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BIOL*235 Final Exam > Ch. 28: Reproductive System (Male) > Flashcards

Ch. 28: Reproductive System (Male) Flashcards

1
Q

What are the male accessory sex glands?

A

Seminal vesicles, prostate, bulbourethral glands.

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2
Q

What are the supporting structures of the male reproductive system?

A

Scrotum, spermatic cord and penis.

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3
Q

Describe the external anatomy of the scrotum.

A

Loose skin and underlying subcutaneous layer that hangs from the root of the penis. Single pouch separated into lateral parts by a median raphe.

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4
Q

Describe the internal anatomy of the scrotum.

A

Scrotal septum divides scrotum into 2 compartments, each containing a testis. The scrotal septum is made up of a subcutaneous layer and muscle tissue (dartos muscle) which is composed of bundles of smooth muscle fibres.

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5
Q

Associated with each testis is the ____ muscle, which is a series of small bands of skeletal muscle that descend as an extension of the internal oblique muscle through the spermatic cord to surround the testes.

A

Cremaster.

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6
Q

What regulates the temperature of the testes?

A

The location of the scrotum, and the contraction of its muscle fibres. It is able to maintain a low temperature because it is located outside of the pelvic cavity. In response to cold temperatures, the cremaster and dartos muscles contract. Contraction of cremaster muscle moves testes closer to body for heat. Contraction of dartos muscle causes scrotum to become tight and reduce heat loss.

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7
Q

Normal sperm production requires a temperature of…

A

2-3 C below core body temperature.

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8
Q

Where do the testes develop?

A

Near kidneys in the posterior part of the abdomen. Begin their descent into the scrotum through the lingual canals during the 7th month of fetal development.

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9
Q

Tunica vaginalis.

A

Partially covers the testes. Derived from peritoneum. Forms during descent of testes.

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10
Q

Hydrocele.

A

Collection fo serous fluid in tunica vaginalis. Caused by testicular injury or epididymis inflammation. No treatment needed.

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11
Q

Tunica albuginea.

A

Internal to tunica vaginalis. Surrounds testes. White fibrous capsule. Dense irregular connective tissue. Extends inward. Forms septa that divide the testis into a series of internal lobules (200-300).

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12
Q

What cells are present in seminiferous tubules?

A

Spermatogenic cells and sustentacular cells (Sertoli).

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13
Q

Spermatogonia develop from…

A

Primordial germ cells, which arise from yolk sac and enter the testes during the 5th week of development.

The spermatogonia remain dormant during childhood, and actively begin producing sperm at puberty.

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14
Q

After a sperm cell is formed, it is released into the…

A

Lumen of the seminiferous tubule, which contains layers of progressively more mature cells.

Primary spermatocytes –> secondary spermatocytes –> spermatids –> sperm cells.

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15
Q

Blood-testis barrier.

A

Tight junctions join neighbouring Sertoli cells in the seminiferous tubules. Substances must first pass through the Sertoli cells before they can reach the developing sperm. Prevents an immune response against the spermatogenic cell’s surface antigens.

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16
Q

Sertoli cells.

A

Support and protect developing spermatogenic cells. Nourish spermatocytes, spermatids, and sperm. Phagocytize excess spermatid cytoplasm as development proceeds. Control movements of spermatogenic cells, and the release of sperm into the lumen of the seminiferous tubule. Produce fluid for sperm transport. Secrete inhibin. Regulate effects of testosterone and FSH.

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17
Q

Which cells secrete testosterone?

A

Interstitial cells (Leydig). Located in spaces between adjacent seminiferous tubules.

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18
Q

Cryptorchidism.

A

Condition where testes do not descend into the scrotum. Occurs in 3% of full-term infants, and 30% of premature infants. Results in sterility if left untreated. Chance of testicular cancer is 30-50x greater. The testes of 80% of boys with this condition will descend spontaneously during the first year of life. The condition can be corrected surgically before 18 months of age if the testes remain undescended.

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19
Q

Spermatogenesis.

A

65-75 days. Spermatogonia undergo mitosis and differentiation into primary spermatocytes –> replicate DNA –> meiosis begins.

Meiosis I: Homologous pairs of chromosomes line up at the metaphase plate –> crossing over –> meiotic spindle pulls one chromosome of each pair to an opposite pole of the dividing cell –> forms 2 secondary spermatocytes (haploid).

Meiosis II: Chromosomes line up in a single file along the metaphase plate –> 2 chromatids of each chromosome separate –> forms 4 spermatids (haploid).

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20
Q

Spermatogonia.

A

Stem cells. Contain diploid number of chromosomes. Undergo mitosis. Some remain near the basement membrane of the seminiferous tubule in an undifferentiated state to serve as a reservoir of cells for future cell division and subsequent sperm production. Others lose contact with basement membrane, squeeze through tight junctions of blood-testis barrier, undergo developmental changes, and differentiate into primary spermatocytes (diploid).

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21
Q

How do spermatogenic cells remain in contact throughout their entire development?

A

As they proliferate, they fail to complete cytoplasm separation via cytokinesis, so the cells remain in contact via cytoplasmic bridges.

This pattern of development accounts for the synchronized production of sperm in any given area of the seminiferous tubule.

This pattern of development is also important for survival, since half of the sperm contain an X chromosome and the other half contain a Y chromosome, and the larger X may carry genes needed for spermatogenesis that are lacking on the smaller Y.

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22
Q

Spermiogenesis.

A

Final stage of spermatogenesis where the 4 haploid spermatids develop into 4 sperm cells. No cell division. An acrosome forms on top of the nucleus which condenses and elongates. A flagellum develops. Mitochondria multiply. Sertoli cells dispose of the excess cytoplasm that sloughs off.

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23
Q

Spermiation.

A

Occurs after spermiogenesis. Sperm cells are released from their connections to Sertoli cells. Fluid secreted by Sertoli cells pushes sperm toward the ducts of the testes.

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24
Q

How many sperm complete spermatogenesis daily?

A

300 million.

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25
Q

Head of sperm.

A

Flat. Pointed. Contains a nucleus with 23 highly condensed chromosomes. Acrosome covers the anterior 2/3rds of the nucleus and is filled with enzymes that help sperm penetrate the secondary oocyte.

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26
Q

Tail of sperm.

A

4 parts.

Neck: constricted region just behind the head that contains centrioles which form the microtubules that comprise the remainder of the tail.

Middle piece: contains mitochondria arranged in a spiral which provide ATP for locomotion of sperm to the site of fertilization and for sperm metabolism.

Principal piece: longest part of tail.

End piece: terminal part that tapers.

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27
Q

Once ejaculated, most sperm do not survive more than ____ hours within the female reproductive tract.

A

48

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28
Q

What hormones change at puberty in the male reproductive system?

A

Hypothalamic neurosecretory cells increase GnRH secretion –> stimulates gonadotrophs in anterior pituitary to secrete LH and FSH.

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29
Q

LH in males.

A

Stimulates interstitial cells to secrete testosterone.

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30
Q

Testosterone in males.

A

Steroid hormone. Synthesized from cholesterol in testes. Principal androgen. Lipid-soluble. Readily diffuses out of interstitial cells into the interstitial fluid and then into blood. Testosterone suppresses LH secretion and GnRH secretion via negative feedback. Stimulates the final steps of spermatogenesis in seminiferous tubules.

31
Q

What can convert testosterone into dihydrotestosterone?

A

5 alpha-reductase.

32
Q

FSH in males.

A

Acts indirectly to stimulate spermatogenesis.

33
Q

How do FSH and testosterone in males work together?

A

FSH and testosterone act synergistically on Sertoli cells to stimulate secretion of androgen-building protein (ABP) into the lumen of the seminiferous tubules and into the interstitial fluid around the spermatogenic cells. ABP binds to testosterone, keeping its concentration high.

34
Q

Inhibin in males.

A

Once the degree of spermatogenesis required for reproductive functions has been achieved, Sertoli cells release inhibin, which inhibits FSH secretion. If spermatogenesis is proceeding too slowly, less inhibin is released which permits more FSH to be secreted.

35
Q

What effects do androgens in males produce?

A

1) Prenatal development.
2) Development of sexual characteristics.
3) Development of sexual function.
4) Stimulation of anabolism.

36
Q

Androgens in prenatal development (males).

A

Before birth, testosterone stimulates the male pattern of development of reproductive system ducts and descent of testes. DHT stimulates development of external genitals. Testosterone is converted in the brain to estrogens which play a role in the development of certain brain regions.

37
Q

Androgens in the development of male sexual characteristics.

A

At puberty, testosterone and DHT bring about development and enlargement of the male sex organs and the development of masculine secondary sex characteristics.

38
Q

Androgens and the development of sexual function (males).

A

Androgens contribute to male sexual behaviour, spermatogenesis, and sex drive.

39
Q

Androgens and stimulation of anabolism (males).

A

Androgens are anabolic hormones, so they stimulate protein synthesis.

40
Q

What are the male reproductive system ducts?

A

Testis ducts, epididymis, ductus deferens, spermatic cord, ejaculatory ducts, and urethra.

41
Q

Ducts of the testis.

A

Pressure generated by fluid secreted by Sertoli cells pushes sperm and fluid along the lumen of seminiferous tubules –> into straight tubules –> lead to the rete testis –> sperm then move into a series of coiled efferent ducts in the epididymis that empty into a single tube (ductus epididymis).

42
Q

Epididymis.

A

Organ that curves along the superior and posterior border of each testis. Comma shape. Consists of tightly coiled ductus epididymis. The efferent ducts from the testis join the ductus epididymis at the head of the epididymis. At its distal end, the tail of the epididymus continues as the ductus deferens. Site of sperm maturation. Helps propel sperm into ductus deferens during sexual arousal by peristaltic contraction of its smooth muscle. Stores sperm which remain viable for up to several months.

43
Q

The ductus epididymis is lined with…

A

Pseudostratified columnar epithelium, and encircled by layers of smooth muscle. The free surfaces of the columnar cells contain stereocilia which are long branching microvilli that increase the SA for reabsorption of degenerated sperm. Connective tissue around the muscle layer attaches the loops of the ductus epididymis and carries blood vessels and nerves.

44
Q

Sperm maturation.

A

Takes place in epididymis. Sperm acquire motility and the ability to fertilize an ovum. 14 days.

45
Q

Ductus deferens.

A

Within the tail of the epididymis, the ductus epididymis becomes less convoluted, and its diameter increases. Beyond this point, the duct is known as the ductus deferens (vas deferens). Conveys sperm during sexual arousal from the epididymis toward the urethra by peristaltic contractions. Stores sperm for several months.

Ampulla: dilated terminal part.

Mucosa: pseudostratified columnar epithelium, lamina propria.

Muscularis: inner longitudinal, middle circular, outer longitudinal smooth muscle.

46
Q

Spermatic cord.

A

Each spermatic cord consists of a ductus deferens as it ascends through the scrotum, the testicular artery, veins that drain the testis and carry testosterone into circulation, autonomic nerves, lymphatic vessels, and the cremaster muscle.

47
Q

Inguinal canal.

A

Spermatic cord and ilioinguinal nerve pass through this oblique passageway in the anterior abdominal wall superior and parallel to the medial half of the inguinal ligament. Originates at deep inguinal ring (slitlike opening in aponeurosis of transverse abdominis muscle). Ends at the superficial inguinal ring (triangular opening in aponeurosis of external oblique muscle).

48
Q

Ejaculatory ducts.

A

Formed by the union of the duct from the seminal vesicle and the ampulla of the ductus deferens. Form superior to the base of the prostate, and pass inferiorly and anteriorly through the prostate. Terminate in prostatic urethra where they eject sperm and seminal vesicle secretions just before the release of semen.

49
Q

Urethra (male).

A

Shared terminal duct of reproductive and urinary systems. 20 cm long. Passes through prostate, deep muscles of perineum, and penis.

Prostatic urethra: 2-3cm, passes through prostate.
Intermediate urethra: 1 cm, passes through deep muscles of perineum.
Spongy urethra: 15-20 cm, passes through corpus spongiosum of penis, ends at external urethral orifice.

50
Q

Seminal vesicles and seminal fluid.

A

Paired pouches. Through the seminal vesicle ducts, the seminal vesicles secrete an alkaline viscous fluid that contains fructose, prostaglandins, and clotting proteins. The alkaline nature of the seminal fluid helps neutralize acidic environment of male urethra and female reproductive tract that otherwise would inactivate and kill sperm. The fructose is used for ATP production by sperm. The prostaglandins contribute to sperm motility and viability and may stimulate smooth muscle contractions within female reproductive tract. The clotting proteins help semen coagulate after ejaculation.

51
Q

Seminal fluid normally constitutes ____ of the volume of semen.

A

60%

52
Q

Prostate.

A

Single donut-shaped gland. Golf ball sized. Surrounds prostatic urethra. Increases in size from birth to puberty. Expands rapidly until age 30. Further enlargement may occur at age 45 where it constricts the urethra and interferes with urine flow. Secretes a milky acidic fluid. Prostate secretions enter the prostatic urethra through prostatic ducts. These secretions contribute to sperm motility and viability.

53
Q

Prostatic secretions make up ____ of the volume of semen.

A

25%

54
Q

Components of prostatic secretions.

A

1) Citric acid: used by sperm for ATP production via Krebs.
2) Proteolytic enzymes: breakdown clotting proteins in seminal fluid.
3) Acid phosphatase.
4) Seminal plasmin: antibiotic that destroys bacteria.

55
Q

Bulbourethral glands.

A

Cowper’s glands. Paired. Pea-sized. Inferior to prostate. Located on either side of the membranous urethra within the deep muscles of perineum. Ducts open into spongy urethra. During sexual arousal, they secrete an alkaline fluid into the urethra that protects the sperm by neutralizing acids in urine. Secrete mucus that lubricates the end of the penis and the lining of the urethra.

56
Q

Semen.

A

Sperm and seminal fluid. The volume of semen in a typical ejaculation is 2.5-5.0 mL with 50-150 million sperm per mL. Alkaline. Milky (from prostatic secretion). Sticky (from seminal fluid and bulbourethral fluid). Provides sperm with a transportation medium, nutrients, and protection.

57
Q

Seminal fluid.

A

Secretions of seminiferous tubules, seminal vesicles, prostate, and bulbourethral glands.

58
Q

When the amount of sperm in a single ejaculation falls below _____ , the male is likely to be infertile.

A

20 million / mL.

59
Q

How can too many sperm without sufficient dilution from seminal fluid result in infertility?

A

The sperm tails will tangle and lose mobility.

60
Q

10-20 minutes after semen has coagulated after ejaculation, semen reliquefies because…

A

Prostate-specific antigen (PSA) and other proteolytic enzymes produced by the prostate break down the clot. Abnormal or delayed liquefaction of clotted semen may cause complete or partial immobilization of sperm, inhibiting their movement through the cervix.

61
Q

Hemospermia.

A

Blood in semen. Caused by inflammation of blood vessels lining the seminal vesicles. Treated with antibiotics.

62
Q

What are the 3 parts of the penis?

A

Body, glans penis, and root.

63
Q

The body of the penis is composed of…

A

3 cylindrical masses of tissue, each surrounded by a tunica albuginea. Skin and a subcutaneous layer enclose all 3 masses. Erectile tissue.

Corpora cavernonsa penis: the 2 dorsolateral masses.
Corpus spongiosum penis: the smaller mid ventral mass, contains spongy urethra and keeps it open during ejaculation.

64
Q

Erectile tissue.

A

Composed of numerous blood sinuses lined by endothelial cells and surrounded by smooth muscle and elastic connective tissue.

65
Q

Glans penis.

A

Distal end of corpus spongiosum penis. Enlarged region. The distal urethra enlarges within the glans penis and forms a terminal slitlike opening, called the external urethral orifice. Foreskin covers the glans penis in an uncircumcised penis.

66
Q

Root of the penis.

A

Attached part. Consists of the bulb of the penis (expanded posterior continuation of the base of the corpus spongiosum penis), and the crura of the penis (the two separated and tapered parts of the corpora cavernosa penis).

66
Q

Root of the penis.

A

Attached part. Consists of the bulb of the penis (expanded posterior continuation of the base of the corpus spongiosum penis), and the crura of the penis (the two separated and tapered parts of the corpora cavernosa penis).

67
Q

Root of the penis.

A

Attached part. Consists of the bulb of the penis (expanded posterior continuation of the base of the corpus spongiosum penis), and the crura of the penis (the two separated and tapered parts of the corpora cavernosa penis).

68
Q

The weight of the penis is supported by…

A

2 ligaments that are continuous with the fascia of the penis.

Fundiform ligament: arises from inferior part of linea alba.
Suspensory ligament: arises from pubic symphysis.

69
Q

How is an erection initiated and maintained?

A

Parasympathetic fibres from sacral spinal cord upon sexual stimulation. The parasympathetic fibres produce and release NO, which causes smooth muscle in the walls of the arteriole supplying erectile tissue to dilate. Large amounts of blood enter the erectile tissue. NO also causes the smooth muscle within the erectile tissue to relax to widen the blood sinuses. Expansion of blood sinuses compresses the veins that drain the penis.

70
Q

What can stimulate an erection?

A

Mechanoreceptors provide direct input to the erection-integrating center in the spinal cord. Sights, sounds, smells and thoughts.

71
Q

Which negative stimuli can inhibit erection?

A

Bad mood, depression, anxiety.

72
Q

Priapism.

A

A persistent and painful erection of the penis that does not involve sexual desire or excitement. Can be several hours. Results from abnormalities of blood vessels and nerves in response to medication used to produce erection in males. Other causes can be spinal cord disorder, leukaemia, sickle-cell disease, pelvic tumour.

73
Q

Ejaculation is a sympathetic reflex coordinated by the _____ part of the spinal cord.

A

Lumbar.
The smooth muscle sphincter at the base of the urinary bladder closes, preventing urine from being expelled during ejaculation, and semen from entering the urinary bladder. Before ejaculation, peristaltic contractions of epididymis, ductus deferens, seminal vesicles, ejaculatory ducts, and prostate propel semen into spongy urethra, leading to emission, which is the small discharge of semen before ejaculation. The musculature of the penis which is supplied by the pudendal nerves also contracts during ejaculation.

BIOL*235 Final Exam (10 decks)

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