Interest Grabber Fast and Slow Messages Section 39-1 Fast and Slow Messages Your endocrine (hormonal) system is the slow message system of your body. Its messages consist of chemicals released by glands into the bloodstream. Your nervous system, on the other hand, is the fast message system of the body. Its messages consist of electrical signals that travel along the membranes of nerve cells. 1. Describe a situation in which the body could use the endocrine system to deliver a “slow” message. 2. Describe a situation in which the body could use the nervous system to deliver a “fast” message. 3. Develop an analogy that illustrates this difference between these two systems.

Section Outline 39–1 The Endocrine System A. Hormones B. Glands C. Hormone Action 1. Steroid Hormones 2. Nonsteroid Hormones D. Prostaglandins E. Control of the Endocrine System 1. Controlling Metabolism 2. Maintaining Water Balance F. Complementary Hormone Action

Hormone Action Section 39-1 Nonsteroid hormone (first messenger) Target cell membrane Receptor Target cell membrane Receptor cAMP (second messenger) Hormone-receptor complex Altered cellular function Nucleus Enzyme activities DNA Altered cellular function Protein synthesis Nucleus Cytoplasm Cytoplasm mRNA

Hormone Action Section 39-1 Nonsteroid hormone (first messenger) Target cell membrane Receptor Target cell membrane Receptor cAMP (second messenger) Hormone-receptor complex Altered cellular function Nucleus Enzyme activities DNA Altered cellular function Protein synthesis Nucleus Cytoplasm Cytoplasm mRNA

Figure 39–2 The Endocrine Glands Section 39-1 Hypothalamus The hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland. Pineal gland The pineal gland releases melatonin, which is involved in rhythmic activities, such as daily sleep-wake cycles. Thyroid The thyroid produces thyroxine, which regulates metabolism. Pituitary gland The pituitary gland produces hormones that regulate many of the other endocrine glands. Pancreas The pancreas produces insulin and glucagon, which regulate the level of glucose in the blood. Parathyroid glands These four glands release parathyroid hormone, which regulate the level of calcium in the blood. Ovary The ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg. Thymus During childhood, the thymus releases thymosin, which stimulates Tcell development. Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics Adrenal glands The adrenal glands release epinephrine and nonepinephrine, which help the body deal with stress.

Interest Grabber A Grizzly Scenario Section 39-2 A Grizzly Scenario Imagine that you are hiking in the Rocky Mountains, and you happen upon a grizzly bear and her cubs. The mother grizzly looks as if she is about to attack you. Terrified, you back away slowly to get out of the bears’ “territory.” You desperately want to turn and run, but you know that might cause the mother bear to attack you. 1. When you are frightened, it triggers the “fight-or-flight” response. Describe the changes that took place in your body the last time you were in a scary situation. 2. Which body structures do you think become readied for this “fight-or flight” response? Why do you think this happens to these structures? 3. Which body structures do you think are slowed down during this “fight-or-flight” response? Why do you think this happens?

Section Outline 39–2 Human Endocrine Glands A. Pituitary Gland B. Hypothalamus C. Thyroid Gland D. Parathyroid Glands E. Adrenal Glands 1. Adrenal Cortex 2. Adrenal Medulla F. Pancreas G. Reproductive Glands

Calcium and glucose levels Concept Map Section 39-2 The Endocrine System regulates Growth Water balance Reproduction Metabolism Calcium and glucose levels Response to stress by means of the by means of the by means of the by means of the by means of the by means of the Pituitary Ovaries Testes Thyroid Pancreas Adrenals Parathyroids

Figure 39–10 Actions of Insulin and Glucagon Section 39-2 Beta cells release insulin into the blood Body cells absorb glucose Blood glucose level increases Liver converts glycogen to glucose Blood glucose level decreases Homeostasis: Normal blood glucose level Blood glucose level increases Blood glucose level decreases Liver converts glycogen to glucose Alpha cells release glucagon into blood

Interest Grabber A Soprano Becomes a Tenor Section 39-3 A Soprano Becomes a Tenor Many changes take place in the human body between the ages of about 9 to 15 years. Think about the changes that you have noticed in yourself and your friends in the last few years. Then, answer the following questions. 1. How does an eight-year-old male’s voice compare to that of an adult male? How does an eight-year-old female’s voice compare to that of an adult female? 2. What do you think causes the differences in the voices? Explain your answer. 3. Another change that occurs between 9 and 15 is a growth spurt, which is a rapid increase in height. Do you think growth spurts occur earlier in males or in females? Explain your answer.

Section Outline 39–3 The Reproductive System A. Sexual Development B. The Male Reproductive System 1. Sperm Development 2. Sperm Release C. The Female Reproductive System 1. Egg Development 2. Egg Release D. The Menstrual Cycle 1. Follicular Phase 2. Ovulation 3. Luteal Phase 4. Menstruation

The Menstrual Cycle Section 39-3

Figure 39–14 The Male Reproductive System Section 39-3 Large intestine Rectum Seminal vesicle Prostate gland Bulbourethral gland Epididymis Testis Scrotum Penis Urethra Vas deferens Pubic bone Urinary bladder

Figure 39–15 The Female Reproductive System Section 39-3 Fallopian tube Ovary Urinary bladder Pubic bone Urethra Vagina Uterus Cervix Rectum

Interest Grabber More Than One Section 39-4 More Than One Fertilization is the fusion of a sperm and an egg to form a zygote, the single cell from which all cells of the human body are derived. When an egg is fertilized, the remarkable process of human development begins. 1. If two eggs are released during ovulation, each can be fertilized by a sperm. What do you think would be the result? Explain your answer. 2. If one zygote splits into two, each can continue development on its own. What do you think would be the result? Explain your answer. 3. Triplets are three babies born at the same time. Describe three ways that triplets could develop.

Section Outline 39–4 Fertilization and Development A. Fertilization B. Early Development 1. Gastrulation 2. The Placenta C. Later Development D. Childbirth E. Early Years 1. Infancy 2. Childhood 3. Adolescence F. Adulthood

Fertilization and Implantaton Section 39-4 Uterine wall Blastocyst Morula 4 cells 2 cells Zygote Ovary Fallopian tube Day 3 Day 2 Day 1 Day 4 Fertilization Day 0 Day 7 Implantation of blastocyst Egg released by ovary

Figure 39–20 The Placenta Section 39-4 Amniotic sac Placenta Umbilical cord Uterus Amnion Fetal portion of placenta Maternal portion of placenta Maternal artery Maternal vein Umbilical arteries Umbilical vein Villus in chorion