Reproductive System Flashcards
Scrotum
Tunica Albuginea, Dartos Muscle, and Cremaster Muscle
Tunica albuginea
Thick, fibrous capsule of the testes
Dartos muscle
Superficial muscle that wrinkles scrotal skin to retain heat
Cremaster muscle
Deep muscle wrapped around the testes that raises testes towards the body
cavity
Testes: Primary Organ
- Ovoid structures within the scrotal sac
- Divided into lobules
- Lobules contain seminiferous tubules
Seminiferous Tubules
- Tubule Lining:
- Spermatogenic cells: Stem cells that mature into spermatozoans
- Sertoli/ Support/ Sustentacular cells: Nurse cells that nourish and protect developing sperm cells
- Outside tubules:
- Leydig or Interstitial Cells secrete testosterone to stimulate spermatogenesis
Epididymides
- Stores immature spermatozoans
- Nourishes them
- Promotes their maturation
(“swimming school”)
Ductus (vas) Deferens
- Upon anticipating ejaculation, the
vas deferens performs intense
peristalsis to deliver sperm from
epididymis to the ejaculatory duct. - Vasectomies prevent the exit of
spermatozoans.
Urethra
- Prostatic urethra: Travels through
the prostate gland - Membranous/ Intermediate urethra:
Travels through the body wall - Penile/ Spongy urethra: Travels
through the penis
External Penile Anatomy
- Function: Copulatory organ
- Shaft: Contains 3 columns of erectile
tissue - Glans penis: Distal end of penis containing about 1000 nerve endings
- Prepuce: The foreskin. Protects the
glans penis.
Internal Penile Anatomy
- Composed of vascular spaces forming erectile tissue
- Corpus cavernosa: Dorsal pair of erectile tissue that produces the erection.
- Corpus spongiosum: Ventral
column that keep the urethra open
during the erection
Semen
Combination of spermatozoans mixed
with bulbourethral fluid, seminal fluid,
and prostatic fluid.
Cowper’s/ Bulbourethral Glands:
Secretes a clear, alkaline, mucus-like fluid in response to sexual stimulation (pre-
ejaculate)
Seminal Vesicles:
- Slightly alkaline fluid
- Contains fructose for energy source
- Contains prostaglandins to stimulate female tract contraction
Prostate Gland:
- Thin, milky, alkaline fluid
- Enhances sperm motility
Spermatogenesis
- Define spermatogenesis: Formation of
male haploid gametes (spermatozoans) - Age of onset: Puberty (12-13 years)
- Requires the brain-testicular axis
Male Hormonal Regulation
- Hypothalamus secretes GnRH Gonadotropin Releasing Hormone
- Anterior pituitary is triggered to release LH & FSH (gonadotropins) Hormones that affect the gonads
- Luteinizing Hormone (LH) will: Stimulate Leydig cells/ Interstitial cells to secrete testosterone
- Follicle Stimulating Hormone (FSH) will: Stimulate Sertoli cells/ Support cells to secrete ABP
- Androgen Binding Protein (ABP) will: Bind testosterone to signal spermatogenesis
- Negative Feedback Inhibition: Stops spermatogenesis
o Adequate testosterone levels (we have enough)
o Inhibin from Sertoli cells (prevents further gonadotropin release)
Testosterone Activity
- Prenatal development (for masculinization)
- Male characteristics (low voice, thicker bones, muscle mass, thick facial/chest/back/arm/leg hair)
- Sexual function (libido/ sex drive)
- Anabolic steroid (for protein synthesis)
Spermatogonia:
Diploid stem cells. Undergo mitosis.
One copy stays at the seminiferous tubule lining while the other is pushed forward to become the primary spermatocyte.
Primary spermatocytes:
Diploid cells. Will undergo meiosis 1 to
turn into secondary spermatocytes.
Secondary spermatocytes:
Haploid cells but with a duplicate copy of genetic material. Will undergo meiosis 2 to
turn into spermatids.
Spermatids:
Haploid cells with a single copy of genetic material. Will undergo spermiogenesis
for morphology change.
Spermiogenesis: Morphology Change
- Nuclei become cone-shaped
- Acrosome cap filled with digestive enzymes forms
- Mitochondria form midpiece
- Microtubules form flagella
- Excess cytoplasm & organelles is shed
- Spermatozoa: Haploid cells, initially non-motile, are released into the tubule lumen.
Ovaries: Primary Organ
- Cortex: Contains blood vessels, lymphatic vessels, and nerve fibers
- Medulla: Contain ovarian follicles (sacs containing oocytes)
