Human Reproduction Quiz

Human Reproduction

• Reproduction is the production of offspring by an organism. Humans reproduce sexually and are viviparous.
• The male reproductive system consists of paired testes, accessory ducts, accessory glands, and external genitalia (penis).

Paired Testes

• Primary sex organs that produce sperm and testosterone.
• Form within the abdomen and descend into the scrotum (at 8th month of pregnancy or shortly after birth) via inguinal canal.
• Scrotum's lower temperature (2-2.5°C lower than body temp.) is crucial for sperm function and spermatogenesis.
• Oval shaped, 4-5cm long, 2-3cm wide.
• Contain approximately 250 testicular lobules.
• Each lobule contains 1-3 coiled seminiferous tubules.
• Seminiferous tubules are lined with spermatogonia (male germ cells) and Sertoli cells (supporting cells).
• Interstitial cells (Leydig cells) outside tubules secrete androgens (hormones).

Accessory Ducts

• Include rete testis, vasa efferentia, epididymis, and vas deferens.
• Conduct sperm from testes:
  • Seminiferous tubules → rete testis (irregular cavities) → vasa efferentia (series of fine tubules) → epididymis (stores sperm temporarily) → vas deferens.
• Vas deferens joins the duct of the seminal vesicle to form the common ejaculatory duct.
• Urethra receives ducts of prostate and Cowper's glands.

Accessory Glands

• Include prostate gland, seminal vesicles, and Cowper's glands (bulbourethral glands).
• Produce seminal plasma (rich in fructose, calcium, and enzymes), which combines with sperm to form semen.
• Seminal plasma functions in sperm transport, nutrition, and counteracting uterine acidity.

Penis (External Genitalia)

• Copulatory organ, made of erectile spongy tissue.
• Erection (filling spongy tissue with blood) facilitates insemination.
• Glans penis/foreskin (prepuse).

Female Reproductive System

• Includes ovaries, accessory ducts (oviducts), uterus, and external genitalia.

Paired Ovaries

• Primary sex organs, producing ova (female gametes) and steroid ovarian hormones (estrogen and progesterone).
• Located on both sides of lower abdomen, connected to pelvic wall and uterus by ligaments.
• Enclosed by a thin epithelium covering the ovarian stroma (outer cortex and inner medulla).
• Contain ovarian follicles, each with an ovum.

Accessory Ducts (Oviducts/Fallopian Tubes)

• Two tubes (10-12cm long), each with 3 parts: infundibulum, ampulla, and isthmus.
• Infundibulum has fimbriae (finger-like projections) to collect the ovum.
• Ciliated epithelium lines oviduct lumen to move ovum towards the uterus.

Uterus (Womb)

• Inverted pear shape, supported by ligaments.
• Consists of 3 parts: fundus, body, and cervix.
• Uterine wall has 3 layers: perimetrium, myometrium, and endometrium, which prepares to receive and nourish fertilized egg.

Vagina

• Opens between urethra and anus; lined with glycogen-rich mucous membrane.
• Bartholin's glands secrete mucus for lubrication.

External Genitalia (Vulva/Pudendum)

• Includes Mons pubis (fatty tissue with pubic hair), vestibule (median channel w/hymen & clitoris).

Mammary Glands (Breasts)

• Pair of glands with glandular tissue and fat.
• Mammary lobes contain clusters of cells (mammary alveoli).
• Alveoli secrete milk; lumens store milk; ducts converge to form mammary ducts leading to lactiferous ducts.

Gametogenesis

• Formation of gametes:
  • Spermatogenesis: formation of sperm in seminiferous tubules of testes, has 2 stages: spermatogenesis & spermiogenesis.
    • Spermatogonia → Spermatocytes → Spermatids → Spermatozoa.
  • Oogenesis: formation of ovum in ovaries
    • Oogonia → Primary oocytes (arrested in prophase I of meiosis) → Secondary oocyte (forms after puberty) → Ovum (after fertilization).

Spermatogenesis - Hormones

• GnRH (Hypothalamus) → LH (anterior pituitary) → Leydig cells → androgens → spermatogenesis.
• FSH (Anterior pituitary) → Sertoli cells → factors for spermiogenesis.
• Negative feedback loop via inhibin.

Structure of Spermatozoa (Sperm)

• Head: oval, formed from nucleus and acrosome.
• Middle piece: axial filament and mitochondria.
• Tail: central axial filament for movement.

Structure of Ovum (Egg)

• Spherical, non-motile, about 0.2 mm in diameter.
• 3 membranes: plasma membrane (innermost), zona pellucida (outer), corona radiata (outermost, follicle cells).

Menstrual Cycle

• Cyclic events from one menstruation to the next, lasting 28-29 days.
• Phases:
  • Menstrual Phase (1-5 days): uterine lining sheds.
  • Follicular/Proliferative Phase (5-13 days): follicle development and estrogen secretion, uterine lining thickens.
  • Ovulatory Phase (14th day): ovulation (release of ovum).
  • Secretory/Luteal Phase (15-28 days): corpus luteum forms, progesterone production maintains uterine lining, prepares for implantation.

Fertilization and Implantation

• Sperm deposited in vagina; fertilization in ampullary-isthmic junction fallopian tube; fertilized egg zygote; zygote undergoes cleavage to form morula.
• Morula develops into blastocyst, which implant into uterine wall.

Pregnancy and Embryonic Development

• Blastocyst implants into the uterine lining.
• Trophoblast forms chorionic villi which interdigitate with uterine tissue to form placenta.
• Placenta acts as barrier between the mother and the fetus for nutrient, gas, and waste exchange.

Parturition and Lactation

• Parturition (labor): process of giving birth, induced by neuroendocrine mechanism.
• Lactation: mammary glands produce milk, milk production is stimulated by hormones.

Test your knowledge on human reproduction, focusing on the male reproductive system and its components. This quiz covers the paired testes, their structure, function, and significance, as well as accessory ducts. Perfect for those studying human biology or related fields.