University:
West Coast University
Course:
PHAR 742 | IPC Endocrine
Academic year:

2024
Views:

66

Pages:

24
Author:

Asal A.

Control of Hormonal Regulation Fred Farris, PhD Ground Plan I. Brain Control of Endocrine Function II. Pituitary Gland I. Brain Control of Endocrine Function Hypothalamus •Almond sized organ located at base of the brain •Below the thalamus •Above the hypophysis (pituitary gland) •Forms floor of 3rd ventricle Hypothalamus as a Control Center •Hypothalamus controls the functioning of the hypophysis •Hypophysis is referred to as master gland, because to influences functioning of so many endocrine tissues •Hypothalamic control mediates actions of: •Neurohypophysis (posterior pituitary) via neural connections •Adenohypophysis (anterior pituitary) via blood vessels known as the portal circulation Hormone Secreted by Hypothalamus for Regulation of Adenohypophysis •Thyrotropin-releasing hormone (TRH) •Gonadotropin –releasing hormone (GnRH) •Growth hormone-releasing hormone (GHRH) •Corticotropin-releasing hormone (CRH) •Somatostatin •Dopamine II. Pituitary Gland Hypothalamus and Hypophysis (a) Hypothalamus and Hypophysis (a) Embryological Origin of the Hypophysis • The two lobes of the hypophysis are of different embryological origin • Adenohypophysis is of glandular origin and arises by invagination from the digestive tract • Neurohypophysis originates from neural tissue • These origins manifest differently in terms of communication routes with hypothalamus and nature of hormones secreted Embryological Origin of Hypophysis Hypothalamus and Hypophysis (b) Adenohypophysis (Anterior Pituitary) • Produces hormones but release into bloodstream is regulated by hormones produced by hypothalamus that reach anterior pituitary via portal circulation • Adenohypophysis hormones include, growth hormone, prolactin, melanocyte-stimulating hormone, corticotropin, thyrotropin, luteinizing hormone, and follicle stimulation hormone Anterior Pituitary Cells and Their Hormones Tropic Effects of Anterior Pituitary • Hormones released from anterior pituitary have Tropic Effects • Tropic = stimulate • Gonadotropin • Corticotropin • Thyrotropin • Somatotropin Actions of Anterior Pituitary Hormones Neurohypophysis (Posterior Pituitary) • Produces no hormones • Consists of axons and axon terminals of 10,000 or more hypothalamic neurosecretory cells • Storage and secretion site for Vasopressin and Oxytocin • Both are nonapeptides synthesized in cell bodies in hypothalamus and transported along axons that form the hypothalamic-hypophyseal tract, ending in the neurohypophysis Control of Posterior Pituitary Secretions Pituitary Hypoactivity • • • • • • • • • • Loss of secondary sexual characteristics Decreased metabolism Dwarfism Diabetes insipidus Hypothyroidism Addison disease Loss of pigmentation Thinning and softening of the slik Decreased libido Retarded dental development Pituitary Hyperactivity • • • • Sexual precocity Goiter Cushing disease Acromegaly, and giantism Hypothalamus Pituitary Adrenal Axis • HPA axis • CRH: Corticotropin Releasing Hormone • ACTH: AdrenoCorticoTropic Hormone Hypothalamus Pituitary Gonadal Axis • HPG axis • GnRH: Gonadotropin Releasing Hormone • FSH: FollicleStimulating Hormone • LH: Luteinizing Hormone Hypothalamus Pituitary Thyroid Axis • HPT axis • THR: Thyrotropin Releasing Hormone • TSH: Thyroid Stimulating Hormone • (Thyrotropin) Acknowledgements ◦ The contents of many of the slides used in this presentation were adapted from material originally prepared by Dr. Gauri Sabnis – Many Thanks for her assistance

Control of Hormonal Regulation

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