1. Chapter 20: Regulation and Reproduction

2. The Endocrine System The endocrine system: --less rapid --longer-lasting than the nervous system -- regulates slower body processes --examples: metabolism and cell growth Nervous system's functions: -- more immediate, --controls body movement, breathing, thinking, coughing, etc. Picture courtesy of: http://kidshealth.org/parent/general/body_basics/endocri ne.html

3. Endocrine System Works by Secreting Hormones: Chemicals that control many systems in the body. --Examples: estrogen, testosterone, insulin --body's chemical messengers: transfer information & instructions from one set of cells to another Regulate mood, growth and development, tissue function, metabolism, etc.

4. Hormones In women hormones support pregnancy and other reproductive processes. Hormone levels vary --stress, infection, amount of minerals in blood

5. Structures of endocrine system: Pineal gland: pine cone shape, produces melatonin melatonin regulates sleep cycles Pituitary gland (master gland): pea-sized gland attached to hypothalamus makes many hormones that control: growth, metabolism, reproduction, blood pressure, secretion of sex hormones, etc.

6. Structures of endocrine system: Thymus: In chest behind sternum –Stimulates production of lymphocytes(WBC) Thyroid gland: –Below larynx; regulates metabolism, calcium levels, nervous sys. development Parathyroid glands: behind thyroid –Help regulate calcium levels

7. Structures of endocrine system: Adrenal glands: on top of kidneys Pancreas: near stomach Ovaries: only in females Testes: only in males

8. Negative Feedback Cycle Hormones have specific tissues they affect. Dumped into blood stream, no ducts Works until desired conditions are reached. –Example: eating a meal, blood sugar (glucose) levels rise, pancreas makes insulin, body tissues take up glucose with help of insulin, sugar levels return to normal

9. Section 2: The Reproductive System Function of the reproductive system: create new life Pituitary gland makes hormones that aid in development of sexual characteristics: –Example: facial hair, breast development –Also stimulates production of sex cells: eggs and sperm

10. Male Reproductive System: External organs: penis, scrotum Internal organs: testes, prostate gland, seminal vesicle, sperm duct –Testes make testosterone and sperm –Sperm mixes with fluid from seminal vesicle to make semen –Semen leaves the male body through the urethra, same tube that carries urine

11. Female Reproductive System: Mainly internal organs: ovaries, cervix, oviduct, uterus, vagina –Eggs: born with all in ovaries; begin release at puberty –Ovulation: monthly release of an egg; ovaries alternate releasing an egg –Egg may become fertilized if in contact with sperm; fertilization usually occurs in oviduct (Fallopian tube) –It is internal fertilization since it occurs inside the female body.

12. Female Reproductive System: Uterus: pear-shaped (normally about the size of a fist), muscular organ –Where a fertilized egg usually develops –Cervix: narrow opening of uterus to outside; has to stretch (dilate) for baby to come out—only 10 cm which is less than 3 inches in diameter Vagina: “birth canal”, muscular tube that pushes the baby from the body—women do not urinate from their vaginas! They urinate through their urethra just like men.

13. Female Reproductive System: The Menstrual Cycle Monthly changes in the female reproductive system –Prepares the body for pregnancy; Controlled by hormones –Cycle varies from 20 to 40 days, average is 28 days Three major changes: maturing of an egg, make female sex hormones, & preparing the uterus

14. Menstrual Cycle Three phases: –Phase 1: Menstruation—flow of blood and tissue cells released from the thickened lining of the uterus; lasts 4 to 6 days –Phase 2: Hormones cause the uterus lining to thicken & development of egg in an ovary Ovulation occurs about 14 days prior to menstruation; egg must be fertilized in 24 hrs Sperm can live in female body for 5 days so fertilization can occur as soon as egg is released

15. Menstrual Cycle Phase 3: Hormones made by ovaries continue to cause uterine lining to thicken If a fertilized egg arrives, uterus nourishes it. If not, the lining begins to break down as hormone levels drop. Menstruation begins and cycle repeats.

16. Menstrual Cycle Ends Cycle begins at ages 9 to 13 on average Continues until age 45 to 60 Menstruation slows down and stops due to a drop in hormone production by ovaries slows. Menopause occurs when both menstruation and ovulation occurs. Can take several years to complete

17. Section 3: Human Life Stages Fertilization: –Size of an egg; sperm smaller –200 to 300 million sperm can be deposited –Only several thousand reach an egg –Secretions of vagina cause changes in the sperm that make it able to fertilize the egg Zygote formation: –Nucleus of egg & sperm join to form zygote

18. Multiple Births Fraternal twins: two eggs Identical twins: one egg that splits into two Triplets: three eggs or three splits Quadruplets: four eggs or four splits

19. Development before birth: Zygote moves to oviduct (Fallopian tube) to uterus (if not, ectopic pregnancy) Implants in uterus after about 7 days Attachment = pregnancy (38 to 39 wks) Embryo: what the zygote is after it attaches to the uterine wall –Placenta –Amniotic sac

20. Embryo At 6 weeks the embryo size is about as big as a grain of rice Organs form & heart beats by 6 weeks At 5 weeks: head with eyes, nose, & mouth 6 & 7 weeks: fingers and toes develop

21. Zygote

22. Embryo at 6 Weeks Gestation: Size less than a grain of rice; heart is beating

23. 7 Weeks Gestation: Amniotic sac present & implanted into uterine wall

24. 10 Weeks Gestation: about size of an olive

25. 14 Weeks Gestation: 3-4 inches long

26. 18 Weeks Gestation

27. Fetus After 2 months of pregnancy, embryo is called a fetus 3 months: fetus is 8 to 9 cm long 4 months: sex can be determined by ultrasound; fetus is 30-38 cm long 9 months: fetus is about 50 cm long & weighs 6-10 pounds

28. Birthing Process Muscular contractions of uterus Amniotic sac ruptures release fluid Birth occurs in minutes to many hours as the contractions push the baby out Placenta (afterbirth) delivers up to an hour after baby Vaginal (natural) versus Cesarean section

29. Stages after birth Infancy: birth to 18 months Childhood: 18 months to puberty Adolescence: teen years Adulthood: 20s to older adulthood (over 60) or death Older adulthood: senior citizens; anyone over 60 Life span averages 75 years