Bio004 lecture exam 5 Male Reproductive System

Testes

Produce sperm and secrete hormones.

System of Ducts

Includes the epididymis, ductus deferens, ejaculatory ducts, and urethra. These ducts transport, store, and assist in the maturation of sperm while conveying them to the exterior.

Accessory Glands

Include seminal vesicles, prostate, and bulbourethral glands. These glands contribute fluids that form semen.

Supporting Structures

Scrotum and penis, which help in the delivery of sperm into the female reproductive tract.

Scrotum

The scrotum is a supporting structure for the testes, consisting of loose skin and subcutaneous tissue.

External Appearance of Scrotum

Appears as a single pouch of skin divided into two lateral parts by a ridge called the raphe.

Internal Structure of Scrotum

Divided into two sacs by the scrotal septum, each containing a testis.

muscle components of scrotum

dartos muscle and cremaster muscle

Dartos Muscle

Smooth muscle fibers within the subcutaneous layer.

Cremaster Muscle

A series of small skeletal muscle bands derived from the internal oblique muscle. It surrounds the testes and regulates their temperature.

Normal Temperature of Testes

2-3°C below core body temperature.

Cold Environment Response

1) Cremaster Muscle contracts, moving the testes closer to the body to absorb heat.
2) Dartos Muscle contracts, tightening the scrotal skin to reduce heat loss.

Warm Environment Response

1) Cremaster Muscle relaxes, moving the testes away from the body to prevent heat absorption.
2) Dartos Muscle relaxes, loosening the scrotal skin to increase heat loss.

Testes (Testicles)

Paired oval glands located in the scrotum.

Development of Testes

Develop near the kidneys in the posterior abdomen and descend into the scrotum during the last half of the 7th month of gestation via the inguinal canals.

protective tissue layers of testes

tunica vaginalis and albuginea, seminiferous tubules

Tunica Vaginalis

A serous membrane derived from the peritoneum; partially covers the testes.

Tunica Albuginea

A white fibrous capsule that extends inward to form septa, dividing the testes into 200-300 lobules.

Seminiferous Tubules

Tightly coiled tubes within each lobule, responsible for sperm production through spermatogenesis.

Spermatogenesis process

The sequence of events that transforms spermatogonia into mature sperm; Spermatogenesis occurs within the seminiferous tubules.

Spermatogenesis process pt 1

Primordial Germ Cells arise from the yolk sac and enter the testes during embryonic development

Spermatogenesis process pt 2

Spermatogonia remain dormant until puberty, when they begin actively producing sperm.

Spermatogenesis process pt 3

Progression: Spermatogonia → Primary Spermatocytes → Secondary Spermatocytes → Spermatids → Sperm Cells (Spermatozoa).

Sertoli (Sustentacular) Cells

Found within the seminiferous tubules, surrounding spermatogenic cells.

Functions of Sertoli Cells

1) Nourish developing sperm
2) phagocytize excess cytoplasm from spermatids
3) regulate the movement and release of sperm into the lumen of the seminiferous tubules
4) produce fluid for sperm transport,
5) secrete inhibin to regulate sperm production
6) form the blood-testis barrier.

Interstitial (Leydig) Cells

Found between seminiferous tubules and produce testosterone, the principal male androgen responsible for masculine characteristics and libido.

Hormonal Control of Testicular Function

GnRH (gonadotropin releasing hormone), LH (Luteinizing hormone), FSH (Follicle-stimulating hormone), Testosterone and DHT (dihydrotestosterone)

GnRH

Gonadotropin-releasing hormone from the hypothalamus stimulates the anterior pituitary to release LH and FSH.

LH

Stimulates Leydig cells to secrete testosterone.

FSH

Along with testosterone, stimulates the production of androgen-binding protein (ABP), which binds testosterone in the seminiferous tubules to stimulate spermatogenesis.

Testosterone and DHT

regulate the development of male characteristics, sexual function, and anabolic effects such as muscle growth.

Sperm Structure - Head

Contains a nucleus with 23 chromosomes and is covered by the acrosome, a vesicle filled with enzymes for oocyte penetration.

Sperm Structure - Tail

Has four parts:
1) Neck (contains centrioles)
2) Middle Piece (contains mitochondria for ATP production)
3) Principal Piece (the longest part of the tail)
4) End Piece (the terminal, tapering portion of the tail).

General function of reproductive system in males

Store and transport sperm cells.

Epididymis

A comma-shaped structure that stores and matures sperm. Sperm gain motility and fertilizing ability here.

Ductus (Vas) Deferens

Transports sperm from the epididymis to the urethra during ejaculation.

Spermatic Cord

Contains the ductus deferens, blood vessels, nerves, and the cremaster muscle.

Ejaculatory Ducts

Formed by the joining of the seminal vesicle and vas deferens, they eject sperm into the prostatic urethra.

Seminal Vesicles

Produce alkaline fluid rich in fructose, prostaglandins, and clotting proteins that help sperm motility and viability.

Prostate

Produces a milky, slightly acidic fluid containing citric acid (for ATP production), proteolytic enzymes (to break down seminal clotting proteins), and seminalplasmin (an antibiotic).

Bulbourethral (Cowper's) Glands

Secrete alkaline fluid to neutralize urine acidity in the urethra and mucus to lubricate the end of the penis during ejaculation.

Semen

A mixture of sperm and seminal fluid (secretions from the seminal vesicles, prostate, and bulbourethral glands).

Volume of Semen

2.5-5 mL per ejaculation, containing 50-150 million sperm/mL.

Sperm Viability

Sperm can survive up to 48 hours in the female reproductive tract.

Penis

Serves as the organ for ejaculation of semen and excretion of urine.

penis structure

1. Body: Contains three cylindrical masses of erectile tissue:
- Corpora cavernosa (dorsolateral masses).
- Corpus Spongiosum (surrounds the urethra).
2) Glans Penis: The enlarged, acorn-shaped end of the corpus spongiosum.
3) Root: Contains the bulb and crura of the penis, attached to muscles and bones of the pelvis.

Hydrocele

Def: A collection of serous fluid in the tunica vaginalis surrounding the testes.
Cause: Injury to the testes or inflammation of the epididymis.
treatment: Often does not require treatment unless symptomatic.

Cryptorchidism

Def: A condition in which one or both testes fail to descend into the scrotum

Prevalence of Cryptorchidism

Occurs in 3% of full-term infants and 30% of premature infants.

treatment of cryptorchidism

1) 80% of cases resolve spontaneously within the first year.
2) Surgical correction is recommended if the testes do not descend by 18 months.

complications of untreated cryptorchidism

1) Sterility: If the condition is bilateral, the high temperature of the abdominal cavity can destroy the spermatogenic cells
2) Increased Risk of Testicular Cancer: 30-50 times greater risk of developing testicular cancer if cryptorchidism is not treated

Varicocele ("Bag of Worms")

Def: An abnormal swelling of the veins that drain the testes (pampiniform plexus)
symptoms: The swelling is more noticeable when standing.
treatment: Usually does not require treatment unless causing discomfort or fertility issues.

Hemospermia

Def: The presence of blood in the semen.
common cause: Inflammation of blood vessels lining the seminal vesicles.
treatment: Typically resolved with antibiotics if infection is the cause.

Priapism

Def: A persistent and painful erection of the penis that occurs without sexual stimulation.
cause: Often related to medication use, blood disorders (such as sickle cell disease), or injury
treatment: Priapism requires medical attention to prevent long-term damage to erectile tissue

Capacitation

Def: The process sperm undergo in the female reproductive tract that enhances their ability to fertilize an oocyte.
location: Occurs as sperm pass through the uterus and uterine tube, where they are affected by secretions in the uterine tube.
function: Increases sperm motility and changes the sperm membrane to facilitate fertilization.