Flashcards in Week 3 CNS regulation of the Autonomic Nervous System Deck (10)
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
1. neural and hormonal signals to pituitary gland-modulate endocrine function
2. neural signals to ANS to coordinate parasymp and symp nervous system
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
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
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)
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
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)
What results from isolated unilateral parasympathetic lesions of the CN IX ?
little effect because of bilateral distribution from nerve to target
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
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