Endocrine and Reproductive Systems. Chapter 39: Biology II

Transcription

1 Endocrine and Reproductive Systems Chapter 39: Biology II

2 The Endocrine System Made up of glands that release their products into the bloodstream These products broadcast messages throughout the body Chemicals released can affect almost every cell in the body

3 Substances produced in one part of an organism that affect another part of the same individual The chemicals that broadcast messages from the endocrine system Hormones

4 Target Cell Cell affected by a particular hormone It takes several minutes, hours or even days, for a hormone to effect a target cell

5 Glands An organ that produces and releases a substance or a secretion Exocrine gland: gland that releases its secretions through tube-like structures called ducts Endocrine gland: gland that releases its secretions directly into the bloodstream

6 Hormone Action Steroid hormones: produces from a lipid called cholesterol Nonsteroid hormones: proteins, small peptides, and modified amino acids

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8 Prostaglandins Hormone-like modified fatty acid produced by a wide range of cells Generally affects only nearby cells and tissues Local hormones Produced by all cells except RBCs

9 Control of the Endocrine System Regulated by feedback mechanisms that function to maintain homeostasis Controlling metabolism Maintaining water balance

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11 Pituitary Gland Bean-sized structure that dangles on a slender stalk of tissue at the base of the skull Secretes 9 hormones that directly regulate many body functions Controls the actions of several other endocrine glands

12 Hormones Secreted by the Pituitary Gland * Interstitial cell stimulating hormone (ICSH)

13 Hypothalamus Part of the brain attached to the posterior pituitary Acts as a control center for recognition and analysis of hunger, thirst, fatigue, anger, and body temperature

14 Hypothalamus

15 Thyroid Gland Located at the base of the neck and wraps around the upper part of the trachea Major role in regulating the body s metabolism Hyperthyroidism and hypothyroidism

16 Parathyroid Glands Found on the back surfaces of the thyroid gland Hormones from the thyroid gland and the parathyroid glands maintain homeostasis in blood calcium levels

17 Adrenal Glands Two pyramid-shaped structures that sit on top of the kidneys Help the body prepare for and deal with stress Control Fight or Flight response Composed of two parts: Adrenal cortex Adrenal medulla

18 Pancreas Digestive organ that has enzymes that secrete substances that break down food Insulin and glucagon released from the pancreas help to keep the level of glucose in the blood stable Diabetes: the pancreas produces too little insulin

19 Reproductive Glands/Gonads Two important functions: Production of gametes (eggs and sperm) Secretion of steroid sex hormones Males and females have the same hormones but in different amounts

20 Steroid Hormones Estrogen: found in greater quantities in women than men and contributes to female sexual characteristics and development Testosterone: found in greater quantities in men than women and contributes to male sexual characteristics and development

21 Male Reproductive System Work together to produce and deliver sperm Testes Epididymis Vas deferens Urethra Penis

22 Male Reproductive System

23 Male Reproductive System

24 Male Reproductive System Scrotum: external sac containing the testes Seminiferous tubule: one of hundreds of tiny tubules in the testes in which sperm are produced Epididymis: structure in the male reproductive system in which sperm fully mature and are stored

25 Male Reproductive System Vas deferens: tube that carries sperm from the epididymis to the urethra Urethra: tube through which urine and semen are released from the body Penis: external male reproductive organ that connects the urethra to the outside of the body

26 Sperm Production in the Testes is Controlled by Hormones Takes about 70 days to make sperm Sperm in various stages of development can be found throughout the testis

27 Male Reproductive System million sperm are released in an average ejaculation The chances of a single sperm fertilizing an egg are quite good

28 Female Reproductive System Produces eggs and prepares the female s body to nourish a developing embryo Ovaries Fallopian tubes Uterus Vagina

29 Female Reproductive System

30 Female Reproductive System Fallopian tube: one of two fluidfilled tubes in human females through which an egg passes after its release from an ovary Uterus: organ of the female reproductive system in which a fertilized egg can develop Vagina: canal in the human fetal reproductive system that leads from the uterus to the outside of the body

31 Eggs Mature and are Released According to Hormonal Cycles Every 28 days (or so) an increase in FSH stimulates a potential egg to complete meiosis I Meiosis II is only completed if a sperm cell enters

32 Female Fertility Facts A woman is born with a finite number of eggs Release of eggs starts with the first menstrual cycle A woman will release between eggs in her lifetime Egg number and quality decreases with age In healthy couples under age 30 who have sex regularly, the chance of getting pregnant is about 25-30% per month. A woman's peak fertility occurs in her early 20s. After age 35 (and especially 40), the chances that a woman can get pregnant drops considerably.

33 Release of the Developing Egg Follicle: cluster of cells surrounding a single egg in the human female reproductive system Ovulation: process in which an egg is released from the ovary

34 Menstrual Cycle Follicular phase Ovulation Luteal phase Menstruation

35 Menstrual Cycle

36 Follicular Phase Level of estrogen in the blood is relatively low The anterior pituitary secretes FSH and LH In the ovaries a follicle develops to maturity More estrogen is made and the lining of the uterus thickens in preparation for receiving a fertilized egg Endometrium: the lining of the uterus

37 Ovulation Shortest time frame: 3-4 days The pituitary gland produces a rush of FSH and LH The follicle ruptures and a mature egg is released into one of the Fallopian tubes

38 Luteal Phase The egg moves through the Fallopian tube and the cells of the ruptured follicle undergo a change Corpus Luteum: the follicle turns yellow and releases estrogen and progesterone to limit LH Greatest chance for fertilization: first 2 days of the luteal phase (10-14 days after the completion of the last menstrual cycle)

39 Luteal Phase If an egg is fertilized by a sperm, it starts to divide After several divisions, a ball of cells will form and implant itself in the lining of the uterus

40 Menstruation If fertilization does not occur, the egg will pass through the uterus without implantation Within 2-3 days of ovulation The follicle breaks down, releasing less and less estrogen and progesterone 3-7 days on average

41 Menstruation Last phase of the menstrual cycle, during which the lining of the uterus, along with blood and the unfertilized egg, is discharged through the vagina Menopause: period of life when the female reproductive system permanently stops the menstrual cycle Can occur as early as a woman s mid 30s

42 Fertilization Process of a sperm joining an egg Sperm swim actively through the uterus into the Fallopian tubes Only about 1% reach the upper region of each Fallopian tube

43 Fertilization Sperm attach to a binding site on the egg A sac in the sperm head ruptures and releases powerful enzymes that break down the protective layer covering the egg Together the egg and sperm form a zygote

44 Early Development Blastocyst: hollow structure of cells, created when the zygote grows Implantation: process in which a blastocyst attaches itself to the wall of the uterus Gastrulation: process of cell migration by which a third layer of cells is formed within the cavity of the blastocyst

45 Early Development Placenta: organ in placental mammals through which nutrients, oxygen, carbon dioxide, and wastes are exchanged between embryo and mother Fetus: name given to a human embryo after eight weeks of development

46 The Reproductive System Sexual development: the first 6 weeks of development, male and female embryos are identical in appearance 7 th week: reproductive organs begin to develop

47 Structure of the Placenta

48 Later Development 4-6 months after fertilization Skeleton forms, hair grows, etc After 6 months the fetus doubles in mass, the lungs fully develop

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50 Birth

51 What s Next? Childbirth Infancy Childhood Puberty and Adolescence Adulthood

52 Sexually Transmitted Diseases