Human Anatomy, 3rd edition Endocrine System Chapter 11 Human Anatomy, 3rd edition Prentice Hall, © 2001

Introduction The endocrine system consists of cells, tissues, & organs that secrete hormones into the blood Hormone – an organic substance secreted by a cell that has an effect on the metabolic activity of another cell or tissue Target cells – cells that are affected by the hormone Have specific receptors for the hormones

How Hormones Work Basic action The hormone combines with a receptor The new molecular structure causes cellular changes

Human Anatomy, 3rd edition How Hormones Work Activation of 2nd messengers Involves a cell membrane receptor Activation of genes Involves intracellular receptors Human Anatomy, 3rd edition Prentice Hall, © 2001

The Hypothalamus & Endocrine Regulation Controls the adrenal medulla Adrenalin Releases hormones Antidiuretic hormone (ADH) Oxytocin Secretes substances that control the anterior pituitary gland Releasing factors Inhibiting factors Human Anatomy, 3rd edition Prentice Hall, © 2001

Overview of the Endocrine System Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pituitary Gland Connected to the hypothalamus Infundibulum Master gland of the endocrine system 2 parts Posterior pituitary Nervous tissue Anterior pituitary Glandular tissue Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pituitary Gland Posterior pituitary Receives hormones from the hypothalamus via axons Anterior pituitary Receives hormones from the hypothalamus via capillaries Human Anatomy, 3rd edition Prentice Hall, © 2001

Posterior Pituitary Produces 2 Hormones Antidiuretic hormone (ADH) Target – kidneys Effect – reabsorption of water Oxytocin Targets – reproductive organs Effects – contractions of smooth muscles (labor contractions, milk ejection; ductus deferens, prostate gland – ejaculations)

Anterior Pituitary Hormones Follicle stimulating hormone (FSH) stimulates gametes Targets – follicle cells (females), testes (males) Effects – follicle development & estrogen secretion (females), sperm maturation (males) Luteinizing hormone (LH) Targets – follicle cells (females), interstitial cells of testes (males) Effects – ovulation, formation of corpus luteum, secretion of progesterone (females), secretion of testosterone (males)

Anterior Pituitary Hormones Thyroid stimulating hormone (TSH) Target – thyroid gland Effect – triggers the release of thyroid hormones Adrenocorticotropic hormone (ACTH) Target – adrenal cortex Effect – cells that produce steroid hormones

Anterior Pituitary Hormones Prolactin Target - breast Effect - stimulates milk production Growth hormone Target – all cells Effect - stimulates growth in general and the skeletal system in particular Melanocyte stimulating hormone (MSH) Target - melanocytes Effect – increases melanin production and distribution Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Pituitary Hormones FG19_05.JPG Title: Pituitary Hormones and Their Targets Notes: This schematic diagram shows the hypothalamic control of the pituitary gland, the pituitary hormones produced, and the responses of representative target tissues. Keywords: pituitary hormones, targets, adrenal medulla, adrenal cortex, thyroid, peripheral tissues, mammary glands, testes, ovaries, melanocytes, kidneys, anterior pituitary, posterior pituitary, ACTH, TSH, GH, PRL, FSH, LH, MSH, ADH, hypothalamus, oxytocin Human Anatomy, 3rd edition Prentice Hall, © 2001

The Thyroid Gland Location – anterior to larynx Thyroid hormones include iodine in their structure Target cells – most cells Effect of thyroid hormones increase energy utilization, oxygen consumption, growth, development

Human Anatomy, 3rd edition The Thyroid Gland Other cells Produce calcitonin (CT) Targets – bone, kidneys Effect – lowers blood calcium levels Human Anatomy, 3rd edition Prentice Hall, © 2001

Control of Thyroid Hormones FG19_08.JPG Title: The Regulation of Thyroid Secretion Notes: This negative feedback loop is responsible for the homeostatic control of thyroid hormone release. Keywords: thyroid activity, regulation, homeostasis, anterior pituitary, TSH, thyroid gland, T3, T4, body temperature Human Anatomy, 3rd edition Prentice Hall, © 2001

The Parathyroid Glands Location – posterior surfaces of thyroid gland Produce parathyroid hormone (PTH) Target cells – bone, kidneys, intestines Effect Increases blood calcium levels Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Thymus Gland Location – posterior to the sternum Hormones enhance lymphycyte production Development Childhood – large Puberty – largest Adulthood – decreases in size Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Adrenal Glands Location – on top of the kidney Structure Capsule Cortex Medulla Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Adrenal Medulla Secretes epinephrine & norepinephrine Target – most cells Effect - stimulates heart beat & tissue metabolism, increases alertness, prepares body to deal with emergencies Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Adrenal Cortex Secretes aldosterone Target – kidneys Effect – increases blood sodium, decreases blood potassium Secretes steroid hormones (cortisol, corticosterone) Target – most cells Effect – conserve blood glucose, anti-inflammatory effects Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pancreas Location – between the spleen and the duodenum Functions – both exocrine and endocrine Endocrine cells are in the Islets of Langerhans Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Islets of Langerhans Glucagon Targets – liver, adipose tissues Effect - increase blood sugar levels Insulin Targets - most cells Effect - decrease blood sugar levels Diabetes mellitis Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Pineal Gland Location = epithalamus Secretes melatonin Light inhibits production Regulates circadian rythms Target – hypothalamus Effects – Inhibits FSH & LH secretion Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Testes Divided into internal compartments containing seminiferous tubules Spermatogenesis Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Seminiferous Tubules Androgens (male sex hormones) Testosterone is the most important Target – most cells Effects – maturation of sperm; protein synthesis in skeletal muscle; male secondary sex characteristics & behaviors Human Anatomy, 3rd edition Prentice Hall, © 2001

The Ovaries – Follicle Cells Estrogen Targets – most cells Effects – follicle maturation; female secondary sex characteristics and behaviors Human Anatomy, 3rd edition Prentice Hall, © 2001

The Ovaries – Corpus Luteum Progesterone Targets – uterus, mammary glands Effects – prepare uterus for implantation, mammary glands for secretion Relaxin Targets – pubic symphysis, uterus, mammary glands Effects – loosens pubic symphysis, relaxes cervical muscles, stimulates mammary gland development http://www.healthsquare.com/fgwh/wh1ch17.htm Human Anatomy, 3rd edition Prentice Hall, © 2001

Hormonal Regulation of the Female Reproductive System FG27_18.JPG Title: The Hormonal Regulation of Female Reproductive Function Notes: A diagrammatic view of the hormonal regulation of female reproductive function. Keywords: hormones, female reproductive functions, hypothalamus, pituitary, estrogens, progestins, GnRH, LH, FSH Human Anatomy, 3rd edition Prentice Hall, © 2001