13. Autonomic nervous system Flashcards
General points
- Role
- Purely ____
- What is the master regulator?
- Maintains the internal environment
- Purely motor
- Hypothalamus
General points
Name the CNS higher centers of the ANS
- Hippocampus
- Neocortex
- Hypothalamus
- Medullary & pontine reticular formation
- Reticulospinal tracts
What is the master regulator of the ANS
Hypothalamus
* Connected to adenohypophysis via portal circulation
* Connected to neurohypophysis via neurons
* Continues caudally as the midbrain and brainstem reticular formation
Name functions of the hypothalamus
- Bladder control
- Vasopressins (ADH) and oxytocin production
- Temperature regulation
- Hunger
- Thirst
- Aggression
- Sexual function
- Sleep regulation
Reticulospinal tracts
* Ventral vs lateral?
- Lateral horn (sympathetic);
- Ventral horn (parasympathetic)
- Many collaterals (bilateral effects)
Describe the 2 neurons of the ANS
Slide 7
- Pre-ganglionic: CB in gray matter, myelinated
- Post-ganglioninc: CB in ganglion outside of CNS, UNmyelinated
Sympathetic: short pre-ganglionic.
Pre = ACh, Post = EPI (a/b adrenergic receptors)
Parasympathetic: long pre-ganglionic, ganglia close to effector organ
Pre/post = ACh (n/mAChRs)
What are ‘boutons en passage’?
Slide 8
Bead-like swellings at the terminal portion of post-ganglionic axons; near the surface of effector cells
Name and locate the pre-ganglionic nuclei of the ANS
- pS nuclei of III, VII, IX, X
- Intermediolateral nucleus (T1-L3) S
- Sacral pS nucleus (S2-S3)
What/where is the pre-ganglionic sympathetic nucleus?
T1-L3; intermediolateral nucleus
Pre-ganglioninic (ACh) = short; Post-ganglionic (EPI) = long
What/where are the preganglionic parasympathetic nuclei?
- Brainstem pS nuclei III, VII, IX, X
- Parasympathetic sacral nucleus (S2-3)
Pre ganglionic (ACh) = long; post-ganglioninc (ACh) = short
The initial pathway for all sympathetic pre-ganglionic axons is the same. Describe it.
Slide 11
CB in intermediolateral nucleus (T1-L3) -> ventral nerve root -> communicans ramus -> sympathetic trunk gangion or other travel to other site -> post-ganglionic fibers then travel along blood vessels
What are the 3 sympathetic ganglia
Sympathetic trunk
Terminal ganglia
Collateral ganglia
The sympathetic chain ganglia is paired, runs along ventrolateral surface of the vertebral column, and continues rostrally as the…
Cervicothoracic vertebral system
Middle cervical ganglion
Cervicothoracic ganglion
Cranial cervical ganglion
Role of ALPHA adrenergic receptor (a1, a2)
- Vasoconstriction - increasing BP
- Internal urethral sphincter contration
- GIT sphincter contraction
- Pupil dilation
BETA adrenergic receptor (B1, B2)- foun where? role?
- Effector organs of post-ganglionic S fibers
- Increased HR and contraction force
- GIT smooth muscle relaxation
- Detrusor relaxation
- Bronchiolar smooth muscle relaxation
nAChRs - found where? blocked by what?
- Neuromuscular synapses
- All autonomic ganglia (pS and S)
- Ion channels (K, Na)
- Blocker by anti-cholinergic (Atropine)
mAChRs - Found where? role?
- Effector organs of post-ganglionic paraS fibers
- GPCRs
- Variable fct (lower HR and BP, increase GI motility, detrusor contraction)
Sympathetic innervation of the eye (steps)
- Hypothalamus - N1
- Lateral tectosegmental spinal tract (lateral funiculus)
- Intermediolateral nucleus (T1-3, lateral grey column) - N2
- Ventral nerve root - spinal nerve - communicans ramus
- Sympathetic trunk
- Cranial cervical ganglion - N3
- Post-ganglionic fibers travel with internal carotid artery, reaches middle ear, travels with ophthalmic branch of CNVi, entering orbital fissure, then ciliary branch of ophthalmic nerve
- Pupillary dilator muscle + smooth muscles of the orbit
Pharmacological testing of Horner syndrome
* Pre-ganglionic lx
* Post-ganglionic lx
* Central lx
- Pre: PHENYLEPHRINE (a1 agonsit) - rapid mydriasis due to denervation hypersensitivity
- Post: HYDROXYAMPHETAMINE (causes NE release)
- Central: COCAINE
Consequences of Horner syndrome
- Miosis
- Ptosis
- 3rd eyelid protrusion
- Enophthalmos (due to orbital smooth muscle relaxation)
- Bulbar conjunctival hyperemia
- Retinal blood vessels congestion
- Warm and pink skin (vasodilation)
- Hypo or anhidriosis
- Sweating (horses)
- Decreased eyelash angle (horses) - dernevation of arrector pilorum
Bladder ctl - parasympathetic pathway
- pS sacral nucleus (S2-3)
- Pelvic nerve (pre-ganglionic neurons)
- Pelvic ganglion
- Detrusor muscle (mAChR) = detrusor contraction
Bladder ctl - sympathetic pathway
- L1-L4 of the Intermediolateral nucleus
- Sympathetic trunk - splanchnic nerves (pre-ganglionic)
- Caudal mesenteric ganglion
- Hypogastric nerve (post-ganglionic)
- Internal smooth muscle urethral sphincter = contraction (a-adrenergic)
- Detrusor = inhibition of contraction (B adrenergic)
Bladder ctl - somatic pathway
- S1-S3
- Pudendal nerve
- nAChRs on striated urethral shincter = contraction
Bladder ctl - sensory pathway
- Bladder distension
- Mechanoreceptors (bladder wall and urethra)
- Pelvic nerve (S2-3)
- DRG - dorsal grey column - white matter
- Pontine micturition center
Which SC tract is responsible of UMN bladder ctl
Corticospinal tract
