CHAPTER 39 THE ENDOCRINE AND REPRODUCTIVE SYSTEMS

1. CHAPTER 39 THE ENDOCRINE AND REPRODUCTIVE SYSTEMS

2. Section 1 The Endocrine System

3. Key Concept Questions • What is the function of the endocrine system? • How does the endocrine system maintain homeostasis?

4. The endocrine system does the following: • regulates metabolism • maintains salt, water, and nutrient balance in the blood • controls the body’s response to stress • regulates growth, development, and reproduction

5. Like the nervous system, the endocrine system sends messages to the body’s cells. • When the body needs an immediate reaction, those messages are sent along the nervous system. • When the body needs to bring about a long-term change, those messages are sent through the endocrine system.

6. receptor target cell hormone bloodstream not a target cell • The endocrine system works more slowly than the nervous system. • only chemical signals • signals move through bloodstream • physically unconnected organs

7. Hormones are chemicals that travel through the bloodstream and affect the activities of other cells. • Produced by endocrine glands • An endocrinegland is an organ that produces and releases hormones directly into the bloodstream or into the fluid around cells. • travel through the circulatory system

8. Hormones affect other cells by binding to specific chemical receptors on those cells. (lock-and-key)- Cells that have receptors for a particular hormone are called targetcells. If a cell does not have receptors or the receptors do not respond to a particular hormone, the hormone has no effect on it.

9. An example of a hormone in action - as people sweat, they lose water and salts. • A hormone signals the kidneys to make less urine and conserve water. • Another hormone signals the kidneys to reabsorb salt from urine and the sweat glands to decrease the amount of salt in sweat.

10. How does the endocrine system maintain homeostasis? • Like most systems of the body, the endocrine system is regulated by feedback mechanisms that function to maintain homeostasis

11. A body’s internal state varies around a certain average value • Homeostasis maintains a dynamic equilibrium in the body.

12. Your body has a variety of feedback mechanisms that detect deviations in the body’s internal environment and make corrections. • A feedbackmechanism is a mechanism in which the last step in a series of events controls the first step.

13. Notice how an increase in TSH causes the release of thyroxine. As the level of thyroxine increases in the blood, the level of TSH decreases. This action causes a decrease in thyroxine, which causes an increase in TSH, and the cycle begins again.

15. Controlling Blood-Glucose Level • Your body’s cells need glucose to perform cellular respiration. • When you digest a large meal, a large amount of glucose is introduced into your body in a short period of time. • Two hormones, insulin and glucagon, control the level of glucose in the bloodstream.

16. Controlling Blood-Glucose Level • Insulin and glucagon are released by the pancreas. • These hormones work oppositely to regulate blood-glucose level. • Insulin lowers blood glucose levels by communicating with the liver to convert glucose into glycogen that can be stored for future use.

17. Controlling Blood-Glucose Level • When glucose levels fall below the normal range, glucagon stimulates the liver to break down glycogen. • This adds more glucose to the bloodstream. • This feedback system regulates blood-glucose levels, so they do not stay too high after a meal and do not drop too low between meals.

18. When the pancreas produces too little insulin, a condition known as diabetesmellitus occurs. • In diabetes mellitus, the amount of glucose in the blood may rise so high that the kidneys actually excrete glucose in the urine • Very high blood glucose levels can damage many organs and tissues, including the coronary arteries.

19. Key Concept Questions • What is the function of the endocrine system? • regulates metabolism • maintains salt, water, and nutrient balance in the blood • controls the body’s response to stress • regulates growth, development, and reproduction

20. Key Concept Questions • How does the endocrine system maintain homeostasis? • The endocrine system is regulated by feedback mechanisms that function to maintain homeostasis

21. SECTION 2 Human Endocrine Glands

22. Key Concept Question • What are the functions of the major endocrine glands?

23. Glands • Pineal • melatonin • Pituitary • many hormones: master gland • Thyroid • thyroxine • Adrenal • adrenaline • Pancreas • insulin, glucagon • Ovary • estrogen • Testes • testosterone

24. HYPOTHALAMUS PITUITARY THYROID THYMUS ADRENAL GLANDS PANCREAS FEMALE GONADS :OVARIES MALE GONADS : TESTES Endocrine glands secrete hormones that act throughout the body. • There are many glands located throughout the body. • Hormones travel through the bloodstream to cells with matching receptors.

25. The hypothalamus is a gland found in the brain. • a structure of both the nervous andendocrine systems • produces releasing hormones,sent to pituitary gland

26. The pituitary gland is found below the hypothalamus in the brain. • controls growth and waterlevels in blood • produces releasing hormones sent throughout the body

27. Thyroidgland • regulates the body’s metabolism • The adrenalglands help the body prepare for and deal with stress • Release epinephrine and norepinephrine

28. Insulin and glucagon released from the pancreas help to keep the level of glucose in the blood stable • The gonads serve two important functions: the production of gametes and the secretion of sex hormones • The female gonads—the ovaries—produce eggs (ova). • Estrogen, progesterone • The male gonads—the testes (singular: testis)—produce sperm. The gonads also produce sex hormones. • testosterone

29. Hormonal imbalances can cause severe illness. • Abnormal hormone levels affect homeostasis. • Hormonal imbalances might be treated with surgery or medicine. • Steroids, a pituitary tumor, or some prescription drugs can make the pituitary overactive and indirectly cause problems.

30. Key Concept Question • What are the functions of the major endocrine glands? • Hypothalamus – controls other glands • Pituitary – controls growth and water levels • Thyroid – regulates metabolism • Adrenal – helps the body deal with stress • Pancreas – controls blood glucose levels • Gonads – produce gametes and sex hormones

31. SECTION 3 The Reproductive System

32. Key Concepts • What are the main functions of the male and female reproductive systems?  • What are the four phases of the menstrual cycle?

33. After birth, the gonads produce small amounts of sex hormones that continue to influence the development of the reproductive organs. However, neither the testes nor the ovaries are capable of producing active reproductive cells until puberty.

34. Puberty is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. • At the completion of puberty, the male and female reproductive organs are fully developed.

35. The onset of puberty varies considerably among individuals. It may occur any time between the ages of 9 and 15, and, on average, begins about a year earlier in females than in males. • Puberty begins when the hypothalamus signals the pituitary to produce increased levels of hormones that affect the gonads.

36. urinary bladder seminal vesicle vas deferens pubic bone prostate gland rectum penis urethra epididymis bulbourethral gland scrotum testis The male reproductive system • There are two main functions of the male reproductive system. • produce sperm cells • deliver sperm to the female reproductive system

37. Sperm Production • Two testes (testicles) (singular – testis) • produce the male gametes, sperm • located inside the scrotum, a sac that hangs from the body. • Produce primary male sex hormone, testosterone. • Testosterone has two main functions. • developing male sexual characteristics • producing sperm

38. potential sperm Meiosis I Meiosis II 4 sperm cells Sperm production in the testes is controlled by hormones. • Testosterone, FSH, and LH stimulate sperm production. • one sex cell divides into four sperm • each sperm has 23 chromosomes

39. Testes are made of hundreds of tightly coiled tubes called seminiferoustubules where sperm cells are produced.

40. Path of Sperm • Seminiferous tubules to epididymis • Epididymis • a long coiled tube attached to the top of each testis. • sperm mature and are stored for up to two weeks • From the epididymis, sperm move to vasdeferens.

41. Path of Sperm • The vas deferens carries sperm into the urethra. • Sperm leave the body by passing through the urethra, the same duct through which urine exits the body.

43. Sperm cell • Head • Midpiece • Tail • Enzymes produced at the tip of the head help the sperm cell to penetrate an egg cell during fertilization. • ATP produced within mitochondria located in the midpiece powers the movement of the tail, allowing the sperm to move through the female reproductive system.

44. Semen • Sperm cells mix with fluids secreted by • seminal vesicles • prostate gland • bulbourethral glands. • Seminal vesicles • lie between the bladder and the rectum • produce a fluid rich in sugars that sperm use for energy.

45. Prostate gland • located just below the bladder • secretes an alkaline fluid that helps to balance the acidic pH in the female reproductive system. • Bulbourethral glands • secrete fluid that neutralizes traces of acidic urine in the urethra and lubricates the path as sperm leave the body. • The fluid that contains sperm mixed with these various secretions is called semen.

47. Sperm Delivery • The penis • male organ that deposits sperm into the female vagina • During arousal, blood collects within spaces separating spongy tissue in the penis, causing the penis to become erect. • The ejection of semen out of the penis through the urethra is calledejaculation.

48. Sperm swim until they encounter an egg cell or until they die. • If a sperm cell does not reach an egg, fertilization does not occur. • About 300-400 million sperm are expelled during ejaculation in 3.5 mL of semen. • Males with fewer than 20 million sperm per mL of semen are generally considered sterile.

49. Why do you think the sperm cell has a tail? • To help the sperm swim through the female reproductive tract to the egg • How do the sperm get from the epididymis to the urethra? • Through the vas deferens • When an adult male has a vasectomy, what structure do you think is being cut and tied off? • Vas deferens

50. uterus fallopian tube ovary cervix pubic bone urinary bladder rectum urethra vagina The female reproductive system. • There are two main functions of the female reproductive system. • produce ova, or egg cells • provide a place where a zygote develops