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6.6 Hormones, homeostasis and reproduction Essential idea: Hormones are used when signals need to be widely distributed. Thyroxin is a hormone produced by the thyroid gland. It's key role is in controlling the metabolism of cells. If affects almost every physiological process in the body including growth and development. Most hormones affect more than one target tissue in more than one way. https://commons.wikimedia.org/wiki/File:Thyroid_system.svg https://commons.wikimedia.org/wiki/File:%28S%29-Triiodthyronine_Structural_Formulae_V2.svg 6.6 – Understandings • Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration. • Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature. • Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite. • Melatonin is secreted by the pineal gland to control circadian rhythms. Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty. • Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty. • The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. Applications: • Causes and treatment of Type I and Type II diabetes. • Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease. • Causes of jet lag and use of melatonin to alleviate it. • The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy. • William Harvey’s investigation of sexual reproduction in deer. Intro to Hormones – crash course Ms. K checks hw (from last week) during the video. Think big picture not all of this is part of our material. The Endocrine System A stimulus is received and processed. Hormones are secreted directly into the blood. carried to the target tissues (the place of intended action). The action of the hormone changes the condition of the tissue. This change in monitored through feedback. Most hormonal change results in negative feedback. Key endocrine glands: 1. 2. 3. 4. 5. 6. 7. 8. Endocrine glands from: http://en.wikipedia.org/wiki/Endocrine_gland The Endocrine System A stimulus is received and processed. Hormones are secreted directly into the blood. carried to the target tissues (the place of intended action). The action of the hormone changes the condition of the tissue. This change in monitored through feedback. Most hormonal change results in negative feedback. Key endocrine glands: 1. 2. 3. 4. 5. 6. 7. 8. Pineal gland Pituitary gland Thyroid gland Thymus Adrenal gland Pancreas Ovary (female) Testes (male) Endocrine glands from: http://en.wikipedia.org/wiki/Endocrine_gland Explain the control of blood glucose (8). Thyroxin: • Secreted by the thyroid gland . • Regulates metabolic rate • Helps control body temperature. Correct functioning of the thyroid requires IODINE in the diet. Lack of dietary iodine causes GOITRE Lack of thyroxin causes: • lack of energy • Depression • Weight gain despite appetite loss • Feeling cold Click for animation Leptin: • Secreted by adipose tissue cells. • Acts on the hypothalamus • Inhibits appetite Leptin is a protein hormone that targets the appetite center of the hypothalamus. Food intake triggers Leptin secretion which in turn inhibits appetite which reduces food intake. This is an example of negative feedback. Spot the mouse treated with Leptin blockers. Leptin and Obesity: should GM Leptin be made available as a treatment for obesity? 6.6.A2 Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease. Leptin treatment for obesity 1949 Scientists discovered the ob/ob or obese mouse. It is a mutant mouse that eats excessively and becomes profoundly obese. It was found that obese mice possess two recessive alleles and consequently do not produce any leptin. Obese mice treated with leptin saw large losses of weight Clinical trials were carried out to see if the effect was similar, but trials failed: • Most people have naturally high levels of leptin • If linked to leptin, obesity in people is due to resistance, of the appetite control center, to leptin • Very few patients in the clinical trial experienced significant weight loss • Many patients experienced side-effects such as skin irritations https://commons.wikimedia.org/wiki/File:Fatmouse.jpg Melatonin: • Secreted by the pineal gland . • Helps control circadian rhythms (including sleep timing and blood pressure). High levels of MELATONIN cause feeling of drowsiness and promote sleep. Falling melatonin levels encourage waking at the end of the night. Melatonin is Melatonin also promotes a drop in core sometimes temperature and probably causes the night advertised as a time body temperature drop. treatment for jet lag why do you think it might work? 6.6 Reproduction 6.6 U.1 A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone. • Initially the development of the embryo is the same in all embryos and embryonic gonads could develop into testis or ovaries. • The developmental pathway for the gonads depends on presence or absence of one gene • When SRY is present the gonads develop into testes. • SRY codes for a DNA binding protein called TDF (testis determining factor). • TDF stimulates the expression of other genes that cause the development of the testis 6.6.S1 Annotate diagrams of the male and female reproductive system to show names of structures and their functions. Can you label and annotate the diagram of the male reproductive system? a. Vas deferens (sperm duct) b. Prostate gland c. urethra d. Penis/erectile muscle e. Seminal vesicle f. epididymis g. testis (pl. testes) h. scrotum 6.6 S.1 Annotate diagrams of the male and female reproductive system to show names of structures and their functions Male Reproductive System: 1. Epididymus: •Large coiled tube (23 ft. long) that surrounds testes. •Stores sperm (about 20 days). •During ejaculation, about 400 million sperm cells are propelled from epididymis. 2. Vas Deferens: • Long muscular ducts from scrotum to back of bladder. • During ejaculation, the sperm pass from epididymis into these two ducts. *Vasectomy: Each vas deferens is cut to prevent sperm from entering urethra. 3. Ejaculatory Duct: • Short duct after two vas deferens ducts unite. 4. Urethra: • Deliver sperm to the exterior. • In males, urine and sperm pass through the urethra. 5. Scrotum • maintains temperature (lower than body) that sperm require for normal development 6.6 S.1 Annotate diagrams of the male and female reproductive system to show names of structures and their functions Accessory Glands: Produce semen. Functions of semen: • Activate sperm cells • Provide nutrients for motility • Counteract acidity of vagina and male urethra A. Seminal vesicles (2): Secrete fluid that nourishes sperm. Contribute about 60% of semen volume. B. Prostate gland: Produces a thin milky secretion. • Largest of semen secreting glands. • Contributes 30% of semen volume. C. Bulbourethral glands • Secrete a clear mucus that neutralizes acid from urine in urethra. Front View of Male Reproductive System 6.6 U.3 Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty Side View of Female Reproductive System 6.6.S1 Annotate diagrams of the male and female reproductive system to show names of structures and their functions. Can you label and annotate the diagram of the female reproductive system? a. uterus b. fallopian tube (oviduct) c. ovary d. endometrium (lining of the uterus) e. cervix f. vagina g. kidney i. bladder h. ureter j. urethra Major Organs of Female Reproductive System: 1. Ovaries: Produce ova (egg) and sex hormones. »Size and shape of large almond. *Follicles: A single egg with surrounding cells that nourish and protect it. Women are born with all of their follicles (40,000 to 400,000). Major Organs of Female Reproductive System: 2. Oviducts (Fallopian Tubes): Transport the egg from the ovary to the uterus. Fertilization occurs here. 3. Uterus • Has thick walls of smooth muscle responsible for uterine contractions and cramps. • Inner mucous lining, which thickens each month in preparation for pregnancy. If fertilization does not occur, breaks down and is discharged during menstruation. • If fertilization occurs, the egg implants here and helps support growth until the placenta develops. 4. Cervix: Lower portion of the uterus, which projects into the vagina. *Pap smear: Examination of cervical tissue to detect abnormalities. Recommended yearly. *Cervical cancer: Most cases caused by a viral infection. 5. Vagina: Thin walled, muscular chamber. • Receives the sperm and penis • Acid pH kills bacteria and sperm cells • Part of birth canal 6.6 S.1 Annotate diagrams of the male and female reproductive system to show names of structures and their functions Frontal View of Female Reproductive System Hormones of the reproductive system! Functions of Estrogen Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty. The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. 01.20.17 Menstrual Cycles What is the function of the fallopian tubes? 6.6 A.1 The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy. 6.6 A.2 William Harvey’s investigation of sexual reproduction in deer • Embryogenesis an early theory of egg development proposed by Aristotle. His idea called the Seed and soil theory, believed that males produce seed, females form an egg which mixes with menstrual blood to develop into a fetus inside the mother • William Harvey tested this idea by shooting deer during mating season • He discovered that it took months for the fertilized egg to develop in the uterus. • This help debunk the idea of spontaneous generation and lead to a better understanding of embryology. (1578-1657) 6.6 U.4 The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. Two Parts to Female Reproduction 1. Uterine Cycle • • • • Days 1-5 – Menstruation (“no” steroids) Days 6-13 - Proliferative phase (Estrogen effect) Day 14 – Ovulation (LH effect) Days 15-28 - Secretory phase (Progesterone effect) 2. Ovarian Cycle •Follicular Phase - FSH promotes development of an ovarian follicle containing an egg ready to be ovulated secretes increasing levels of estrogen •Luteal Phase –LH promotes ovulation and development of corpus luteum that secretes progesterone Female Menstrual Cycle /Uterine Cycle : Approximately 28 days. • Menstruation: Days 1-5 of cycle. – Walls of endometrium break down. – Caused by falling levels of progesterone and estrogen. – Can last 3 to 7 days. • Pre-Ovulatory /Proliferative phase (Estrogen effect): Starts around day 6 of cycle. – Rising estrogen levels cause the endometrium to start thickening. • Ovulation (LH effect) : Occurs around day 14 of cycle. – FSH stimulates growth of ovarian follicle. – LH causes follicle to finish meiosis I (secondary oocyte) and to be released by ovary. – Corpus luteum: Starts to secrete estrogen and progesterone. • Post-ovulatory Secretory phase (Progesterone effect): Starts around day 15. – Endometrium continues to grow in response to rising estrogen and progesterone. – If no fertilization occurs, corpus luteum degenerates and menstruation occurs. – If fertilization occurs, embryo maintains corpus luteum. Female Cycle 01.23.17 Today! • • • • CC Review of Female anatomy/cycles Diagram menstrual cycle hormones Complete HW (due at end of period). Practice short answer questions – Keys tomorrow. 6.6.U8 The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. 6.6.U8 The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones. 01.23.17 Today! • • • • CC Review of Female anatomy/cycles Diagram menstrual cycle hormones Complete HW (due at end of period). Practice short answer questions – Keys tomorrow.