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Human Reproduction. 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.
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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
8 months 4 weeks 5 months
