Chapter 15

Chapter 15 - Chapter 15 Secretory Hypothalamus o...

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Chapter 15 Secretory Hypothalamus o Homeostasis o Overview Periventricular Lie right next to wall of third ventricle Complex mix of neurons of different functions o One group constitutes the suprachiasmatic nucleus and lies just above the optic chiasm Receive direct retinal innervation and function to synchronize circadian rhythms with the daily light-dark cycle o Other cells control the ANS, regulat outflow of sympathetic and parasympathetic innervation of the visceral orgran o Neurosecretory neurons Extend axons down toward the stalk of the pituitaru gland Pituitary Hypothalamic control of the posterior pituitary o Largest cells are magnocellulaar neurosecretory cells Extends axons around the optic chiasm Substances released into blood by neurons are neurohormones Magnocellular neurosecretory cells release two neurohormones: oxytocin and vasopressin Oxytocin causes uterus to contract and stimulates ejection of milk from mammary glands o Release may be stimulated by the somatic sensations generated by a suckling baby Vasopressin (Antidiuretic hormone adh) regulates blood volume and salt concentration o Acts directly on the kidneys and leads to water retention and reduced urine production Hypothalamic control of the anterior pituitary o Actual gland o Cells of the anterior lobe synthesize and secrete a wide range of hormones that regulate secretions from other glands throughout the body
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o Anterior lobe is under control of neurons in the periventricular area called parvocellular neurosecretory cells These neurons secrete hypophysiotropic hormones into uniquely specialized capillary bed at the floor of the third ventricle o Regulation of adrenal glands consist of two parts, shell called adrenal cortex and a center called the adrenal medulla Adrenal cortex produces the steroid hormone cortisol Cortisol acts to mobilize energy
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Chapter 15 - Chapter 15 Secretory Hypothalamus o...

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