The Hypothalamus A crucial part of the CNS that takes some part in regulating mo

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The Hypothalamus A crucial part of the CNS that takes some part in regulating mo

Zolondz, Julie, Features Editor has reference to this Academic Journal, PHwiki organized this Journal The Hypothalamus A crucial part of the CNS that takes some part in regulating most organs 3 major functions (we will review 2 today). Regulating release of hormones from pituitary gl in addition to . Regulating the ANS; i.e., general visceral motor functions we reviewed last time. Regulating the “appetitive behaviours” (eating, drinking, mating). The 3 functional zones of the hypothalamus in addition to the nuclei contained therein. Regulation of Pituitary: Parvocellular (anterior) ad magnocellular (posterior) neurosecretory systems. Overview of ANS functional anatomy (sympathetic, parasympathetic systems). Regulation of autonomic functions by descending projections from the hypothalamus. Regional anatomy. A. Anterior-posterior sections of hypothalamus in addition to review key nuclei. B. Descending pathway in addition to sc nuclei. C. Clinical Note: Horner’s Syndrome.

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I. 3 Functional Zones General location of hypothalamus: – ventral to thalamus – just over optic chiasm in addition to pituitary stalk (infundibulum). – divided in half by 3rd ventricle Hypothalamic Nuclei

Hypothalamus (Fig. 15-1, 2) Periventricular zone – a thin nuclei bordering the 3rd ventricle. – regulates release of endocrine hormones from anterior pituitary gl in addition to (See Table 15-1). -uses neurosecretion as a portal vein system, rather than a neurotransmitter across a synapse. Middle zone – regulates hormone release from posterior pituitary. – regulates ANS. Lateral zone – integration in addition to transmission of info from limbic system structures (important in emotional regulation – will view next lecture (limbic system). 3 Functional hypothalamic zones (Fig. 15-14) – Mediolateral zones

Hypothalamic peptides as long as anterior pituitary (Table 15-1) II. Regulation of Pituitary: Parvocellular in addition to Magnocellular Neurosecretory Systems Parvocellular system in addition to the anterior pit. – Small-diameter neurons in several hypothalamic nuclei (of periventricular zone) – most medial – regulate anterior pituitary hormone release by neurovascular rather than synaptic transmission. Parvocellular System (Fig. 15-4A) Note the various nuclei

Neurosecretion in addition to Portal Vein System (Fig. 15-5): Note the path: Parvocellular neurosecretory cells anterior lobe via portal vein. Chemicals released are peptides, which either promote or inhibit the release of hormones from anterior lobe secretory cells (Table 15-1). Magnocellular system in addition to the posterior pituitary. – Here, peptide hormones are produced by large-diameter hypothalamic neurons from same nuclei of the middle zone. – Axons deliver these hormones down the infundibular stalk in addition to terminate on fenestral capillaries (“leaky”) of the posterior pit – this is 1 place lacking a BBB. Magnocellular System (Fig. 15-4B) Note the paraventricular in addition to supraoptic nuclei Hormones: Vasopressin (ADH) – peptide which incr bp by its effects on vascular smooth muscle as well as by promoting H2O reabsorption from DCTs of kidneys to decr urine vol. Oxytocin – incr uterine contraction in addition to milk ejection from mammary gl in addition to s.

III. Overview of Autonomic Nervous System Sympathetic in addition to Parasympathetic systems – Fig. 15-7. Clearly distinct anatomical locations of preganglionic (central) neurons. Sympathetic: T1 L3 Parasympathetic: brainstem nuclei (reviewed last time): S2 S4 (sacral spinal cord). Also different locations of post-ganglionic neurons. Fig. 15-7 – The ANS Sympathetic: peripheral ganglia located relatively close to the spinal cord (sympathetic trunk). Parasympathetic: peripheral ganglia located close to target organs (i.e., terminal ganglia of X). Note: organs distal to splenic flexure of colon served by sacral parasympathetic nuclei. For both systems, anatomical location of central neurons is analogous.

Sympathetic: intermediate zone of spinal cord (intermediolateral cell column) – Fig. 15-9. Parasympathetic: the 4 spinal cord nuclei reviewed last time (general visceral motor column): III, VII, IX, X in addition to in sacral sc intermediate zone. IV. Descending Projections from the Hypothalamus Regulate Autonomic Functions See Fig. 15-9 Descending pathways controlling autonomic nervous system (Fig. 15-9): From middle functional Zone: parasympathetic n. (using ADH in addition to oxytocin) + several other areas bs parasym n. (dorsal motor n. of X) + preganglionic neurons (both sym in addition to parasym) of sc.

Fig. 15-8. Note: Mechanism of regulation Is very analogous to the way the Cortex regulates descending Motor pathways in addition to motor Neurons. 1 Difference: Visceromotor Regulation involves the 2-neuron Circuit (pre- in addition to postganglionic) Some bs n. also contribute to autonomic system regulation: Solitary n intermediolateral n. (also known as long as chemosensory mechs) – a tie between viscero- sensory in addition to visceromotor. Ventral lateral medulla – adrenergic descending projections regulating bp. Postmedullary reticular as long as mation – complex “reflex” response involving both visceral in addition to somatic changes; e.g., startle incr bp. Raphe nuclei – projections from hypothalamus uses serotonin to spinal autonomous nuclei. V. Regional Anatomy Sections through the hypothalamus – Schematic of major nuclei – Fig. 15-3. Anterior hypothalamic section, showing preoptic region – Fig. 15-10.

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Fig. 15-3 – Major nuclei Anterior hypothalamus – Fig. 15-10 Note the preoptic region Paraventricular Nucleus – Fig. 15-11 This nucleus contributes to all 3 functions we have discussed: 1. Parvocellular division anterior pituitary 2. Magnocellular division posterior pituitary 3. Autonomic division descending paths

Posterior Hypothalamus Fig. 15-17. Section reveals mammillary bodies. These, along with Lateral zone noted earlier, play important role in behavioural Regulation in addition to the limbic system. Mid-medullary Section B. Descending Pathways in addition to Spinal Cord Nuclei Descending fibres In dorsolateral tegmentum. DLF also contains ascending in addition to descending fibres to hypothalamus. Adrenergic cell group in VL medulla – analogous to intermedio- lateral location in sc. Intermediolateral sympathetic (preganglionic) nucleus in thoracic sc. Parasympathetic preganglionic nucleus in intermediate zone of sacral sc.

Spinal cord nuclei in addition to paths: Fig. 15-21 C. Clinical Note: Horner’s Syndrome – damage to dorsaolateral pons/medulla or any part of descending autonomic control system disturbance of sympathetic functions: e.g., PICA occlusion. Pupillary constriction on same side. Partial drooping of eyelid. Decr secretory, incr warmth in addition to redness on same side of face. Decr sympathetic function in addition to unopposed parasympathetic function.

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