Structural and Functional Organization of the Male Reproductive System

Question 1

What are the systems of ducts contained within the testes?

Answer 1

Epididymis, ductus deferens, ejaculatory ducts, and urethra.

Question 2

What are the components of the accessory sex glands?

Answer 2

Seminal vesicles, prostate, bulbourethral glands.

Question 3

What is the purpose of the seminiferous tubules?

Answer 3

They produce sperm via spermatogenesis.

Question 4

What is the purpose of Sertoli cells?

Answer 4

They support, detect, and nourish spermatogenic cells;

Phagocytize degenerating spermatogenic cells;

Secrete fluid for sperm transport;

Release the hormone Inhibin, which regulates sperm production.

Question 5

What cells secrete testosterone?

Answer 5

Leydig cells

Question 6

What hormone promotes the development of masculine characteristics, and what hormone is responsible for the male sex drive?

Answer 6

Androgen

Testosterone

Question 7

The scrotum is __ - __ degrees C below body temperature to assist in the production and survival of sperm.

Answer 7

2-3 degrees Celsius.

Question 8

What are the three stages of spermatogenesis?

Answer 8

Meiosis I
Meiosis II
Spermiogenesis

Question 9

When does spermatogenesis begin, and how long is the spermatogenesis cycle?

Answer 9

Begins at puberty.

Cycle lasts 65-75 days.

Question 10

During what phase of spermatogenesis do chromosomes replicate?

Answer 10

Meiosis I.

There is NO replication in Meiosis II.

Question 11

Sperm are produced at what rate per day, and can survive for how long in the female reproductive tract?

Answer 11

300 million per day.

They can survive for 48 hours in the female reproductive tract.

Question 12

What are the four portions of the tail of a sperm cell?

Answer 12

Neck

Middle piece (contains mitochondria that provide ATP for locomotion)

Principle piece (longest portion)

End piece

Question 13

What is the comma shaped organ that lies along the posterior border of the testes?

Answer 13

Epididymis.

It is the site of sperm maturation, the process where sperm acquires motility and the ability to fertilize a secondary oocyte.

It also stores sperm to be propelled during sexual arousal via peristaltic movement into the ductus deferens.

Sperm may remain in storage for several months.

Question 14

What portion of the male sex organ penetrates the inguinal canal? What is it composed of?

Answer 14

Ductus deferens.

Three layers of muscle that force sperm toward the urethra via peristaltic movement. Functionally, it stores sperm which remains viable for several months.

Question 15

What substances do the seminal vesicles secrete? What do those substances do?

Answer 15

An alkaline, viscous fluid that contains fructose, prostaglandins, and clotting proteins.

-Fructose is used for ATP production by sperm.
-Prostaglandins contribute to sperm motility and viability.
-Clotting proteins help semen coagulate after ejaculation.

These fluids constitute 60% of semen volume.

Question 16

The prostate attains its size by what age, and remains stable at that size until what age?

Answer 16

30, further enlargement can occur at 45.

Question 17

What fluid does the prostate secrete?

Answer 17

A milky, slightly acidic fluid (pH 6.5) that contains citric acid and acid phosphatase, as well as protein digesting enzymes like PSA.

Prostatic secretions make up 25% of semen volume.

Question 18

What is the purpose of the secretion that the bulbourethral glands produce during sexual arousal?

Answer 18

They secrete an alkaline substance that protects passing sperm from acidic urine, and they secrete a lubricating fluid for the end of the penis and lining of the urethra to decrease the number of damaged sperm during ejaculation.

Question 19

What is the volume of semen in a typical ejaculation, and how much sperm is contained within it?

Answer 19

2.5 to 5 milliliters

50 to 150 million sperm per milliliter

*If the number falls below 20 million per milliliter, the male is likely infertile.

Question 20

What is the pH of semen, and what is the cause of its pH level?

Answer 20

Alkaline pH of 7.2-7.7 due to the larger volume of fluid from the seminal vesicles.

Question 21

What is the composition of the body of the penis?

Answer 21

Three cylindrical masses of tissue. The two dorsolateral masses are called the Corpora Cavernosa penis.

The smaller midventral mass is called the Corpus Spongiosum penis, and it contains the urethra.

The distal end of the Corpus Spongiosum penis is a slightly enlarged region called the glans penis.

Question 22

Describe how erection occurs.

Answer 22

Parasympathetic impulses cause the release of neurotransmitters and local hormones, including Nitric Oxide, which relaxes the vascular smooth muscle in the penile arteries.

The arteries supplying the penis dilate causing large quantities of blood to enter the sinuses.

This causes expansion, which puts compression on the veins that drain the penis, which slows blood flow.

*Ejaculation is a sympathetic reflex coordinated by the lumbar spine. As part of the reflex, the smooth muscle sphincter at the base of the urinary bladder closes to prevent urine from exiting during ejaculation.

Question 23

What do neurosecretory cells in the hypothalamus secrete at the onset of puberty? What does it do?

Answer 23

Gonadotropin-releasing hormon (GnRH)

This hormone causes the anterior pituitary gland to increase the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

Question 24

What do luteinizing hormone and follicle-stimulating hormone do?

Answer 24

LH stimulates Leydig cells to secrete testosterone, which is the principle androgen.

FSH and testosterone work together to stimulate spermatogenesis (make sperm).

Question 25

How do Sertoli cells contribute to spermatogenesis?

Answer 25

Once the correct degree of spermatogenesis is achieved, Sertoli cells secrete Inhibin, a hormone that inhibits the secretion of FSH (which is necessary for spermatogenesis).