The Reproductive System Part 1

Describe sexual reproduction

The process of producing offspring by uniting gametes

What are the organs of reproduction grouped into?

1. Gonads (testis and ovaries where they produce gametes and secrete hormones)

2. Ducts (transport, receiving, and storing gametes)

3. Accessory sex glands (produce material that support gametes)

What are the male structures of reproduction?

1. Testes

2. System of ducts (ductus epididymis, ductus deferens, ejaculatory duct, urethra)

3. Accessory sex glands (seminal vesicles, prostate gland, bulbourethral glands)

4. Supporting structures (penis)

What is the scrotum?

Cutaneous outpouching (sac) of the abdomen that supports the testes

• A vertical septum divides it into two sacs, each containing a single testis

What do the muscles in the scrotum do?

The dartos and cremaster muscles regulates testicular temperature required for sperm production by either bringing them closer to the pelvic cavity or farther

What organ is in the scrotum?

The test (oval-shaped glands)

Where do the testes develop on and descent into?

Develop high on the embryo’s posterior abdominal wall and descent into the scrotum through the inguinal canal

What do the testes contain?

Seminiferous tubules (in which sperm cells are made)

What are embedded along spermatogenic cells?

Sertoli cells

What are the functions of Sertoli cells?

• The tight junction of these cells form the blood-testis barrier that prevents an immune response against the surface antigens on the spermatogenic cells

• Nourish spermatocytes, spermatids, spermatozoa

• Mediate effects of testosterone and FH on spermogensis

• Phagocytes excess spermatids

• Control movements of spermatogenic cells and release of spermatozoa into the lumen of the seminiferious tubule

• Secrete fluid for sperm transport and the hormone inhibin

What are Leydig cells?

Located between seminiferous tubules to secrete testosterone

Describe the steps of spermatogensis

• The process is in which seminiferious tubules produce haploid sperm

  1. Begins as diploid spermatogia. Undergo mitosis to reserve future stem cells and to develop (2n) primary spermatocytes for sperm production

  2. Diploid primary spermatocytes undergo meiosis I forming haploid secondary spermatocytes

  3. Meiosis II occurs and makes haploid spermatids connected by cytoplasmic bridges

  4. Maturation of spermatids into sperm

  5. Release of sperm (spermiation)

Describe what sperm is

• Consists of a head, midpiece, and tail

• Functions to fertilize a secondary oocyte

• Midpiece contains many mitochondria for ATP for locomotion

What is a acrosome?

• Covers 2/3rds of the nucleus of a mature sperm and is a cap-like vesicle filled with enzymes (hyaluronidase and proteases) and helps to penetrate secondary oocyte

What are the hormones released at puberty by the anterior pituitary glands?

1. Follicle-stimulating hormone for initiation of spermatogenesis

2. Lutenizing hormone for assisting spermatogensis and production of testosterone

What does testosterone specifically control?

Controls male secondary sex characterstics like

1. stimulation of anabolism

2. hair growth

3. lowering of the voice

4. development of libido (sex drive)

• Overall tho, controls growth, development, functioning, stimulating bone growth, protein anabolism, and sperm maturation

• Negative feedback regulates the testosterone production

What hormone does Sertoli cells secrete against FSH?

Inhibin to regulate the rate of spermatogenesis

Name parts of the duct system?

1. Seminiferous tubules

2. Straight tubules

3. Rete testis

What is the epididymis?

Comma-shaped organ that lies along the posterior border of the testis

How are sperm transported out of the testes?

Through the efferent ducts in the epididymis which empty into a single tube called the ductus epididymis

What is the ductus epididymis lined with?

Stereocilia and is the site of sperm maturation and storage

What does the ductus deferens do?

Stores sperm and propels them towards the urethra for ejaculation

What is the spermatic cord?

• Supporting structure of the male reproductive system that ascends out of scrotum

• Consists of the ductus deferens, testicular artery, veins and lymphatics that drain semen and carry testosterone, and autonomic nerves (cremaster muscle)

What is the ejaculatory ducts?

Formed by the union of ducts of the seminal vesicles and ducti deferns

• Function is to eject spermatozoa into the prostatic urethra

What is the urethra?

Shared terminal duct of the reproductive and urinary systems that release urine and semen

• Subdivided into the prostatic, membranous, and spongy portions

What do seminal vesicles secrete?

Alkaline, viscous fluid that contains:

1. Alkaline for neutralizing acid

2. Frutose for ATP production

3. Prostaglandins for sperm motility and viability

4. Semenogelin is the main protein for coagulation after ejaculation

What does the prostate gland secrete?

Milky, slightly acidic fluid that contains

1. Citric acid for atp

2. Acid phosphate

3. Proteolytic enzymes for which liquidy coagulated semen

What do the bulbourethral (Cowper’s) glands do?

Secrete mucus for lubication and an alkaline substance for neutralizing acid

What is semen a mixture of?

Spermatozoa and accessory sex glands that provide the fluid in which spermatozoa are transported, provides nutrients, and neutralizes the acidity of the male urethra and female vagina

• Contains antibiotic, seminal plasmin, and prostatic enzymes to aid in movement into FEMALE

Once ejaculated, liquid semen does what?

Coagulates due to clotting proteins from the seminal vesicles

• AFTER 10-20 minutes, it becomes liquid again because PSA and proteolytic enzymes produced by the prostate break down the clots

What is the penis?

Contains the urethra and is a passageway of ejaculation of semen and release of urine

• Consists of a root, body, and glans Penis (each covered by the tunica albuginea)

• Covering the glans Penis is a foreskin

What are the two dorolateral masses in the penis?

Corpora cavernosa

What is the small midventral mass of the penis?

Corpora spongiosum (keeps it open during ejaculation)

Upon sexual stimulation, what happens?

Sacral parasympathetic fibers initiate and maintain an erection

What happens to the penis under the influence of nitric oxide release?

Arteries that supply the penis dilate and blood enters the penile sinuses in the erectile tissues

• Also causes it to relax, resulting in widening of the blood sinuses

What happens after an erection to stimulate relax?

Sympathetic stimulation is required to relax

• Smoth muscle sphincter closes at the urinary bladder, followed by semen being released from the urethra

• Caused by peristaltic contractions to release semen