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Human Anatomy and Physiology II- Reproductive System
Terms in this set (155)
Male primary sex organs= testes
Female primary sex organs= ovaries
-Produce sex cells (gametes): sperm and egg and secrete sex hormones
What are the primary sex organs for males and females? What do they produce?
Accessory Reproductive Organs
ducts, glands, and external genitalia
Male= manufacture sperm and deliver them to the female reproductive tract
Female= produce eggs that can be fertilized by sperm to form a zygote
What is the role of the male reproductive tract? Female reproductive tract?
sperm-producing male gonads- lie within scrotum
-- Seminiferous tubules (sperm are produced here)
-- Rete Testis
2) Epididymis (sperm are stored here until ejaculation)
3) Ductus Deferens
4) Ejaculatory Duct
Outline the path that sperm take from testes to outside of the body
1) Seminal Glands
2) Prostate Gland
3) Bulbourethral Glands
What are the three main glands that empty their secretions into the ducts during ejaculation?
a sac of skin that hangs outside the abdominopelvic cavity at the root of the penis; encloses testes
Viable sperm cannot be produced at core body temperature, so the superficial location of the scrotum provides a temperature about 3 degrees lower
Why must the testes be located outside of the abdominopelvic cavity?
smooth muscle; wrinkles scrotal skin; pulls scrotum close to body
Muscle that pulls the scrotum closer to the body in cold temperatures and relaxes to let the testicles be farther away from the body in warmer weather; elevates the testes
When it is cold, the testes are pulled closer to the warmth of the body and the scrotum becomes shorter and heavily wrinkled.
When it is warm, the scrotal skin is flaccid and loose to increase the surface area and the testes hang lower, away from the body trunk.
How do the dartos and cremastor muscles help regulate temperature of the testes?
Narrow, coiled tubules that produce sperm in the testes.
interstitial endocrine cells (Leydig cells)
testosterone-producing cells lying in the soft connective tissue surrounding the seminiferous tubules
Consists of spermatogenic ("sperm-forming") cells embedded in substantially larger columnar cells called sustenocytes (supporting cells that play several roles in sperm formation)
What does the epithelium of the seminiferous tubules consist of?
copulatory organ; designed to deliver sperm into the female reproductive tract; contains the penile urethra which carries both semen and urine
A long, coiled duct on the outside of the testis in which sperm mature and are stored until ejaculation
ductus deferens (vas deferens)
the duct that conveys sperm from the testicle to the urethra.
duct formed by the union of the vas deferens with the duct of the seminal vesicle; its fluid is carried into the urethra
vas deferens is cut and sealed off; sperm are still produced, but can no longer reach the body exterior
terminal portion of the male duct system; transports urine and semen
1) Prostatic Urethra- portion surrounded by prostate
2) Intermediate part of Urethra (membranous urethra)- in the urogenital diaphragm
3) Spongy Urethra- runs through the penis and opens to the outside at the external urethral orifice
What are the three regions of the urethra?
The male _____________ _________ produce the bulk of semen
secrete a fluid with substances that increase sperm motility or fertilizing ability; accounts for about 70% of semen volume
Donut-shaped gland that surrounds urethra; secretes sperm-activating fluid that makes up about 30% of semen volume; uses citrate as a nutrient
produce a thick, clear mucus, some of which drains into the spongy urethra and lubricates the glan penis when a man becomes sexually excited. The mucus neutralizes traces of acidic urine and lubricates the urethra prior to ejaculation
milky white, somewhat sticky mixture of sperm, testicular fluid, and accessory gland secretions; provides a transport medium and nutrients and contains chemicals that protect and activate the sperm and facilitate their movement
enlargement and stiffening of the penis, results from engorgement of the erectile bodies with blood
nitric oxide; also stimulates the bulbourethral glands, the secretion of which lubricates the glans penis
Sexual excitement triggers a parasympathetic reflex that promotes the release of _________ ____________ locally. What else does the PNS stimulate?
-NO relaxes smooth muscle in the penile blood vessel walls, dilating these arterioles and the erectile bodies fill with blood.
- Expansion of the corpora cavernosa of the penis compresses their drainage veins, retarding blood outflow and maintaining engorgement. Corpus spongiosum functions to keep urethra open
What effect does nitric oxide (NO) have during erection? Describe how corpora cavernosa and corpus spongiosum are involved in erection.
1) Arousing stimulus triggers Parasympathetic input to penis
2) Local Nitric Oxide (NO) release
3) Relaxation of smooth muscle in penile arterioles
4) Trapping of blood in sinusoids
5) Enlargement and stiffening of penis
Describe the process of erection
propulsion of semen from the male duct system; under sympathetic control
1) Internal Urethral sphincter muscle constricts, preventing expulsion of urine or reflux of semen into the bladder
2) Reproductive ducts and accessory glands contract, emptying their contents into the urethra
3) Semen in the urethra triggers the bulbospongiosus muscles of the penis undergo a rapid series of contractions, propelling semen from the urethra at a speed of up to 11mph
When impulses provoking erection reach a critical level, a spinal reflex (triggered by sympathetic input) is initiated. Describe this reflex.
entire ejaculatory event
follows orgasm; a period of muscular and psychological relaxation; penile arteries constrict, reducing blood flow into the penis and force blood from the penis into the general circulation- penis soon becomes flaccid
Erectile Dysfunction (ED)
the inability to attain an erection; usually occurs when the PNS nerves serving the penis do not release enough NO
Increase the release of NO
What do the drugs Viagra and Cialis do?
the process that occurs in the seminiferous tubules of the testes that produce male gametes (sperm)
-Gametes are haploid (n)
- When sperm and egg fuse, they form a fertilized egg that reestablishes the typical diploid chromosomal number of human cells (2N)
Are gametes haploid or diploid? Does this change during fertilization?
nuclear division that occurs in the gonads; consists of two consecutive nuclear divisions that follow one round of DNA replication. Its product is four daughter cells instead of two, each with half as many chromosomes as typical (diploid) body cells
The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell (2n-->n)
Prophase I: crossing over occurs
Metaphase I: independent assortment occurs
What are the important events that occur during meiosis I?
sister chromatids separate; mirrors mitosis
Meiosis I: 2 haploid daughter cells
Meiosis II: 4 haploid daughter cells
How many daughter cells are there after meiosis I? Meiosis II?
sperm forming cells
outermost tubule cells which are in direct contact with the epithelial basal lamina; stem cells. Divide more or less continuously by mitosis
Type A and B daughter cells
Spermatogenesis begins during puberty, and from then on, each mitotic division of a spermatogonium results in two distinctive daughter cells. What are they?
Type A Daughter Cell
remains at the basal lamina to maintain the pool of dividing germ cells
Type B Daughter Cell
gets pushed toward the lumen, where it becomes a primary spermatocyte destined to produce four sperm
a cell that divides to form two secondary spermatocytes
two smaller haploid cells formed after the primary spermatocytes undergo meiosis I; form spermatids
daughter cells of secondary spermatocytes; formed after the secondary spermatocytes undergo meiosis II
spermatid elongates, sheds its excess cytoplasmic baggage, and forms a tail
male gamete or sex cell produced in the testes; has a head, midpiece, and tail which correspond to genetic, metabolic, and locomotor regions respectively
- Head: consists almost entirely of its flattened nucleus, which contains the compacted DNA. Also has
helmetlike structure that adheres to the top of the nucleus; contains hydrolytic enzymes that enable sperm to penetrate and enter an egg
-Midpiece: contains mitochondria spiraled tightly around the microtubules of the tail
-Tail: flagellum produced by one centriole. The mitochondria provide the metabolic energy (ATP) needed for whiplike movements of the tail
What do they head, midpiece, and tail of sperm consist of?
Sustenocytes (sertoli cells)
nonreplicating supporting cells which extend from the basal lamina to the tubule lumen
- Basal compartment
- Adluminal compartment
Sustenocytes are bound together by tight junctions that divide the seminiferous tubule into two compartments. What are they?
Blood Testis Barrier
prevents antibodies in the blood from getting to the germ cells; formed by the tight junctions between sustenocytes
- Prevents the membrane antigens of differentiating sperm from escaping through the basal lamina into the bloodstream where they would activate the immune system.
----- Since no sperm are formed until puberty, they are absent when the immune system is being programmed to recognize a person's own tissues
----- the tight junctions of the sustenocytes open to allow type B daughter cells to pass
What is the function of the blood-testis barrier?
Provide nutrients, secretes testicular fluid (provides the transport medium for sperm in the lumen), phagocytosing damaged cells
Besides forming the blood-testis barrier, what other functions do sustenocytes have?
Hypothalamic-pituitary-gonadal (HPG) axis
regulates the production of gametes and sex hormones; the relationship between the hypothalamus, anterior pituitary gland, and gonads
Gonadotropin-releasing hormone (GnRH)
controls release of two anterior pituitary gonadotropins: FSH and LH
Follicle Stimulating Hormone (FSH)
stimulates spermatogenesis by stimulating the sustenocytes to release ABP
Androgen-Binding Protein (ABP)
keeps the testosterone concentration in the vicinity of the spermatogenic cells high, which in turn stimulates spermatogenesis
Leutinizing Hormone (LH)
binds to the interstitial endocrine cells in the soft connective tissue surrounding the seminiferous tubules, prodding them to secrete testosterone
a protein hormone produced by sustenocytes, serves as a "barometer" of the normalcy of spermatogenesis
1. Hypothalamus releases GnRH
2. GnRH binds to the pituitary gonadotropic cells, prompting them to secrete FSH and LH into the blood
- FSH stimulates release of ABP
- LH stimulates release of testosterone
3. Testosterone stimulates the maturation of sex organs, development and maintenance of secondary sex characteristics and libido (sex drive)
4. Rising levels of testosterone feed back to inhibit hypothalamic release of GnRH and act directly on the anterior pituitary to inhibit gonadotropin relaese
5. Inhibin release to inhibit anterior-pituitary release of FSH and hypothalamic release of GnRH when sperm count in elevated
Describe the process of the hypothalamic-pituitary-gonadal (HPG) axis
1) GnRH which indirectly stimulates the testes via its effect on FSH and LH release
2) Gonadotropins (FSH and LH), which directly stimulate the testes
3) Gonadal hormones (testosterone and inhibin), which exert negative feedback controls on the hypothalamus and anterior pituitary
- The balance is established during puberty and the amount of testosterone and sperm produced remains fairly stable throughout life
The amount of testosterone and sperm produced by the adult testes reflects a balance among the three interacting sets of hormones that make up the HPG axis. What are they? When is the balance established?
Targets accessory organs (ducts, glands, and the penis) causing them to grow to adult size and function
Besides prompting spermatogenesis, what else does testosterone target?
Male Secondary Sex Characteristics
features induced in nonreproductive organs by the male sex hormones develop at puberty (pubic, axillary, and facial hair, deepening voice as larynx enlarges)
female gonads that produce female gametes (ova) and sex hormones (estrogens and progesterones)
Areas within the ovary in which individual eggs develop; saclike structures
immature egg contained in each follicle
single layer of follicle cells surrounding the oocyte
Vesicular Follicle (antral or tertiary)
fully mature follicle distinguished by its central fluid-filled cavity called the antrum
glandular yellow structure; product of ruptured follicle
Uterine (Fallopian) Tubes
form the initial part of the female duct system; receive the ovulated oocyte and are the sight where fertilization generally occurs
Fimbriae stiffen and sweep the ovarian surface. Try to carry the oocyte into the uterine tube where it begins its journey toward the uterus. Oocyte is carried toward uterus by a combination of muscular peristalsis and beating cilia.
What is the purpose of the fimbriae that drape over the ovary?
hallow, thick-walled, muscular organ that receives, retains, and nourishes a fertilized ovum
narrow neck of uterus which projects into vagina
Papanicolaou (Pap) Smear
cervical smear test; cells from the epithelium covering the cervical tip are scraped away and examined for abnormalities. Most effective way to detect cervical cancer
- Perimetrium: outermost layer
- Myometrium: smooth muscle layer
- Endometrium: mucosal lining
--- Functional Layer
--- Basal Layer
What are the three layers of the uterine wall? Include any sublayers
undergoes cyclic changes in response to blood levels of ovarian hormones and is shed during menstruation
stem cells of endometrium; helps form a new functional layer after menstruation ends
thin-walled tube; provides a passageway for delivery of an infant and for menstrual flow. Female copulatory organ
small, protruding structure composed largely of erectile tissue; richly innervated with nerve endings and becomes swollen with blood and erect during tactile stimulation
type of X-Ray examination that detects breast cancers too small to feel
process that forms eggs (female gametes)
Starts before birth- born with a lifetime supply of primary oocytes. Arrested in development (prophase I) until puberty.
When does oogenesis start?
stem cells that produce primary oocytes by mitotic division
- Before puberty, all of the primordial follicles that are recruited undergo apoptosis
- Beginning at puberty, FSH rescues a small number of growing follicles from that fate each month.
---- In each cycle, one of the rescued follicles is "selected" to become the dominant follicle and continue meiosis I, ultimately producing two haploid cells (1st polar body and secondary oocyte)
---- The secondary oocyte is ovulated. If fertilized by sperm, meiosis II is completed, forming a functional ovum and 2nd polar body.
(If no fertilization- secondary oocyte deteriorates)
How does oogenesis occur after puberty?
The secondary oocyte is ovulated
What cell type is ovulated?
- ONE functional gamete
- 20% meiosis error rate
- unequal distribution of cytoplasm
- FOUR functional gametes
- 3-4% meiosis error rate
- equal distribution of cytoplasm
Compare oogenesis and spermatogenesis
monthly series of events associated with the maturation of an egg
1) Follicular Phase (days 1-14)
2) Ovulation (day 14)
3) Luteal Phase (14-28)
What are the phases of the ovarian cycle?
Phase of the ovarian cycle when the dominant follicle is selected and begins to secrete large amounts of estrogens
Primordial follicles --> Primary follicles --> Secondary follicles
follicle is responsive to hormones and antrum becomes much larger; directed by FSH and LH
Describe the pre-antral and antral phases of the follicular phase
a layer of connective tissue and epithelial cells that condenses around the follicle
thick transparent extracellular layer secreted by oocyte that encapsulates it
large fluid-filled cavity; distinguishes vesicular follicles from all prior follicles
Outer layer of cells surrounding the oocyte. These cells are secreted by follicle cells.
occurs when the ballooning ovary wall ruptures and expels the secondary oocyte, still surrounded by its corona radiata, into the peritoneal cavity
Fraternal twins: more than one oocyte is ovulated
Identical twins: fertilization of a single oocyte, followed by separation of the fertilized eggs daughter cells during early development
Describe how fraternal twins develop? Identical twins?
After ovulation, the ruptured follicle collapses and the antrum fills with clotted blood. Corpus luteum is formed and secretes progesterone and estrogen
- If pregnancy occurs, the CL stays for a couple of months and pumps out hormones to support the pregnancy
- If no pregnancy occurs, CL degenerates
What happens to the corpus luteum if pregnancy occurs? If no pregnancy occurs?
1) GnRH stimulates FSH and LH secretion (gonadotropins)
2) FSH and LH stimulate follicles to grow, mature, and secrete sex hormones
3) Negative feedback inhibits gonadotropin (FSH and LH) release- estrogens and inhibin exert negative feedback on hypothalamus. Only the dominant follicle survives the dip in FSH- the other developing follicles fail to develop further and deteriorate.
4) Positive feedback stimulates gonadotropin release
- High estrogen levels from mature follicle causes increased gonadotropin release (LH SURGE)
5) LH surge triggers ovulation and formation of the corpus luteum
6) Negative feedback inhibits LH and FSH release- hormones released from CL inhibits gonadotropin release
Describe the hormonal interactions during the ovarian cycle
Uterine (Menstrual) Cycle
a series of cyclic changes that the uterine endometrium goes through each month as it responds to the waxing and waning of ovarian hormones in the blood
Endometrial changes are coordinated with the phases of the ovarian cycle, which are dictated by gonadotropins released by the anterior pituitary
How are the ovarian and uterine cycles related?
1) Menstrual Phase (Days 1-5)
2) Proliferative Phase (Days 6-14)
3) Secretory Phase (Days 15-28)
What are the 3 phases of the Menstrual Cycle?
the phase of the menstrual cycle during which the uterus sheds all but the deepest part of its endometrium. The functional layer of the endometrium detaches from the uterine wall
endometrium rebuilds itself under the influence of rising blood levels of estrogens, the basal layer of the endometrium generates a new functional layer
Occurs at the end of the proliferative phase in response to the sudden release of LH from the anterior pituitary
When does ovulation occur in the menstrual cycle?
endometrium prepares for an embryo to implant. Rising levels of progesterone from the CL act on the estrogen-primed endometrium, causing the arteries to elaborate and convert the functional layer to a secretory mucosa
period of life when the reproductive organs grow to adult size and become functional. These changes occur in response to rising levels of gonadal hormones (testosterone and estrogen)
cessation of ovulation and menstruation
2. Short Term Hormonal Contraceptives
3. Intrauterine Devices (long-term)
What are the four main methods of birth control?
Short Term Hormonal Contraceptives
contain hormones that inhibit body's natural hormone production (injectables, patch, pills)
- Estrogen pill raises estrogen level enough that it will mask changes/fluctuations in estrogen that occur over the 28 days because fluctuation causes LH surge.
- Progesterone thickens cervical mucus and blocks passage of sperm and can cause endometrium to thin. The layer is not functional or effective for any implant to be nurtured.
makes environment inhospitable to potential implant
How do birth control pills work?
intrauterine device (IUD)
small, T-shaped device inserted by a physician inside the uterus to prevent pregnancy; prevent sperm from fertilizing. Could contain copper which is spermicidal
1) Tubal Ligation ("tubes tied")
What are the two methods of sterilization?
the developing human organism from fertilization to week 8
the developing human organism from week 9 until birth
occurs when a sperm's chromosomes combine with those of an egg (secondary oocyte) to form a fertilized egg, or zygote
- Leak out of vagina because of gravity
- Vagina is acidic (3.8-4.5)
Why don't some sperm reach the uterus?
1) Approach- aided by enzymes on its surface, a sperm cell weaves its way past granulosa cells of the corona radiata
2) Acrosomal Reaction- binding of the sperm to receptors in the zona pellucida causes Ca2+ levels within the sperm to rise, triggering the acrosomal reaction. Acrosomal enzymes from many sperm digest holes through the zona pellucida, clearing a path to the oocyte membrane
3) Binding- the sperm's membrane binds to the oocyte's sperm-binding receptors
4) Fusion- sperm and oocyte plasma membranes fuse. Sperm contents enter the oocyte
5) Blocks to polyspermy- oocyte sperm-binding membrane receptors are shed, Ca2+ levels in the oocytes cytoplasm rise, triggering the cortical reaction (exocytosis of cortical granules). As a result, the zona pellucida hardens and the sperm-binding receptors are clipped off
Describe the process of sperm penetration and blocks to polyspermy
involves the release of acrosomal enzymes that digest holes through the zona pellucida- a sperm that comes along later, after hundreds of sperm have undergone acrosomal reactions to expose the oocyte membrane is in the best position to be THE fertilizing sperm
1) Oocyte completes meiosis II, forming the ovum and second polar body
2) Sperm and ovum nuclei swell, forming pronuclei
3) The DNA in each pronucleus replicates. The pronuclei approach each other and a mitotic spindle forms between them.
4) Chromosomes of the pronuclei intermix. Fertilization is accomplished and the cell, now called a zygote, is ready for the first cleavage division.
Describe what happens after the fusion of the sperm and egg?
a period of fairly rapid mitotic divisions of the zygote without intervening growth. The foal is to produce small cells with high SA:V ration to enhance uptake of nutrients
A fluid-filled sphere formed about 5 days after fertilization of an ovum that is made up of an outer ring of cells and inner cell mass. This is the structure that implants in the endometrium of the uterus.
occurs when the blastocyst implants in the wrong place: uterine tube or peritoneal cavity
Human Chorionic Gonadotropin (hCG)
LH-like hormone secreted by the implanted blastocyst; triggers CL to continue releasing hormones (progesterone and estrogen) and promotes placenta development
Between the second and third month, the placenta assumes the role of progesterone and estrogen production
- CL degenerates and the ovaries remain inactive until after birth
When does hCG start to drop after pregnancy?
They are antibody tests that detect hCG in a woman's blood or urine
How do pregnancy tests work?
formation of placenta
temporary pancake-shaped organ that originates from both embryonic and maternal (endometrial) tissues
fetal part of placenta
What part of the placenta come in contact with maternal blood?
maternal part of placenta
endometrial cells that surround the implanted embryo; becomes compressed and degenerates as fetus develops, while the decidua basalis villi increase in number and branch off more profusely
An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.
amnion sac contains this fluid that protects the developing embryo against physical trauma and helps maintain a constant homeostatic temperature
forms part of gut; sac that hangs off of embryo
links the embryo to the placenta and ultimately becomes part of the urinary bladder
- Starts as a fist-sized organ, the uterus fills most of the pelvic cavity by 16 weeks
- As pregnancy continues, the uterus pushes higher into the abdominal cavity, exerting pressure on abdominal and pelvic organs
- As birth nears, the uterus reaches the level of the xiphoid process and occupies most of the abdominal cavity
---- the crowded abdominal organs press against diaphragm (restrictive to breathing)
Describe uterine enlargement during pregnancy
causes pelvic ligaments and the pubic symphysis to relax, widen, and become more flexible
the series of events that expel the infant from the uterus
A hormone released by the posterior pituitary that stimulates uterine contractions during childbirth and milk ejection during breastfeeding.
______________ causes the placenta to release prostaglandins
stimulate the synthesis of more gap junctions in uterine smooth muscle (allows signals to progress through the body faster)
Involves prostaglandins and oxytocin; greater distension of the cervix causes the release of more oxytocin which causes greater contractile force
Describe the positive feedback mechanism involved in uterine contractions
1) Dilation Stage- the time from labor's onset until the cervix is fully dilated by the baby's head (about 10cm in diameter)
- Baby's head is engaged and rotates
2) Expulsion Stage- lasts from full dilation to delivery of the infant, or actual childbirth.
- Crowning occurs when the largest dimension of the baby's head distends to the vulva
- Head exits from the perineum and once the head has been delivered the rest of the baby's body is delivered
- Umbilical cord is clamped and cut
3) Placental Stage- delivery of the placenta and its attached fetal membranes, called the afterbirth, is accomplished within 30 mins after birth of infant
Describe the 3 stages of labor
delivery of the infant through an incision made through the abdominal and uterine walls
production of milk by the hormone-prepared mammary glands
stimulates milk production
actual ejection of milk from the alveoli of the mammary glands; caused by oxytocin
1) Stimulation of mechanoreceptors in nipples send impulses to hypothalamus
2a) Hypothalamus releases prolactin-releasing factors (PRFs)
3a) Prolactin is released and targets mammary glands
4a) Increased milk production
2b) hypothalamus triggers oxytocin release from PP and stimulates myoepithelial cells of breasts to contract
3b) Let-down reflex: milk is ejected through ducts of nipples
Recommended textbook explanations
Introduction to Anatomy and Physiology
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Laboratory Manual to Accompany Hole's Human Anatomy and Physiology
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Hole's Essentials of Human Anatomy & Physiology (High School Edition)
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