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A&P II Final Exam Review Slides
Lectures 18-21Reproductive System
Pregnancy, Growth, and Development
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Male Reproductive System
Pathway of spermatozoa travel:
Testis → Epididymis → Vas (ductus) deferens → Ejaculatory duct → Urethra
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001• There are three main functions of the
male reproductive system– Produce and maintain sex cells
(sperm)– Transport sperm and
supplemental fluids to the female reproductive tract
– Secrete male sex hormones
• Sex organs can be divided into– Primary sex organs (gonads) =
testes (sperm, hormones)– Accessory (secondary) sex
organs = internal and external reproductive organs Descent of testes begins
1-2 months before birth under the influence of testosterone
Descent is necessary for viable sperm production
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Structure of the Testis
Surrounded by the tunica albuginea – a tough, white, fibrous capsule that encloses each testicle
Septa divide each testicle into about 250 lobules
Each lobule contains 1-4 highly coiled seminiferous tubules that produce sperm
Interstitial cells (of Leydig) lie in between seminiferous tubules and secrete male sex hormones
Rete Testis
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Spermatogenesis – Production of sperm
Spermatogonium (2n)
Primary spermatocyte (2n)
Secondary spermatocyte (n)
Spermatid (n)
Spermatozoan (n)
Spermiogenesis
Meiosis I
Meiosis II
Know the order of events below and the ploidy at each step!
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Seminiferous Tubules and Sperm MaturationFigures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Spermatogonium = stem cell
Supporting cells are sustentacular cells
They:
1. are important in regulating and supporting spermatogenesis
2. help maintain the blood-testis barrier (important in protecting developing sperm from immune attack)
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Structure of a Sperm Cell
Only flagellum in human body
Head of sperm contains:
1) Genetic Material2) Enzymes used to penetrate the egg during fertilization are contained in the acrosome
Mitochondria
Capacitation is the complete maturation of sperm to become fully functional (able to fertilize an egg). This is normally not entirely complete until the sperm enter the female reproductive tract.
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Epididymis
- Maintains fluid produced in the seminiferous tubules- Recycles damaged sperm and cellular debris- Store and protects sperm, and aids in their maturation
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Takes about 2 weeks for sperm to travel through the epididymis
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Ductus (Vas) Deferens• muscular tube about 45 cm long; transports sperm ( can store sperm for several months)• extends from epididymis to ejaculatory duct
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
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Seminal VesiclesSeminal Vesicles• attached to ductus deferens near base of bladder• secretes alkaline fluid (60% of the volume of semen)• secretes fructose, prostaglandins, and proseminogelin• begins capacitation of sperm• contents empty into ejaculatory duct
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Prostate• surrounds beginning of urethra• ducts of gland open into urethra• secretes a thin, milky, slightly acidic fluid (20-30% of semen volume)• secretion enhances fluid mobility• contains seminalplasmin• composed of tubular glands in connective tissue• also contains smooth muscle
Bulbourethral gland• secretes thick, alkaline mucus - helps lubricate the tip of the penis (glans) and neutralize any urinary acids in urethra• fluid released in response to sexual stimulation
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Semen
• sperm cells
• secretions of seminal vesicles, prostate gland, and bulbourethral glands (seminal fluid)
• slightly alkaline
• prostaglandins
• nutrients
• enzymes (protease, seminalplasmin, fibrinolysin)
• 20-100 million sperm cells per milliliter
• usually about 2-5 ml of fluid per ejaculate
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Scrotum
• pouch of skin and subcutaneous tissue• dartos muscle – smooth muscle in dermis; contracts to cause wrinkling of the scrotum (traps heat)• medial septum divides scrotum into two chambers• each chamber lined with a serous membrane• each chamber houses a testis and epididymis
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Cremaster muscle can retract or drop testes to maintain optimum temperature for sperm development
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Penis (Root, Body [shaft], Glans)
Preputial glands in the prepuce (foreskin) produce a waxy material called smegma. This can be a source of bacterial growth if hygiene is poor.
Circumcision is the surgical removal of the prepuce.
Corpora cavernosa and spongiosum (surrounds urethra) are the male erectile tissues of the penis.
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Erection, Orgasm, and Ejaculation
Erection • parasympathetic nerve impulses cause release of nitric oxide to dilate blood vessels in penile erectile tissues • blood accumulates in erectile tissues
Orgasm• culmination of sexual stimulation• accompanied by emission and ejaculation
Emission and Ejaculation• emission is the movement of semen into urethra• ejaculation is the movement of semen out of the urethra• largely dependent on sympathetic nerve impulses
Bulbospongiosus m.
Ischiocavernosus m.
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• hypothalamus controls maturation of sperm cells and development of male secondary sex characteristics
• negative feedback controls concentration of testosterone
Hormonal Control of Male Reproduction
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Actions of Testosterone (2o Sex Char.)
• increased growth of body hair
• sometimes decreased growth of scalp hair
• enlargement of larynx and thickening of vocal cords
• thickening of skin
• increased muscular growth
• thickening and strengthening of the bones
Know these actions
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Functions of the Female Reproductive System
• Produce and maintain sex cells (eggs) – a function of the ovaries, the primary sex organs
• Transport eggs to site of fertilization• Produce female sex hormones• Provide favorable environment for development of
offspring• Move offspring to outside (birth)
Secondary sex organs of the female - Internal: Fallopian (uterine) tubes, uterus, vagina - External: mons pubis, labia majora and minora, clitoris, vestibular glands
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Organs of the Female Reproductive System
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
(Bartholin’s glands)
(Skene’s glands; lesser vestibular glands)
(In anteflexion)
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Ligaments of Uterus and Ovaries
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 18
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Overview of the Ovarian CycleOvarian cycle – events occurring monthly in an ovary (oocyte growth and meiosis occur); cycle is usually about 28 days long
Two phases: 1) Follicular phase 2) Luteal phase
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Ovarian Cycle – Preovulatory (Follicular) Phase
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
(FSH)Thecal and granulosa cells produce estrogens
8-10 days after beginning of cycle
10-14 days
Meiosis I
LH
Meiosis II started
Many OneFew
(Graafian)
1.5 cm
Estrogen
(FSH)
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Ovarian Cycle – Postovulatory (Luteal) Phase
(Day 14)
LH
Lipids used to synthesize progestins, e.g., progesterone (prepares uterine lining for implantation)
12 days post ovulation
If fertilization has not occurred
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
LH
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Oogonium = stem cell
Primary oocyte – diploid cell; result of mitotic division of oogonium
Secondary oocyte – haploid cell; result of meiotic division of primary oocyte
Polar body – shed genetic material during meiotic divisions
Ovum – haploid gamete in metaphase II of meiosis that is released from ovary at ovulation
Oogenesis – generation of ova (gametes) in ovary
How does oogenesis differ from spermatogenesis? How is it the same?
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Uterine (Fallopian) Tubes
Segments of the uterine tube:
- Infundibulum contains fimbriae (inner surfaces lined with cilia that beat toward center)
- Ampulla (middle, muscular segment)
- Isthmus (segment connected to the uterine wall)
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Oocytes are transported by
- ciliary action
- peristalsis
(Parasympathetic NS activity a few hours before ovulation)
Fallopian tubes are site of fertilization of egg by sperm and transport fertilized egg to uterus for implantation
Fertilization usually occurs around here
Fallopian tube = salpinx [salping(o)-]
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Uterus (hyster(o)-)
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Functions:
- Mechanical protection (fetus)
- Nutritional support (fetus)
- Waste removal (fetus)
- Ejection of fetus at birth
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Uterus and Endometrium
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Two layers of endometrium: 1)Basilar zone, 2) Functional Zone
Under the influence of estrogen and progesterone, ute
rine glands, blood vessels, and epithelium in the functional zone of the endometrium change with the phases of the uterine (menstrual) cycle
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Vagina
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Major functions:
- Passageway for elimination of menstrual fluids
- Receives penis and holds sperm prior to passage into uterus
- Inferior portion of birth canal for fetal delivery
Acidity of vagina protects adults from bacterial infections
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Female External Reproductive Organs
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Includes the structures external to the vagina (within vestibule):
- mons pubis - labia majora and minora - clitoris (and prepuce) - vestibular structures (enclosed within labia minora)
Opening of ducts of greater vestibular glands (Bartholin’s) – mucous secretions
Perineum
Female external genitalia = pudendum or vulva
Know the terms on this slide
anterior
posterior
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Female Erection, Lubrication, and Orgasm
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Uterine (Menstrual) Cycle
Proliferative phase – functional layer of endometrium thickens under the influence of estrogen
Secretory phase – Arteries elaborate and uterine glands enlarge, coil, and begin secreting glycogen under progesterone’s influence
Functional
Basilar
*
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Hormonal Regulation of Ovarian Activity
Figure from: Marieb, Anatomy & Physiology, Pearson, 2004
Estrogen is the predominant hormone prior to ovulation (follicular phase)
Progesterone is the predominant hormone after ovulation (luteal phase)
inhibits LH and FSH during most of the reproductive cycle
(Day 10)
16-24 GnRH pulses/day
48GnRH pulses/day
36 GnRH pulses/day
1-4 GnRH pulses/day
Changes in pulse rate of GnRH control secretion of LH/FSH. GnRH release is controlled by estrogen, inhibin, and progesterone.
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Effects of Estrogens (2o sex characteristics)
• development of breasts and ductile system of the mammary glands
• increased adipose tissue in breasts, thighs, and buttocks
• increased vascularization of skin
• Maintenance of the function of accessory reproductive glands/organs
• CNS effects, e.g., sex drive, “feminization”
•Repair/growth of endometrium (following menses)
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Overview of Female Reproductive Cycle
You should understand these events, and their timing, for the exam
Ovarian cycle
Uterine cycle
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Male and Female Climacteric
• usually occurs in late 40s or early 50s (perimenopause)• reproductive cycles stop for 6 months to 1 year• ovaries no longer produce as much estrogen and progesterone due to depletion of ovarian follicles• some female secondary sex characteristics may disappear• sustained rise in GnRH and LH/FSH may produce hot flashes (LH) and fatigue• risk of atherosclerosis increases• hormone therapy may prevent effects on bone tissue
Female climacteric = menopause
Male climacteric (andropause)• more gradual than female climacteric • usually occurs after age 50• slowly declining levels of testosterone• sperm (gamete) production continues (even into 80s!)
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Mammary Glands
Mammary glands as shown are for women in last trimester of pregnancy or who are nursing.
The areola, a ring of pigmented skin, covers large sebaceous glands that give it a bumpy appearance. Sebum reduces chapping and cracking of the nipple. Figures from: Martini,
Anatomy & Physiology, Prentice Hall, 2001
Size of mammary glands in a nonpregnant/nonlactating woman reflects amount of adipose tissue present.
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Pregnancy, Growth, and Development
Pregnancy (gestation) is the presence of a developing offspring in the uterus - About 38-42 weeks (9 months) in length - Divided into trimesters (about 3 months each) - Called the ‘prenatal’ (before birth) stage of development
Embryological development – 1st 8 weeksFetal development – 9weeks to term.
Growth is an increase in size. Involves increases in cell numbers and cell sizes
Development is the continuous process by which an individual changes from one life phase to another - Prenatal (development in utero) - Neonatal (first 28 days after birth) - Postnatal (from birth until maturity) - Aging and death
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Major Events in Each Trimester
• First trimester (weeks 1-12)– Most critical period (most vulnerable to drugs,
alcohol)– Embryological and early fetal development– Rudiments of all major organ systems appear
• Second trimester (weeks 13-24)– Development of organs and organ systems
(almost complete by end of sixth month)– At end of trimester, fetus looks human
• Third trimester (weeks 25 to birth)– Rapid fetal growth– Deposition of adipose tissue– Major organ systems become functional– At 35 weeks: (~2.5 Kg), fetus can usually survive if
born early (twins typically born during this time)
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Prenatal Terminology and Times
Prenatal Development
(38-42 weeks)
1st trimester
2nd trimester
3rd trimester
Embryological (week 1 to 8)
Fetal (week 9 to birth)
Date of conception – add 14 days to the date of the onset of the last menstrual period
Due Date – add 266 days to the date of conception (about 280 days from the onset of the last menstrual period)
(Rule of thumb from onset of last menstrual period: Subtract 3 months from the month of the last period, then add 4 days unless pregnancy covers an entire month of February, then add 7 days)
Week1-12
13-25
26-38
Know items in red37
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Hormonal Changes During Pregnancy
Hormone Source Effect
Human Chorionic Gonadotropin Placenta Maintains corpus luteum until week 12
Estrogen/Progesterone Corpus luteum/ placenta Stimulate and maintain uterine lining, inhibit FSH and LH, inhibit uterine contractions, and enlarge reproductive organs
Relaxin Corpus luteum/ placenta Possibly causes pelvic ligaments to relax, widen, and become flexible; inhibits uterine contractions; promotes uterine blood vessel growth
Human Chorionic Somatomammotropin (also Placental Lactogen)
Placenta Mammary gland development; glucose-sparing effect in mother; weak GH-type effect
Human Chorionic Thyrotropin Placenta Increases size/activity of thyroid and parathyroid glands
Aldosterone Adrenal cortex Increases fluid retention
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Hormonal Changes During Pregnancy
Relative concentrations of three hormones in maternal blood during pregnancy
Secreted mainly by placenta after about 12 weeks
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 39
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Early Embryonic Stage
Three primary germ layers form
Gastrula stage
2 weeks(~2mm long)
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Functions of the Placenta
Table from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
Mnemonic for placental functions:IRENE ImmuneRespiratoryEndocrineNutritionalExcretory
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Factors Contributing to Onset of Labor
• as birth approaches, progesterone levels decrease (allowing increase in uterine contractions); estradiol continues to rise and upregulates oxytocin receptors on uterus
• prostaglandins synthesized which may initiate labor
• stretching uterine tissue stimulates release of oxytocin
• oxytocin stimulates uterine contractions
• fetal head stretches uterus, cervix, vagina, and vulva
• positive feedback results in stronger and stronger contractions and greater release of oxytocin
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Stages of Labor
Stages of labor:
1. Dilation - Cervix dilates and effaces, and fetus begins moving toward cervical canal; “water breaks” (amniotic membrane ruptures) late in this phase.
2. Expulsion – Cervix is pushed open by approaching fetus (positive feedback cycle) and baby’s head enters vagina.
3. Placental – placenta and fetal membranes are “delivered”
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Parturition = process of giving birth
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Milk-Letdown Reflex
Recall that oxytocin (OT) is a stimulus for smooth muscle contraction and is secreted by the neurohypophysis
OT stimulates myoepithelial cells in the walls of the lactiferous ducts and sinuses
Know this pathway
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
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