Reproductive System Notes PDF

THE REPRODUC TIVE SYSTEM  The Reproductive System designed to produce offspring and to perpetuate the species – The male produces gametes called sperm cells – The female produces gametes called ovum – The joining of a sperm cell and an ovum i...

THE REPRODUC TIVE SYSTEM  The Reproductive System designed to produce offspring and to perpetuate the species – The male produces gametes called sperm cells – The female produces gametes called ovum – The joining of a sperm cell and an ovum is fertilization – Fertilization results in the formation of a zygote - Zygote develops into embryo The Reproductive System Primary reproductive organs (gonads) (cont’d) - Functions of mature gonads: Producing gametes (gametogenesis) – Spermatozoa (sperm) in male – Ova (eggs) in female Secreting sex hormones  The Reproductive System Reproductive tract – System of specialized ducts that transport or house gametes after they are produced Accessory sex glands – Empty supportive secretions into reproductive tract – For example prostate gland in males and uterus glands in females External genitalia – Externally visible portions of reproductive system  The Male Reproductive System Functions: – Production of sperm (spermatogenesis) – Delivery of sperm to female Organs: – The Testes Sperm-producing organs Suspended outside abdominal tract in skin- covered sac (scrotum)  The Male Reproductive System The testes (cont’d) In the abdomen during development, and descend into the scrotum during the 7th month of gestation The lower temperature (3ºC) below normal body temperature helps sperm production The penis The organ used to deposit semen into the female It is a transporting and supporting structure  The Male Reproductive The reproductive tractSystem Epididymis (x2) Ductus (vas) deferens (x2) Ejaculatory duct (x2) Urethra The accessory glands Seminal vesicles Prostate gland Secrete fluid (semen) into the reproductive Bulbourethral gland tract The testes are located in the scrotum which is an outpouching of the abdominal wall Each testicle is separated from the other by a septum (Protects against the spreading of infection) The temperature of the testes is carefully regulated by moving them closer to (in cold environment) or farther away from the body (in hot environment) 2 muscles are responsible for this movement; Cremaster and Dartos muscle (smooth muscles) The testes contain: Seminiferous tubules 80% of testicular mass Produce sperm (spermatogenesis) Leydig cells In the connective tissue between the seminiferous tubules Produce testosterone under the control of the pituitary gland’s secretion of luteinizing hormone  Each sperm has: a head, a middle piece and a tail ucleus: Contains the genetic information osome: Filled with enzymes that break down the membrane of the ovum and allow the sperm to penetrate ochondria: Provide energy for the movement of the tail ail: Gives the sperm its motility (swim) Testosterone: Once produced: Some is secreted into the blood where it is transported (bound to plasma proteins) to site of action Some goes into the lumen of the seminiferous tubules where it helps with sperm production and delivery of sperm to the female A small portion of testosterone gets converted to estrogen by Testosterone: Controls development, growth, and maintenance of male sex organs Stimulates muscle buildup and bone development Causes sperm maturation Causes thyroid cartilage enlargement Produces body hair patterns Testes: Tunica albuginea white fibrous capsule Lobules 250-300 per testicle Separated by septum Seminiferous tubules 1-3 in each lobule Where sperm is produced Rete testis Network connecting seminiferous tubules to the Fig 27.79b epididymis Testes: Spermatic Ducts Efferent ductules Approx 12 per testicle Posterior part of testis Epididymis Posterior part of testis Sperm maturation and storage Head, long body, slender tail Fig 27.9b  Ductus (vas) deferens Passes between urinary bladder and ureter Widens into terminal = ampulla Connects into seminal Ejaculatory vesicle duct Passes through prostate gland Empties into urethra Urethra terminal duct of the system common passageway for sperm coming from the Accessory Glands 1. Seminal vesicles Posterior to bladder Yellowish secretion (viscous part of semen, 60% of the semen) Fructose (nourishment for sperm) Prostaglandins (stimulate smooth muscle contractions) Fibrinogen (Semen temporarily clots within vagina) Accessory Glands 2. Prostate gland Inferior to bladder Secretes an alkaline fluid that neutralizes the acidity of the vagina Clotting enzymes and fibrinolysin Milky secretion (30% of semen) Fig 27.11b Accessory Glands 3. Bulbourethral glands Small, spherical Secrete clear, slippery fluid during sexual arousal Lubricates the urethra for spermatozoa to pass through Fig 27.11b The Penis Delivers sperm to female reproductive tract Consists of base, shaft, glans (head) and foreskin Tissues that make up the penis include the dorsal nerve, blood vessels, connective tissue and erectile tissue (corpus spongiosum and corpus cavernosum). The urethra passes from he the bladder to the tip of the penis  The Female Reproductive System Functions: – Cyclical production of ova (oogenesis) – Reception of sperm – Transport of sperm and ovum to common site for union (fertilization or conception) Product of fertilization is known as an embryo After first two months of intrauterine development, The Female Reproductive System Functions (cont’d): – Maintenance of the developing fetus until it can survive in outside world (gestation or pregnancy) Formation of placenta – Giving birth to the baby (parturition) – Nourishing infant after birth by milk production (lactation)  The Female Reproductive Organs: System – Oviducts (uterine or Fallopian tubes) In close association with ovaries Pick up ovum on ovulation (once per month), and transport it to the uterus if it is not fertilized by the sperm Serve as site for fertilization which occurs in upper third of tube  The Female Reproductive System Organs (cont’d): - Uterus Site of menstruation and egg implantation Responsible for maintenance of fetus during development Uterine wall made of 3 layers: endometrium (innermost), myometrium, perimetrium (outermost) The Female Reproductive System Organs (cont’d): - Uterus Lower portion of uterus which opens into vagina is the cervix – Cervical canal (the interior of cervix) – Single, small opening that serves as pathway for sperm – Serves as passageway for delivery of baby from uterus  The Female Reproductive System Organs (cont’d): – Vagina Muscular, expandable tube that connects uterus to external environment Passageway for menstrual flow Vaginal opening is located in perineal region between  The Female Reproductive System – Vagina and External Genitalia of the Female Vagina partially covered by thin mucous membrane, hymen (typically disrupted by first sexual intercourse) External genitalia: vulva Labia minora and labia majora are skin folds that surround vaginal and urethral openings Clitoris is a small erotic structure located at anterior  The Female Reproductive System Characterized by complex cycling Ovaries – Primary female reproductive organs Produce ova (oogenesis) Secrete female sex hormones – Estrogen » Essential for ova maturation and  The Female Reproductive System – Estrogen (cont’d) » Essential for transport of sperm from vagina to fertilization site in oviduct » Contributes to breast development in anticipation of lactation – Progesterone » Important in preparing suitable environment for nourishing a developing embryo/fetus » Contributes to breasts’ ability  The Female Reproductive - System Oogenesis: In female fetus (before birth), the female cells called oogonia divide by mitosis to produce primary oocytes - Primary oocytes are surrounded by follicular cells in the ovary and are now part of the primary follicles (around 700.000 are produced) and await further development until puberty  The Female Reproductive - System At puberty, the ovarian cycle begins that the immature egg or oocyte inside the primary follicle will develop and will be ejected from the ovary (ovulation, one egg per month) - Only about 450 eggs will be produced from the store of 700.000 primary follicles (oocytes) - Ovulation will stop at menopause  The Menstrual Cycle Average menstrual cycle lasts 28 days Normally interrupted only by pregnancy Finally terminated by menopause Comprises 2 distinct cycles: i) ovarian cycle (within the ovaries), and ii) endometrial cycle (within the endometrium of the uterus)  The Ovarian Cycle Consists of two alternating phases: – Follicular phase Dominated by presence of maturing follicles – Luteal phase Characterized by presence of corpus luteum  Follicular Phase Operates first half of cycle A single layer of granulosa cells in primary follicle proliferates to form several layers that surround the oocyte Oocyte inside each follicle enlarges Theca cells in follicle secrete increased amounts of estrogen  Follicular Phase Rapid follicular growth continues during follicular phase – One follicle usually grows more rapidly and matures about 14 days after onset of follicular development Follicle ruptures to release oocyte from ovary Event is called ovulation Released oocyte enters  Luteal phase Last 14 days of ovarian cycle Old follicular cells undergo structural transformation to form corpus luteum Becomes highly vascularized Becomes fully functional within four days after ovulation  Luteal phase Continues to increase in size for another four or five days Secretes progesterone along with smaller amounts of estrogen If released ovum is not fertilized and does not implant, corpus luteum (a yellow body) degenerates within about 14 days after its formation and becomes  Endometrial Cycle Menstrual phase Proliferative phase Secretory phase  Menstrual Phase Characterized by discharge of blood and endometrial debris from vagina First day of menstruation is considered start of new cycle Coincides with end of ovarian luteal phase and onset of follicular phase  Proliferative Phase Begins concurrent with last portion of ovarian follicular phase – Endometrium starts to repair itself and proliferate under influence of estrogen from newly growing follicle Estrogen-dominant proliferative phase lasts from end of menstruation to ovulation  Secretory Phase Uterus enters this phase after ovulation, when new corpus luteum is formed Corpus luteum secretes large amounts of progesterone and estrogen – Progesterone converts endometrium to highly vascularized, glycogen-filled tissue If fertilization and implantation do not occur – Corpus luteum degenerates Pregnancy and Embryonic Development – Fertilization normally occurs in upper third of oviduct (ampulla) – Both ovum and sperm must be transported to the ampulla  Pregnancy and Embryonic Development – Fertilization must occur within 24 hours after ovulation Sperm usually survive about 48 hours but can survive up to five days in female reproductive tract – Sperm deposited in vagina travel through cervical canal and uterus to upper third of oviduct  Pregnancy and Embryonic Development First sperm to reach ovum – Fuses with plasma membrane of ovum – Triggers chemical change in ovum’s surrounding membrane that makes outer layer impermeable to entry of any more sperm – Head of fused sperm gradually pulled into ovum’s cytoplasm – Within hour, sperm and egg nuclei fuse Fertilized ovum now called a zygote  Pregnancy and Embryonic Development Fertilized ovum divides mitotically – Within week grows and differentiates into blastocyst capable of implantation Blastocyst implants in endometrial lining by means of enzymes released by trophoblasts – Enzymes digest endometrial tissue Carve hole in endometrium for  Pregnancy and Embryonic Development After implantation, the placenta develops – Organ of exchange between maternal and fetal blood – Acts as transient, complex endocrine organ that secretes essential pregnancy hormones Human chorionic gonadotropin: maintains corpus luteum until placenta takes over function in last two trimesters  Pregnancy and Embryonic The placenta Development performs the functions of the digestive system, the respiratory system, and the kidneys for the fetus – Nutrients and oxygen diffuse from the maternal blood across the thin placental barrier into the fetal blood, whereas carbon dioxide and other metabolic wastes simultaneously diffuse from the fetal blood into the maternal blood Maternal Body Systems and Gestation The period of gestation (pregnancy) is about 38 weeks from conception (40 weeks from the end of the last menstrual period) Physical changes within mother to meet demands of pregnancy: – Uterine enlargement – Breasts enlarge and develop ability to produce milk – Volume of blood increases 30  Maternal Body Systems and Gestation (cont’d) Physical changes (cont’d): – Respiratory activity increases by about 20 percent – Urinary output increases – Kidneys excrete additional wastes from fetus – Nutritional requirements increase  Labor [[CATCH: C17-F28-HP4ce here, p. 770]]  Preparation of the Breasts for Lactation During gestation – Elevated placental estrogen and progesterone promote development of ducts and alveoli in mammary glands  Mammary Gland Anatomy Produce milk in females Contain 15 to 20 lobes or compartments separated by adipose tissue Each lobe are several smaller compartments known as lobules Lobules contain milk-secreting cells called alveoli  Pathology Enlarged Prostate The prostate gland enlarges in almost every older adult man. It constricts the urethra, making urination difficult. It can lead to kidney damage and bladder infections. Enlarged prostate glands can be treated surgically. The prostate gland can also hypertrophy or enlarge due to infections or tumors.  Pathology Prostate Cancer Cancer of the prostate gland is the third most prevalent type of cancer in men. Slow-growing cancer that is not easily detected. Regular checkups for the detection of enlargement or any abnormal changes in the gland are an important to detect prostate cancer.  Pathology Cervical cancer Slow-growing cancer common in women between the ages of 30 and 50. Conditions that can lead to this type of cancer include frequent intercourse with multiple sex partners, sexually transmitted diseases (e.g., gonorrhea and syphilis), frequent cervical inflammation, and multiple pregnancies. Yearly Pap smear tests are significant  Pathology Breast cancer is leading cause of death in women (one in eight women), but men can also get breast cancer. Symptoms of this disease include lumps, leakage, or puckering of the nipple and changes in skin texture. Malignant tumors can spread to other body parts, yet early detection can lead to effective treatment and survival. Mammography uses low-intensity X-rays to detect tumors that are less than 1 cm. If a tumor is detected, a biopsy is performed. Most tumors of the mammary glands are  Pathology Premenstrual syndrome (PMS) is a series of symptoms during the premenstrual phase. The cause of PMS is not known, so treatment is aimed at relieving the symptoms (irritability, fatigue, depression). Endometriosis: Endometrial tissue grows outside the uterus when endometrial cells pass through the fallopian tubes to the pelvic cavity. When estrogen and progesterone levels rise, the tissue proliferates and grows, then degenerates resulting in bleeding. It causes severe premenstrual and menstrual  Pathology Sexually transmitted diseases are spread by intimate sexual contact with sexual partners who harbor the infection. These diseases are caused by bacteria, viruses, and protozoa. Trichomonas Gonorrhea Syphilis Genital herpes and warts AIDS