The Endocrine System

1. The Endocrine System What is the function of the endocrine system? How does the endocrine system maintain homeostasis?

2. What’s it all about? • The endocrine system is made up of glands that release their products into the bloodstream. These products broadcast messages throughout the body. Video Clip

3. Hormones • Hormones are chemicals that travel through the bloodstream and affect the activities of other cells. Hormones do this by binding to specific chemical receptors on those cells. • Cells that have receptors for a particular hormone are called target cells. Lock and key

4. Glands • A gland is an organ that produces and releases a substance or a secretion. • Exocrine glands: release their secretions through tubelike structures called ducts directly to the organs that need them. • Sweat glands • Tear glands • Digestive glands • Endocrine glands: release their hormones directly into the blood stream. • There are 10 major endocrine glands in the body

5. Control of the Endocrine System • Like most systems of the body; the endocrine system is regulated by feedback mechanisms that function to maintain homeostasis.

6. Feedback • Feedback mechanisms are best described as a process that helps keep body conditions near a normal, steady state. • Example: An increase in the level of insulin in the blood would result in a decrease in the amount of glucose in the blood.

7. Actions of Insulin and Glucagon Beta cells release insulin into the blood Body cells absorb glucose Blood glucose level increases Blood glucose level decreases Liver converts glycogen to glucose Homeostasis: Normal blood glucose level Blood glucose level increases Blood glucose level decreases Liver converts glycogen to glucose Alpha cells release glucagon into blood

8. https://www.youtube.com/watch?v=CLv3SkF_Eag

9. Endocrine Glands • Hypothalamus • Pituitary gland • Parathyroid glands • Thymus • Adrenal Glands • Pineal Gland • Thyroid • Pancreas • Ovary • Testis

10. Growth Waterbalance Reproduction Metabolism Calciumand glucoselevels Responseto stress Pituitary Testes Thyroid Pancreas Adrenals Ovaries Parathyroids The Endocrine System regulates by meansof the by meansof the by meansof the by meansof the by meansof the by meansof the

11. The Pituitary Gland: “ Master Gland” • The pituitary gland secretes nine hormones that directly regulate many body functions and controls the actions of several other endocrine glands. • Releases a hormone that causes the release of estrogen.

12. The Pituitary Gland

13. Hypothalamus • The hypothalamus controls the secretions of the pituitary gland.

14. https://www.youtube.com/watch?v=nNLsXKkLSTs

15. Thyroid gland • The thyroid gland has the major role in regulating the body’s metabolism.

16. Parathyroid Glands • Hormones from the thyroid gland and the parathyroid glands maintain homeostasis in blood calcium levels.

17. Adrenal Glands • The adrenal glands help the body prepare for and deal with stress. • Also regulates the glucose levels in blood.

18. Pancreas • Insulin and glucagon released from the pancreas help to keep the level of glucose in the blood stable. • Insulin decreases blood sugar • Glucagon increases sugar level

19. Hormone Action • Hormones may be classified as belonging to two general groups • Steroid hormones: produced from a lipid called cholesterol, can pass through cell membranes easily (target cells) • Non-steroid hormones: include proteins, small peptides, and modified amino acids: cannot pass through cell membranes of target cells

20. Feedback Mechanism • Recall that feedback inhibition occurs when an increase in any substance “feeds back” to inhibit the process that produced the substance in the first place.

21. https://www.youtube.com/watch?v=WVrlHH14q3o

22. The Reproductive System

23. Sexual reproduction (Review) • Meiosis -process of reduction division in which the number of chromosomes per cell is cut in half • Haploid- a cell that contains only a singleset of chromosomes. (single set of genes) • Gamete- Sex cell, sperm or egg • Gonads- ovaries or testes • Hormones- • Estrogen (female) • Testosterone (male)

25. Hormones • Puberty begins when the hypothalamus signals the pituitary to produce increased levels of two hormones that affect the gonads. • These hormones are follicle-stimulatinghormone (FSH) and luteinizing hormone (LH) • FSH & LH in males stimulates the production of testosterone • FSH & LH in females stimulates the production of estrogen

26. The Female Reproductive System • The main function of the female reproductive system is to produce ova (egg). In addition, the female reproductive system prepares the female’s body to nourish a developing embryo. • Ovaries produce and release the egg • Follicles are clusters of cells that surround a cell egg. • Female hormone is estrogen has direct effect on the changes within the uterus.

27. Egg Development • Each ovary contains about 400,000 primary follicles. • The function of a follicle is to help an egg mature for release into the reproductive tract, where it can be fertilized. Eggs develop within their follicles. • Approximately every 28 days, under the influence of FSH, a follicle gets larger and completes the first meiotic cell division.

28. Menstrual Cycle • Menstrual in Latin means month • About a 28 day cycle • Regulated by hormones • During the menstrual cycle, an egg develops and is released from an ovary. The uterus is prepared to receive a fertilized egg. • If fertilized then the egg is implanted in the uterus. • If an egg is not fertilized then it is discharged along with the uterus lining.

29. Phases • Follicular phase- Starts with low levels of estrogen. Body reacts releases FSH and LH which cause a follicle to develop. • Ovulation- shortest phase 3-4 days sudden rush of FSH & LH causes follicle to rupture and a mature egg is released into one of the fallopian tubes

30. Luteal Phase- Starts after the egg is released and moves through fallopian tube. The cells of the ruptured follicle undergo a change, turn yellow and is called corpus luteum. This continues to release estrogen and progesterone. • Menstruation- If no fertilization within 2-3 days of ovulation the egg will pass through the uterus without implantation. Corpus luteum will begin to disintegrate. Estrogen levels drop and the uterus lining will detach and be discharged along with the egg and blood. Lasts 3-7 days

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

32. Fetus usually develops in the uterus • Egg is fertilized in the fallopian tube.

33. The Male Reproductive System • The main function of the male reproductive system is to produce and deliver sperm (internal fertilization) • Testes are adapted to produce sperm cells. • Sperm (male gamete) transports genetic information • Haploid • Testosterone

34. Urinary bladder Pubic bone Vas deferens Urethra Penis Seminal vesicle Large intestine Prostate gland Rectum Scrotum Bulbourethral gland Epididymis Testis The MaleReproductive System

35. Fertilization • Fertilization occurs in the fallopian tube • After fertilization the zygote begins to undergo mitosis • Four days after it is a solid ball of about 64 cells. • 7 days after implantation occurs.

37. Placenta • The placenta is a vital organ that connects the mother and the embryo. • It is the embryo’s organ of respiration, nourishment and excretion. (diffusion) • It is also a means of getting rid of metabolic wastes (excretion). CO2 passes from fetus to parent is the greatest amount. • Wastes diffuse into the mother’s blood from the embryo’s blood. • Their blood does not mix!

39. Amniotic sac Placenta Umbilical cord Fetalportion of placenta Maternalportion ofplacenta Villus in chorion Amnion Uterus Amnion Umbilical cord Maternal artery Maternal vein Umbilical arteries Umbilical vein Figure 39–20 The Placenta

40. Fetus • After 8 weeks of development the embryo is called a fetus.

41. Embryonic Stem Cells • Cells that are capable of differentiating into any type of cell.