Popular in Human Anatomy and Physiology II
Popular in Biological Sciences
This 10 page Class Notes was uploaded by Jess Graff on Thursday May 12, 2016. The Class Notes belongs to BMS 508 at University of New Hampshire taught by Mary Katherine Lockwood, PhD in Spring 2016. Since its upload, it has received 8 views. For similar materials see Human Anatomy and Physiology II in Biological Sciences at University of New Hampshire.
Reviews for BMS 508
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 05/12/16
BMS 508.03 5/9/2016 Chapter 28 (cont) Reproduction (cont) Male Reproductive Functions (cont) • 2 Steps in Capacitation Spermatozoa become motile • When mixed with secretions of seminal glands Spermatozoa become capable of fertilization • When exposed to female reproductive tract • Semen Typical ejaculation releases 2–5 mL Abnormally low volume may indicate problems • With prostate gland or seminal glands Sperm count • Is taken of semen collected after 36 hours of sexual abstinence • Normal range 20–100 million spermatozoa/mL of ejaculate • Gonadotropin-Releasing Hormone Is synthesized in hypothalamus • Carried to pituitary by hypophyseal portal system Is secreted in pulses • At 60–90 minute intervals Controls rates of secretion of: • FSH and LH • Testosterone (released in response to LH) • FSH and Testosterone Target nurse cells of seminiferous tubules Nurse cells • Promote spermatogenesis and spermiogenesis • Secrete androgen-binding protein (ABP) • Negative Feedback Spermatogenesis is regulated by: • GnRH, FSH, and inhibin As spermatogenesis accelerates: • Inhibin secretion increases • Inhibin and FSH Elevated FSH levels • Increase inhibin production • Until FSH returns to normal If FSH declines: • Inhibin production falls • FSH production increases • Luteinizing Hormone Targets interstitial cells of testes Induces secretion of: • Testosterone • Other androgens • Testosterone Is the most important androgen Stimulates spermatogenesis • Promoting functional maturation of spermatozoa Affects CNS function • Libido (sexual drive) and related behaviors Stimulates metabolism • Especially protein synthesis • Blood cell formation • Muscle growth Establishes male secondary sex characteristics • Distribution of facial hair • Increased muscle mass and body size • Characteristic adipose tissue deposits Maintains accessory glands and organs of male reproductive tract Functions like other steroid hormones • Diffuses across target cell membrane • Binds to intracellular receptor • Hormone–receptor complex • Binds to DNA in nucleus • Circulating in bloodstream • Bound to one of two types of transport proteins • Gonadal steroid-binding globulin (GBG) carries 2/3 of circulating testosterone • Albumins carry 1/3 of testosterone • Estradiol Is produced in relatively small amounts (2 ng/dL) 70% is converted from circulating testosterone • By enzyme aromatase 30% is secreted by interstitial and nurse cells of testes The Female Reproductive System • The Female Reproductive System • Produces sex hormones and functional gametes • Protects and supports developing embryo • Nourishes newborn infant • Organs of the Female Reproductive System • Ovaries • Uterine tubes • Uterus • Vagina • External genitalia • Structural Support • Ovaries, uterine tubes, and uterus are enclosed in broad ligament • Uterine tubes • Run along broad ligament • Open into pelvic cavity lateral to ovaries • The mesovarium • Stabilizes position of each ovary • Oogenesis • Also called ovum production • Begins before birth • Accelerates at puberty • Ends at menopause • Fetal Development • Between third and seventh months: • Primary oocytes prepare for meiosis • Stop at prophase of meiosis I • Atresia • Is the degeneration of primordial follicles • Ovaries have about 2 million primordial follicles at birth • Each containing a primary oocyte • By puberty: • Number drops to about 400,000 • The Ovarian Cycle • After sexual maturation • A different group of primordial follicles is activated each month • Is divided into: • Follicular phase (preovulatory phase) • Luteal phase (postovulatory phase) • Ovarian follicles • Are specialized structures in cortex of ovaries • Where oocyte growth and meiosis I occur • Primary oocytes • Are located in outer part of ovarian cortex • Near tunica albuginea • In clusters called egg nests • Uterine Tube and Fertilization • For fertilization to occur: • Secondary oocyte must meet spermatozoa during first 12–24 hours • Fertilization typically occurs: • Near boundary between ampulla and isthmus • Uterine tube provides nutrient-rich environment by secretions from peg cells • Containing lipids and glycogen • Nutrients supply spermatozoa and developing pre-embryo • The Uterus • Provides for developing embryo (weeks 1–8) and fetus (week 9 through delivery) • Mechanical protection • Nutritional support • Waste removal • The Uterine Wall • Has a thick, outer, muscular myometrium • Has a thin, inner, glandular endometrium (mucosa) • The perimetrium • Is an incomplete serous membrane • Continuous with peritoneal lining • Covers fundus and posterior surface of uterine body and isthmus • Two Divisions of Endometrium • The functional zone • Contains most of the uterine glands • Contributes most of endometrial thickness • Undergoes dramatic changes in thickness and structure during menstrual cycle • The basilar zone • Attaches endometrium to myometrium • Contains terminal branches of tubular endometrial glands • The Uterine Cycle (Menstrual Cycle) • Is a repeating series of changes in endometrium • Lasts from 21 to 35 days • Average 28 days • Responds to hormones of ovarian cycle • Menses and proliferative phase • Occur during ovarian follicular phase • Secretory phase • Occurs during ovarian luteal phase • Menses • Is the degeneration of functional zone • Occurs in patches • Is caused by constriction of spiral arteries • Reducing blood flow, oxygen, and nutrients • Weakened arterial walls rupture • Releasing blood into connective tissues of functional zone • Degenerating tissues break away, enter uterine lumen • Entire functional zone is lost • Through external os and vagina • Only functional zone is affected • Deeper, basilar zone is supplied by straight arteries • The Proliferative Phase • Epithelial cells of uterine glands • Multiply and spread across endometrial surface • Restore integrity of uterine epithelium • Further growth and vascularization • Completely restores functional zone • Occurs at same time as: • Enlargement of primary and secondary follicles in ovary • The Secretory Phase • Endometrial glands enlarge, increasing rate of secretion • Arteries of uterine wall • Elongate and spiral through functional zone • Begins at ovulation and persists as long as corpus luteum remains intact • Peaks about 12 days after ovulation • Glandular activity declines • Generally lasts 14 days • Ends as corpus luteum stops producing stimulatory hormones • Menarche • The first uterine cycle • Begins at puberty (age 11–12) • Menopause • The termination of uterine cycles • Age 45–55 • Hormones and the Follicular Phase • Begins with FSH stimulation • Monthly • Some primordial follicles develop into primary follicles • As follicles enlarge: • Thecal cells produce androstenedione • Androstenedione • Is a steroid hormone • Is an intermediate in synthesis of estrogens and androgens • Is absorbed by granulosa cells and converted to estrogens • Interstitial Cells • Scattered throughout ovarian stroma • Also secrete small amounts of estrogens • Circulating estrogens • Are bound primarily to albumins • Lesser amounts carried by gonadal steroid-binding globulin (GBG) • Three types: estradiol, estrone, and estriol • Estradiol • Is most abundant • Has most pronounced effects on target tissues • Is dominant hormone prior to ovulation • Estrogen Synthesis • Androstenedione is converted to testosterone • Enzyme aromatase converts testosterone to estradiol • Estrone and estriol are synthesized from androstenedione • Five Functions of Estrogen • Stimulates bone and muscle growth • Maintains female secondary sex characteristics • Such as body hair distribution and adipose tissue deposits • Affects central nervous system (CNS) activity • Especially in the hypothalamus, where estrogens increase the sexual drive • Maintains functional accessory reproductive glands and organs • Initiates repair and growth of endometrium • Summary: Hormonal Regulation of the Female Reproductive Cycle • Early in follicular phase of ovarian cycle: • Estrogen levels are low • GnRH pulse frequency is 16–24/day (1 per 60–90 minutes) • As tertiary follicles form, concentration of circulating estrogens rises steeply • And GnRH pulse frequency increases to 36/day (1 per 30– 60 minutes) • In follicular phase: • Switchover occurs • When estrogen levels exceed threshold value for about 36 hours • Resulting in massive release of LH from the anterior lobe of the pituitary gland
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'