12_Reproductive System.pptx

Reproductive System Chapter 23, Human Anatomy (LibreTexts) "Movements_at_gestational_age_of_9_weeks.gif" is in the Public Domain Functions of Reproductive System • Production of egg and sperm cells • Transport and maintenance of these cells • Produce sex hormones • Nurture the developing offsprin...

Reproductive System Chapter 23, Human Anatomy (LibreTexts) "Movements_at_gestational_age_of_9_weeks.gif" is in the Public Domain Functions of Reproductive System • Production of egg and sperm cells • Transport and maintenance of these cells • Produce sex hormones • Nurture the developing offspring Gonads and Gametes • Primary sex organs called gonads: • Ovaries in female reproductive system • Testes in male reproductive system • Gonads produce sex cells called gametes that contain a half set of chromosomes: • ovaries produce oocytes (eggs or ova) • testes produce sperm • Gonads also produce large amounts of sex hormones: • estrogen and progesterone are most important in female reproductive system • androgens (including testosterone) are most important in male reproductive system Fertilization and Embryonic Development • Fertilization: sperm and oocyte meet in the uterine tubes. Chromosomes from sperm and oocyte combine to form a complete set of chromosomes • Fertilized oocytes = zygote, which is one cell • Zygote will divide to be 2 cells, then 4, then 8, etc • Zygote is called morula when reaches a solid ball of 16 cells, which then becomes a blastocyst (a hollow ball of cells) that will implant into uterus. • After implantation (3 weeks), blastocyst is called an embryo. • After 8 weeks, the embryo is called a fetus. Sexual Differentiation • Bipotential gonad: No sexual difference can be observed in the gonads until the 6th week of embryonic life in humans. Undifferentiated gonads of XX or XY individuals are apparently identical and can form either ovaries or testes. • Factors that determine sexual differentiation: presence or absence of the SRY gene on the Y chromosome, other genes regulating gonadal development, sex hormones, presence of testis. • Genetic test before week 10 determines presence (or absence) of SRY gene. • Anatomical ultrasound at week 20 determines presence (or absence) of external male genitalia. • Reproductive systems are dormant until puberty. At puberty, the hypothalamus and pituitary gland “wake up” the gonads that then start producing sex hormones and develop gametes. Sexual Differentiation (“Sexual Differentiation” by Jonathan Marcus is licensed under CC BY SA 3.0) Overview of Female Reproductive System • Internal Genitalia: • • • • • Ovaries Uterine or Fallopian tubes Uterus Cervix Vagina • External Genitalia: • Vulva (includes Mon Pubis, Labia minora and Labia majora) • Breast • Female Perineum: external area between vulva and anus, which includes the urethral, vaginal and anal orifices. Overview of Male Reproductive System • Internal Genitalia: • • • • • • • Testes Vas deferens Epididymis Seminal vesicle Prostate Bulbourethral gland Ejaculatory duct • External Genitalia: • Penis and urethra • Scrotum • Male Perineum: external area between scrotum and anus (does not include penis), which includes only the anal orifice. Homologues of Female and Male • The male and female reproductive organs are related during development, sharing a common developmental path. This makes them biological homologues. These organs differentiate into the respective sex organs in males and females. • Homologues: • Ovaries and Testes: gonads • Clitoris and Penis: both contain erectile tissues • Labia minora and Prepuce: both made of mucosa covering the erectile tissues • Labia majora and Scrotum: both made of skin that covers external genitalia Note on Terms Used • Genetic sex, gonadal sex and anatomic sex might not match because of genetic or hormonal influences. • Sex and gender are different. Sex is assigned at birth, while gender is how a person identifies. • Here I will use the phrases "male", "XY", "individuals with testes” or “individuals that have been assigned a male sex at birth” to refer to the anatomy of an individual with testes that may (or may not) make sperm. • I will use the phrases "female", "XX", and "individuals with ovaries” or “individuals that have been assigned a female sex at birth” to refer to the anatomy of an individual with ovaries that may (or may not) make ova (eggs). Female Reproductive System Female Reproductive System – Lateral View (“Female Reproductive System” by OpenStax is licensed under CC BY 3.0) Female Reproductive System – Anterior View (“Female Reproductive System” by OpenStax is licensed under CC BY 3.0) Ovaries • 2 almond-size gonads in pelvis that produce oocytes (eggs) • Held in place by ligaments: Mesovarium, Broad ligament (part of peritoneum), Suspensory ligament, Ovarian ligament • Surface covering of simple cuboidal epithelium • Tunica albuginea white, dense connective tissue • Cortex where follicles develop • Medulla with blood and lymphatic vessels and nerves • Connected to uterus by Fallopian (or uterine) tubes Ligaments (“Uterus and Ligaments” by Henry Gray is in the Public Domain) Ovarian Cycle • 28-day cycle average (range 21-32 days) • Regulated by hormones • 2 simultaneous processes: • Oogenesis to produce oocytes • Folliculogenesis to develop ovarian follicles Oogenesis • Start with oogonia (germ cells) dividing to primary oocytes before birth • From birth to puberty, cell division stops • At puberty, one ovulation usually occurs per cycle • Prior to ovulation, primary oocyte divides unevenly to form: • one secondary oocyte with most of the cytoplasm that will ovulate • one small cell, called first polar body, that divides and/or breaks down • Secondary oocyte is ovulated =pushed out of the ovary and into the uterine tubes. • If sperm penetrates the secondary oocyte, then oocyte divides unevenly to get a 2nd small polar body and one mature oocyte. • If sperm does NOT penetrate then the secondary oocyte breaks down after 24 hours. Folliculogenesis • Ovarian follicle = oocyte + supporting cells surrounding it • Follicle grows and develops, resulting in ovulation in every cycle • 1-2 millions primordial follicles present at birth • At puberty, a few primordial follicles become primary follicles with thicker layers of cells in each cycle • Primary becomes secondary follicles • Secondary becomes tertiary follicle as follicular fluid collects in antrum (inside follicle) • Per cycle, only one tertiary follicle can develop to ovulation, the rest undergo breakdown • At ovulation, secondary oocyte inside the tertiary follicle is released but follicular cells remain in ovary to form corpus luteum/albicans Folliculogenesis Image EM × 1100; Micrograph provided by the Regents of University of Michigan Medical School © 2012.(“Folliculogenesis ” by OpenStax is licensed under CC BY 3.0) Ovarian Cycle Phases • Follicular phase (first half): maturation of oocytes and follicles until a secondary oocyte is pushed out a tertiary follicle and into the uterine tubes. • Luteal phase (second half): Follicular cells remaining in the ovary after ovulation become corpus luteum which will produce hormones to support early pregnancy until the placenta is formed. If not pregnant, then corpus luteum becomes corpus albicans and stops making hormones. Female Accessory Organs LM × 400, LM × 20; Micrographs provided by the Regents of University of Michigan Medical School © 2012. (“ Uterus & Nearby Organs” by OpenStax is licensed under CC BY 3.0) Uterine Tubes • Also called Fallopian tubes • 4 sections, from medial to lateral: • • • • Isthmus adjacent to uterus Ampulla where fertilization takes place Infundibulum widens and open-ended Fimbriae are finger-like projections to catch the ovulated oocyte • Mucosa is lined with simple ciliated columnar epithelium to move ovulated oocyte toward uterus • Smooth muscle in the wall also contracts to direct oocyte to uterus • Fertilization of oocyte takes place in uterine tubes, then zygote travels down to uterus where it implants. Uterus • Site of implantation of the embryo • Supports and protects the developing embryo/fetus • Ejects the fetus during labor • 3 sections: • Fundus • Body • Cervix • Mucin-secreting glands in cervix create mucus plug at external opening to vagina to prevent pathogens from entering the uterus. Plug thins during ovulation to allow more sperm entry into uterus. Uterine Layers • Wall has 3 layers: • Endometrium innermost layer lined with simple columnar epithelium • Myometrium is thick layer of smooth muscles for contractions • Perimetrium is serous membrane covering the outside, continuous with broad ligament • Endometrium is divided into 2 layers: • Basal layer is next to smooth muscles, permanent and does not change • Functional layer is superficial. Thickens in response to hormones in preparation for pregnancy and sheds during menstruation. Uterine Cycle • Runs concurrently with ovarian cycle • 3 phases: 1) Menstruation (period) sheds endometrium: Corresponds to early follicular phase in ovarian cycle. 2) Proliferative phase thickens endometrium. Corresponds to follicular phase in ovarian cycle. Ovulation marks the end of proliferative phase. 3) Secretory phase prepares for implantation. Corresponds to the luteal phase in ovarian cycle. Ovarian and Menstrual Cycles (“Ovarian and Menstrual Cycles“ by OpenStax is licensed under CC BY 3.0) Vagina • Canal made of thick smooth muscle • Functions as an exit from uterus during menses and childbirth • Inner mucous membrane with transverse rugae is lined with non-keratinized stratified squamous epithelium • Home to family of bacteria (normal flora) to maintain acidic environment for prevention of infection Vulva • Vulva is the entire area, includes: • • • • Mon pubis fat pad covered with pubic hair Labia majora are the larger lips Labia minora are the smaller lips, protecting the clitoris Clitoris is the most sensitive area Vulva (“Vulva” by OpenStax is licensed under CC BY 3.0) Breasts • Provides milk (lactation) to nourish baby • The secretory units of the mammary glands are alveoli, which are divided into groups within lobules. Each lobule secretes breast milk into a lactiferous duct. The lactiferous ducts from each lobule eventually merge into lactiferous sinuses, which drain through the nipple. • The nipple is surrounded by a pigmented region of the skin called the areola. Within the areola are areolar glands, which are sebaceous glands that secrete a moistening and lubricating oily substance. Anatomy of the Breast (“Anatomy of the Breast“ by OpenStax is licensed under CC BY 3.0) Male Reproductive System Male Reproductive System – Lateral View (“Male Reproductive System” by OpenStax is licensed under CC BY 3.0) Testes: External Anatomy • Testes is plural of testis • 2 male gonads • Inside the scrotum which hangs exteriorly to keep temperature of testes 3ºC below body temperature, needed to develop sperm correctly. • Covered by: • Tunica vaginalis: serous membrane; superficial • Tunica albuginea: tough, white, dense connective tissue; deep • Tunica albuginea projects internally into the testes to form septa. • The septa form the lobules. • Each lobule contains seminiferous tubules. Testes: Internal Anatomy • Tunica albuginea projects internally into the testes to form septa. • The septa form the lobules: 300-400 lobules • Within each lobules, coiled seminiferous tubules have germ cells that develop into sperm and other cells for support. • From lumen of seminiferous tubules, immature sperm called spermatids move to: • Rete testis • Efferent ductule • Epididymis Testis Seminifer ous tubules (“Testis” by KL Nguyen is licensed under CC BY 4.0 / A derivative from the original work) Spermatogenesis • Production of new spermatids (immature sperm cells) • Starts at puberty • Cycle takes 64 days • Asynchronously occurring in seminiferous tubules • Spermatogonia (germ cells) line the basement membrane of seminiferous tubules. • Spermatogonia divide into primary spermatocytes, then secondary spermatocytes, and then into spermatids. Spermatogenesis Image EM × 900; Micrograph provided by the Regents of University of Michigan Medical School © 2012.(“ Spermatogenesis and Spermiogenesis” by OpenStax is licensed under CC BY 3.0) Spermiogenesis • Maturation of spermatids into sperm (aka spermatozoa) • Occurs in epididymis and takes about 12 days • The spermatid sheds its excess cytoplasm, and the nucleus elongates. • A structure called the acrosome cap forms over the nucleus. • A tail forms from the microtubules. • 85,000 times smaller than the ovum (egg) • 100 – 300 millions produced each day • Sperm is now able to swim. Spermatogenesis and Spermiogenesis EM × 900; Micrograph provided by the Regents of University of Michigan Medical School © 2012.(“ Spermatogenesis and Spermiogenesis” by OpenStax is licensed under CC BY 3.0) Sperm (“Sperm” by OpenStax is licensed under CC BY SA 3.0) Sperm Pathway • (from epididymis to) • Ductus deferens / Vas deferens • Ejaculatory duct • Urethra Ductus Deferens • Tube lined with pseudostratified epithelium and very thick smooth muscles in the walls to propel sperm out of body during ejaculation (sperm can swim but is slow). • Starts in the scrotum, travels up in spermatic cord that contains nerves, blood and lymphatic vessels to inguinal canal into abdomen, and ends at posterior urinary bladder as ampulla. Semen • Thick, milky fluid of ejaculation • Semen is composed of sperm + seminal fluids • 5% is sperm • 95% are seminal fluids secreted from the followings: • 2 seminal vesicles • Prostate gland • 2 bulbourethral (Cowper’s) glands Seminal Vesicles • Posterior to urinary bladder • Secretion is added to sperm at ampulla • Has fructose (energy) for sperms • Makes 60% of semen • Duct of seminal vesicles merge with ampulla forming ejaculatory duct Prostate Gland • Size of a walnut, glandular and muscular tissues • Base of the urinary bladder • Urethra runs through the center of it • Secretes an alkaline, milky fluid to nourish sperm, liquefy semen and fight UTIs Bulbourethral glands • Also called Cowper’s glands • Inferior to prostate gland • Secretes salty lubricants Male Anatomy Front View (“ Male Genital System Front View” by Bioscope, HUG, DIP and Odile Fillod is licensed under CC BY SA 4.0) Penis • Composed of 3 columns of erectile tissue: • 2 corpora cavernosa, larger lateral chambers • 1 corpus spongiosum, smaller, contains urethra • Glans penis, very sensitive, is at the tip. It contains urethral orifice. • Prepuce (foreskin) covers the glans penis • Erectile tissues have venous spaces surrounding central artery • Sexual excitement causes blood to flow into central artery and venous spaces • Erectile tissues filled with blood compress veins, and blood cannot flow out. This causes erection. Penis (“Penis” by OpenStax is licensed under CC BY 3.0) Scrotum • Skin-covered, highly pigmented, muscular sack • Testes inside • 2-4 degrees cooler than body temperature, ideal to make sperms • Regulate temperature of testes by contractions of the dartos and cremaster muscles: relax at high temperature, contract at low temperature to maintain testes at proper temperature. • Raphe in the middle to separate right and left side • Blood vessels and nerves to testes travel through spermatic cord Scrotum and Internal Structures (“Scrotum and Internal Structures” by OpenStax is licensed under CC BY 3.0) Clinical Anatomy: Ectopic Pregnancy • Zygote implants in fallopian tube instead of uterus • Tube unable to expand to accommodate growing embryo • Embryo develops for up to 8 weeks • Tube may burst if embryo not removed • Symptoms: severe cramping Ectopic Pregnancy "Ectopic Pregnancy" by BruceBlaus is licensed under CC BY-SA 4.0 Clinical Anatomy: Ovarian and Cervical Cancer • Ovarian cancer originates in the fallopian tubes and occurs in the ovaries • Cervical cancer is found in the cervix • Both cause vaginal bleeding and pelvic pain, but cervical cancer also causes increased vaginal discharge and pain during sex • Only cervical cancer can be detected through Pap smear • Human Papillomavirus (HPV) is a group of more than 200 viruses, some of which can be sexually transmitted and can cause cervical cancer. • HPV vaccines decrease chances of infection from HPV, and thus chances of having cervical cancer. Cervical Cancer "Cervical-cancer" by Lolaia is licensed under CC BY-SA 4.0 Clinical Anatomy: Prostate Diseases • Benign prostatic hyperplasia (BPH), also called prostate gland enlargement, is a non-cancerous enlargement of the prostate gland. It is common in older men and caused by hormonal changes. It leads to more frequent and sometimes painful urination. • Prostate cancer is malignant and is caused by the formation of nodules in the prostate gland. Early diagnosis is key to prevent metastasis, thus a digital rectal exam is performed to men over 50 years of age. Radiotherapy or surgical removal of the prostate gland are the treatments used. Enlarged Prostate "Normal-vs-enlarged-prostate" by or Akcmdu9 is licensed under CC BY-SA 3.0