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9
The Endocrine System
PART A
PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University
ESSENTIALS
OF HUMAN
ANATOMY
& PHYSIOLOGY
EIGHTH EDITION
ELAINE N. MARIEB
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
The Endocrine System
 Uses chemical messages (hormones) that are
released into the blood
 Hormones control several major processes
 Reproduction
 Growth and development
 Mobilization of body defenses
 Maintenance of much of homeostasis
 Regulation of metabolism
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormone Overview
 Cells secrete hormones into blood
 Blood transfers hormones to target sites
 The hormones regulate activity of other cells
Types of hormones:
 Amino acid-based hormones (proteins)
 Steroids – made from cholesterol
 Prostaglandins – made from lipids
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Mechanisms of Hormone Action
 Hormones affect only certain tissues or
organs (target cells or organs)
 Hormones can trigger cells to produce certain
proteins, enzymes, reactions, cell divisions
 Hormone levels in the blood are maintained
by negative feedback:
 A stimulus or low hormone levels in blood
triggers the release of more hormone
 Hormone release stops once a certain level
in the blood is reached
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Stimuli of Endocrine Glands
 Endocrine glands:
 Hypothalmus
 Pituitary and
Pineal glands
 Thyroid gland
 Thymus gland
 Adrenal cortex
 Pancreas
 Gonads
(testis & ovaries
Figure 9.2a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Endocrine
 Pituitary Gland: near hypothalamus of brain
 Growth Hormone- general metabolism,
growth of muscles and bones
 Prolactin (PRL)- milk production
 Adrenocorticotropic hormone (ACTH)regulates adrenal glands on-top of kidneys
 Thyroid-stimulating hormone (TSH)- growth
& activity of thyroid (Immune System)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Functions of Other Anterior Pituitary
Hormones
Pituitary Gland:
 Gonadotropic hormones Regulate hormonal activity of the gonads
 Follicle-stimulating hormone (FSH)
Stimulates ovaries and sperm development
 Luteinizing hormone (LH)
Triggers ovulation and testosterone
production
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Posterior Pituitary
Pituitary Gland
 Oxytocin - stimulates contractions of the
uterus during labor, milk ejection
 Antidiuretic hormone (ADH)
 Triggers kidneys to retain water
 Can inhibit urine production
 In large amounts, causes raised blood
pressure (vasopressin)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Thyroid Gland
Thyroid Gland
 Found at the base of the throat
 Thyroid hormone- thyroxine has
Iodine. Important in metabolism.
 Calcitonin- triggers calcium to
move from blood into bones.
(parathyroid triggers calcium to
move from bone to blood)
Goiters- not enough iodine
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Adrenal Glands
Adrenal Glands: sits on top of the kidneys
Aldosterone- regulates mineral content in
blood, water, and electrolyte balance
Glucocorticoids (cortisone and cortisol)promote normal cell metabolism
Sex hormones- androgens (male) and some
estrogen (female)
Epinephrine & Norepinephrine- prepare the
body to deal with short-term stress
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Islets
Pancreas: The islets of the pancreas produce
hormones (formerly called islets of langerhans)
 Insulin – allows glucose to move from
blood into cells
 Glucagon – allows glucose to move from
cells into blood
 These hormones are antagonists that
maintain blood sugar homeostasis
Diabetes: issues with insulin hormone
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pineal and Thymus Glands
Pineal Gland: found in brain
 Melatonin- triggers the body’s wake and
sleep cycles
Thymus Gland: found under sternum
 Thymosin- white blood cells, important in
developing the immune system
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Ovaries
Ovaries
 Estrogens-
 stimulates development of secondary female
characteristics, female reproductive organs,
prepares uterus to receive a fertilized egg,
maintains pregnancy, milk production
 Progesterone - produced by the corpus luteum
 acts with estrogen to bring about the
menstrual cycle, helps in the implantation of
an embryo in the uterus
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Testes
Testes
 Androgens-
 Testosterone is most important androgen.
Responsible for male secondary sex
characteristics, growth of male
reproductive system, sperm production
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings