Monash University BMS1052 - Human Neurobiology Lecture Notes PDF

BMS1052 – Human Neurobiology The Secretory Hypothalamus Lesson 1 – The hypothalamo–pituitary axis Week 9  Lesson Objectives By the end of this lesson and associated readings, you should be able to : Describe the structure and key components of the hypothalam...

BMS1052 – Human Neurobiology The Secretory Hypothalamus Lesson 1 – The hypothalamo–pituitary axis Week 9  Lesson Objectives By the end of this lesson and associated readings, you should be able to : Describe the structure and key components of the hypothalamus, including main pathways to and from the hypothalamus and pituitary Understand the basic organisation of the hypothalamo–pituitary axis and how it relates to function Understand the functional importance of the division of the pituitary into anterior and posterior divisions Readings: Bear Chapters 15 and 16 Patterns of communication in the nervous system A B C The Structure of the Hypothalamus The hypothalamus sits below the thalamus, along the walls of the third ventricle It is connected by a stalk to the pituitary gland, which is positioned below the base of the brain, just above the roof of your mouth The hypothalamus integrates somatic and visceral responses in accordance with the needs of the brain The Structure of the Hypothalamus Paraventricular nucleus Supraoptic nucleus Median eminence  The Structure of the Hypothalamus Hypothalamus is connected to the pituitary gland by a stalk comprised of nerve fibres and specialised portal vessels – the infundibulum The pituitary gland is divided into the anterior (front) and posterior (back) portions The Structure of the Hypothalamus The anterior pituitary  Parvocellular neurosecretory cells in the hypothalamus (paraventricular nucleus) produce neuro- hormones (releasing factors) that are released into the vicinity of portal vessels in the median eminence cells, transported to the anterior pituitary where they cause the release of hormones from specialised secretory cells Neurosecretory cells Preoptic Area in the paraventricular nucleus Gonadotropin Median eminence releasing hormone (GnRH) Portal vessels Thyrotropin releasing (hypothalamo – hormone portal circulation) (TRH) Hypophyseal portal veins Anterior pituitary Corticotropin releasing hormone Contains: (CRH) Follicle stimulating hormone (FSH) Luteinising hormone (LH) Thyroid stimulating hormone (TSH) Growth Hormone Adrenocorticotropic hormone (ACTH) Releasing Hormone Growth hormone (GH) (GHRH)  Paraventricular nucleus Supraoptic nucleus (magnocellular) (parvocellular) Median eminence Portal vessel fenestrations  Parvocellular neurosecretory cells in the hypothalamus (paraventricular nucleus) produce neuro- hormones (releasing factors) that are released into the vicinity of portal vessels in the median eminence cells, transported to the anterior pituitary where they cause the release of hormones from specialised secretory cells Neurosecretory cells Preoptic Area in the paraventricular nucleus Gonadotropin Median eminence releasing hormone (GnRH) Portal vessels Thyrotropin releasing (hypothalamo – hormone portal circulation) (TRH) Anterior pituitary Corticotropin releasing hormone Contains: (CRH) Follicle stimulating hormone (FSH) Luteinising hormone (LH) Thyroid stimulating hormone (TSH) Growth Hormone Adrenocorticotropic hormone (ACTH) Releasing Hormone Growth hormone (GH) (GHRH) The Structure of the Hypothalamus  Different anterior pituitary cell types HORMONE CELL TYPE TARGET / FUNCTION Follicle stimulating hormone Gonadotrophs Gonads / Reproduction Luteinising hormone Thyroid stimulating hormone Thyrotrophs Thyroid / Development and energy expenditure Adrenocorticotropic hormone Corticotrophs Adrenal / Stress Growth hormone Somatotrophs Widespread anabolic actions Different cells produce specific hormones in the anterior pituitary that then act on different tissue targets in the peripheral circulation The posterior pituitary The posterior pituitary Integration of autonomic and neuroendocrine systems The posterior pituitary