Reproductive Systems Lecture Notes PDF

11/5/20 Chapter 22 Reproductive Systems The Reproductive System • An organ system that works together for the purpose of reproduction - Differentiate between sexes - Include internal and external parts - Generally consist of gonads (where gametes are made), ducts, and openings 1 11/5/20...

11/5/20 Chapter 22 Reproductive Systems The Reproductive System • An organ system that works together for the purpose of reproduction - Differentiate between sexes - Include internal and external parts - Generally consist of gonads (where gametes are made), ducts, and openings 1 11/5/20 Produce _________ and _________ fluid Passage of Sperm: Outside of Body Sperm _________ Sperm _________ _________ Sperm _________ Sperm Produce ____ -rich fluid Produce _________ and _________ fluid Passage of Ovum: Outside of Body Ovum _________ _________ Ovum _________ Fetus _________ Fetus Male Reproductive System Bladder (urinary system) Seminal vesicle Vas deferens Prostate gland • External part: - Penis Testis Scrotum Bulbourethral gland Urethra • Internal part: Epididymis Penis - Epididymis Vas deferens Urethra Seminal vesicle Prostate gland Bulbourethral gland Testis Scrotum Pathway of Sperm Animation Figure 20.4a 2 11/5/20 • Functions: - Penis: sexual intercourse - Testis: generate sperm; produce sex hormone (testosterone) - Scrotum: the sac that contain testis - Epididymis: sperm maturation, transport and storage - Vas deferens: the tube that transports mature sperm from epididymis to the urethra - Urethra: the tube that carries urine from the bladder to outside of the body; ejaculate semen (in males) - Seminal vesicles: produce a sugar-rich fluid that provides sperm with a source of energy to help them move - Prostate: secrete fluid that nourishes and protects sperm - Bulbourethral gland: produce fluid to lubricate the urethra and to neutralize any acidity due to urine residue Female Reproductive System Ovary Oviduct Uterus Endometrium Bladder (urinary system) Urethra Cervix Vagina Vaginal Urinary opening opening Vulva • External part: - Vulva • Internal part: - Ovary Oviduct Uterus Endometrium Cervix Vagina Figure 20.5a 3 11/5/20 • Functions: - Vulva: the female external genitals - Ovary: produce eggs; secrete sex hormones (estrogen and progesterone) - Oviduct: the tube that transports an ovum from an ovary to the uterus - Uterus: the home to a developing fetus - Endometrium: the mucous membrane lining the uterus - Cervix: the narrow neck-like passage forming the lower end of the uterus - Vagina: the tube leading from the external genitals to the cervix Gametogenesis • The production of gametes (sex cells) in gonads (testes and ovaries) - Involve the process of meiosis • Different forms in males and females: - Spermatogenesis (male): begin at puberty; occur continuously - Oogenesis (female): begin before birth and resume at puberty; occur during menstruation 4 11/5/20 Spermatogenesis: the whole developmental process of proliferation of the sperm mother cells to mature sperm; occurs in the tubules of the testes Sperm mother cells Oogenesis: the creation of an ovum; consist of 3 steps Before or shortly after birth: Oogonium (2n) à Primary Oocyte (2n) At puberty: Primary Oocyte (2n) à Secondary oocyte (n) à Ovum (n) Ovulation: the release of an ovum from the ovary in the middle of the menstrual cycle 5 11/5/20 The Menstrual Cycle (a) Ovarian follicles Follicles Ovulation Corpus luteum 28-day cycle on average – Starting from the 1st day of bleeding Pituitary gland releases FSH and LH: FSH stimulates follicles to produce estrogen; LH stimulates corpus luteums to produce progesterone (b) Hormone levels Figure 20.8 LH Estrogen FSH Progesterone Days (c) Thickness of endometrium Menstruation Ovulation occurs 10-12 hours after the LH peak Endometrium (lining of the uterus) Fertility Test measure FSH level on day 3 of the menstrual cycle to indicate the ability to get pregnant If the egg quantity and quality is low, the FSH level may be high – produced by the pituitary to stimulate the ovary to produce eggs 6 11/5/20 Produce _________ and _________ fluid Passage of Sperm: Outside of Body Sperm _________ Sperm _________ _________ Sperm _________ Sperm Produce _________ and _________ fluid Produce ____ -rich fluid Passage of Ovum: Outside of Body Ovum _________ _________ Ovum _________ Fetus _________ Fetus Fertilization • Occur when both sperm and ovum are present in the oviduct 1 Follicle cell Sperm penetrates follicle cells. 2 Sperm head binds to the covering on the egg cell. 3 • Out of 300 million sperms ejaculated, only 200 reach egg in oviduct 4 Egg nucleus n 2n Sperm releases enzymes to get through the layer. Egg and sperm membranes fuse. Sperm nucleus n 5 Sperm nucleus enters egg cell. Figure 20.11 7 11/5/20 If the ovum is fertilized, a hormone HCG is produced – Over-the counter pregnancy test HCG level doubles every 2 days. Pregnancy can be detected 7 to 10 days past ovulation. In Vitro Fertilization (IVF) • TIME Magazine (June 10, 2013) – Frontiers of Fertility - “An estimated 48.5 million couples worldwide are unable to conceive after five years of trying - “For the past years, the average billed cost for a single IVF cycle is $12,400” - “Just one cycle is usually not enough” – Successful rate: 42% (35 yrs), 22% (40 yrs), 5% (45 yrs) - “Insurance companies don’t cover infertility treatments” 8 11/5/20 Male Infertility • Male infertility is mostly related to problems with sperm formation or production - Low sperm counts Improperly shaped sperm Low motility Low sperm viability (probably due to chemical exposure, e.g. pesticides) Increase with alcohol and drug use, and smoking - Female Infertility • Female infertility can be caused by a number of factors: - Age: peaks at 22~26; decline rapidly after 40 Damage to the oviduct Low hormone levels Cervical narrowing or blockage Poor egg quality Unexplained causes - 9 11/5/20 Birth Control • Hormonal methods - Birth control pills: contain estrogen and/or progesterone; counter the hormone fluctuations of a menstrual cycle to prevent ovulation • Barrier methods - Condom: keep sperms from reaching eggs; reduce sexually transmitted disease (STD) • Sterilization: block oviducts or cut vas deferens • Fertility awareness: abstinence for the 4 days before and after predicted time of ovulation Pregnancy • The process of carrying a developing baby inside the female reproductive tract - 40 wks in humans; 9-wk old fetus has all its limbs and organs in place - Embryo implants in the wall of the uterus - A placenta is developed to sustain pregnancy Figure 20.13 Embryo at 1 month Figure 20.14 Fetus at 9 weeks 10 11/5/20 Childbirth • The process of normal childbirth is categorized in three stages of labor: Stage 1: Cervix Dilation Placenta Stage 2: Expulsion Umbilical cord Uterus Stage 3: Delivery of placenta Placenta (detaching) Umbilical cord Cervix Figure 20.16 Childbirth Caesarean section (C-section): the delivery of a baby through an incision in the mother’s belly and uterus Planned: • The baby is not in a head-down position close to due-day - Having C-section before - Health problems (heart disease, infection) - Carrying more than one baby - Unplanned: The baby is too big to be delivered - Labor is slow and hard - The baby is at risk due to placenta or umbilical cord problems - 11