Study Guide: The Human Reproductive System (Anatomy & Physiology)

Reproductive System Overview

The human reproductive system is responsible for producing, storing, and transporting gametes, as well as supporting the development of offspring. There are significant anatomical and physiological differences between the male and female reproductive systems.

Differences Between Male & Female Reproductive Systems

• Male Reproductive System: Produces and delivers sperm; includes testes, ducts, accessory glands, and penis.

• Female Reproductive System: Produces eggs (ova), supports fertilization and fetal development; includes ovaries, uterine tubes, uterus, and vagina.

• Key Differences: Males have external genitalia and produce many small gametes (sperm), while females have internal reproductive organs and produce fewer, larger gametes (eggs).

Gonads

Definition and Types

• Gonad: A reproductive organ that produces gametes and sex hormones.

• Male Gonads: Testes (singular: testis)

• Female Gonads: Ovaries

Male Reproductive System

Accessory Glands and Their Functions

• Seminal Vesicles: Secrete alkaline fluid with fructose to nourish sperm and enhance motility.

• Prostate Gland: Produces a slightly acidic fluid containing enzymes that help activate sperm.

• Bulbourethral (Cowper's) Glands: Secrete mucus to lubricate the urethra and neutralize acidic urine residues.

Path of Sperm from Testes to External Urethral Orifice

1. Seminiferous tubules (in testes)

2. Rete testis

3. Efferent ductules

4. Epididymis

5. Vas (ductus) deferens

6. Ejaculatory duct

7. Urethra (prostatic, membranous, and spongy/penile sections)

8. External urethral orifice

Organ Monitoring Tubular Fluid and Sperm Maturation

• Epididymis: Monitors and adjusts the composition of tubular fluid, recycles damaged sperm, and is the site of sperm maturation and motility acquisition.

Interstitial Endocrine Cells

• Interstitial (Leydig) Cells: Located in the testes, these cells produce testosterone, the primary male sex hormone.

Regulation of Testosterone Levels

• Testosterone levels are kept high locally in the seminiferous tubules by the action of luteinizing hormone (LH) from the anterior pituitary, which stimulates Leydig cells.

Sperm Production (Spermatogenesis)

• Occurs in the seminiferous tubules of the testes.

• Regulated by hormones: follicle-stimulating hormone (FSH), LH, and testosterone.

Thermoregulation of Testes

• Cremaster muscle and dartos muscle regulate the temperature of the testes by moving them closer or further from the body.

• Optimal temperature for spermatogenesis is about 2–3°C below core body temperature.

Female Reproductive System

Uterine Wall Layers

• Perimetrium: Outer serous layer

• Myometrium: Thick muscular middle layer

• Endometrium: Inner mucosal layer; undergoes cyclic changes during the menstrual cycle

Layer Undergoing Cyclic Changes

• The endometrium undergoes dramatic changes in thickness and structure during the uterine (menstrual) cycle in response to hormones.

Site of Fertilization

• Fertilization most commonly occurs in the ampulla of the uterine (fallopian) tube.

Phases of Ovarian and Uterine Cycles

Cycle	Phases	Dominant Hormones
Ovarian	Follicular, Ovulation, Luteal	Estrogen (follicular), LH surge (ovulation), Progesterone (luteal)
Uterine	Menstrual, Proliferative, Secretory	Estrogen (proliferative), Progesterone (secretory)

Hormonal Changes if Pregnancy Does Not Occur

• If fertilization and implantation do not occur, the corpus luteum degenerates.

• Levels of progesterone and estrogen fall.

• This hormonal drop triggers the shedding of the endometrial lining (menstruation).

Key Terms and Definitions

• Gonad: Organ that produces gametes and sex hormones (testes in males, ovaries in females).

• Spermatogenesis: The process of sperm production in the seminiferous tubules.

• Oogenesis: The process of egg (ovum) production in the ovaries.

• Corpus luteum: Structure formed from the follicle after ovulation; secretes progesterone.

• Menstrual cycle: Regular cyclic changes in the endometrium, preparing for possible pregnancy.

Summary Table: Male vs. Female Reproductive Systems

Feature	Male	Female
Primary Gonad	Testes	Ovaries
Main Gamete	Sperm	Ovum (egg)
Accessory Glands	Seminal vesicles, prostate, bulbourethral glands	None (glands associated with lubrication)
Site of Fertilization	N/A	Uterine tube (ampulla)
Hormonal Regulation	Testosterone, FSH, LH	Estrogen, progesterone, FSH, LH

Additional info: Some details, such as the names of the uterine tube segments and the specific hormonal changes, have been expanded for academic completeness.