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Explore the anatomy and hormonal controls of the male and female reproductive systems. From sperm production to the menstrual cycle, understand the key stages and feedback mechanisms involved.
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Objectives: • To identify the anatomy of the Male Reproductive System • To understand the hormonal controls in sperm production • To identify the anatomy of the Female Reproductive System • To understand the hormonal controls involved in the 4 stages of the Menstrual Cycle
Let’s Compare • Male System – simple! • Female System – complicated !! • Let’s look at the Male System first. • All it does is produce 2-4 million sperm cells per day starting at puberty and continuing until the day you die!
Anatomy of the Seminiferous Tubule • Spermatagonia – 2n reproductive cells that undergo meiosis to produce haploid sperm cells • Interstitial Cells – Produce testosterone • Sertoli Cells – provide nourishment for the developing sperm cells
Hormonal Control of Sperm Production • It all starts in your…..BRAIN!! • The Hypothalamussecretes many hormones into your blood including GnRH which stimulates the Pituitaryto secrete 2 hormones called: FSH – Follicle Stimulating Hormone LH – Lutenizing Hormone • FSH – stimulates sperm production • LH – stimulates testosterone production
Testosterone • Promotes more sperm production AND the development of secondary sex characteristics • Negative Feedback • As levels of testosterone rise the hypothalamus detects the levels and…… • …stops the production of GnRH from the Hypothalamus which…… • …stops the production of LH from the Pituitary which…….. • …reduces the production of testosterone from the Interstitial Cells • This is called Negative Feedback
Hormonal Feedback Hypothalamus Releasinghormone Anteriorpituitary Negative feedback LH FSH Spermproduction Testosterone production
Positive feedback • As dropping testosterone levels are detected, the _____________ starts to release ___________, which causes the __________gland to release ____________, which increases the production of ______________. • This is called Positive Feedback
Semen • Semen, not to be confused with “seaman”, is the fluid that sperm cells swim in. • There are three glands that secrete the fluids: • Prostate gland – secretes an alkaline buffer that neutralizes the acidic environment of the vagina. • Seminal vesicles – secrete a fructose solution that provides energy for the sperm cells • Cowper’s gland – secretes a mucous that lines the urethra to prevent the sperm from contacting any urine residue
Menstrual Cycle • 28 day cycle that begins at puberty and continues until menopause • Consists of 4 stages: • Menstruation (your period) • Follicle Stage • Ovulation • Corpus Luteum Stage
#1 Menstruation • 4-6 days • Endometrium and unfertilized egg are removed from the uterus. • Pituitary gland releases FSH which stimulates the follicles in the ovaries.
#2 Follicle Stage • One follicle usually “becomes the chosen one” and continues to enlarge. • The ovaries release Estrogen which thickens the endometrium. • Rising levels of Estrogen send negative feedback to the Hypothalamus (GnRH) and Pituitary which stops the production of FSH. • Positive feedback initiates the release of LH from the Pituitary.
#3 Ovulation • Around day 14, LH levels are at their highest and cause the stimulated follicle to rupture and release it’s egg. • The egg is swept by the fimbria into the oviduct • You are most fertile at this point. (Vulnerable to becoming pregnant!)
#4 Corpus Luteum Stage • The ruptured follicle changes into a yellowish structure called the Corpus Luteum. • It releases estrogen and progesterone (pregnancy hormone) • If pregnancy results: • The zygote releases hCG (Human Chorionic Gonadotropin Hormone) sending PF to the Pituitary. • Estrogen and progesterone levels stay high, preventing the release of FSH by the pituitary (NF)
#4 Corpus Luteum Stage • If pregnancy does not occur: • No hCG results in NF, causing; • Estrogen and progesterone levels drop, causing the endometrium to deteriorate and menstruation begins again. • Dropping levels of estrogen and progesterone cause the pituitary to begin releasing FSH (PF)
Birth Control Pills • Trick your body into thinking it is pregnant. • If your body thinks it is pregnant, you won’t ovulate. • Without an egg being released, you cannot become pregnant. • Each pill has different amounts of progesterone. • The “pill” can be prescribed to regulate your period because of the specific levels of hormones found in each pill
Pregnancy Tests • Check for the presence of hCG (Human Chorionic Gonadotropin) in the mother’s urine • The fertilized egg releases hCG
Terms to remember: • Fertilization – union of egg and sperm inside the oviduct. Fertilization and Implantation • Implantation – attachment of fertilized egg into the endometrium 6 to 8 days after fertilization. • Gastrulation – 16 to 18 days after fertilization • Embryo – term used to refer to the developing ball of cells after gastrulation up to 8 weeks. • Fetus – after 8-10 weeks • Make Room For the Baby
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