Homeostasis Aldosterone Thymus Gland Hyperglycemia Chapter 12 Key Terms Hormones Melatonin Homeostasis Aldosterone Thymus Gland Hyperglycemia Hypophysis Hypothalamus Infundibulum Acidosis Adrenal Gland Alpha Cells Beta Cells Chief Cells Insulin Androgens Ovaries Testes

Chapter 12: Endocrine system ANATOMY & PHYSIOLOGY Chapter 12: Endocrine system

Introduction Purpose Works closely with the nervous system Homeostasis: maintaining the body’s internal environment within certain narrow ranges Involves growth, maturation, metabolism, and reproduction Works closely with the nervous system Hypothalamus sends chemical signals (neurotransmitters) to the endocrine system Endocrine Glands Ductless glands that secrete hormones directly into bloodstream

Hormones Negative feedback loop 3 chemical categories Mechanism by which hormones function 3 chemical categories Modified amino acids Protein hormones Steroid hormones

Hypothalamus Controls the pituitary gland Infundibulum Funnel shaped extension from hypothalamus to pituitary gland Produces chemical signals Releasing hormones Releasing inhibitory hormones

Endocrine Glands Pituitary Gland (A) Thyroid Gland (B) Parathyroid Gland Adrenal Gland (C) Testes (D) Ovaries (E) Pancreas (F) Thymus Gland (G) Pineal Gland (H)

Pituitary Gland Also known as the Hypophysis, and also the “Master Gland” Divided into two lobes Anterior Pituitary Gland Posterior Pituitary Gland

Anterior Pituitary Gland Growth Hormone (GH) Stimulates cell growth and division Stimulates bone and muscle growth Pituitary Dwarfism: result of too little GH Gigantism: result of too much GH Thyroid Stimulating Hormone (TSH) Stimulates thyroid to release its hormone

Anterior Pituitary Gland Adrenocorticotropic Hormone (ACTH) Stimulates adrenal cortex to secrete its hormone (Cortisol) Helps reduce inflammation Melanocyte-stimulating Hormone (MSH) Stimulates production of melanin in the skin Follicle-stimulating Hormone (FSH) Stimulates the production of sperm in males Stimulates development of follicles in ovaries

Anterior Pituitary Gland Luteinizing Hormone (LH) Stimulates production of progesterone and ovulation in ovary Stimulates production of testosterone in males Lactogenic Hormone (LTH) AKA Prolactin Stimulates milk production in a pregnant female May cause decrease in male sex hormones

Posterior Pituitary Gland Antidiuretic Hormone (ADH) AKA Vasopressin Maintains body’s water balance by promoting water reabsorption in the kidneys Oxytocin Stimulates contraction of smooth muscles in the uterus Sometimes given to help induce labor if the uterus does not contract sufficiently on its own during childbirth

Thyroid Gland Consists of two lobes connected by a smaller band called the isthmus Stimulated by TSH from the Pituitary Gland Requires Iodine to function properly Iodine deficiency causes goiters Releases T3 and T4 Contain 3 and 4 Iodine atoms Regulate metabolism of carbs, fats, proteins for proper growth and development

Thyroid Gland Calcitonin Hypothyroidism Hyperthyroidism Lowers calcium and phosphate concentrations in the blood Inhibits release of ions from bones, and increases excretion of ions by the kidneys Hypothyroidism Low levels of thyroid hormones Cretinism Hyperthyroidism Too much secretion of thyroid hormones

Parathyroid Gland 4 small glands on posterior surface of thyroid gland Made of chief cells and oxyphil cells Releases Parathyroid Hormone (PTH) Raises blood calcium levels by causing bone matrix to break down, releasing calcium and phosphate ions into bloodstream

Adrenal Gland Located on top of the kidneys Adrenal Medulla Epinephrine (adrenaline) and Norepinephrine (noradrenaline) Released as a response to signals of the autonomic nervous system Fight or flight hormones Causes a breakdown of glycogen to glucose Stimulates release of fatty acids from fat cells

Adrenal Cortex Aldosterone Cortisol (Hydrocortisone) Cortisone Regulates Na reabsorption and K excretion by kidneys Released by outer layer of cortex Cortisol (Hydrocortisone) Helps maintain blood glucose levels between meals Synthesizes glucose from amino acids Cortisone Steroid often give as medication to reduce inflammation

Adrenal Cortex Androgens Addison’s disease Cushing’s syndrome Promotes development of male characteristics Addison’s disease Not enough hormones secreted by adrenal cortex Causes change of electrolyte balance in blood Cushing’s syndrome Blood glucose concentrations remains high, causing puffy skin and obesity because of excess tissue fluid

Pancreas Part of digestive and endocrine systems Alpha Cells Secretes Glucagon Raises blood sugar level Beta Cells Secretes Insulin Lowers blood sugar level

Diabetes Mellitus Deficiency in insulin production Type 1 Type 2 Previously called juvenile diabetes Body does not produce insulin 5% of diabetics Type 2 Body does not use insulin properly (insulin resistance) Previously called adult onset diabetes Balanced diet, exercise, proper body weight

Testes and Ovaries Ovaries Testes Releases estrogen and progesterone Promote development of female characteristics Control menstrual cycle Testes Releases testosterone Promotes development of male reproductive structures and male characteristics Both controlled by LH and LTH from Pituitary gland

Thymus Gland Located in the mediastinum Helps in development of the immune system Thymosin Promotes production of T lymphocytes

Pineal Gland Melatonin Serotonin Secreted directly into cerebrospinal fluid Inhibits secretion of LH and LTH Regulates circadian rhythms (feeling of tired and onset of sleep) Bright light inhibits secretion of melatonin Serotonin Acts as neurotransmitter and vasoconstrictor Stimulates smooth muscle contractions