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Questions and Answers
What is one of the primary functions of the testes?
Which reproductive technique involves the freezing of sperm for later use?
What is evaluated when assessing sperm quality?
Which accessory reproductive organ is responsible for storage and maturation of sperm?
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What effect does heat-stress have on sperm integrity?
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Which of the following is NOT a function of accessory reproductive organs?
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Which technique is used to detect compromised viability in sperm, oocytes, and embryos?
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What type of conditions may negatively impact fertility according to the research interests?
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Which of the following is a key focus area in the research mentioned?
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What is the primary function of the seminal vesicles?
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Which component is primarily responsible for enhancing sperm motility and fertilization?
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What role does the bulbourethral gland play prior to ejaculation?
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What is the pH range of a typical ejaculate, and why is this significant?
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What is the primary composition of prostatic secretions?
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During ejaculation, what is the primary function of the smooth muscle contractions in the seminal vesicles and prostate?
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Which of the following statements about the spongy urethra is incorrect?
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What percentage of semen volume does the prostate account for?
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What is the primary function of the testes?
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How does the scrotum respond to warm temperatures?
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Which muscle raises the testes within the scrotum?
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What is the structure that supports spermatogenesis in the testes?
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What is the temperature of blood in the testicular arteries compared to the blood in the testicular veins?
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Which structure is primarily involved in sperm maturation and storage?
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During which physiological process does smooth muscle contraction occur to expel sperm into the urethra?
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What is the function of Leydig cells within the testes?
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What role do myoid cells play in the seminiferous tubules?
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What is the approximate length of the ductus deferens?
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Study Notes
The Scrotum
- A sac of skin and superficial fascia located outside the abdominopelvic cavity at the root of the penis.
- Contains the paired testes.
- Sperm production is temperature sensitive.
- The scrotal location allows the testes to maintain a temperature ~3°C lower than core body temperature.
- Regulated by temperature changes.
- Cold temperature raises the scrotum to the body and wrinkles the scrotal skin, reducing surface area and heat loss.
- Warm temperature lowers the scrotum and relaxes the skin, increasing surface area and distance from the body for cooling.
The Testes
- Lie within the scrotum.
- Approximately 4 cm long and 2.5 cm wide.
- Primary function is to produce sperm and androgens (such as testosterone).
- Each testis is divided into lobules, each of which contains 1-4 tightly coiled seminiferous tubules (site of spermatogenesis).
- Sperm pass from the seminiferous tubules through the rete testis & into the efferent ducts of the epididymis.
- The epididymis is where sperm undergo further maturation (acquire motility & fertilization ability) and storage until ejaculation.
- Interstitial (Leydig) cells produce androgens.
- Sustentacular (Sertoli) cells support spermatogenesis.
- Spermatogonia, spermatocyte, and spermatid all form sperm.
- Myoid cells contract to move sperm and fluid through tubules.
The Penis
- The male copulatory organ. Responsible for delivering sperm into the female reproductive tract.
- Attached root and free shaft that ends in an enlarged tip known as the glans penis.
- Loose fold of skin that covers the glans penis is called the prepuce or foreskin.
- Internal anatomy includes: spongy urethra, corpus spongiosum, and corpora cavernosa.
- Erection occurs when vascular spaces fill with blood.
Male Duct System
- Epididymis, ductus deferens (vas deferens), ejaculatory duct, and urethra.
Epididymis
- Regions: caput (head), corpus (body), and cauda (tail).
- Structure: Highly coiled duct ~6 m long. Pseudo-stratified epithelia with stereocilia.
- Function: Sperm maturation (acquisition of motility and fertilizing ability). Sperm storage in cauda possible for several months. Sperm is ejaculated from the caudal epididymis, not the testes.
Ductus Deferens
- Also called vas deferens.
- ~45 cm long.
- Runs upwards from the epididymis through the inguinal canal into the pelvic cavity.
- Descends over the posterior bladder wall.
- Terminal end expands to form the ampulla of the ductus deferens.
- Finally joins with the duct of the seminal vesicle to form the ejaculatory duct.
- Structure: Mucosa: Pseudo-stratified epithelium. Muscular layer: Thick layers of smooth muscle.
- Ejaculation: Peristaltic waves of smooth muscle contraction expel sperm into the urethra.
- Vasectomy is a method of contraception that involves severing the ductus deferens.
Urethra
- Terminal portion of the male duct system.
- Conveys both urine and semen.
- Three regions: Prostatic urethra, membranous urethra, and spongy urethra.
- Mucosa contains scattered urethral glands that secrete mucus into the lumen just before ejaculation.
Accessory Glands
- Seminal Vesicles, Prostate, Bulbourethral glands.
Seminal Vesicles
- Large hollow glands (~15 cm uncoiled).
- Outer fibrous capsule with a thick inner layer of smooth muscle (contracts during ejaculation).
- Secretes yellow viscous alkaline fluid containing fructose, ascorbic acid, coagulating enzymes, and prostaglandins (enhance sperm motility and fertilization).
- Accounts for 70% of semen volume.
Prostate
- Single doughnut-shaped gland that encircles the urethra just inferior to the bladder.
- Outer thick capsule containing 20-30 compound tubulo-alveolar glands embedded in smooth muscle and connective tissue.
- Secretes milky acidic fluid containing citrate, several enzymes, and prostate-specific antigen (activates sperm).
- Accounts for up to 30% of semen volume.
- Contraction of smooth muscle causes prostatic secretions to enter the urethra.
Bulbourethral Glands
- Inferior to the prostate.
- Secretes a thick clear alkaline mucus (neutralizes traces of acidic urine in the urethra prior to ejaculation).
Semen
- A mixture of sperm, testicular fluid, and accessory gland secretions.
- Function:
- Transport medium for sperm.
- Provides nutrients and chemicals that protect and activate sperm.
- Facilitates sperm movement.
- Components:
- Prostaglandins: Stimulate contraction in the female tract, facilitating sperm uptake.
- Relaxin: Enhances sperm motility.
- Clotting factors: Promote semen coagulation.
- Typical ejaculate is 2-5 ml of semen containing 15-150 x 106 sperm/ml (pH 7.2).
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Description
This quiz covers the anatomy and physiology of the scrotum and testes, focusing on their structure, function, and the importance of temperature regulation in sperm production. Test your knowledge on the reproductive system and learn about the roles of androgens and spermatogenesis.
