The Endocrine System 2 (2023) PDF

WEEK 16 MPharm Programme Normal Systems The Endocrine System 2 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA112 The Endocrine System WEEK 16 Anterior Pituitary Hormones Thyroid-stimulating hormone (TSH) Promotes vascularisation & growth of the thyro...

WEEK 16 MPharm Programme Normal Systems The Endocrine System 2 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA112 The Endocrine System WEEK 16 Anterior Pituitary Hormones Thyroid-stimulating hormone (TSH) Promotes vascularisation & growth of the thyroid gland Stimulates secretion of thyroid hormones Secretion stimulated by TRH from hypothalamus Adrenocorticotropic hormone (ACTH) Controls growth of the adrenal cortex Stimulates secretion of cortisol by adrenal cortex Secretion stimulated by CRH from hypothalamus Slide 33 of 85 MPharm PHA112 The Endocrine System WEEK 16 Anterior Pituitary Hormones Follicle-stimulating hormone (FSH) Stimulates growth & development of ovarian follicles (F) Promotes ovarian secretion of oestrogen (F) Required for sperm production (M) Secretion stimulated by GnRH from the hypothalamus Slide 34 of 85 MPharm PHA112 The Endocrine System WEEK 16 Anterior Pituitary Hormones Luteinizing hormone (LH) Responsible for ovulation & development of the corpus luteum (F) Regulates ovarian secretion of sex hormones (F) Stimulates testes to secrete testosterone (M) Secretion stimulated by GnRH from hypothalamus Prolactin (PRL) Enhances breast development & milk production (F) Secretion inhibited by DA from hypothalamus Slide 35 of 85 MPharm PHA112 The Endocrine System WEEK 16 Anterior Pituitary Hormones Slide 36 of 85 MPharm PHA112 The Endocrine System WEEK 16 Slide 37 of 85 MPharm PHA112 The Endocrine System WEEK 16 Posterior Pituitary Hormones Slide 38 of 85 MPharm PHA112 The Endocrine System WEEK Posterior Pituitary Hormones 16 Vasopressin Antidiuretic hormone (ADH) Regulates urinary H2O loss & water balance in the body Promotes renal water re-absorption  regulation of plasma volume & osmotic pressure Oxytocin Stimulates uterine contraction during childbirth & milk ejection during breast-feeding Secretion stimulated by birth canal & breast suckling reflexes Slide 39 of 85 MPharm PHA112 The Endocrine System WEEK 16 Slide 40 of 85 Posterior Pituitary Hormones MPharm PHA112 The Endocrine System WEEK The Pineal Gland 16 Tiny, pine cone-shaped gland – located in diencephalon Secretes melatonin – ‘hormone of darkness’ Production stimulated by suprachiasmatic nucleus (SCN) – body’s master ‘biological clock’ Main functions: Synchronizes body’s circadian rhythms with the 24-hr ‘day-night’ or ‘light-dark’ cycle Promotes sleep Influences reproductive activity – onset of puberty Slide 41 of 85 MPharm PHA112 The Endocrine System WEEK 16 Pineal Gland & Melatonin Secretion Slide 42 of 85 MPharm PHA112 The Endocrine System WEEK 16 The Peripheral Endocrine Glands Slide 43 of 85 MPharm PHA112 The Endocrine System The Thyroid Gland WEEK 16 Located in the neck, just below the larynx Two lobes of endocrine tissue joined in middle by narrow strip of gland (isthmus) Consists of 2 distinct secretory cell types Follicular cells Secrete two iodine-containing hormones Tetra-iodothyronine (T4 or thyroxine) Tri-iodothyronine (T3) Parafollicular or C cells Secrete calcitonin (peptide hormone) Slide 44 of 85 MPharm PHA112 The Endocrine System WEEK 16 Slide 45 of 85 The Thyroid Gland MPharm PHA112 The Endocrine System Thyroid Hormone WEEK 16 Synthesis, Storage & Release Formed from iodide (I-) & tyrosine Synthesis of tyrosine-containing thyroglobulin (TG) in follicular cells & export into colloid Active uptake of iodide (I-) by follicular cells, oxidation (to ‘active’ iodide) & diffusion into colloid Attachment of iodide to tyrosine residues in TG  MIT & DIT Coupling of MIT & DIT  Tri-iodothyronine (T3) DIT & DIT  Tetra-iodothyronine (T4) T3 & T4 are attached to TG & stored in colloid until release Slide 46 of 85 MPharm PHA112 The Endocrine System Thyroid Hormone WEEK 16 Synthesis, Storage & Release Release stimulated by TSH Endocytosis of synthesised TG-containing colloid by follicular cells Proteolytic digestion of TG to release T3 & T4 MIT & DIT Secretion / diffusion of T3 & T4 into blood & transportation in carrier (TBG)-bound form T4 converted to active T3 in the liver & kidneys Iodide removed from MIT & DIT and recycled Slide 47 of 85 MPharm PHA112 The Endocrine System WEEK 16 Thyroid Hormone Synthesis, Storage & Release Slide 48 of 85 MPharm PHA112 The Endocrine System WEEK 16 Thyroid Hormone Synthesis, Storage & Release Slide 49 of 85 MPharm PHA112 The Endocrine System WEEK 16 Functions of Thyroid Hormone Effect on Normal Growth & CNS Development Effects on normal growth mediated via GH & IGF-1 Stimulates GH secretion & hepatic production of IGF-1 Promotes GH & IGF-1 effects on protein synthesis & skeletal growth Required for normal development of the nervous system in infants & children Promotes normal CNS activity in adults Slide 50 of 85 MPharm PHA112 The Endocrine System WEEK Functions of Thyroid Hormone 16 Effect on Metabolic Rate & Heat Production Increases the overall basal metabolic rate & heat production (‘calorigenic effect’) main regulator of resting O2 consumption & energy expenditure Effect on Intermediary Metabolism Biphasic effects on carbohydrate, fat & protein metabolism Effect on Sympathetic Activity Increases cellular responsiveness to catecholamines via receptor up-regulation   myocardial contractility & HR Slide 51 of 85 MPharm PHA112 The Endocrine System WEEK 16 TH – Control of Release & Functions Slide 52 of 85 MPharm PHA112 The Endocrine System WEEK 16 Control of Thyroid Secretion Slide 53 of 85 MPharm PHA112 The Endocrine System WEEK The Adrenal Glands 16 ‘Adrenal’ – ‘next to the kidney’ Paired organs that cap the kidneys Each consists of 2 distinct secretory organs: an outer adrenal cortex Secretes 3 types of steroid hormones Mineralocorticoids (aldosterone) Glucocorticoids (cortisol) Sex hormones (Dehydroepiandrosterone, DHEA) an inner adrenal medulla Secretes catecholamines – AD & NA Slide 54 of 85 MPharm PHA112 The Endocrine System WEEK 16 Slide 55 of 85 The Adrenal Glands MPharm PHA112 The Endocrine System The Adrenal Cortex WEEK 16 Consists of three layers or zones: Zona glomerulosa Mineralocorticoids (aldosterone) Regulate Na+ & K+ balance & BP homeostasis Zona fasciculata Glucocorticoids (cortisol) Long-term control of metabolism Adaptation to stress Zona reticularis Sex hormones (Dehydroepiandrosterone, DHEA) Supplement gonadal sex steroids Slide 56 of 85 MPharm PHA112 The Endocrine System