
preganglionic and postganglionic neurons for SNS
Preganglionic – lateral horn of T1 to L2/L3
Postganglionic:
- could send signal to sympathetic chains (release Ach)
- signal to specialized postganglionic neurons (closer to target organs also release Ach)
* ** if an axon makes it all the way to the target organ, it will release NOREPINEPHRINE
preganglionic and postganglionic neurons for PNS
Preganglionic – CN nuclei 3, 7, 9, 10 and lateral horn of S2-S4
Postganglionic - close to target organs, release Ach along the way
which system uses only ACH as the neurotransmitter and which also uses epinephrine and norepinephrine
Parasympathetic – uses only ACH
Sympathetic – uses ACH, epinephrine, and norepinephrine
what is unusual regarding the adrena medulla in the SNS
Only has one afferent Does not have two chains Releases epinephrine when stimulated This, in turn, causes the fight or flight cascading release of hormones (fight/flight in the kidney)
which three structures have only SNS and no PNS innervation
- Sweat glands
- Piloerector muscles
- Peripheral blood vessels in skin
CN nuclei containing PNS preganglionic neurons
Edinger Westphal nucleus - Located in the midbrain - Related to CN III Lacrimal and superior salivatory nuclei - Located in the pons - Related to CN VII Inferior salivatory nucleus - Located in the medulla - Related to CN IX Dorsal vagal nucleus - Located in the medulla - Related to CN X
what is referred pain and why do we get it
Pain felt at a site distant to the cause of pain
Has to do with visceral afferents
- caused by the convergence of somatosensory & visceral afferents on a single pain tract cell
what causes horner’s syndrome? what are the s/s
Cause: a lesion in the descending sympathetic innervation to the face
S/S:
- Pupillary constriction (myosis)
- Dry face (***no sweat), warm, and very red
- Ptosis
- PICA also affected (seen as part of lateral medullary/Wallenburg’s syndrome)
what causes autonomic dysreflexia? what are the s/s
Cause: lesion in upper thoracic or cervical spinal cord which interrupts asc pathways (SC and brain not communicating)
S/S:
- Severe hypertension
- **Sweating above the level of the lesion with flushing of the skin
- Pounding headache
- Blurred vision
- Nausea
- Bradycardia
- Pilomotor erections
Note: the above s/s may occur in unison or any combination, but may not all occur at once
what should a clinician do if they recognize autonomic dysreflexia
Remove stimulus if possible
Stop all activity
Place patient upright
Call 911
general organization of the hypothalamus
Regions of the hypothalamus are organized:
Anterior to posterior
Midline to lateral
nuclei/areas tied to the ANS
- anterior hypothalamus
Preoptic nuclei – thermoregulation
