ENDOCRINOLOGY (hypothalamus)

ENDOCRINOLOGY (hypothalamus)

1. Hypothalamus

   • Posterior pituitary/ neurohypophysis
     • Axons sent from the hypothalamus to the posterior pituitary causing release of hormones to the bloodstream
     • Secretes two structurally similar peptide hormones
       • Oxytocin
         • Released due to mechanical stimulation at the nipple or nearing the end of pregnancy
         • Released from periventricular neurones
         • Expels foetus in labour (contraction) and sperm progression along the ductus deferens in males
         • Oxytocics mimic oxytocin and induce labour
       • Vasopressin (ADH)
         • Released due to an increase in solute concentration or fall in blood volume/pressure
           • Detected by osmoreceptors in the hypothalamus
           • Results in water retention at the kidneys and vasoconstriction to increase blood pressure
           • ADH deficiency causes diabetes insipidus
             • Can be central (secondary) or nephrogenic (primary)
             • Treated with vasopressin analogues (Desmopressin)
         • Released from supraoptic neurones
   • Anterior pituitary/ adenohypophysis
     • Secrets six peptide hormones In response to hypothalamic signals
       • Thyroid releasing hormone released from the hypothalamus in response to stress anfd cold temperature causes release of thyroid stimulating hormone from the anterior pituitary
         • See thyroid gland mindmap
       • Growth hormone releasing hormone is stimulated by stress, exercise and sleep and causes release of growth hormone from the anterior pituitary
         • See growth hormone mindmap
         • Growth hormone inhibiting hormone inhibits releaseof growth hormone
       • Prolectin releasing hormone released form hypothalamus causing the release of prolactin from the anterior pituitary
         • Prolactin inhibiting hormone inhibits release of prolactin
         • See gonad midmap
       • Corticotrophin releasing hormone from the hypothalamus stimulates adrenocorticotropin releasing hormone to be released from the anterior pituitary
         • See adrenal cortex mindmap
       • Gonadotropin releasing hormone causes release of leutinising hormone and follicle stimulating hormone from the anterior pituitary
         • See gonad mindmap
     • Hypothalamus release neurones into the hypophyseal portal system that stimulates endocrine cells
   • Connected to pituitary via infundibulum, held in place by sellae
   • Release of substance from peripheral glands con control the hypothalamus by negative feedback
     • Primary disease - problem with peripheral gland (unresponsive to hormone stimulating hormone or doesn't release endocrine hormone
     • Secondary disease - pituitary doesn't respond to hypothalamus or doesn't release stimulating hormone
     • Tertiary disease - hypothalamic problem; doesn't release releasing hormone

Images and files in the map