Chapter 25: Reproductive System

What are the primary sex organs?

Testes (males) and ovaries (females)

What are the accessory sex organs?

Glands and external genitalia

Why are testes located in the scrotum?

To stay about 3°C cooler than body temp, which is better for sperm production

What does the cremaster muscle do?

Raises and lowers the testes

What does the dartos muscle do?

Wrinkles the scrotal skin to help with temperature regulation

What is the tunica albuginea?

Fibrous capsule that surrounds each testis

What is the function of seminiferous tubules?

They are where sperm are formed

What cells support sperm development and form the blood-testis barrier?

Sustentacular (Sertoli) cells

What cells produce testosterone?

Interstitial (Leydig) cells

What is spermatogenesis?

The process of sperm formation; begins at puberty and makes ~400 million sperm/day

What are the 3 stages of spermatogenesis?

1. Formation of spermatocytes

2. Meiosis

3. Spermiogenesis (final shaping of sperm)

What is the epididymis and what happens there?

Coiled duct (~6m) where sperm mature and gain ability to swim; journey takes ~20 days

What do the seminal vesicles secrete?

60% of semen: fructose, prostaglandins, proteins, alkaline fluid

What does the prostate gland secrete?

25–30% of semen; helps sperm motility and contains PSA (used in prostate cancer screening)

What is the role of the bulbourethral glands?

Secrete mucus before ejaculation to cleanse urethra and protect sperm

What are the main functions of the female reproductive system?

Produces ova, supports a developing embryo, and follows the menstrual cycle

What are the internal female reproductive organs?

Ovaries, uterine tubes, uterus, vagina

What are the ligaments that hold the ovaries in place?

• Broad ligament

• Suspensory ligament

• Ovarian ligament

What is the tunica albuginea in females?

It’s the fibrous capsule around the ovary (like in testes)

What does the ovarian cortex contain?

Developing follicles with oocytes

What are the 3 phases of the ovarian cycle?

1. Follicular phase

2. Ovulation

3. Luteal phase

What happens during ovulation?

The oocyte exits the ovary and enters the uterine tube

What does the corpus luteum do?

Secretes progesterone to prepare for embryo implantation

Where does fertilization usually occur?

In the infundibulum of the uterine tube

What are the layers of the uterine wall?

• Perimetrium – outer layer

• Myometrium – thick smooth muscle

• Endometrium – inner layer where embryo implants

What are the 3 phases of the uterine (menstrual) cycle?

• Menstrual phase (days 1–5): functional layer is shed

• Proliferative phase (days 6–14): endometrium rebuilds

• Secretory phase (days 15–28): endometrium prepares for implantation

What are the 3 layers of the vagina?

• Adventitia (outer connective tissue)

• Muscularis (smooth muscle)

• Mucosa (stratified squamous epithelium)

What structures make up the external female genitalia?

Mons pubis, labia majora & minora, clitoris, vestibule, hymen

What are the mammary glands?

Modified sweat glands that produce milk after childbirth

What happens during fertilization?

• Sperm binds to zona pellucida

• Acrosomal reaction

• Sperm & egg membranes fuse

• Cortical reaction prevents more sperm from entering

• Nuclei of sperm and egg fuse

What hormone is released by the hypothalamus to start the reproductive hormone chain?

GnRH (Gonadotropin-releasing hormone)

What two hormones does the anterior pituitary release in response to GnRH?

FSH (Follicle-stimulating hormone) and LH (Luteinizing hormone)

What does FSH do in females?

Stimulates follicle growth in ovaries

What does LH do in females?

Triggers ovulation and formation of corpus luteum

What hormone does the corpus luteum mainly secrete?

Progesterone (and some estrogen)

What does estrogen do during the cycle?

Builds up the endometrial lining (especially during proliferative phase)

What hormone spikes just before ovulation?

LH

What happens if fertilization does NOT occur?

Corpus luteum degenerates → progesterone drops → endometrial lining is shed (menstruation)

What are the 3 phases of the ovarian cycle?

• Follicular phase – follicle grows (days 1–13)

• Ovulation – egg released (day 14)

• Luteal phase – corpus luteum forms (days 15–28)

What are the 3 phases of the uterine cycle?

1. Menstrual phase – lining sheds (days 1–5)

2. Proliferative phase – lining rebuilds (days 6–14)

3. Secretory phase – lining thickens for implantation (days 15–28)

What is the function of inhibin in males?

Released by Sertoli cells to inhibit FSH and reduce sperm production when not needed

What hormones control the endometrium?

Estrogen and progesterone

What structure releases estrogen before ovulation?

Growing ovarian follicle

What is the result of the hormone drop in the luteal phase (if no pregnancy)?

Menstruation (endometrial lining is shed)

What hormone dominates the secretory phase?

Progesterone