Copyright © 2004 Lippincott Williams & Wilkins Chapter 11 The Endocrine System: Glands and Hormones

Copyright © 2004 Lippincott Williams & Wilkins The Endocrine System Consists of a group of glands that produce hormones Works with nervous system to control and coordinate all other body systems Effects body systems by chemical stimuli

Copyright © 2004 Lippincott Williams & Wilkins Hormones Chemical messengers with regulatory effects on cells or organs Some affect many tissues –Growth hormone –Thyroid hormone –Insulin Some affect a specific tissue (target tissue) –Thyroid-stimulating hormone (TSH) –Adrenocorticotropic hormone (ACTH)

Copyright © 2004 Lippincott Williams & Wilkins Hormone Chemistry Amino acid compounds –Proteins or related compounds –Include all hormones except steroids Steroids –Lipids derived from the steroid cholesterol –Produced in adrenal cortex and sex glands

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-1: What are hormones and what are some effects of hormones? Chemical messengers with regulatory effects on cells or organs

Copyright © 2004 Lippincott Williams & Wilkins Hormone Regulation Negative feedback (most common) –Endocrine gland oversecretes hormone –Tissue becomes too active –Activity causes gland to decrease secretion Positive feedback –Hormone response produces more hormone Rhythmic pattern

Copyright © 2004 Lippincott Williams & Wilkins Negative feedback control of thyroid hormones

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-2: Hormone levels are normally kept within a specific range. What is the most common method used to regulate secretion of hormones? –Negative feedback

Copyright © 2004 Lippincott Williams & Wilkins The Endocrine Glands and Their Hormones Tissues other than endocrine glands also secrete hormones –Brain –Digestive organs –Kidney

Copyright © 2004 Lippincott Williams & Wilkins The endocrine glands

Copyright © 2004 Lippincott Williams & Wilkins The Pituitary Pituitary (hypophysis) gland –Master gland –Releases hormones that affect working of other glands –Controlled by hypothalamus

Copyright © 2004 Lippincott Williams & Wilkins The hypothalamus, pituitary gland, and target tissues ZOOMING IN What two structures does the infundibulum connect? The hypothalamus and pituitary gland

Copyright © 2004 Lippincott Williams & Wilkins Control of the Pituitary Hypothalamus Sends releasing hormones (RH) and inhibiting hormones (IH) –Hormones stimulate or suppress anterior pituitary secretions Produces antidiuretic hormone (ADH) and oxytocin –Stored in posterior pituitary –Nerve impulses stimulate secretions

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-3: What part of the brain controls the pituitary? Hypothalamus

Copyright © 2004 Lippincott Williams & Wilkins Hormones of the Anterior Lobe Growth hormone (GH) or somatotropin Thyroid-stimulating hormone (TSH) or thyrotropin Adrenocorticotropic hormone Prolactin (PRL) Gonadotropins –Follicle-stimulating hormone (FSH) –Luteinizing hormone (LH)

Copyright © 2004 Lippincott Williams & Wilkins Hormones of the Posterior Lobe Antidiuretic hormone (ADH) Oxytocin

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-4: What are the hormones from the anterior pituitary? –Growth hormone (GH) or somatotropin –Thyroid-stimulating hormone (TSH) or thyrotropin –Adrenocorticotropic hormone –Prolactin (PRL) –Gonadotropins Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Checkpoint 11-5: What hormones are released from the posterior pituitary? –Antidiuretic hormone (ADH) –Oxytocin

Copyright © 2004 Lippincott Williams & Wilkins The Thyroid Gland Largest endocrine gland Lateral lobes on either side of larynx Connecting band (isthmus) Enclosed by connective tissue capsule

Copyright © 2004 Lippincott Williams & Wilkins Thyroid gland (anterior view) ZOOMING IN What structure is superior to the thyroid?Larynx Inferior to the thyroid?Trachea

Copyright © 2004 Lippincott Williams & Wilkins Hormones of the Thyroid Gland Thyroxine (T4) –Principle hormone –Increases energy and protein metabolism Triiodothyronine (T3) –Increases energy and protein metabolism Calcitonin –Regulates calcium metabolism –Works with parathyroid hormone and vitamin D

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-6: What is the effect of thyroid hormones on cells? –Increase energy and protein metabolism

Copyright © 2004 Lippincott Williams & Wilkins The Parathyroid Glands Four glands in posterior capsule of thyroid Secrete parathyroid hormone (PTH) –Works with calcitonin to regulate calcium metabolism

Copyright © 2004 Lippincott Williams & Wilkins Parathyroid glands (posterior view)

Copyright © 2004 Lippincott Williams & Wilkins Calcium Metabolism Calcium balance requires –Calcitriol (dihydroxycholecalciferol) Produced by modifying vitamin D in liver then in kidney –Parathyroid hormone –Calcitonin

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-7: What mineral is regulated by calcitonin and parathyroid hormone (PTH)? –Calcium

Copyright © 2004 Lippincott Williams & Wilkins Adrenal Glands Two small glands on top of kidneys Each gland has two parts that act as separate glands –Medulla –Cortex

Copyright © 2004 Lippincott Williams & Wilkins The adrenal gland ZOOMING IN What is the outer region of the adrenal gland called? The inner region? Cortex Medulla

Copyright © 2004 Lippincott Williams & Wilkins Hormones from the Adrenal Medulla Fight-or-flight hormones –Epinephrine (adrenaline) –Norepinephrine (noradrenaline)

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-8: The main hormone from the adrenal medulla also functions as a neurotransmitter in the sympathetic nervous system. What is the name of this hormone? –epinephrine

Copyright © 2004 Lippincott Williams & Wilkins Hormones from the Adrenal Cortex Glucocorticoids –Cortisol or hydrocortisone Mineralocorticoids –Aldosterone Sex hormones

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-9: What three categories of hormones are released by the adrenal cortex? –Glucocorticoids –Mineralocorticoids –Sex hormones Checkpoint 11-10: What effect does cortisol have on glucose levels in the blood? –Cortisol raises the glucose level

Copyright © 2004 Lippincott Williams & Wilkins The Pancreas and Its Hormones Islets of Langerhans are specialized pancreas cells that secrete Insulin –Lowers blood sugar level –Stimulates manufacture of amino acids into protein Glucagon –Increases blood sugar

Copyright © 2004 Lippincott Williams & Wilkins Microscopic view of pancreatic cells

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-11: What two hormones produced by the islets of the pancreas act to regulate glucose levels in the blood? –Insulin –Glucagon

Copyright © 2004 Lippincott Williams & Wilkins The Sex Glands Ovaries and testes produce hormones to maintain reproductive organs Develop secondary sex characteristics

Copyright © 2004 Lippincott Williams & Wilkins Hormones of the Sex Glands Male sex hormone –Testosterone Female sex hormones –Estrogen –Progesterone

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-12: In addition to controlling reproduction, sex hormones confer certain features associated with male and female gender. What are these features called as a group? –Secondary sex characteristics

Copyright © 2004 Lippincott Williams & Wilkins The Thymus Gland Mass of lymphoid tissue in upper chest superior to heart Important in development of immunity Produces thymosin –Assists in maturity of T lymphocytes

Copyright © 2004 Lippincott Williams & Wilkins The Pineal Gland Cone-shaped structure posterior to midbrain Produces melatonin –Influences sleep–wake cycles –Appears to delay onset of puberty

Copyright © 2004 Lippincott Williams & Wilkins Other Hormone-Producing Tissues Substances that regulate body actions are also produced by –Stomach –Small intestine –Kidneys –Brain –Atria of heart –Placenta

Copyright © 2004 Lippincott Williams & Wilkins Prostaglandins Group of hormones made by most body tissues Produced, act, and rapidly inactivated in or close to origin Constrict structures Dilate structures Promote inflammation

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-13: What are some organs other than the endocrine glands that produce hormones? –Stomach –Small intestine –Kidneys –Brain –Atria of heart –Placenta

Copyright © 2004 Lippincott Williams & Wilkins Hormones and Treatment Hormones are extracted from animal tissue, manufactured in the lab, or genetically engineered –Growth hormone –Insulin –Adrenal steroids –Epinephrine (adrenaline) –Thyroid hormones –Oxytocin –Androgens –Estrogen and progesterone

Copyright © 2004 Lippincott Williams & Wilkins Hormones and Stress Stress response involves both nervous and endocrine system Hormones released during stress help body cope Unchecked levels of hormones can harm body

Copyright © 2004 Lippincott Williams & Wilkins Checkpoint 11-14: What are some hormones released in time of stress? –Epinephrine –ACTH –Glucocorticoids

Copyright © 2004 Lippincott Williams & Wilkins Aging and the Endocrine System Pancreas –Adult-onset diabetes mellitus Thyroid –Decreased hormone secretion Pituitary –Decreased gonadotropic hormones –Decreased growth hormone Gonads –Decreased sexual activity –Loss of bone mass