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Endocrine & Reproductive Systems Chapter 34 Biology 34.1 The Endocrine System • Hormones and Glands o Chemicals that are released in one part of the body and travel to other parts. o Hormones act on specific cells called target cells or the message is ignored. o Over 40 glands exist in our bodies o Ex: gland: pancreas • hormone: insulin • target cells: liver, muscles Gland Location Job Hormones Released Hypothalamus Brain -Master control Sends Releasing -signals pituitary Hormone to pituitary Pituitary Brain ADH, oxytocin, growth hormones Pineal Brain Thyroid Neck (at trachea) Controls hormone secretion of glands Control sleep/wake cycles Maintains metabolism Parathyroid Next to thyroid Regulate calcium Pancreas Abdomen near Maintains blood stomach sugar level Parathyroid hormoneincrease blood Ca levels -insulin- decreases blood sugar levels -glucagon- increases blood sugar levels Thymus Chest thymosin Adrenal Above kidneys Responds to stress Immune response Melatonin -thyroxine- metabolism rates -calcitonin- reduce blood Ca levels epinephrine (also called adrenaline) Norepinehprine • Exocrine Glands o Tube-like structures (ducts) that secrete directly out of body or into digestive system. • Ex: tear ducts, bile duct, sweat glands • Endocrine Glands o Release hormones directly into blood • Ex: pituitary, adrenal, thyroid • Prostaglandins o Small hormone-like substances secreted by cells o “local hormones” • Steroid v non-steroid hormones 34.2 Glands of the Endocrine System • How is the Endocrine System Controlled? o The HYPOTHALAMUS o Regulated by negative feedback o Maintaining water balance (ADH) keeps levels of many hormones in check. o Controlling metabolism also affects many hormones o Body temperature is another method of regulation 34.3 The Reproductive System • How Hormones Relate to the Reproductive System Hormone Releasing Hormone Follicle Stimulating Hormone (FSH) Source Hypothalamus Pituitary Luteinizing Hormone Pituitary (LH) Estrogen Progesterone Testosterone Function Stimulates pituitary Stimulates sperm production or Stimulates follicle and oocyte development in ovary Stimulates testes to produce testosterone or in females causes follicle to mature and break open Follicle and corpus luteum Causes endometrium to thicken; development of secondary sex traits Corpus luteum Causes and maintains endometrial thickening; controls menstrual cycle. Testes Stimulates sperm production; development of secondary sex traits • Male Reproductive System o Testes (2) • produce sperm and sex hormones. (equivalent to ovaries) • contained in scrotum maintain temperature suitable for sperm o Epididymis (2) • sperm maturation site • coiled duct from testes. o Vas deferens (2) tube for mature sperm to travel from epididymis to ejaculatory duct. o Ejaculatory duct (2) conduct sperm to penis. o Urethra- dual purpose duct for sperm or urine. o Penis- organ for sexual intercourse and expels semen o Accessory Glands • Seminal vesicle secretes fructose and prostaglandin • Prostate gland secretes buffer • Bulbourethral gland secretes mucus • Female Reproductive System o Ovaries (2) • oocyte production and maturation • sex hormone production o Oviducts (2) fallopian tubes • connecting tube between ovaries and uterus • fertilization occurs here. o Uterus • chamber for embryonic growth and development. • endometrium- inner lining necessary for embryo • myometrium- muscle layers for contractions. o Cervix • secretes mucus to enhance sperm mobility into uterus. • mucus helps reduce embryonic infection. o Vagina organ for intercourse and childbirth o Clitoris external organ sensitive to sexual stimulation. o Vulva external fat padded skin • Sperm and Egg Production o For every immature sperm, 4 mature sperm are produced o For every immature egg, 1 mature egg is produced o Sperm consist of a head with DNA, mid-piece with mitochondria and a flagellum. o Eggs contain all of the cytoplasm and organelles needed once fertilized • Ovarian and Menstrual Cycles o Assume this to be a 28 day cycle, but it does vary in reality. Phase Events # of Days Follicular Phase Menstruation; endometrium breaks down 1-5 (includes two parts) Follicle matures; endometrium rebuilds 6-13 Egg released from ovary Ovulation Luteal Phase 14 Corpus luteum forms & secretes progesterone; endometrium thickens 15-28 • Fertilization and Embryonic Development o Gamete formation o Fertilization • Sperm + egg = zygote • 2 haploid cells become 1 diploid o Implantation • Burrow into uterus as blastocyst o Gastrulation • Ectoderm, mesoderm, endoderm o Neurulation o 8 weeks = fetus o 4-6 mo: complex and specialized cells/tissues o 7-9 mo: organ systems mature; size and mass changes of fetus o 40 weeks is full term pregnancy