Flashcards in Week 3 CNS regulation of the Autonomic Nervous System Deck (10)
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1
What is the primary function of the hypothalamus?
-Particularly the PVN (paraventricular nucleus) is the master controller of homeostasis
-receives input about temp, pressure, electrolytes, fluid, weight
-sends
1. neural and hormonal signals to pituitary gland-modulate endocrine function
2. neural signals to ANS to coordinate parasymp and symp nervous system
2
Describe the connections between the hypothalamus and ANS that allows it to control autonomic responses.
Efferent connections reciprocal to afferent ones
Hypothalamus to Brain Stem
1. medial forebrain bundle (MFB): in dorsolateral tegmentum
2. dorsal longitudinal fasciculus (DLF)
3. mamillotegmental tract (MTegT)
Hypothalamus to spinal cord-ill defined
4. hypothalamo-spinal tract: in lateral part of medulla and ends on lateral horn of symp/pre neurons
3
Describe the sympathetic medullary regulating center and how it controls cardiovascular function.
NTS=nucleus tractus solitarius
1. Neurons in NTS in medulla assess bp changes from baroreceptors fibers (via CN IX and X) and top down input from hypothalamus
-Increased input (high bp)-->inhibit activity in RVLM and decrease sympathetic tone to heart
-decreased input (low bp)-->reduce inhibition at RVLM and increase sympathetic tone
4
What are the medullary regulating centers for regulation of CV function?
1. NTS=nucleus tractus solitarius
2. DMV=dorsal motor nucleus of vagus
3. NA=nucleus ambiguus (IX, X)
5
Describe the parasympathetic medullary regulating center and how it controls cardiovascular function.
1. NTS projects to DMN and NA of CN X to modulate parasympathetic innervation to heart
-increased input (high bp)-->increase parasympathetic tone and decrease hr
-decreased input (low bp)-->decrease parasympathetic tone
6
What lesions can cause Horner's syndrome? (interruption of sympathetics)
1. peripheral lesions
-unilateral lesion to superior cervical ganglion
-preganglionic cell bodies in T1-T4
-postganglionic cell bodies in superior cervical ganglion -unilateral
2. Central lesions
-medulla (lateral medullary syndrome)- unilateral Horner's due to vascular lesion of PICA
-Cervical spinal cord injury (bilateral Horners)
7
What results from isolated unilateral parasympathetic lesions of the CN IX ?
little effect because of bilateral distribution from nerve to target
-also uncommon
8
What are the effects of lesions affecting the oculomotor nerve CNIII parasympathetics? (e.g. uncal herniation)
-mydriasis: dilated pupils
-loss of light reflex
-loss of accommodation
Lesion of somatomotor part of CNIII also causes
-"big" ptosis-loss of innervation to levator palpebrae superioris
9
What symptoms result from parasympathetic pathology from central lesion in pons or tumor at internal acoustic meatus affecting CN VII?
-dry eye/loss of tears
-dry mouth
10
