The Hypophysis or Pituitary Gland: Functions, Anatomy, and Disorders

Introduction to the Hypophysis or Pituitary Gland

The Hypophysis or Pituitary gland by Filippo Malshyti, Filippo Nadin and Matteo QuerinuzziTable of contents

1. Introduction
2. Main Functions
3. Anatomy of the pituitary gland
4. The Anterior pituitary
5. The Posterior pituitary
6. Regulation of the gland
7. Disorders and dysfunctions

Overview of the Pituitary Gland

1. INTRODUCTION ❏ It is considered the "master gland" of the body, because it regulates and controls several body factors; ❏ it is part of the hypothalamic-hypophyseal system.

Main Functions of the Pituitary Gland

2. Main functions ❏ Growth ❏ Metabolism (how your body transforms and manages the energy from the food you eat) ❏ Reproduction ❏ Response to stress or trauma ❏ Lactation ❏ Water and sodium (salt) balance ❏ Labor and childbirth

Anatomy of the Pituitary Gland

3. Anatomy of the pituitary gland ❏ The hypophysis is about 1 cm in diameter; ❏ It is located in a small bone cavity called sella turcica and is connected to the hypothalamus through stalk of blood vessels or nerves; ❏ Is divided in two parts: the Anterior pituitary and the Posterior pituitary; between them there is the pars intermedia, with different origins. Hypophyse

The Anterior Pituitary

4. The Anterior pituitaryGeneral information ❏ It could also be called adenohypophysis ❏ It is the larger of the two divisions and can be considered as a proper endocrine gland ❏ it originates from an outgrowth of the oral ectoderm known as Rathke's pouch and is formed by epithelial cells ❏ It is responsible for producing and releasing several hormones which control other endocrine glands and regulate growth, metabolism and reproduction ❏ We can divide the hormones in tropines and other hormones

Anterior Pituitary Tropines

TROPINES: ❏ Thyroid-Stimulating Hormone (TSH): stimulates the thyroid gland to produce T3 and T4, essential for our own metabolic rate and energy production from the food ❏ Adrenocorticotropic Hormone (ACTH): stimulates the adrenal glands to release cortisol, involved in the body's stress response ❏ FSH and LH: role in sexual development and reproduction by affecting the function of the ovaries and testes inito Hypothalamic-pituitary-ovarian axis HYPOTHALAMUS + GnRH 7 PITUITARY GLAND LH FSH + OVARY Estrogen Progesterone SEX HORMONES TSH? TYROID T3 T4 Q TSH MEDA CAREI ®Growth hormone GH Hormones ormone 'T ne (FSH) e (GnRH)

Other Anterior Pituitary Hormones

OTHER HORMONES: ❏ Growth Hormone (GH): its main function is to stimulate the development of the vertebrate organism by promoting the growth and mitotic division of cells of almost all body tissues ❏ Prolactin (PRL) : responsible for lactation and breast tissue development ❏ Melanocyte Stimulating Hormone (MSH): group of hormones important for protecting the skin from UV rays, development of pigmentation and control of appetitee 3 8 0 0 a 8 8 8 8

The Posterior Pituitary

5. The Posterior pituitary❏ Also called neurohypophysis; ❏ FUNCTION: storing and releasing hormones produced by the hypothalamus; ❏ is composed by: ❖ pars nervosa -> Herring bodies and pituicytes; infundibular stalk -> unmyelinated axons; ❖ ❏ it releases two types of hormones: oxytocin and Antidiuretic hormone (ADH) or vasopressin.OH Tyr C H2N,, O N Cys H H HN S Pro 1 lle Leu HN O N N N Gln IZ N H O H2N O Asn Gly O NH2 OXYTOCIN: ❏ Involved in childbirth and lactation: stimulates uterine contraction and releases milk during breastfeeding; ❏ is produced by nerve cell bodies in the paraventricular nucleus. O O H NH2 Cys SOH Cys O 1H2N,, O N Phe H HN H2N NH2 S Pro - N Cys S HN N Gln IZ O H2N N Asn O NH2 NH2 Gly Arg VASOPRESSIN (A,DH): " Regulates water balance in the body, maintaining a proper blood volume and pressure; ❏ it also controls the levels of sodium; ❏ is produced by nerve cell bodies in the supraoptic nucleus. N ZIO IZ N O H Tyr

Neurohypophysis and Hypothalamus Relationship

How is neurohypophysis related to hypothalamus? Hormones produced by neurosecretory cells (in the infundibulum), regrouped in Herring bodies, which originate in the hypothalamus, are released directly in the bloodstream (in capillaries); so oxytocin and ADH are produced in the hypothalamus to be transported later on in the neurohypophysis for the release. Hypothalamus Infundibulum Pituitary Gland

Regulation of the Gland

6. Regulation of the gland " The functioning of the pituitary gland is tightly regulated through a system known as the hypothalamus axis ❏ The hypothalamus sends chemical signals in the form of releasing or inhibiting hormones through a network of blood vessels that connects it to the anterior pituitary. These signals instruct the pituitary gland to either release or suppress the secretion of its hormones. Hypothalamus Negative Feedback CRH Corticotropin Releasing Hormone Anterior Pituitary ACTH Adrenocorticotropic Hormone Adrenal Cortex HPA Axis CORT Cortisol

Disorders and Dysfunctions of the Pituitary Gland

7. Disorders and dysfunctions ❏ Divided in three types: Excess hormone production (pituitary hyperfunction), deficiency in hormone production (pituitary hypofunction) and structural causes. ❏ Hormonal excess diseases occur when the pituitary gland produces too many hormones. ❏ Prolactinoma (excess prolactin), Acromegaly and Gigantism (excess of growth hormone), Cushing's disease (excess ACTH) and Pituitary hyperthyroidism (excess TSH) are some example of hormonal excess diseases. 3593❏ Hormonal deficiency diseases and disorders occur when the pituitary gland produces fewer hormones than necessary. ❏ Hypopituitarism is a disease caused from compressive pituitary tumors. ❏ GH deficiency, secondary adrenal insufficiency, central hypothyroidism, hypogonadotropic hypogonadism and diabetes insipidus are types of hormonal deficiency disorders.❏ Structural diseases affect the shape of the pituitary gland and cause serious changes in the body. ❏ There are lots of structural pathologies of the pituitary gland the most common are: non-secreting pituitary adenomas, craniopharyngioma, hollow saddle syndrome and hypophysitis. a b

Diagnosis and Treatments for Pituitary Conditions

Diagnosis and treatments ❏ To understand if you suffer from pituitary disease you must do hormonal tests, magnetic resonance and visual field tests. ❏ The treatments may be pharmacological, surgical or radiotherapeutics.THANKS for THE ATTENTION!