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Questions and Answers
What are gonads?
What are gonads?
Primary sex organs
What are the two types of gonads?
What are the two types of gonads?
What is the function of gonads?
What is the function of gonads?
Producing gametes and secreting hormones
What are the male gametes called?
What are the male gametes called?
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What are the female gametes called?
What are the female gametes called?
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What is the duct system of the male reproductive system?
What is the duct system of the male reproductive system?
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Which of these structures is NOT part of the duct system?
Which of these structures is NOT part of the duct system?
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What is the function of the epididymis?
What is the function of the epididymis?
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What is the function of the ductus deferens?
What is the function of the ductus deferens?
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What is the function of the urethra?
What is the function of the urethra?
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What are the three regions of the urethra?
What are the three regions of the urethra?
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What happens to the internal urethra sphincter during ejaculation?
What happens to the internal urethra sphincter during ejaculation?
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What are the accessory organs of the male reproductive system?
What are the accessory organs of the male reproductive system?
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Where are the seminal vesicles located?
Where are the seminal vesicles located?
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What does the secretion from the seminal vesicle contain?
What does the secretion from the seminal vesicle contain?
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What is the function of the prostate?
What is the function of the prostate?
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What is the function of the bulbourethral glands?
What is the function of the bulbourethral glands?
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What is the primary function of bulbourethral gland secretions?
What is the primary function of bulbourethral gland secretions?
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What is semen?
What is semen?
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What is the function of the liquid portion of semen?
What is the function of the liquid portion of semen?
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Semen inhibits bacteria.
Semen inhibits bacteria.
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What are the two primary components of external genitalia in the male reproductive system?
What are the two primary components of external genitalia in the male reproductive system?
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What is the scrotum?
What is the scrotum?
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The scrotum maintains the testes at a temperature 3 degrees Celsius lower than normal body temperature.
The scrotum maintains the testes at a temperature 3 degrees Celsius lower than normal body temperature.
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What is the function of the penis?
What is the function of the penis?
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What is the glans penis?
What is the glans penis?
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What is the function of the erectile tissue in the penis?
What is the function of the erectile tissue in the penis?
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What is the function of the male reproductive system?
What is the function of the male reproductive system?
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Where are sperm produced?
Where are sperm produced?
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What is the process of sperm production called?
What is the process of sperm production called?
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What hormone is secreted in increasing amounts during puberty that stimulates spermatogenesis?
What hormone is secreted in increasing amounts during puberty that stimulates spermatogenesis?
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Explain the process of a new sperm cell being formed.
Explain the process of a new sperm cell being formed.
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What are the three regions of a sperm cell?
What are the three regions of a sperm cell?
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What is the function of the acrosome?
What is the function of the acrosome?
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What is the function of testosterone?
What is the function of testosterone?
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Study Notes
Human Reproductive System
- The reproductive system involves the production of gametes (sex cells) and secretion of hormones
- The gonads are the primary sex organs
- Testes are the male gonads
- Ovaries are the female gonads
- Sperm are the male gametes
- Ova (eggs) are the female gametes
Male Reproductive System Anatomy
- Testes: Produce sperm and testosterone
-
Duct system: Transports sperm
- Epididymis: Stores and matures sperm
- Ductus (vas) deferens: Transports sperm to urethra
- Urethra: Carries both urine and sperm
-
Accessory organs: Produce fluids for semen
- Seminal vesicles: Produce a thick, yellowish secretion (60% of semen) containing fructose (sugar) and vitamin C
- Prostate: Encircles the urethra; secretes a milky fluid to help activate sperm
- Bulbourethral glands: Produce a thick, clear mucus that cleanses the urethra, and acts as a lubricant
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External genitalia:
- Penis: Male organ of copulation
- Scrotum: Houses testes; maintains testes at 3°C below normal body temperature
Male Reproductive System - Testes
- Each testis is attached to the trunk by the spermatic cord, which contains blood vessels and nerves
- Tunica albuginea: Outer capsule of each testis
- Septa: Extensions of tunica albuginea that divide the testis into lobules
- Seminiferous tubules: Coiled structures within the lobules; sperm forming factories
- Interstitial cells: Produce testosterone, located in the seminiferous tubules
Male Reproductive System - Duct System
- Epididymis: Highly convoluted tube adjacent to the testes; stores immature sperm
- Ductus (vas) deferens: Runs from the epididymis; transports sperm through the inguinal canal and arches over the urinary bladder; connects to the ejaculatory duct
- Ejaculatory duct: Passes through the prostate to merge with the urethra
-
Urethra: Transports sperm and urine; regions include:
- Prostatic urethra: Surrounded by the prostate gland
- Membranous urethra: Connects to the penis
- Spongy (penile) urethra: Runs the length of the penis; opens at the external urethral orifice
Male Reproductive System - Semen
- Semen is a milky white mixture of sperm and fluids from accessory glands
- Provides a transport medium
- Sperm are streamlined cells (tadpoles)
- Fructose provides sperm with energy
- Semen's alkalinity neutralizes the acidic environment of the vagina
- Inhibits bacteria
Male Reproductive System - External Genitalia
- Scrotum: Supports the testes; maintains testes at a lower temperature crucial for sperm development
- Penis: Male organ of copulation; has three areas of spongy erectile tissue around the urethra; erections occur as this tissue fills with blood
Male Reproductive Functions
- Produce sperm: Through spermatogenesis
- Produce hormone testosterone: Stimulates reproductive organ development, sex drive, and causes secondary sex characteristics
Spermatogenesis
- Sperm production begins at puberty and continues throughout life
- Spermatogonia (primitive stem cells) divide rapidly
- Follicle-stimulating hormone (FSH) increases during puberty
- Sperm are formed in the seminiferous tubules of the testis
- Meiosis is the special type of nuclear division in gonads; results in four daughter cells (gametes)
- Spermatids are nonmotile; cells are modified into sperm during spermiogenesis
- Spermatogenesis takes about 64 to 72 days for completion
- Sperm has three regions: head (acrosome & nucleus), midpiece (mitochondria), and tail (axial filament)
Testosterone Production
- FSH: Promotes sperm production
- LH: Activates interstitial cells to produce testosterone
- Testosterone: Essential for male secondary sex characteristics (deepening of voice, hair growth, skeletal muscle enlargement, bone growth/density)
Female Reproductive System Anatomy
-
Ovaries: Produce eggs (ova) and hormones (estrogen and progesterone)
- Ovarian follicles: Contain immature eggs (oocytes)
- Ovulation: Mature egg is released from the ovary
- Corpus luteum: Forms after ovulation; produces progesterone
- Uterine (fallopian) tubes: Carry eggs (ova) to uterus
- Uterus: Houses and nourishes fertilized egg (embryo/fetus) during pregnancy
- Vagina: Passageway from cervix to exterior
- External genitalia: Mons pubis, labia majora & minora, clitoris, urethral orifice, vaginal orifice, and greater vestibular glands
Oogenesis and Ovarian Cycle
- Oogenesis: Formation of eggs (ova)
- Oogonia: Female stem cells in developing fetus
- Oogonia undergo mitosis to produce primary oocytes
- Primary oocytes remain inactive until puberty
- FSH: Causes follicles to mature each month
- Meiosis: Begins in primary oocytes; completed only if fertilization occurs
- Ovulation: Secondary oocyte is released; surrounded by corona radiata
- Ovum: Formed when the second meiotic division is completed if fertilized
- Estrogen: Major effect of follicle cells; causes secondary sex characteristics
- Progesterone: Produced by corpus luteum; crucial in maintaining pregnancy (prepares breasts for lactation)
Uterine Cycle (Menstrual Cycle)
- Cycle of changes in endometrium about 28 days
- Regulated by estrogen and progesterone
- FSH and LH regulate the production of estrogens and progesterone
- Ovulation occurs typically on day 14 of the cycle
- Stages:
- Menstrual phase (days 1-5): Endometrial layer is shed
- Proliferative phase (days 6-14): Endometrium is repaired, thickens, and becomes vascularized; estrogen levels rise; ends with ovulation
- Secretory phase (days 15-28): Progesterone levels rise; endometrium increases in size and become vascularized; readies for implantation; if no fertilization occurs, corpus luteum degenerates and menstrual flow begins
Mammary glands
- Present in both sexes, functioning only in females.
- Modified sweat glands, producing milk.
- Stimulated by hormones, mainly estrogen, to grow in size.
- Parts include areola, nipple, lobes, lobules, alveolar glands, lactiferous ducts, and lactiferous sinuses
Pregnancy and Embryonic Development
- Pregnancy: Beginning from fertilization to birth
- Conceptus: Developing offspring
- Embryo: From fertilization to week 8
- Fetus: Week 9 to birth
- Gestation: From last menstrual period to birth (approximately 280 days)
Accomplishing Fertilization
- Oocyte viable up to 24 hours after ovulation
- Sperm viable up to 48 hours
- Sexual intercourse must occur no more than 2 days before ovulation and 24 hours after
- Sperm must travel to the uterine tube
- Sperm attracted to the oocyte by chemicals (chemotaxis)
- Enzymes break down follicle cells of the corona radiata around the oocyte during sperm arrival
- Sperm undergoes acrosomal reaction (important to penetrate oocyte)
- Oocyte undergoes second meiotic division to produce an ovum & a polar body.
- Genetic material of sperm and oocyte join for fertilization
Events of Embryonic/Fetal Development
- Zygote: First cell of new individual, formed from sperm & ovum fusion
- Cleavage: Rapid mitotic divisions
- Morula: Ball of 16 cells
- Blastocyst: Hollow ball-like structure; contains trophoblast and inner cell mass; secretes hCG
- Trophoblast: Outer layer of blastocyst; develops chorionic villi; combines with uterine tissues to make placenta
- Inner cell mass: Forms the embryo
- Amnion: Fluid-filled sac surrounding developing embryo
- Umbilical cord: Blood vessel-containing stalk connecting embryo to placenta
- Placenta: Barrier between mother & embryo; supplies nutrients and oxygen; removes wastes; produces hormones essential to maintaining pregnancy
- Primary germ layers: Form various systems in the embryo (Ectoderm, Mesoderm, & Endoderm)
Childbirth (Parturition)
- Labor: Series of events expelling the infant from the uterus
- Rhythmic, expulsive contractions; positive feedback mechanism
- False labor (Braxton Hicks contractions): Weak/irregular uterine contractions
- Estrogen levels rise; uterine contractions begin; placenta releases prostaglandins; oxytocin released.
- Combined hormone actions (oxytocin & prostaglandins) initiate contractions & force baby deeper into the pelvis
- Stages of labor:
- Dilation: Cervix dilates to 10 cm; amnion ruptures ("breaking the water")
- Expulsion: Infant passes through cervix & vagina
- Placental: Delivery of the placenta
Developmental Aspects of the Reproductive System
- Gender Determination: Determined at fertilization; males have XY, females have XX chromosomes
- Early Development: Reproductive system structures of males & females are identical
- Gonad Development: Gonads do not form until week 8
- Hormone Influence: Testosterone presence/absence determines accessory reproductive organ development
- Childhood: Reproductive system inactive
- Puberty: Reproductive system organs function for childbearing; typically ages 10-15; males experience testes/scrotum enlargement; females experience budding breasts & menarche (first menstrual period)
- Menopause: Ovaries stop functioning as endocrine organs; childbearing ends; hot flashes & mood changes may occur in females.
Effects of Pregnancy on the Mother
- Anatomical changes: Enlargement of uterus; exaggerated lumbar curvature (lordosis); relaxation of pelvic ligaments and pubic symphysis
-
Physiological changes:
- Gastrointestinal: Morning sickness (due to elevated progesterone/estrogen); heartburn (organ crowding); constipation
- Urinary: Kidneys have additional burden; urine production increases; uterus compresses bladder, causing stress incontinence;
- Respiratory: Nasal mucosa congestion and swelling; vital capacity and respiratory rate increases; dyspnea
- Cardiovascular: Blood volume increases; blood pressure & pulse increases; varicose veins
A Closer Look: Contraception
- Methods for preventing pregnancy
- Hormonal contraceptives: Birth control pill, morning-after pill
- Barrier methods: Condoms, diaphragms, cervical caps, spermicidal foams, gels, sponges
- Intrauterine devices (IUDs): Plastic or metal device inserted into uterus
- Sterilization: Tubal ligation (females), vasectomy (males)
- Rhythm/Fertility Awareness: Avoid intercourse during fertile period
- Coitus interruptus: Withdrawal before ejaculation
- Abortion: Termination of pregnancy; includes RU486 (abortion pill)
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