Ch 27 and 28 Reproductive Systems PDF

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Ch 27 and 28: Reproductive Systems 1. Welcome to the Reproductive System | Khan Academy a. Male: testes (millions of sperm per day) and penis i. Testes: produces testosterone b. Female: Ovary (1 egg per month), uterus, breasts (lactation) i. Ovary: produces estrogen and progesterone c. Hypothalamus: releases GnRH: Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. d. Pregnancy: sperm + egg → zygote, implants in the uterus to grow, gestation: Fetal development period from the time of conception until birth. For humans, the full gestation period is normally 9 months, Labor: giving birth 2. Anatomy of the Male Reproductive System | Khan Academy a. Testes: spermatogenesis → the creation of sperm i. Also creates testosterone b. Scrotum: contains the testes and regulates the temperature of the testes i. Cremaster muscle: The cremaster muscle lowers and raises the testis in order to control its temperature. ii. Dartos muscle: The dartos muscle is the scrotal part of the dartos fascia, composed of smooth cells. In the scrotum, the tunica dartos acts to regulate the temperature of the testicles, which promotes spermatogenesis. It does this by expanding or contracting to wrinkle the scrotal skin. c. Epididymis: provides a space for the sperm to hang and develop, on top of the testes. Sperm develops flagella tails and gains energy for their long journey. d. Vas deferens: The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra, the tube that carries urine or sperm outside of the body, in preparation for ejaculation. e. Spermatic cord: The spermatic cord is the cord-like structure in males formed by the vas deferens (ductus deferens) and surrounding tissue that runs from the deep inguinal ring down to each testicle. It’s serosal covering, the tunica vaginalis is an extension of the peritoneum that passes through the transversalis fascia. f. Seminal Vesicle: provide fluid for sperm that makes up semen. i. Semen: semen refers to the seminal fluid that contains millions of sperms. The fluid is alkaline (pH above 7), and it is rich in fructose which is used for ATP. g. Prostate gland: The prostate gland is a male reproductive organ whose main function is to secrete prostate fluid, one of the components of semen. The muscles of the prostate gland also help propel this seminal fluid into the urethra during ejaculation h. Bulbourethral glands (2): Bulbourethral glands, also called Cowper's Gland,

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either of two pea-shaped glands in the male, located beneath the prostate gland at the beginning of the internal portion of the penis; they add fluids to semen during the process of ejaculation. Urethra: the duct by which urine is conveyed out of the body from the bladder, and which in male vertebrates also conveys semen. Penis: penetrates the vagina so that sperm can be conveyed inside the female body.

3. Transport of Sperm via Erection and Ejaculation | Khan Academy: a. Transport of sperm i. Erection: when the penis is filled with blood 1. Starts in the brain from sexual excitement ii. Ejaculation: the expulsion of sperm out of the reproductive tract b. Structures of the Penis: i. Corpora Cavernosa: either of two masses of erectile tissue forming the bulk of the penis and the clitoris. ii. Corpus Sponginosum: a mass of erectile tissue alongside the corpora cavernosa of the penis and terminating in the glans. c. Norepinephrine: comes from the sympathetic nervous system, stimulates the penis to open up and allow blood into penis d. Nitric Oxide: Vasodilation, Nitric oxide dilates blood vessels, raising blood supply and lowering blood pressure. e. An erection starts in your brain. Something you saw, felt, smelled, heard, or thought makes your nerves send chemical messages to the blood vessels in your penis. The arteries relax and open up to let more blood flow in; at the same time, the veins close up. Once blood is in the penis, pressure traps it within the corpora cavernosa. Your penis expands and holds the erection. When the inflow of blood stops and the veins open, your penis becomes soft. f. When ejaculation occurs, sperm is forcefully expelled from the tail of the epididymis into the deferent duct. Sperm then travels through the deferent duct through up the spermatic cord into the pelvic cavity, over the ureter to the prostate behind the bladder. 4. Spermatogenesis | Khan Academy: a. Testes: makes sperm and testosterone b. Seminiferous Tubules: makes sperm travels to → the epididymis c. Sertoli Cells: A Sertoli cell (a kind of sustentacular cell) is a "nurse" cell of the testicles that is part of a seminiferous tubule and helps in the process of spermatogenesis, the production of sperm. It is activated by follicle-stimulating hormone (FSH) secreted by the adenohypophysis and has FSH receptor on its membranes. d. Spermatagonium: a precursor to the mature form of sperm e. Spermatagonium divides and differentiates by mitosis and becomes a primary spermatocyte. f. The spermatocyte moves through the tight junction and the spermatocyte

becomes larger by gaining more cytoplasm. g. It then divides and differentiates by meiosis to make two secondary spermatocytes h. Each primary spermatocyte has 23 three pairs of chromosomes (each chromosome is a pair of sister chromatids) i. Mitosis vs Meiosis: Cells divide and reproduce in two ways, mitosis and meiosis. Mitosis results in two identical daughter cells, whereas meiosis results in four sex cells. j. Each secondary spermatocyte has 23 chromosomes and sister chromatid configurations. k. They differentiate into spermatids (2 spermatids per secondary spermatocyte) l. Spermatids are more embedded in the Sertoli cells for nutrients m. Meiosis 2 occurs: During meiosis II, the sister chromatids within the two daughter cells separate, forming four new haploid gametes. The mechanics of meiosis II is similar to mitosis, except that each dividing cell has only one set of homologous chromosomes. n. Spermatids differentiate into Spermatizoa → the mature motile male sex cell of an animal, by which the ovum is fertilized, typically having a compact head and one or more long flagella for swimming. o. Spermatozoa gain more mitochondria and flagella in the epididymis in hopes of meeting an egg. 5. Testosterone | Khan Academy: a. Testosterone is produced by the testes in the Leydig cells b. When testosterone sees a cell it wants to enter it crosses the cell membrane and it meets a carrier protein. The carrier protein brings testosterone to the nucleus. It is released and binds onto a gene in the nucleus. It influences the functions of the gene. c. Testosterone can be converted to: i. Dihydrotestosterone (DHT) ii. Estrogen d. Testosterone functions: i. Makes reproductive organs male ii. Sperm production iii. Induces secondary sex characteristics 1. Stimulates the process of anabolism and male fat distribution 2. Stimulates bone growth iv. Increases sex drive and possible aggression v. Causes the creation of more red blood cells (erythropoietin) e. Too much testosterone i. Possible increased risk of prostate cancer ii. Male pattern baldness f. Regulate the production of Testosterone: i. Feedback loop: self-regulation

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Hypothalamus senses the amount of testosterone in the blood 1. If not enough blood it tells the anterior pituitary gland to send more hormones to the testes to increase testosterone production 2. If there is too much testosterone in the blood it tells the anterior pituitary gland to stop sending signals to the testes.

6. Anatomy of Female Reproductive System | Khan Academy a. The uterus is where the baby grows. i. Amniotic fluid: the fluid surrounding a fetus within the amnion b. Needs of the baby i. Oxygen ii. Nutrients (eg. glucose) iii. Gets rid of waste c. Placenta: The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it. d. Umbilical Cord: The umbilical cord carries oxygenated blood and nutrients from the placenta to the fetus through the abdomen, where the navel forms. It also carries deoxygenated blood and waste products from the fetus to the placenta. e. Wharton’s Jelly: Wharton's jelly is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides (hyaluronic acid and chondroitin sulfate). 7. Basics of Egg Development | Khan Academy: a. Function of Ovaries i. Oogenesis: egg creation while in gestation ii. Oocytes: eggs iii. Production of female sex hormones 1. Estrogen 2. Progesterone 3. Inhibin b. Oogonia: an immature female reproductive cell that gives rise to primary oocytes by mitosis. c. Oogonia are turned into primary oocytes by mitosis they are (2n) d. Primary oocytes (2n) begin meiosis 1: reduce chromosome copy number e. Primary oocytes get stuck in miotic arrest most die but some are able to leave f. Primary oocytes stay in miotic arrest for 13 years than during puberty they split into secondary oocytes. One cell gets all of the cytoplasm and one does not get any. The second one is a polar body that dies. g. Secondary oocyte becomes ovulated and is sent to the uterine tube where it meets sperm → meiosis 2 occurs h. The secondary oocyte reduced its chromosome number and creates another polar body

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The secondary oocyte than becomes an ovum than a zygote If the secondary oocyte does not meet the sperm it does NOT complete that second stage of meiosis

8. Ovarian Cycle | Khan Academy a. Ovarian Cycle: The normal sex cycle that includes development of an ovarian follicle, rupture of the follicle, discharge of the ovum, and formation and regression of a corpus luteum. i. In the ovary, the oocyte completes meiosis 1 then is ejected out of the ovary as a secondary oocyte for fertilization. ii. Inside the ovaries, the eggs develop in follicles: an ovarian follicle is a fluid-filled sac that contains an immature egg, or oocyte. iii. Primordial Follicle: Primordial follicles consist of an oocyte surrounded by a single layer of flattened granulosa cells iv. Granulosa cells secrete estrogen, progesterone, and inhibin 1. A granulosa cell or follicular cell is a somatic cell of the sex cord that is closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals. v. Primary follicle: A primary follicle is an immature ovarian follicle, which is surrounded by single or several layers of cuboidal. The layers of granulosa cells and the oocyte start to be separated by the zona pellucida: the thick transparent membrane surrounding a mammalian ovum before implantation. Granulosa cells nourish the egg through gap junctions in the zona pellucida. Through the gap junctions the granulosa cells send in chemical signals that keep the primary oocytes stuck in place. vi. Preantral follicle: granulosa cells divide and become greater in number, theca starts to form. Theca + LH = androstenedione 1. Granulosa cells turn androstenedione into estrogen and release it into the blood vii. Early antral follicle viii. Antrum: The follicular antrum is the portion of an ovarian follicle filled with follicular fluid. The appearance of the follicular antrum during follicular maturation is the first sign that a follicle has reached the next stage of maturation. It has changed from a primary follicle to a secondary follicle. 1. The fluid in the antrum pushes the edges of the follicle and forces it to expand. ix. Dominant follicle: A dominant ovarian follicle refers to the follicle that enlarges to release an ovum during a menstrual cycle. Usually approximately 10 Graafian follicles begin to mature where one becomes a dominant follicle and the rest become atretic ovarian follicles. 1. Atresia: the degeneration of those ovarian follicles which do not ovulate during the menstrual cycle. x. A woman loses 15-25 eggs per menstruation cycle from atresia and one

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egg (dominant follicle) survives. Cumulus Oophorus: refers to an appearance in the ovary in which multiple granulosa cells enlarge around a developing oocyte. These support cells ("cumulus cells") serve multiple functions in the maturation of the oocyte. 1. Cumulus Oophorus and the egg separate together from the follicle and float around the antrum. The follicle increases in size as it gets filled with more fluid from the granulosa cells. Mature follicle: in an ovary that contains a liquid-filled cavity and that ruptures during ovulation to release an egg. 1. Pushes on the edge of the ovary. The egg pops out onto the surface of the ovary. The follicle turns into the corpus luteum: secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively 1. If no fertilization happens the corpus luteum dies by apoptosis 2. If the egg gets fertilized the corpus luteum continues to release hormones. The egg than implants in the endometrium

9. Meet the Placenta | Khan Academy: a. The uterus is where the baby grows. i. Amniotic fluid: the fluid surrounding a fetus within the amnion b. Needs of the baby i. Oxygen ii. Nutrients (eg. glucose) iii. Gets rid of waste c. Placenta: The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it. d. Umbilical Cord: The umbilical cord carries oxygenated blood and nutrients from the placenta to the fetus through the abdomen, where the navel forms. It also carries deoxygenated blood and waste products from the fetus to the placenta. e. Wharton’s Jelly: Wharton's jelly is a gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides (hyaluronic acid and chondroitin sulfate). f. Blood supply to the uterus is the uterine artery which supplies oxygen g. Uterine veins takes deoxygenated blood from the uterine h. Basal plate: Between this plate and the uterine muscular fibres are the stratum spongiosum and the boundary layer; through these and the basal plate the uterine arteries and veins pass to and from the intervillous space. i. The uterine arteries supply blood, nutrients and oxygen through the basal plate and the uterine veins take blood out.

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Trophoblast cells (baby): a layer of tissue on the outside of a mammalian blastula, supplying the embryo with nourishment and later forming the major part of the placenta. i. The fetus cells (trophoblast) push into the placenta, within the trophoblast is a blood vessel which is in very close contact with the mother's RBC. O2 enters the fetus RBC and CO2 leaves and enters the pool of blood. j. Umbilical vein: is a vein present during fetal development that carries oxygenated blood from the placenta into the growing fetus. k. Chorionic plate: is a layer of vascularized chorio- allantois (trophoblast and mesoderm) that comprises. the fetal side of the placental disc. As such, it's inner. surface borders, or provides a roof for, the blood-filled. 10. Reproductive Cycle Graph-Follicular Phase | Khan Academy: a. Day 0: Gonadotropin Hormone Levels: The anterior pituitary gland is releasing FSH and LH: affect development of follicles in the ovarian cycle. i. FSH stimulates the growth of granulosa cells which secrete estrogen 1. More FSH → more Granulosa cells → more estrogen ii. LH is making the thecal cells around the granulosa cells produces androstenedione which the granulosa cells turn into estrogen iii. OVER ALL HIGH ESTROGEN LEVELS b. Proliferative phase: During the proliferative phase in the uterus, the wall of the endometrium begins to thicken. This phase of the uterus begins at the end of menstruation and lasts until ovulation, when the egg is ejected from the ovary. Estrogen stimulates the proliferation of cells in the endometrium of the uterus. c. Day 7: The hypothalamus and anterior pituitary gland sense that the estrogen levels are super high so they begin to release less FSH and LH. d. Day 7-14: Granulosa cells are producing a lot of estrogen, progesterone, and inhibin. Inhibin increases which decreases FSH. i. If estrogen is released to a very high level it can tell the brain that it wants to release more FSH and LH. The brain tries to release a high amount of FSH and LH. Instead the LH levels are high but the FSH levels are low due to inhibin. ii. Day 14: This LH plus the FSH pushes the development of the follicle to its final step of ovulation which releases the egg. 11. Reproductive Cycle Graph-Luteal Phase | Khan Academy: a. Secretory Phase: Day 14: egg was expelled from the follicle so the follicle is left over i. LH is really high → LH and FSH makes the follicle turn into the corpus luteum. ii. Estrogen is greatly reduced because the follicle is no more, but progesterone is greatly increased. iii. Blastocyst: The blastocyst phase is the development stage prior to implantation of the embryo in the mother's uterus.

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The egg implants in the endometrium Progesterone stimulates the uterine lining to prepare for implantation and gestation. 1. It stimulates the development of Spiral arteries allowing the embryo to have access to blood and nutrients. 2. It also increases uterine secretions → for nourishment 3. It reduces the contractility of the muscles of the uterus Corpus luteum produces lots of progesterone and some estrogen which suppresses the FSH and LH secretion 1. It is also releasing inhibin which actively suppresses FSH production 2. The corpus luteum needs FSH and LH to survive so it starts to atrophy and die off. 3. When it dies off the progesterone and estrogen levels begin to die off. This is when the end of the luteal phase is triggered. 4. Menstruation behinds to occur → endometrium begins to shed 5. When progesterone and estrogen levels drop the FSH and LH levels begin to increase again which stimulates more follicular development to start the whole cycle all over again. 6. The corpus luteum only dies if no pregnancy occurs. If pregnancy occurs: When a blastocyst implants into the endometrium the resulting embryo that develops from the blastocyst start to release HCG → keeps corpus luteum alive 1. Human Chorionic Gonadotropin: HCG is a protein-based hormone produced during pregnancy that tells a woman's body that it's pregnant. HCG helps maintain the production of important hormones like progesterone and estrogen, which are essential for the development of the embryo and fetus. The corpus luteum is alive so it continues to release estrogen and progesterone to keep the endometrial lining healthy for pregnancy. 1. Most pregnancy tests work for checking for the presence of HCG in the urine. 2. No progesterone is released for the rest of the pregnancy 3. The corpus luteum being kept alive means its continued hormone release maintains the endometrium lining.

12. Estrogen | Khan Academy: a. Estrogen comes from: i. The ovaries ii. Placenta iii. Adrenal glands on top of kidneys iv. Breasts (fat cells) b. Ovaries:

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The anterior pituitary gland makes FSH which stimulates follicles in the ovaries to develop. When follicles in the ovaries develop two cells team up and release estrogen (theca cells and granulosa cells) c. The bloodstream transports estrogen all over the body i. Once estrogen gets to its target it crosses over the cell membrane and is picked up by the carrier protein → brings it to the nucleus and binds to genes to change its expression d. In males estrogen has a role in maturation of sperm and pairs with testosterone to increase sex drive. e. In females: i. Estrogen stimulates the growth of the ovaries and the follicles, and growth of smooth muscle in the uterus and uterine tubes. ii. Estrog...