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This lesson will increase your knowledge of concepts covered in the following TEKS for biology:. 3.c – Evaluate impact of research on scientific thought, society, and the environment 3.e – Evaluate models according to their adequacy in representing biological objects or events
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This lesson will increase your knowledge of concepts covered in the following TEKS for biology: 3.c – Evaluate impact of research on scientific thought, society, and the environment 3.e – Evaluate models according to their adequacy in representing biological objects or events 3.f – Research and describe the history of biology and contribution of scientists 10.a – Interpret the functions of systems in organisms 10.b – Compare the interrelationships of organ systems to each other and to the body as a whole 11.a – Identify and describe the relationships between internal feedback mechanisms in the maintenance of homeostasis
QUESTION: Why is the U.S. government still spending billions of dollars funding scientific research? Based on Nature, February 5, 2004.
Advances in Biological Knowledge Molecular Biology and Genetics Immunology Anatomy Knowledge The unknown Is still greater than the known Ecology Evolution Today
QUESTION: If you had to design a study to investigate the effects of a new drug on human health, what type of design would you use?
Two-group experimental design Identity the variable which will test the hypothesis CONTROL GROUP EXPERIMENTAL GROUP The variable being tested The variable being tested is absent is present Record results Record results Compare and analyze the test results Report on experimental design, test results, and conclusions drawn from results Based on: Starr, C., Biology: Concepts and Applications, Brooks/Cole, Thomson Learning
QUESTION: Why can nonscientists have confidence in the information published in the reputable popular press (TimeMagazine, U.S. News & World Report, Newsweek)?
Reputable Popular Press Scientific Methodologies Observation Hypotheses Tests of hypotheses Results World knowledge in scientific journals Publication Rejection Peer review Submission of paper to scientific journal
Overview of Lesson • Female reproductive system and menstrual cycle • Menopause • Hormone replacement therapy • Women’s Health Initiative
Pathway of Egg if Unfertilized Follicle of ovary Oviduct Uterus Vagina
Female System Based on:Mader, S., Inquiry Into Life, Wm. C. Brown Publishers
Menstrual cycle: the cyclic buildup and breakdown of the endometrium as the uterus prepares monthly for a blastocyst
Hormones and Menstrual Cycle Negative feedback Negative feedback Based on: Mader, S., Inquiry Into Life, McGraw-Hill
Negative Feedback & Homeostasis Overview Negative feedback effects of estrogen and progesterone are the prime homeostatic mechanisms maintaining female sex characteristics at a relatively constant level Hypothalamus Pituitary Follicle Female sexuality Releasing hormone (GnRH) LH & FSH Negative Feedback Egg Development Estrogen & Progesterone
Hormonal Regulation of Ovarian and Uterine Cycles Based on Mader, S., Inquiry, Wm. C. Brown Publishers
(Graafian) follicle Ovulation Based on: Mader, S., Inquiry Into Life, McGraw-Hill
Hormones and Menstrual Cycle Pituitary produces FSH and LH FSH and LH cause follicle to develop and release egg Follicle produces estrogen and progesterone Estrogen and progesterone thicken endometrium to prepare for implantation of fertilized egg and suppress production of FSH and LH Egg not fertilized Egg fertilized
If the Egg is Fertilized Fertilized egg implants in endometrium Embryo sends out hormonal message to the old follicle (corpus luteum) to let it know an embryo is present Old follicle continues to produce estrogen and progesterone to maintain endometrium
Human Development Based on: Mader, S., Inquiry Into Life, McGraw-Hill
Family Planning Calendar Based on Mader, S., Inquiry, Wm. C. Brown Publishers
If the Egg is Not Fertilized Unfertilized egg does not implant No hormonal message is sent to the old follicle and it stops production of estrogen and progesterone Without estrogen and progesterone, the endometrium breaks down and the menstrual flow occurs
Hormonal Regulation of Ovarian and Uterine Cycles Uterine Cycle Based on Mader, S., Inquiry,Wm. C. Brown Publishers
Overview of Lesson • Female reproductive system and menstrual cycle • Menopause • Hormone replacement therapy • Women’s Health Initiative
Menopause • In a woman’s 40s, estrogen production declines • Symptoms of early menopause (perimenopause) appear and may last for 5 years • Eventually estrogen production stops, menstrual cycle stops and woman enters menopause • Average age to enter menopause is 51
Symptoms of Early Menopause • Hot flashes • Dry skin • Brittle hair • Insomnia • Vaginal dryness • Mood swings
Changing hormone levels with menopause Based on: Medical Essay: Supplement to Mayo Clinic Health Letter, October 1999 The uneven rising and falling of hormone levels during perimenopause may be responsible for menstrual irregularities and other problems associated with menopause.
Overview of Lesson • Female reproductive system and menstrual cycle • Menopause • Hormone replacement therapy • Women’s Health Initiative
Early History of HRT • In early 1900s, scientists used extracts from pig ovaries to treat menopausal women • By the early 1940s estrogen was being produced from pregnant mares’ urine (Premarin) • By 1960s, the recommendation was that every women over 50 begin to using HRT
Estrogen Only Therapy • Beginning in 1960s, estrogen only was given to treat women with symptoms of menopause • By 1970s, realized that estrogen only therapy increased rate to uterine cancer
Today’s Hormone Replacement Therapy • Estrogen combined with progestin • Lowers risk of uterine cancer
Short-Term Benefits of HRT • Cools hot flashes • Combats insomnia • Reduces vaginal dryness • Levels mood swings
Pre-2002 Hypothesized Long-Term Benefits of HRT • Retards osteoporosis • Reduces the risk of heart disease • Neutralizes the risk of uterine cancer • Reduces the risk of Alzheimer’s and colon cancer
Osteoporosis: a bone thinning disease that sets the stage for serious fractures Based on: Newsweek Special Issue, Spring/Summer 1999
MENOPAUSE AND BONE LOSS IN WOMEN Based on: A Harvard Woman Health Watch Special Report 1996
MENOPAUSE AND BONE LOSS IN WOMEN Based on: A Harvard Woman Health Watch Special Report 1996
THE HEART OF THE MATTER:annual deaths per 100,000 U.S. women Heart disease kills 6 times more women in their post-menopausal years than does breast cancer Based on: Harvard Health Letter, October 1997
Hypothesized Long-Term Risks of HRT • Promotes the formation of gallstones and blood clots • Increases the risk of breast cancer
Spread of Breast Cancer Based on: Campbell et al.’s Biology: Concepts & Connections, Benjamin Cummings Cancerous breast cells spread through the lymphatic and circulatory systems to other areas of the body. Lymphatic and Circulatory Systems
Overview of Lesson • Female reproductive system and menstrual cycle • Menopause • Hormone replacement therapy • Women’s Health Initiative
Before the Women’s Health Initiative Study, studies had shown a positive relationship between taking HRT and lower heart disease (a correlation). Why isn’t this type of correlative study used as proof that HRT reduces heart disease?
Women who took HRT may have more financial resources, better health care and be more health conscious than women that didn’t use HRT. Researchers could not tell “whether hormones made women healthy-or whether healthy women were more likely to take hormones.” Correlation does not prove causation!
Women’s Health Initiative • Study began in 1993 and was to last 15 years • Involved 67,000 in three random clinical trials (Dietary Modification, Calcium/Vitamin D supplements, and HRT) • HRT trial involved 16,000 women to assess the pros and cons of estrogen-progestin therapy (half received HRT and half received placebo) • HRT trial was stopped in July 2002 when health risks were discovered • Other two trials were continued
Women’s Health Initiative • Women taking HRT • increased risk of breast cancer, stroke, and heart disease • decreased risk of hip fractures, colorectal cancer, and heart vessel disease (if taken early) • Length of use may be a key factor
But does HRT really result in significant health risks? • Viewed as percentages: • Heart attack rate was 29% higher in HRT group • Stroke rate was 41% higher in HRT group • Viewed as absolute numbers: • Instead of 30 heart attacks per 10,000 women, 37 women would have heart attacks • Instead of 21 strokes per 10,000 women, 29 women would have strokes • Instead of 30 breast cancers per 10,000 women, 38 women would have breast cancer
Health Advisories • Health advisories are made from a population perspective • Individuals must decide how to respond to health advisories from a personal perspective
A Boost for Hormone Therapy 2007 Update New Eng Journal Med Younger post-menopausal women 50-59 yrs of age post hysterectomy (took estrogen alone) showed up to 40% less calcium-based plaque in heart arteries than placebo group
Next Lesson Prostate Cancer
Lymphatic System Based on: Mader, S., Inquiry into Life, Wm. C. Brown Publishers
Circulatory System Back Based on: Mader, S., Inquiry Into Life, McGraw-Hill