下丘脑与垂体的内分泌功能.ppt

Endocrine versus Nervous system Nervous system performs short term crisis management Endocrine system regulates long term ongoing metabolic Endocrine communication is carried out by endocrine cells releasing hormones Alter metabolic activities of tissues and organs Target cells Paracrine communication involves chemical messengers between cells within one tissue Hypophysis = pituitary Releases 9 important peptide hormones All 9 bind to membrane receptors and use cyclic AMP as a second messenger Anterior pituitary originates from epithelium; posterior pituitary from neural tissue The anterior lobe (adenohypophysis) Subdivided into the pars distalis, pars intermedia and pars tuberalis Contains axons of hypothalamic nerves neurons of the supraoptic nucleus (SON) and paraventricular nucleus (PVN) manufacture antidiuretic hormone (ADH = vasopressin, AVP), oxytocin (OXT) and Neurophysin (NP) ADH decreases the amount of water lost at the kidneys, elevates blood pressure OXT stimulates contractile cells in mammary glands, stimulates smooth muscle cells in uterus Transportation: NP-1 + OT; NP-2 + VP in axoplasm of the neuron’s fibers Release: Exocytosis Hormone Effects on Gene Activity Three Methods of Hypothalamic Control over the Endocrine System Hormones of the adenohypophysis Thyroid stimulating hormone (TSH) Triggers the release of thyroid hormones Thyrotropin releasing hormone promotes the release of TSH Adrenocorticotropic hormone (ACTH) Stimulates the release of glucocorticoids by the adrenal gland Corticotrophin releasing hormone causes the secretion of ACTH Follicle stimulating hormone (FSH) Stimulates follicle development and estrogen secretion in females and sperm production in males Leutinizing hormone (LH) Causes ovulation and progestin production in females and androgen production in males Gonadotropin releasing hormone (GnRH) promotes the secretion of FSH and LH Hormones of the adenohypophysis Prolactin (PRL) Stimulates the development of mamm