What does the male reproductive system consist of? (5 total)

1. penis

2. testes

3. scrotum

4. a series of ducts (epididymis, vas deferens, ejaculatory ducts, and urethra)

5. accessory sex glands (seminal vesicles, prostate gland, and bulbourethral glands)

a sac that surrounds the testes

scrotum

What does the scrotum consist of?

1. skin

2. dartos muscle

outer layer of the scrotum

skin

- the inner layer of scrotum

- a type of smooth muscle that is attached to the skin of the scrotum via connective tissue

dartos muscle

- a type of skeletal muscle that attaches to each testis

- an extension of the internal oblique muscle

cremaster muscle

What are the 3 functions of the scrotum?

1. supports the testes

2. protects the testes

3. regulate temperature of testes

The testes produce sperm.

Normal sperm production requires a temperature around ___°C; higher temperatures kill sperm.

34°C

The scrotum maintains the temperature of the testes at 34°C by contracting or relaxing the ____________ and the ____________.

- cremaster muscle

- dartos muscle

1. Contraction of the cremaster muscle brings the testes _______________, which allows the testes to absorb body heat.

2. Contraction of the dartos muscle causes the scrotum to _____________, which reduces heat loss.

1. closer to the body

2. become tight (i.e. wrinkled in appearance)

1. Relaxation of the cremaster muscle moves the testes ________________, which reduces exposure to body heat.

2. Relaxation of the dartos muscle causes the scrotum to _____________, which increases heat loss.

1. further away from the body

2. become loose

A gonad is a reproductive organ that produces ________ (sex cells such as sperm or eggs).

gametes

The structure of each testis consists of what 4 parts?

1.  tunica vaginalis

2. tunica albuginea

3. seminiferous tubules

4. Leydig cells

a layer of white connective tissue that surrounds the testis

tunica vaginalis

- an additional layer of white connective tissue that is deep to the tunica vaginalis

- divides the testis into sections called lobules

tunica albuginea

1. The lobules of the testis contain coiled structures called ______________, which produce sperm cells.

2. Each *** contains sperm cells at various stages of development that are surrounded by a ____________ (connective tissue) on one side and by a _____ on the other side.

1. seminiferous tubules

2. basement membrane; lumen

Sperm cells are given different names as they develop in the seminiferous tubule. What are the names of these different stages? (5 total)

1. spermatogonium

2. primary spermatocyte

3. secondary spermatocyte

4. spermatid

5. spermatozoon

- the production of sperm in the seminiferous tubules of the testes

- it takes about 2½ months (≈ 75 days) for this process to occur

spermatogenesis

- also called sustentacular cells

- nourish, protect, and stimulate the development of sperm cells

Sertoli cells

⇒ Hence, Sertoli cells are vital to the process of spermatogenesis.

Sandwiched between the developing sperm cells in the seminiferous tubules are __________.

Sertoli cells

1. _________ secrete a fluid that transports sperm from the seminiferous tubules to the epididymis.

2. This transport function of these* cells is necessary because sperm produced in the testes are immature, which means that they are nonmotile (unable to move) and, therefore, are incapable of fertilizing an ovum. Sperm do not become mobile until they mature in the __________.

1. Sertoli cells

2. epididymis

1. also called spermatozoon (the plural form is spermatozoa)

2. consists of what 2 components?

1. sperm cell

2. head and tail

The head of a sperm cell is divided into what 2 regions?

1. acrosome

2. nucleus

a sac that contains enzymes that penetrate the ovum during fertilization

acrosome

contains the DNA, which is haploid (i.e. consists of 23 total chromosomes: 22 autosomes and 1 X or Y sex chromosome)

nucleus of sperm cell

What are the 4 regions a sperm cell's tail divides into?

1. neck

2. middle piece (which contains mitochondria that produce energy/ATP)

3. principal piece

4. end piece

True or False: During fetal development and childhood, the testes can produce sperm.

False.

Once, the male reaches puberty, however, the testes start making sperm and continue to do so for most of the male’s life.

- also called interstitial cells

- located between the seminiferous tubules

- secrete testosterone into the blood

Leydig cells

What are the 2 functions of the testes?

1. produce sperm

2. produce testosterone

1. The fluid secreted by the Sertoli cells transports sperm from the ______________ to the ________, which is the beginning of the male duct system.

2. The male duct system consists of a series of tubes that are continuous with one another; it sequentially consists of the ________, ________, ________, and the ______.

1. seminiferous tubules; epididymis

2. epididymis; vas deferens; ejaculatory ducts; urethra

a coiled tube located above each testis

epididymis

What does the epididymis consist of? (2 total)

1. layer of epithelial cells that line a lumen

2. underlying layer of smooth muscle

What are the 3 functions of the epididymis?

1. site of sperm maturation (takes 2 weeks)

2. propels sperm

3. stores sperm

a long tube that extends off of the epididymis, ascends the scrotum, enters the pelvic cavity, courses past the urinary bladder, and then ends as an expanded region called the ampulla

vas deferens (also called the ductus deferens)

What are the 2 functions of the vas deferens?

1. propels sperm

2. stores sperm

During ejaculation, the smooth muscle in the wall of the ________ and the ________ contracts.

- epididymis

- vas deferens

a collective term that refers to various structures in the scrotum that are bundled together into a cord by connective tissue

spermatic cord

What 6 structures are included in the spermatic cord?

1. vas deferens

2. testicular artery (supplies blood to the testes)

3. pampiniform plexus of testicular veins (drains blood from the testes)

4. lymphatic vessels

5. nerves

6. cremaster muscle

1. There are 2 ____________; each is formed by the union a seminal vesicle with the ampulla of the vas deferens.

2. During ejaculation, these* allow sperm to move from the __________ into the _______.

1. ejaculatory ducts

2. vas deferens; urethra

the terminal part of the male duct system

urethra

The male urethra consists of what 3 anatomical regions?

1. prostatic urethra

2. membranous (intermediate) urethra

3. penile urethra

the part of the urethra that runs through the prostate gland

prostatic urethra

the part of the urethra located between the prostate gland and the penis

membranous (intermediate) urethra

- also called the spongy urethra

- the part of the urethra that runs through the corpus spongiosum of the penis

- At the tip of the penis, this* opens to the outside environment as the external urethral orifice

penile urethra

During ejaculation, the ______________ at the base of the urinary bladder is closed, thereby preventing urine from entering the urethra.

urinary sphincter

The accessory sex glands add secretions to sperm during ejaculation to form semen. What are the 3 male accessory sex glands?

1. seminal vesicles

2. prostate gland

3. bulbourethral glands

- paired glands that secrete fructose, an alkaline fluid containing bicarbonate (HCO3-) ions, and prostaglandins into the ejaculatory duct during ejaculation.

- Recall that each one of these unites with ampulla of the vas deferens to form the ejaculatory duct

seminal vesicles

- a single gland that is about the size and shape of a chestnut

- secretes citric acid and seminalplasmin into the urethra during ejaculation

prostate gland

- also called Cowper’s glands

- paired glands that are about the size and shape of a pea

- secrete mucus and an alkaline fluid containing bicarbonate (HCO3-) ions into the urethra during ejaculation

bulbourethral glands

- a mixture of sperm and the secretions of the accessory sex glands

- this* has a slightly alkaline pH of about ___

- semen

- 7.5

What does semen consist of? (7 total)

1. sperm

2. alkaline fluid containing bicarbonate (HCO3-) ions

3. fructose

4. citric acid

5. prostaglandins

6. mucus

7. seminalplasmin

- causes semen to have a slightly alkaline pH

- neutralizes the acidic environment in the female vagina so that sperm can survive in this area

alkaline fluid containing bicarbonate (HCO3-) ions

serves as a nutrient that sperm use to produce energy (ATP) via cellular respiration

fructose

serves as a nutrient that sperm use to enter the Krebs Cycle in order to produce energy (ATP)

citric acid

– Note that there are more bicarbonate ions in semen than citric acid; therefore, the pH of semen is overall slightly alkaline.

chemicals that eventually stimulate the contraction of smooth muscle in the female reproductive tract, which helps to move sperm towards the ovum to cause fertilization

prostaglandins

lubricates the urethra during ejaculation

mucus

a chemical that kills bacteria that may be present in the male urethra and/or female reproductive tract

seminalplasmin

What are the 3 regions of the penis?

1. glans

2. body

3. root

- the tip of the penis

- shaped like an acorn

- in an uncircumcised male, loose skin called prepuce (foreskin) surrounds the glans

glans

- also called the shaft

- the middle and longest part of the penis

body

- the part of the penis that attaches to the rest of the male’s body

- surrounded by the bulbospongiosus muscle, which is a type of skeletal muscle

root

- connective tissue that is organized into a sponge-like network of spaces that fill with blood to cause an erection

- supplied with blood via penile arteries and drained of blood via penile veins

erectile tissue

In the body of the penis, there are 3 cylindrical columns of erectile tissue:

- 2 ____________, which are fused together

- 1 ____________

- 2 corpora cavernosa (singular is corpus cavernosum)

- 1 corpus spongiosum

The penile (spongy) urethra passes through the ______________.

corpus spongiosum

1. In the root, the corpus spongiosum enlarges, forming the bulb of the penis; in addition, the corpora cavernosa spread apart, forming the _____ of the penis.

2. In the glans, only the ____________ is present and it is expanded.

1.  crura (singular is crus)

2. corpus spongiosum

- a state of hardness that is characteristic of the penis when sexually aroused

- a reflex that is coordinated by the spinal cord

erection

An erection involves __________ nerves that extend from the sacral spinal cord to the smooth muscle of penile arteries.

parasympathetic nerves

Penis mechanism.

1. During sexual excitement, the parasympathetic nerves from the sacral spinal cord release __________.

2. This* causes the smooth muscle in the walls of the penile arteries to relax, resulting in _________.

3. *** of the penile arteries brings a large amount of blood to the __________ of the penis, which expands as it fills up with this blood.

1. nitric oxide (NO)

2. vasodilation

3. erectile tissue

Penis mechanism.

4. Expansion of the erectile tissue ________ nearby penile veins, which prevents blood from leaving the erectile tissue.

5. The net result of the __________ of penile arteries and *** of penile veins is that a large volume of blood stays in the erectile tissue, which makes the penis erect.

4. compresses (closes)

5. vasodilation

- Note that depression, a bad mood, worrying about a problem, and/or performance anxiety can cause the brain to inhibit the erection reflex, and the penis remains flaccid (non-erect) even when sexual stimuli are present.

- the expulsion of semen from the penis

- occurs when the penis becomes extremely excited by sexual stimuli

- a reflex that is coordinated by the spinal cord

ejaculation

Ejaculation reflex of the spinal cord.

1. ________ nerves that extend from the upper lumbar spinal cord to the smooth muscle of the epididymis, vas deferens, and ejaculatory ducts and to the secretory cells of the accessory sex glands.

2. ________ nerves that extend from the lower lumbar spinal cord to the bulbospongiosus muscle around the root of the penis.

1. Sympathetic

2. Somatic

Mechanism of ejaculation.

1. When sexual excitement of the penis becomes extremely intense, the ________ nerves from the upper lumbar spinal cord stimulate the contraction of the smooth muscle of the epididymis, vas deferens, and ejaculatory ducts. This causes stored sperm to be propelled from the epididymis into the urethra.

2. In addition, these nerves stimulate the accessory sex glands to release their secretions into the urethra. ______ is formed as these secretions mix with sperm.

1. sympathetic

2. Semen

Mechanism of ejaculation.

3. Then the ________ nerves from the lower lumbar spinal cord stimulate the contraction of the bulbospongiosus muscle. This causes the semen to be propelled from the urethra to the outside environment, and the man experiences an _______ (a sense of intense pleasure).

3. somatic; orgasm

1. On average, the amount of semen ejaculated from the penis is about __ mL and contains about ___ million sperm.

2. Such a large number of sperm are released because only about ___ of them will make it to the ampulla of the fallopian tubes, which is where fertilization takes place. The rest of the sperm die along the way in the vagina and uterus.

1. 3 mL; 300 million (i.e. 100 million sperm/mL)

2. 100

1. A man is considered to be infertile if his sperm count is below ___ million sperm/mL) because none of the sperm will reach the ovum.

2. Frequent ejaculations (more than __ per week) can lead to a low sperm count due to the fact that the testes cannot produce sperm quick enough to keep up with the fast pace by which the sperm are being released from the body.

1. 20

2. 4

- However, this infertility is usually temporary and reverses once the frequency of ejaculation decreases and the testes have a chance to produce more sperm.

What are the 4 major male reproductive hormones?

1. Gonadotropin Releasing Hormone (GnRH)

2. Follicle Stimulating Hormone (FSH)

3. Luteinizing Hormone (LH)

4. Testosterone

When do male reproductive hormones start being released and for how long?

These hormones are secreted once the male reaches puberty, and they continue to be released for most of the male’s adult life.

True or False: There is some testosterone released by the testes during fetal development; however, this secretion stops soon after birth, and there isn’t any significant amount of testosterone produced during childhood.

True.

secreted by the hypothalamus in a pulsatile fashion (i.e. the hypothalamus secretes a small amount of GnRH periodically throughout the day)

Gonadotropin Releasing Hormone (GnRH)

causes the anterior pituitary gland to secrete FSH and LH

Gonadotropin Releasing Hormone (GnRH)

- secreted by the anterior pituitary gland

- stimulates spermatogenesis

- achieves this goal by activating the Sertoli cells

Follicle Stimulating Hormone (FSH)

- secreted by the anterior pituitary gland

- stimulates the Leydig cells to secrete testosterone into the blood

Luteinizing Hormone (LH)

- secreted by the Leydig cells of the testes

- Functions include: development of primary sex characteristics (growth of reproductive organs), development of secondary sex characteristics (low pitched voice, increased body hair, skeletal muscle growth), stimulates spermatogenesis, increases libido, increases aggressiveness

testosterone

What 2 hormones do sperm cells require in order to progress through the carious stages of spermatogenesis?

testosterone and follicle stimulating hormone (FSH)

1. In many target cells, the effects of testosterone are mediated by _____________.

2. In such cases, target cells contain an enzyme called ____________ that converts the testosterone into #1.

1. dihydrotestosterone (DHT)

2. 5-alpha reductase

Testosterone and DHT are examples of ________.

androgens

a hormone that promotes masculine characteristics

androgen

What are the 3 major types of androgens?

1. testosterone

2. dihydrotestosterone (DHT)

3. adrenal androgen

Androgens.

1. secreted by the testes in men

2. a conversion product of testosterone found in men

3. secreted by the adrenal gland in both men and women.

1. testosterone

2. dihydrotestosterone (DHT)

3. adrenal androgen

1. The main adrenal androgen is ______________, which is secreted by the adrenal gland in both men and women.

2. In men, the effects of adrenal androgen are _____ to those of testosterone and DHT, which are much more potent.

3. In women, the only androgen present is ____________ and its concentration is small.

1. dehydroepiandrosterone (DHEA)

2. trivial

3. adrenal androgen

Adrenal androgen is responsible for what 3 features in women? 

1. axillary hair

2. pubic hair

3. libido

Some DHEA can be converted into estrogen; therefore, DHEA is a small source of estrogen in postmenopausal women. Note that once a woman goes through menopause, the secretion of estrogen by the ovaries declines to insignificant amounts. 

Testosterone secretion is ultimately regulated by the hypothalamus via a ________________.

negative feedback system

1. The release of _____ causes the anterior pituitary to secrete LH.

2. LH then acts on the testes to promote secretion of ________ and the blood concentration of this* increases.

3. A high blood concentration of #2, however, inhibits #1 secretion from the _________ and LH secretion from the anterior pituitary.

1. GnRH

2. testosterone

3. hypothalamus

1. Without the release of LH, the testes are not stimulated to secrete any more testosterone and the blood concentration of testosterone ________.

2. Therefore, a person who takes ____________ for bodybuilding will have a lowered blood concentration of ______ testosterone, which results in infertility (testosterone is required for spermatogenesis), atrophy of the testes (the testes shrink due to lack of stimulation from LH and testosterone), and violent mood swings (due to the effects of testosterone on behavior).

1. decreases

2. anabolic steroids (testosterone-like drugs); natural

condition in which the testes do not descend into the scrotum

cryptorchidism

ejaculation that occurs too early, for example, during foreplay or shortly after penetration

premature ejaculation

a surgical procedure in which part of or the entire prepuce (foreskin) is removed

circumcision

- fluid-filled sacs in or on an ovary

- relatively common, usually noncancerous, and frequently disappear on their own

ovarian cysts

may result from the weakening of supporting ligaments and pelvic musculature associated with age or disease, traumatic vaginal delivery, chronic straining from coughing or difficult bowel movements, or pelvic tumors

uterine prolapse

surgical removal of the uterus, is the most common gynecological operation

hysterectomy

a perineal cut between the vagina and anus made with surgical scissors to widen the birth canal

episiotomy

- surgical procedure to increase breast size and shape

- surgical procedure that involves decreasing breast size by removing fat, skin, and glandular tissue

breast augmentation and reduction

the most common cause of breast lumps in females, one or more cysts and thickenings of alveoli develop

fibrocystic disease of the breasts

1. female reproductive cycle can be disrupted by many factors; but often occur together in female athletes

2. female athlete develops __________ from intense pressure by parents, coaches, etc.

3. absence of menstruation (occurs due to reduced secretion of gonadotropin-releasing hormone)

4. because estrogens help bones retain calcium and other minerals, chronically low levels of estrogens are associated with loss of bone mineral density

1. female athlete triad

2. disordered eating

3. amenorrhea

4. premature osteoporosis

- restricting the number of children by various methods designed to control fertility and prevent conception

- refers to the premature expulsion of the products of conception from the uterus, usually before the 20th week of pregnancy (may be naturally occuring - miscarriage - or be induced intentionally)

birth control methods and abortion

- most common cancer in males between the ages of 20 and 35

- arises from spermatogenic cells within the seminiferous tubulues

testicular cancer

- prostate becomes swollen and tender

- one of the most common chronic infections in men of the middle and later years

- prostate cancer is the leading cause of death from cancer in men in the US

prostate disorders

previously termed impotence, this is the consistent inability of an adult male to ejaculate or to attain or hold an erection long enough for sexual intercourse

erectile dysfunction

- a cyclical disorder of severe physical and emotional distress

- appears during the postovulatory phase of the female reproductive cycle and dramatically disappears when menstruation begins

premenstrual syndrome (PMS)

characterized by the growth of endometrial tissue outside of the uterus

endometriosis

What is responsible for secreting citric acid and seminalplasmin into the urethra during ejaculation?

prostate gland