Reproductive Anatomy Quiz
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Questions and Answers

What enhances the effects of testosterone on spermatogenesis?

  • Binding of testosterone to ABP (correct)
  • Inhibin secretion by Sertoli cells
  • Increased levels of FSH
  • Decline in LH secretion

    • Which hormone primarily inhibits FSH secretion from the anterior pituitary?

  • LH
  • Inhibin (correct)
  • GnRH
  • Testosterone

    • What happens to LH levels when testosterone levels increase?

  • LH levels remain constant
  • LH levels increase directly
  • LH levels decrease due to feedback (correct)
  • LH secretion is stimulated

    • At what age does the average sperm production rate typically decline significantly?

    <p>50 years old</p> Signup and view all the answers

    What initiates spermatogenesis at puberty?

    <p>Increased levels of GnRH and testosterone</p> Signup and view all the answers

    What is the primary function of the vas deferens during ejaculation?

    <p>To propel spermatozoa towards the urethra</p> Signup and view all the answers

    What structure is formed by the fusion of the vas deferens and the duct from the seminal vesicle?

    <p>Ejaculatory duct</p> Signup and view all the answers

    Which glands are responsible for the secretion of prostatic fluid during ejaculation?

    <p>Prostate gland</p> Signup and view all the answers

    What role does the bulbourethral glands play in the male reproductive system?

    <p>They secrete fluid into the penile urethra</p> Signup and view all the answers

    How long is the vas deferens in humans?

    <p>Approximately 35 cm</p> Signup and view all the answers

    What is the primary function of the seminal vesicle?

    <p>To secrete seminal fluid</p> Signup and view all the answers

    What is the relationship between the ejaculatory duct and the prostate gland?

    <p>The ejaculatory duct runs through the prostate gland</p> Signup and view all the answers

    Which structure connects the testes to the vas deferens?

    <p>Epididymis</p> Signup and view all the answers

    What is the primary function of seminiferous tubules?

    <p>Spermatogenesis</p> Signup and view all the answers

    Which part of the male urethra runs through the prostate gland?

    <p>Prostatic Urethra</p> Signup and view all the answers

    What temperature range is optimal for effective spermatogenesis?

    <p>3-5ºC below core body temperature</p> Signup and view all the answers

    At what developmental stage do spermatogonia begin dividing and increasing in number?

    <p>At puberty (11-14 years old)</p> Signup and view all the answers

    What do primary spermatocytes develop into after undergoing meiosis?

    <p>Secondary spermatocytes</p> Signup and view all the answers

    What characterizes the secondary spermatocytes during their development?

    <p>They remain coupled by cytoplasmic bridges</p> Signup and view all the answers

    What is the final stage of spermatogenesis known as?

    <p>Spermiogenesis</p> Signup and view all the answers

    What happens to the daughter cells produced during mitosis of spermatogonia?

    <p>One retains germ cell stocks and one continues dividing</p> Signup and view all the answers

    What surrounds the spaces between the seminiferous tubules?

    <p>Connective tissue and blood vessels</p> Signup and view all the answers

    What structure is responsible for the production of testosterone within the testes?

    <p>Leydig cells</p> Signup and view all the answers

    What triggers the synthesis of nitric oxide in the endothelial cells of the erectile tissue?

    <p>Binding of acetylcholine to muscarinic receptors</p> Signup and view all the answers

    Which mechanism is responsible for increasing blood flow to the penis during arousal?

    <p>Relaxation of smooth muscle in the erectile tissue</p> Signup and view all the answers

    What is the role of cyclic guanosine monophosphate (cGMP) in the process of erection?

    <p>To stimulate relaxation of smooth muscle cells</p> Signup and view all the answers

    Which enzyme is responsible for breaking down cGMP in the smooth muscle cells of the penis?

    <p>Phosphodiesterase type-5 (PDE5)</p> Signup and view all the answers

    What is the effect of the sympathetic division of the autonomic nervous system on the arteries supplying the penile erectile tissue at rest?

    <p>They are constricted, leading to a flaccid state</p> Signup and view all the answers

    During an erection, what occurs in relation to venous outflow from the penis?

    <p>Venous outflow becomes occluded, maintaining pressure</p> Signup and view all the answers

    What effect do psychogenic stimuli have on penile erection?

    <p>They promote an increase in autonomic tone</p> Signup and view all the answers

    What is the primary role of mucus secreted from the bulbourethral glands during intercourse?

    <p>To lubricate the urethra for easier passage</p> Signup and view all the answers

    What is the primary function of Prostate-Specific Antigen (PSA)?

    <p>Breaks down the semen clot to release spermatozoa</p> Signup and view all the answers

    Which gland contributes approximately 5% of the total semen volume?

    <p>Prostate gland</p> Signup and view all the answers

    How does the autonomic nervous system regulate male sexual function?

    <p>By regulating both erection and ejaculation through different pathways</p> Signup and view all the answers

    What triggers the process of emission during male sexual function?

    <p>Tactile and psychogenic stimuli</p> Signup and view all the answers

    Which physiological mechanism is responsible for the rigidity of the penis during erection?

    <p>Decreased vascular resistance and smooth muscle relaxation</p> Signup and view all the answers

    What prevents the backflow of semen during ejaculation?

    <p>Rhythmic contraction of skeletal muscles at the base of the penis</p> Signup and view all the answers

    What is the average semen volume expelled during ejaculation?

    <p>2-6 mL</p> Signup and view all the answers

    Which substance facilitates smooth muscle relaxation during erection?

    <p>Cyclic guanosine monophosphate (cGMP)</p> Signup and view all the answers

    Study Notes

    Vas Deferens

    • Also known as the ductus deferens
    • Approximately 35cm long in humans, connecting the epididymis to the urethra
    • Consists of an epithelial layer and three layers of smooth muscle
    • Smooth muscle layers propel spermatozoa during ejaculation

    Seminal Vesicles

    • Glands located on the posterior aspect of the bladder
    • Approximately 5cm long
    • Secrete seminal fluid into the ejaculatory duct during ejaculation

    Ejaculatory Duct

    • Short duct, approximately 2cm long
    • Formed by the fusion of the vas deferens and the duct from the seminal vesicles
    • Runs through the prostate gland and fuses with the urethra

    Prostate Gland

    • Single, domed shaped gland located beneath the bladder
    • Penetrated by the prostatic urethra and the ejaculatory ducts
    • Composed of glandular epithelium, connective tissue and smooth muscle
    • Smooth muscle contraction expels prostatic fluid into the prostatic urethra during ejaculation

    Bulbourethral (Cowper's) Glands

    • Pair of small exocrine glands located beneath the prostate gland and at the base of the penis
    • Secretion flows into the penile urethra during ejaculation

    Epididymis

    • C-shaped organ, typically 3.5cm long
    • Located on the posterior surface of each testis
    • Connects the testes to the vas deferens

    Urethra

    • The terminal portion of both the urinary and reproductive ductal system in males
    • Originates from the inferior portion of the urinary bladder
    • Approximately 20cm long
    • Divided into three parts:
      • Prostatic Urethra: Runs through the prostate gland where it fuses with the ejaculatory ducts
      • Membranous Urethra: Short portion at the base of the prostate gland
      • Penile Urethra: Runs through the penis

    Testes

    • Pair of oval glands, approximately 5cm by 2.5cm and weighs 10-15g in adults
    • Subdivided into approximately 400 lobules each containing seminiferous tubules
    • The seminiferous tubules are responsible for spermatogenesis
    • Spaces between the tubules are filled with connective tissue, blood and lymph vessels, and Leydig cells (responsible for testosterone production)

    Spermatogenesis

    • Occurs in the seminiferous tubules beginning at puberty
    • Involves transforming primordial germ cells into spermatozoa
    • Optimal rates occur at 3-5°C below core body temperature
      • This is why the testes are located in the scrotum
      • Failure of the testes to descend (cryptorchidism) can impair spermatogenesis
    • In prepubertal males:
      • Seminiferous tubules are simple
      • Small numbers of germ cells are arranged around the periphery, surrounded by supporting Sertoli cells
    • Beginning at puberty (11-14 years old):
      • Spermatogonia divide, increasing the number of cells at the base of the tubule
      • Spermatogonia undergo a series of transformations into spermatazoa
      • Developing cells move towards the lumen of the seminiferous tubules
    • More developed cells are closer to the lumen of the tubule

    Mitosis

    • Spermatogonia located close to the periphery of the seminiferous tubule
    • Cells undergo mitotic division, creating one daughter cell that remains at the periphery and another that undergoes further division.

    Meiosis

    • Spermatogonia become primary spermatocytes
    • Primary spermatocytes undergo meiosis, forming two secondary spermatocytes
    • Secondary spermatocytes undergo the second meiotic division, producing two spermatids

    Spermiogenesis

    • The final stage of spermatogenesis
    • Involves the metamorphosis of spermatids
    • Maturing spermatozoa remain associated with Sertoli cells
    • Testosterone effects on spermatogenesis are enhanced by the secretion of ABP by Sertoli cells, which increases local testosterone concentration

    Regulation and Production of Spermatozoa

    • Initiation of Spermatogenesis: Triggered at puberty by increased GnRH, LH, FSH, testosterone, and ABP. Regulated by negative feedback from testosterone and inhibin.
    • Production Rates: Healthy 20-year-old men produce approximately 6.5 million sperm/gram/testis/day. This rate declines with age.

    Male Sexual Function: Erection

    • Enabled by engorgement of penile erectile tissue with blood
    • Penile erectile tissue are typically relatively empty due to arterioles being constricted by noradrenaline released from the sympathetic nervous system.
    • During arousal, there are changes in autonomic tone caused by psychogenic stimuli or spinal reflexes.
    • These changes result in an increased blood flow to the penis and relaxation of smooth muscle in penile erectile tissue, leading to an increase in diameter and length
    • The process is enhanced by decreased venous outflow
    • The parasympathetic division of the autonomic nervous system stimulates bulbourethral gland secretion, providing lubrication.
    • NO and cGMP are crucial in smooth muscle relaxation causing engorgement.
    • PDE5 breaks down cGMP leading to penile flaccidity.

    Male Sexual Function: Emission

    • The transfer of spermatozoa and fluids from accessory glands into the urethra
    • Triggered by tactile and psychogenic stimuli
    • Mediated by sympathetic nervous system activity affecting smooth muscles in the vas deferens and prostate

    Male Sexual Function:Ejaculation

    • Rapid filling of the urethra during emission stimulates further contractions
    • Involves rhythmic contraction of skeletal muscles at the base of the penis
    • Prevents backflow of semen into the bladder through urethral constriction
    • Average semen volume is 2-6 mL, primarily from seminal fluid

    Nervous System Control in Male Sexual Function

    • Autonomic nervous system regulates erection (parasympathetic) and emission/ejaculation (sympathetic)
    • Psychogenic stimuli and mechanical stimulation activate reflex pathways for sexual function

    Physiological Mechanisms in Male Sexual Function

    • Erection involves NO release leading to cGMP production, causing smooth muscle relaxation
    • Emission combines sperm and fluids via muscular contractions
    • Ejaculation results from coordinated muscle contractions and nerve reflexes, effectively expelling semen

    Male Reproductive Anatomy Overview

    • The male reproductive anatomy consists of structures involved in sperm production, maturation, and transportation.

    Prostate-Specific Antigen (PSA)

    • A proteolytic enzyme
    • Breaks down the semen clot formed by semenogelin, releasing spermatozoa

    Bulbourethral Gland Secretions

    • Clear alkaline mucus secreted during sexual arousal
    • Neutralizes acidity from residual urine in the urethra
    • Acts as a lubricant for intercourse and semen flow

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    Male Reproductive System PDF

    Description

    Test your knowledge on the male reproductive system, including the vas deferens, seminal vesicles, and prostate gland. This quiz covers their structure, function, and role during ejaculation. Perfect for students studying human anatomy.

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