Reproductive System-Chapter 28

Question 1

Explain the function of primary sex organs

Answer 1

Primary sex organs are the gonads (testes & ovaries). They produce sex hormones and gametes.

Question 2

Explain the function of secondary (accessory) sex organs

Answer 2

The secondary sex organs are the duct systems (which carry gametes away from the gonads to the site of fertilization (in females) and outside of the body (in males). They also contain glands (secretions) and external genitalia.

Question 3

Gonad

Answer 3

Ovaries in females and testes in males. They produce sex cells called gametes.

Question 4

Gamete

Answer 4

Sex cells produced in the gonads that unite at fertilization to initiate the formation of a new individual.

Question 5

Meiosis

Answer 5

A type of sex cell division that starts off with a diploid parent cell and produces haploid daughter cells called gametes.

Question 6

Fertilization

Answer 6

The process by which two gametes (sex cells) fuse to form a new diploid cell containing genetic material derived from both parents.

Question 7

Zygote

Answer 7

The diploid cell produced at the end of fertilization.

Question 8

Describe the location of the testes

Answer 8

The testes are small, oval organs located in the scrotum.

Question 9

What is the function of the pampiniform plexus?

Answer 9

The pampiniform plexus is a plesux of veins surrounding the testicular artery. It is a means to provide thermoregulation by precooling arterial blood prior to its reaching the testes.

Question 10

What is the function of the dartos muscle?

Answer 10

When it is cold, it wrinkles the scrotum (from underneath) and moves them upward to push them closer to the body for warmth.

Question 11

WHat is the function of the cremaster muscle?

Answer 11

When it is cold, it contracts to pull the testes closer to the body for warmth.

Question 12

What is the spermatic chord and where is it located?

Answer 12

It is a multilayered structure that is a tubelike passageway that houses the ductus deferens, blood vessels, and nerves supplying each tesits. It originates in the inguinal canal, and travels from within the abdomen to the scrotum.

Question 13

Describe the structure of the testis?

Answer 13

They are relatively small, oval organ. Each is covered anteriorly and laterally by the tunica vagtinalis. The outer layer of the t.v. is the parietal layer and there is an inner visceral layer deparated by a cavity filled with serous fluid. A thick, whitish fibrous capsule, the tunica albuginea covers the testis and lies immediately deep to the visceral tunica layer of the t.v.

Question 14

What is the location and function of interstitial cells?

Answer 14

Also known as Leydig cells. They reside in the interstitial spaces.They are stimulated by leutinizing hormone to produce androgen, beginning in puberty.

Question 15

What is the location and function of sustentacular cells?

Answer 15

Also known as Sertoli cells, or nurse cells. THey are located in the seminiferous tubules. They provide a protective environment for developing sperm; their cytoplasm, helps nourish the developing sperm; and they release inhibin when sperm count is high.

Question 16

Define spermatogenesis

Answer 16

It is the process of sperm development that occurs within the seminiferous tubule of the testis. It doesn’t begin until puberty, when significant levels of FSH and LH stimulate the testes to begin gamete development.

Question 17

Describe spermatagonia

Answer 17

They are primordial germ (stem) cells. THey are diploid. They first divide by mitosis. They lie near the base of the seminiferous tubule, surrounded by the cytoplasm of a sustentacular cell.

Question 18

Describe spermatogonium

Answer 18

When spermatagonia divide by mitosis, one of the cells produced is a new spermatogonium (a new germ cell) to ensure that the numbers of spermatagonia never become depleted.

Question 19

Describe primary spermatocytes

Answer 19

When spermatagonia divide by mitosis, one becomes a spermatogonium, and the other cell is a committed cell called the primary spermatocyte. THey are diploid and are the cells that undergo meiosis.

Question 20

Describe secondary spermatocytes

Answer 20

WHen a primary spermatocyte undergoes meiosis I, the two cells produced are called secondary spermatocytes. They are haploid cells. They are still surrounded by the sustentacular cell cytoplasm, but are closer to the lumen, ropposed to the base of the seminiferous tubule.

Question 21

Describe spermatids

Answer 21

Secondary spermatocytes complete meiosis II to form spermatids. They are a haploid cell, THey are still surrounded by the sustentacular cell cytoplasm, very near to the lumen of the seminiferous tubule, They have a circular appearance.

Question 22

Describe sperm

Answer 22

During spermiogenesis, the newly formed spermatids differentiate to become anatomically mature spermatazoa, or sperm. THe spermatid sheds excess cytoplasm and its nucleus elongates.

Question 23

Describe spermiogenesis

Answer 23

It is the final state of spermatogenesis in which the newly formed spermatids differentiate to become anatomically mature sperm.

Question 24

Describe the structural parts of a sperm and describe the function of each

Answer 24

During spermiogenesis, the spermatid sheds its cytoplasm and the nucleus elongates. A structure called the acrosome cap forms over the nucleus. It contains digestive enzymesthat help penetrate the secondary oocyte for fertilization.As the spermatid elongates, a tail, also called the flagellum, forms from the organized microtubules withing the cell. The tail is attached to a midpiece or neck region containing mitochondria and a centriole. These mitochondria provide the energy to move the tail.

Question 25

Describe the function of rete testis

Answer 25

It is a meshwork of interconnected channels in the mediastinum testis that receive sperm from the seminiferous tubules. The channels of the rete testis merge to form the efferent ductules.

Question 26

Describe the function of the efferent ductules

Answer 26

They connect the rete testis to the epididymis. They are lined with both ciliated columnar epithelia that gently propel the sperm toward the epididymis and nonciliated columnare epithelia that absorb excess fluid secreted by the seminiferous tubules. The efferent ductules drain into the epididymis.

Question 27

Describe the function of the epididymis

Answer 27

It stores sperm until they are fully mature and capable of being motile.

Question 28

Describe the function of the ductus deferens

Answer 28

Also called the vas deferens. It is a thick-walled tube that travels withing the spermatic cork, through the inguinal canal, and then within the pelvic cavity before it nears the prostate gland. Contraction of the muscularis layer of the ductus deferens is necessary to move sperm through, since sperm do not exhibit motility until they are ejected from the penis.

Question 29

Describe the function of the ejaculatory duct

Answer 29

It conducts sperm (from the ductus deferens) and a component of seminal fluid (from the seminal vesicle) toward the urethra.

Question 30

Describe the function of the urethra

Answer 30

It transports semen from both ejaculatory ducts to the outside of the body. It also transports urine from the bladder to the outside of the body.

Question 31

Describe the function of seminal vesicles

Answer 31

They secrete a viscous, whitish-yellow, alkaline fluid containing both fructose and prostaglandins. Fructose nourishes sperm as they travel through the female reproductive tract. Prostaglandins are hormonelike substances that promote the windening and slight dilation of the os of the cervix, which facilitates sperm entry into the uterus.

Question 32

Describe the function of the prostate gland

Answer 32

It secretes a slightly milky fluid that is weakly acidic and rich in citric acid, seminalplasmin and prostate-specific antigen (PSA). The citric acid is a nutrient for sperm health, the seminalplasmin is an antibiotic that combats urinary tract infections in the male, and the PSA acts as an enzyme to help liquify semen following ejaculation.

Question 33

Describe the function of the bulbourethral gland

Answer 33

They secrete a clear, viscous mucin that forms mucus. As a component of the seminal fluid, this mucus protects the urethra and serves as a lubricant during sexual intercourse.

Question 34

Describe the function of the scrotum

Answer 34

It is one of the external genitalia of males. It is a skin-covered sac between the thighs that houses the testes and provides the cooler environment needed for normal sperm development and maturation. It is homologous to the labia majora in the female.

Question 35

Describe the function of the spermatic cord

Answer 35

The blood vessels and nerves supplying each testis travel from within the abdomen to the scrotum in a multi-layered structure-the spermatic cord. It originates in the inguinal canal.

Question 36

Describe the function of the penis

Answer 36

It is one of the external genitalia of males.

Question 37

Describe the regulation of spermatogenesis and testosterone

Answer 37

1) GnRH secreted by the hypothalamus stimulates the anterior pituitary to secrete FSH & LH. 2) LH stimulates interstitial cells to secrete testosterone. FSH stimulates sustentacular cells to secrete androgen-binding protein (ABP), which keeps testosterone levels high in the testes. 3) Testosterone stimulates spermatogenesis but inhibits GnRH secretion and reduces the anterior pituitary’s sensitivity to GnRH. 4) Rising sperm count levels cause sustentacular cells to secrete inhibin, which further inhibits FSH secretion. 5) Testosterone stimulates libido and development of secondary sex characteristics.

Question 38

List several male secondary sex characteristics

Answer 38

Secondary sex characteristics in males include the duct system and accessory glands. Ductus deferens, Spermatic cord, Seminiferous tubules prostated gland, bulbourethral glands, seminal vesicles, epididymis, ejaculatory duct.

Question 39

Describe the location and structure of the ovaries

Answer 39

They are paired, oval organs located within the pelvic cavity lateral to the uterus.

Question 40

Describe the process of oogenesis

Answer 40

Oogenesis is the maturation of a primary oocyte to a secondary oocyte.. It begins in a female fetus, when primary oocytes form in primordial follicles. THe ovary and these follicles remain inactive in childhood. At puberty, a select number of primordial follicles each month undergoes maturation and produces a female gamete (secondary oocyte).

Question 41

Compare and contrast oogenesis and spermatogenesis.

Answer 41

Oogenesis begins in a female fetus, when primordial oocytes form in primordial follicles. SPermatogenesis does not begin until puberty, when significant levels of FSH and LH stimulate the testis to begin gamete development. Both spermatogonia and oogonia are diploid cells.Both divide first by mitosis. In males, one of the cells produced is a new germ cell, and the other is a committed cell, the primary spermatocyte. In females, mitotic division occurs before birth and produces primary oocytes. The primary oocytes start the process of meiosis, but are arrested in prophase I. IN males, the primary spermatocyte undergoes meiosis I and the two cells produced are called secondary spermatocytes. They are haploid. In females, beginning in puberty, follicles are stimulates to mature from primary follicles. Oocytes are inside follicle. Some primary follicles mature into secondary follicles monthly. Usually only one secondary follicle matures into a vesicular follicle. At this time, the primary oocyte finishes meiosis I., and two cells form. One is a polar body, non functional. The other is the secondary oocyte. IN males, the secondary spermatocyte completes meiosis II to form spermatids. In females, the secondary oocyte continues to develop and reaches metaphase II before it is arrested again. This secondary oocyte does not complete meiosis unless it is fertilized by sperm. IN the final stage of spermatogenesis, , called spermiogenesis, the newly formed spermatids differentiate into mature sperm. In females, at the time of ovulation, the follicle ruptures, expelling the secondary oocyte. The uterine lining prepares for possible implantation of a fertilzied oocyte. IF the secondary oocyte is fertilized, it completes the second meiotic division and becomes an ovum. If not, it degenerates.

Question 42

Describe the development of follicles (folliculogenesis)

Answer 42

THousands of ovarian follicles are in the ovarian cortex. An ovarian follicle consists of an oocyte surrounded by follicle cells (or granulosa cells) which support the oocyte. 1) Ap primordial follicle, containing a primary oocyte, matures into a primary follicle. Easch primary follicle secretes estrogen as it continues to mature, which stimulates changes in the uterine lining. 2) a secondary follicle forms from a primary follicle. Each secondary follicle contains a primary oocyte, many layers of granulosa cells, and a fluid-filled space called an antrum. This space accumulates serous fluid and increases in volume as ovulation nears. The oocyte is forced toward one side of the follicle. 3) A vesicular follicle forms from a secondary follicle. It becomes quite large, and contains a secondary oocyte. The secondary oocyte has complete meiosis I and is arrested in teh second meiotic metaphase. Typically, only one vesicular follicle develops each month. 4) WHen a vesicular follicle ruptures and expels its oocyte (ovulation), the remnants of the follicle in the ovary turn into a yellowish structure called the corpus luteum, which secretes progesteron and estrogen. These hormones stimulate and support the continuing buildup of the uterine lining. When a corpus luteum undergoes regression, it turns into a white connective tissue scar called the corpus albicans.

Question 43

Corpus albicans

Answer 43

When a corpus luteum undergoes regression (break down), it turns into a white connective scar, the corpus albicans. Most are completely reabsorbed, and only a few may remain within an ovary.

Question 44

Corpus luteum

Answer 44

When a vesicular follicle ruptures and expels its oocyte, the remnants of the follicle in the ovary turn into a yellowish structure called teh corpus luteum, which secretes progesterone and estrogen to stimulate and support the continuing buildup of the uterine lining.

Question 45

Ovarian cortex

Answer 45

Deep to the tunica albuginea, the outer portion of the ovary is the cortex. It contains ovarian follicles.

Question 46

Ovarian medulla

Answer 46

Deep to the tunica albuginea, the inner part of the ovary is the medulla. It is composed of areolar connective tissue and contains branches of the ovarian blood vessels, lymph vessels, and nerves.

Question 47

Primordial follicle

Answer 47

The most primitive type of ovarian follicle. It consists of a primary oocytesurrounded by a single layer of flattened follicle cells.

Question 48

Primary follicle

Answer 48

It forms from a primordial follicle and consists of a primary oocyte surrounded by one or more layers of cuboidal follicular cells, which are now called granulosa cells. Each primary follicle secretes estrogen as it continues to mature, which stimulates changes in teh uterine lining. SOme connective tissue derived cells, called thecal cells, are located around and on the periphery of the ovarian follicle. These cells help initiate and control follicle development by secreting androgens, which are converted to estrogen by the granulosa cells.

Question 49

Secondary follicle

Answer 49

It forms from a primary follicle. Each contains a primary oocyte, many layers of granulosa cells, and a fluid-filled space, the antrum. In this space, serous fluid accumulates and increases in volume as ovulation nears. The oocyte is forced toward one side of the follicle, where it is surrounded by a cluster of follicle cells termed the cumulus oophorus.

Question 50

Vesicular follicle

Answer 50

It forms from a secondary follicle. It becomes large and contains a secondary oocyte. A secondary oocyte has complete meiosis I and is arrested in teh second meiotic metaphase. Typically, only one vesicular follicle forms each month. It eventualy ruptures (ovulation) and expels the oocyte.

Question 51

Tunica albuginea

Answer 51

Deep to the outer layer of the ovary, the germinal epithelium, is a dense connective tissue capsule, the tunica albuginea.

Question 52

Describe the regulation of teh ovarian cycle

Answer 52

1) Hypothalamus secretes GnRH, which stimulates anterior pituitary to secrete FSH & LH 2) FSH & LH stimulate follicular development. 3) Maturing ovarian follicles secrete inhibin (which inhibits FSH production) and low levels of estrogen (which initially inhibit both the hypothalamus and the anterior pituitary). 4) Estrogen also assists with the development of the vesicular follicle. 5) Vesicular follicle produces a large threshold amount of estrogen, which stimulates the hypothalamus and anterior pituitary. 6) An LH surge from the anterior pituitary induces ovulation. 7) The corpus luteum forms under the influence of LH. 8) The corpus luteum secretes large amounts of progesterone, estrogen, and inhibin, which inhibit the hypothalamus and anterior pituitary.

Question 53

Describe the events that occur during each phase of the ovarian cycle

Answer 53

1) Follicular phase-occurs during days 1-13 of an approx. 28 day cycle. About 20 primordial follicles are stimulated by FSH and LH to mature into primary follicles. As they develop, their follicular cells release inhibin, which helps inhibit further FSH production, preventing excessive ovarian follicle development. A few of the primary follicles mature and become secondary follicles (those that don’t mature undergo atresia). Late in teh follicular phase, usually only one secondary follicle matures into a vesicular follicle. Under the influence of LH, the volume of fluid increases in the antrum, and the oocyte is forced toward one side.. As the secondary follicle matures into a vesicular follicle, its primary oocyte finishes meiosis I, and two cells form. One of these cells receives a minimal amount of cytoplams, and forms a polar body, which is nonfunctional. The other receives the bulk of the cytoplasm and becomes the secondary oocyte, which continues to develop until it reaches metaphase II of meiosis, then it is arrested again. It doesn’t complete meiosis unless fertilized. 2)Ovulation-occurs on day 14 of the 28-day cycle. It is the release of teh secondary oocyte from a vesicular follicle. Typically, only one ovary ovulates each month. They take turns. Ovulation is induced when there is a peak in LH secretion. The follicle cells in teh vesicular follicle increase their rate of fluid secretion, causing further swelling within the follicle. Follicle eventually ruptures, expelling secondary oocyte. 3) Luteal phase-occurs during days 15-28 of the cycle, when the remaining follicle cells in the ruptured vesicular follicle become the corpus luteum. It secretes progesterone and estrogen that build op the uterine lining in preparation for implantation of a fertilzed oocyte. The corpus luteum has a lifespan of about 10 to 13 daysif the secondary oocyte isn’t fertilized, after which it regresses and becomes a corpus albicans. As the corpus luteum regresses, its levels of secreted progesterone and estrogen drop, causing the uterine lining to be shed in a process called menstruation.

Question 54

Describe the regulation of the uterine cycle

Answer 54

The cyclical changes in teh endometrial lining occur under the influence of estrogen and progesterone secreted by the corpus luteum. The corpus luteum degenerates and progesterone level drops dramatically if fertilization doesn’t occur. Without significant levels of progesterone, the functional layer lining sloughs off, and the next uterine cycle begins with the menstrual phase.

Question 55

Describe the events that occur during each phase of the uterine cycle.

Answer 55

1) Menstrual phase- occurs approx. during days 1-5 of the cycle. It is marked by sloughing off of the functional layer and lasts through the period of menstrual bleeding. 2) Proliferative phase-spans approx. 6-14 days. The initial development of the new functional layer of the endometrium overlaps the time of follicle growth and estrogen secretion by the ovary. 3) Secretory phase- occurs at approx. days 15-28. There is an increase in progesterone secretion from the corpus luteum, resulting in increased vasularization and development of uterine glands.

Question 56

Explain the effect of implantation of a fertizized egg on the ovarian and menstrual cycles.

Answer 56

If the secondary oocyte is fertilized and successfully implants in the uterine lining, it is now a pre-embryo, and starts secreting human chorionic gonadotropin (hCG), a hormone that entersu the mother’s blood and acts on the corpus luteum. It mimics the effects of LH and continues to stimulate the corpus luteum, which continues to produce progesterone and estrogen, which maintains and continues building the unterine lining. After 3 months, the placenta of the developing fetus starts producing its own progesterone and estrogen. Typically, by the end of the third month, the corpus luteum has usually regressed and formed a corpus albicans.

Question 57

Describe the function of the two major female sex hormones, progesterone and estrogen

Answer 57

Progesterone is necessary in breast development and pregnancy (functional layer growth after ovulation), causes increase in blood velles distribution, uterine gland size and nutrient production. Estrogen stimulates development and maintenance of female sex organs, regulates the menstrual cycle, and regulates secondary sex characteristics. It initiates and maintains growth of the functional layer of the endometrium.

Question 58

WHich organs are considered part of the female duct system?

Answer 58

The uterus, uterine tubes, and the vagina.

Question 59

Describe the structure and function of the uterine tubes

Answer 59

Also called the fallopian tubes or oviducts, extend laterally from both sides of the uterus toward the ovaries. They are small in diameter, max length of 10-12 cm. after puberty. They are covered and suspended by the mesosalpinx-the broad ligament of the uterus. They are composed of four segments: infundibulum; ampulla; isthmus; and uterine part. The wall of the uterine tube consists of a mucosa, a muscularis, and a serosa. The uterine tube captures the ovulated secondary oocyte, provides the site for fertilization, and transports the oocyte to the uterus.

Question 60

Describe the structure and function of the uterus

Answer 60

It is a pear-shaped, thick-walled muscular organ within the pelvic cavity. It has a lumen that connects to the uterine tubes superolaterally and to the vagina inferiorly. It is partitioned into the fundus, body, isthmus and cervix. Following fertilization, the pre-embryo makes contact with the uterine lining and implants in the inner uterine wall. The uterus then supports, protects and nourishes the developing embryo/fetus by forming a vascular connection that later develops into the placenta. It ejects the fetus at birth. If an oocyte isn’t fertilized, the muscular wall of the uterus contracts and sheds its inner lining as menstruation.

Question 61

Describe the three layers of the uterine wall

Answer 61

It is composed of three concentric tunics: 1) perimetrium-outer tunic (a serosa)it is continuous with the broad ligament.2) myometrium-the thick, middle tunic formed from three intertwining layers of smooth muscle. 3) endometrium-an intricate mucosa composed of a simple columnar epithelium and an underlying lamina propria. The lamina propria is filled with compound tubular glands (also called uterine glands), which enlarge during the uterine cycle.

Question 62

Describe the endometrium of the uterus

Answer 62

There are two distinct layers that form the endometrium. The deeper layer, the basal layer (also called the stratum basalis) is immediately adjacent to the myometrium and is a permanent layer that undergoes few changes during each uterine cycle. The more superficial of the two endometrial layers is the functional layer (or stratum functionalis). Beginning at puberty, the functional layer grows from the basal layer under the influence of progesterone and estrogen., and if fertilization doesn’t occur, the functional layer is shed as menses. The basal layer gives rise to a new functional layer after the end of each menses.

Question 63

Describe the structure and function of the vagina

Answer 63

It is a thick-walled, fibromuscular tue that forms the inferiormost region of the female reproductive tract. It connects the uterus with the outside of the body and functions as the birth canal and as the copulatory organ of the female, and as the passageway for menstruation.

Question 64

Describe the female external genitalia.

Answer 64

Also called the vulva. The mons pubis is an expanse of skin and subcutaneous connective tissue immediately anterior to the pubic symphysis. The labia majora are paired, thickened folds of skin and connective tissue. THey contain numerous sweat and sebaceous glands. The labia minora are paired folds immediately internal to the labia majora. They contain a highly vascular layer of areolar connective tissue.The clitoris is a small erectile body, located at the anterior regions of the labia minora. it is homologous to the penis. Two small bodies, the corpora cavernosa form the body of the clitoris.

Question 65

Describe the structure and function of the mammary glands

Answer 65

Mammary glands are composed of glandular tissue and a variable amount of fat. They are subdivided into lobes, then further into lobules. The lobules contain secretory units termed alveoli. The function of the glands is to produce breast milk to nourish an infant.

Question 66

Describe the regulation of lactation.

Answer 66

A woman starts to produce breast milk when she has recently given birth. The hormone prolactin is produced in the anterior pituitary and is responsible for milk production. WHen the amount of prolactin increases, the mammary gland grows and forms more expanded alveoli. The hormone oxytocin, produced by the hypothalamus and released from the posterior pituitary, is responsible for milk ejection. THis is stimulated by suction on the nipple by the infant.

Question 67

Describe the thre major stages of the sexual response in females

Answer 67

1) Excitement-the reproductive organs become engorged with blood. The uterus shifts from an anteverted position to a more erect position withing the pelvic cavity. Mucus is produced for lubrication by the vestibular glands and glands withing the vaginal wall. The erectile tissue of the clitoris swells as it engorges with blood and becomes very sensitive. Heart rate, BP, respiratory rate increase as orgasm nears. 2) Orgasm- refers to the time period where there are intense feelings of pleasure. The vagina and uterus contract rhythmically for several seconds. 3) Resolution-The uterus returns to its original position and the vaginal wall relaxes. Excess blood leaves the other reproductive organs. Women can begin again!

Question 68

Describe the three major stages of the sexual response in males

Answer 68

1) Excitement-blood enters the erectile bodies of the penis and fills the venous spaces. The erectile bodies become rigid, a process called erection. The rigid erectile bodies compress the veins that drain blood away from the venous spaces. The spaces fill with blood, but the blood cannot leave the erectile bodies until the sexual excitement ceases. Parasympathetic innervation facilitates the release of nitrous oxide wihich assists with erection. Increased BP, heart rate and respiratory rate. 2) Orgasm-INtense feelings of pleasure, release of tension, expulsion of semen. The internal urethral sphincter of the urinary bladder contracts to ensure that no urine enters the urethra during ejaculation. EJaculation occurs with the help of rhythmic contraction of the smooth muscle in the wall of the urethra. Parasympathetic innervation is necessary to achieve an erection, but sympathetic innervation promotes ejaculation. 3) resolution-marked by feelings of intense relaxation. The sympathetic division is stimulated to contract the central artery of the penis and contract small muscles around erectile bodies and shunts most of the blood to oter veins, returning the penis to its flacid condition. 4) refractory period-the man cannot attain another erection. This period may last for many minutes or for hours.