Hypothalamus pituitary gland By Dr.Isabel Hwang Department of Physiology Faculty of Medicine University of Hong Kong Hong Kong
Hypothalamus & pituitary gland By Dr. Isabel Hwang Department of Physiology Faculty of Medicine University of Hong Kong Hong Kong
Copyright The McGraw-Hill Companies,Inc.Permission required for reproduction or display. Central nervous system (a) (b) Hypothalamus ⑧ Hormones Autonomic ganglion ①r⊙ Anterior Adrena ⊕orO pituitary medulla Endocrine Posterior gland cell pituitary Hormone Hormones Hormones (epinephrine Hormone
Hypothalamus Contains neural centers for hunger,thirst,and body temperature. Contributes to the regulation of sleep, wakefulness,emotions,etc Stimulates hormonal release from anterior pituitary. Produces anti-diuretic hormone (ADH)and oxytocin. Coordinates sympathetic and parasympathetic reflexes
Hypothalamus • Contains neural centers for hunger, thirst, and body temperature. • Contributes to the regulation of sleep, wakefulness, emotions, etc • Stimulates hormonal release from anterior pituitary. • Produces anti-diuretic hormone (ADH) and oxytocin. • Coordinates sympathetic and parasympathetic reflexes
Hypothalamus 。 Secretes releasing inhibiting hormones that regulate release of hormones from anterior pituitary Function as tropic*hormones to either stimulate or inhibit release of anterior pituitary hormones 5 releasing hormones and 2 inhibiting hormones that regulate the glandular cells in the anterior pituitary *hormone that stimulates the secretion of another hormone, and often the growth of hormone-secreting gland
Hypothalamus • Secretes releasing & inhibiting hormones that regulate release of hormones from anterior pituitary • Function as tropic* hormones to either stimulate or inhibit release of anterior pituitary hormones • 5 releasing hormones and 2 inhibiting hormones that regulate the glandular cells in the anterior pituitary *hormone that stimulates the secretion of another hormone, and often the growth of hormone-secreting gland
CopyrightThe McGraw-Hill Companies,Inc.Permission required for reproduction or display. pRwro, Hypothalamus (to posterior pituitary） eminence Optic chiasm Arterial blood supply Infundibulum- Hypothalamo-pituitary portal vessels 6 Median eminence Short portal vessels Anterior pituitary Posterior pituitary Arterial blood supply o venous circulation Sphenoid bone Sella turcic To venous circulation
Structure of the Pituitary Gland ·Two distinct lobes ·Anterior pituitary (adenohypophysis;pars distalis) true endocrine tissue secretes classic hormones 。Posterior pituitary (neurohypophysis;pars nervosa) neural tissue secretes neurohormones
Structure of the Pituitary Gland • Two distinct lobes • Anterior pituitary (adenohypophysis; pars distalis) • Posterior pituitary (neurohypophysis; pars nervosa) - true endocrine tissue - secretes classic hormones - neural tissue - secretes neurohormones
Relationship between the hypothalamus and the pituitary The cells in the anterior pituitary are the target cells of the neurotransmitters secreted by the hypothalamic neurons (neuroendocrine)which have a stimulatory or inhibitory effect on the anterior pituitary cells
Relationship between the hypothalamus and the pituitary • The cells in the anterior pituitary are the target cells of the neurotransmitters secreted by the hypothalamic neurons (neuroendocrine) which have a stimulatory or inhibitory effect on the anterior pituitary cells
Cont'd This Hypothalamic-pituitary portal system (or hypophyseal portal system)acts as a one way chemical messenger system between the hypothalamus and anterior pituitary gland The anterior pituitary then reacts to these chemical signals by either increasing or decreasing the release of hormones that affect other cells in the body
Cont’d • This Hypothalamic – pituitary portal system (or hypophyseal portal system) acts as a one way chemical messenger system between the hypothalamus and anterior pituitary gland • The anterior pituitary then reacts to these chemical signals by either increasing or decreasing the release of hormones that affect other cells in the body
Hypophyseal portal system: A network of blood vessels that delivers hormones to anterior pituitary from hypothalamus
Hypophyseal portal system: • A network of blood vessels that delivers hormones to anterior pituitary from hypothalamus
Anterior versus Posterior Structural difference: the anterior pituitary is made up of secretory cells within a glandular epithelium. the posterior pituitary consists largely of nerve fibers and neuroglial*cells Specialised cells that surround neurons,providing mechanical and physical support and electrical insulation between neurons
Anterior versus Posterior • Structural difference: - the anterior pituitary is made up of secretory cells within a glandular epithelium. - the posterior pituitary consists largely of nerve fibers and neuroglial* cells * Specialised cells that surround neurons, providing mechanical and physical support and electrical insulation between neurons