lecture 18, the male reproductive system

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19 Terms

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the male and female reproductive system consist of

  1. gonads

    • testes in males and ovaries in females

    • produce gametes

    • egg or sperm

  2. ducts

    • function in the transportation and storage of gametes

    • allows for transport

  3. accessory glands

    • produce secretions that lubricate gamete passageways and support gametes

      • nutrients and buffer

      • need to be able to support the gamete

<ol><li><p>gonads</p><ul><li><p>testes in males and ovaries in females</p></li><li><p>produce gametes</p></li><li><p>egg or sperm</p></li></ul></li><li><p>ducts</p><ul><li><p>function in the transportation and storage of gametes</p></li><li><p>allows for transport</p></li></ul></li><li><p>accessory glands</p><ul><li><p>produce secretions that lubricate gamete passageways and support gametes</p><ul><li><p>nutrients and buffer</p></li><li><p>need to be able to support the gamete</p></li></ul></li></ul></li></ol><p></p>
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the male reproductive system

  • the testes are the male gonads

    • located within a sac-like structured called the scrotum (low temperature)

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the scrotum consists of

  • skin and connective tissue

  • comprised of two layers

    1. the tunica vaginalis

      • the outer covering of the scrotum

      • a serous membrane (peritoneum)

    2. the tunica albuginea

      • comprises the inner capsule of the scrotum

      • extends toward the inside of the testicles dividing into 250-300 lobules (segregates compartments)

      • each lobule contains

        • seminiferous tubules (sperm reproduced, mitotic division)

        • Leydig cells (also called interstitial cells) floating between

<ul><li><p>skin and connective tissue</p></li><li><p>comprised of two layers</p><ol><li><p>the tunica vaginalis</p><ul><li><p>the outer covering of the scrotum</p></li><li><p>a serous membrane (peritoneum)</p></li></ul></li><li><p>the tunica albuginea</p><ul><li><p>comprises the inner capsule of the scrotum</p></li><li><p>extends toward the inside of the testicles dividing into 250-300 lobules (segregates compartments)</p></li><li><p>each lobule contains</p><ul><li><p>seminiferous tubules (sperm reproduced, mitotic division)</p></li><li><p><strong>Leydig cell</strong>s (also called interstitial cells) floating between</p></li></ul></li></ul></li></ol></li></ul><p></p>
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the seminiferous tubules

  • the seminiferous tubules are the site of sperm production

  • sperm are produced by a process called spermatogenesis (just mitosis but with different cell structures)

  • seminiferous tubules from each lobule unite to form the rete testis

    • a net of seminiferous tubules that the sperm must pass through when they exit the testes (all lobules to his one location)

<ul><li><p>the seminiferous tubules are the site of sperm production</p></li><li><p>sperm are produced by a process called <strong>spermatogenesi</strong>s (just mitosis but with different cell structures)</p></li><li><p>seminiferous tubules from each lobule unite to form the rete testis</p><ul><li><p>a net of seminiferous tubules that the sperm must pass through when they exit the testes (all lobules to his one location)</p></li></ul></li></ul><p></p>
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spermatogenesis

  • spermatogonia (2n cells)

    • mitosis

      • photocopying

      • create population of diploid

      • too many chromosome to be sperm

  • 1x primary spermatocyte (2n cell)

    • meiosis I

      • still have double genetic material

      • haploid

  • 2x secondary spermatocyte (n cells)

    • meiosis II

      • segregate sister chromatids

  • 4x spermatid (n cells )

    • spermiogenesis

      • sperm develop and acrosome and a flagellum

      • not mature yet

      • has to be able to swim and break egg membrane

  • 4x spermatozoa (n cells)

    • still haploid

    • mature now and capable of fertilization

  • spermatogenesis produces 4 haploid spermatozoa from 1 diploid primary spermatocyte

<ul><li><p>spermatogonia (2n cells)</p><ul><li><p>mitosis</p><ul><li><p>photocopying</p></li><li><p>create population of diploid</p></li><li><p>too many chromosome to be sperm</p></li></ul></li></ul></li><li><p>1x primary spermatocyte (2n cell)</p><ul><li><p>meiosis I</p><ul><li><p>still have double genetic material </p></li><li><p>haploid</p></li></ul></li></ul></li><li><p>2x secondary spermatocyte (n cells)</p><ul><li><p>meiosis II</p><ul><li><p>segregate sister chromatids</p></li></ul></li></ul></li><li><p>4x spermatid (n cells )</p><ul><li><p>spermiogenesis</p><ul><li><p>sperm develop and acrosome and a flagellum</p></li><li><p>not mature yet</p></li><li><p>has to be able to swim and break egg membrane</p></li></ul></li></ul></li><li><p>4x spermatozoa (n cells)</p><ul><li><p>still haploid</p></li><li><p>mature now and capable of fertilization</p></li></ul></li><li><p><mark data-color="blue" style="background-color: blue; color: inherit">spermatogenesis produces 4 haploid spermatozoa from 1 diploid primary spermatocyte</mark></p></li></ul><p></p>
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histology of the testes: Leydig cells

  • also called the interstitial cells

    • in between everything to help provide support

  • located in the connective tissue that surrounds the seminiferous tubules

  • predominately secrete testosterone

    • endocrine tissue

      • primarily functioning for reproduction

    • testosterone is needed for the development of male sex characteristic and spermatogenesis

      • facial hairs

      • deep voice

    • females don’t have this production of testosterone

<ul><li><p>also called the interstitial cells </p><ul><li><p>in between everything to help provide support</p></li></ul></li><li><p>located in the connective tissue that surrounds the seminiferous tubules</p></li><li><p>predominately secrete testosterone</p><ul><li><p>endocrine tissue</p><ul><li><p>primarily functioning for reproduction</p></li></ul></li><li><p>testosterone is needed for the development of male sex characteristic and spermatogenesis</p><ul><li><p>facial hairs </p></li><li><p>deep voice</p></li></ul></li><li><p>females don’t have this production of testosterone</p></li></ul></li></ul><p></p>
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histology of the testes: seminiferous tubules

  • the walls of the seminiferous tubules contain

    1. germ cells

      • gametes in various stages of development (on the wall)

    2. seratoli cells (sustentacular cell)

      • located between the germ cells

      • extend from the basement membrane to the lumen of the tubule

      • cells contain tight junctions which form the blood-testos barrier

        • protect the sperm from blood components such as alcohol, drugs, etc.

      • support and nourish developing sperm cells

        • “want glucose?” allows them to be well fed

      • regulate sperm production

      • need protein channels to take in what we need

<ul><li><p>the walls of the seminiferous tubules contain</p><ol><li><p>germ cells</p><ul><li><p>gametes in various stages of development (on the wall)</p></li></ul></li><li><p>seratoli cells (sustentacular cell)</p><ul><li><p>located between the germ cells</p></li><li><p>extend from the basement membrane to the lumen of the tubule</p></li><li><p>cells contain tight junctions which form the blood-testos barrier</p><ul><li><p>protect the sperm from blood components such as alcohol, drugs, etc.</p></li></ul></li><li><p>support and nourish developing sperm cells</p><ul><li><p>“want glucose?” allows them to be well fed</p></li></ul></li><li><p>regulate sperm production</p></li><li><p>need protein channels to take in what we need</p></li></ul></li></ol></li></ul><p></p>
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sperm structure

  1. head

    • contains the haploid sperm cell nucleus

      • 23 chromosomes

    • also contains the acrosome (like toolkit)

      • contains enzymes that assist in penetration of the egg during fertilization

        • helps to digest membrane

  2. body

    • the mid-piece of the sperm

    • contains a large number of mitochondira

      • produce large quantities of ATP needed for sperm to swim to the egg

      • swim far so need lots of mitochondria

  3. tail

    • flagellum formed from microtubules (whips to move)

    • propels the sperm forward

      • eukaryotic organism

  • one cell

<ol><li><p>head</p><ul><li><p>contains the haploid sperm cell nucleus</p><ul><li><p>23 chromosomes</p></li></ul></li><li><p>also contains the acrosome (like toolkit)</p><ul><li><p>contains enzymes that assist in penetration of the egg during fertilization </p><ul><li><p>helps to digest membrane</p></li></ul></li></ul></li></ul></li><li><p>body</p><ul><li><p>the mid-piece of the sperm</p></li><li><p>contains a large number of mitochondira</p><ul><li><p>produce large quantities of ATP needed for sperm to swim to the egg</p></li><li><p>swim far so need lots of mitochondria</p></li></ul></li></ul></li><li><p>tail</p><ul><li><p>flagellum formed from microtubules (whips to move)</p></li><li><p>propels the sperm forward</p><ul><li><p>eukaryotic organism</p></li></ul></li></ul></li></ol><ul><li><p>one cell</p></li></ul><p></p>
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ducts for sperm transport

  • once the sperm have formed they move from seminiferous tubules into the rete testis

  • from the rete testis they move into the

    1. epididymis

    2. vas deferens (ductus deferens)

    3. ejaculatory duct

    4. urethra

    5. penis

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epididymis

  • located at the posterior, superior and lateral border of the testis

  • sperm mature here

  • during ejaculation the sperm move into the vas deferens

<ul><li><p>located at the posterior, superior and lateral border of the testis</p></li><li><p>sperm mature here </p></li><li><p>during ejaculation the sperm move into the vas deferens</p></li></ul><p></p>
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vas deferens (ductus deferens)

  • enters into the pelvic cavity (come back in, transit through)

  • loops over the posterior surface of the bladder (up and over)

  • a vasectomy severs and ties the vas deferens in order to prohibit sperm transport

    • sperm continue to be produced but are broken down by macrophages in the epididymis

  • sperm move from the vas deferens into the ejaculatory duct

  • want to make sure defense against urine

<ul><li><p>enters into the pelvic cavity (come back in, transit through)</p></li><li><p>loops over the posterior surface of the bladder (up and over)</p></li><li><p>a vasectomy severs and ties the vas deferens in order to prohibit sperm transport</p><ul><li><p>sperm continue to be produced but are broken down by macrophages in the epididymis</p></li></ul></li><li><p>sperm move from the vas deferens into the ejaculatory duct</p></li><li><p>want to make sure defense against urine</p></li></ul><p></p>
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ejaculatory duct

  • formed from the union of the vas deferens and the duct from the seminal vesicle (produces a component of semen)

<ul><li><p>formed from the union of the vas deferens and the duct from the seminal vesicle (produces a component of semen)</p><p></p></li></ul><p></p>
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urethra

  • functions to transport both sperm and urine

  • contains three segments

    1. the prostatic portion → passes through the prostate gland

    2. the membranous portion → passes through the urogenital diaphragm

    3. the penile portion → passes through the penis

  • opens into the glans penis

<ul><li><p>functions to transport both sperm and urine</p></li><li><p>contains three segments</p><ol><li><p>the prostatic portion → passes through the prostate gland</p></li><li><p>the membranous portion → passes through the urogenital diaphragm</p></li><li><p>the penile portion → passes through the penis</p></li></ol></li><li><p>opens into the glans penis</p></li></ul><p></p>
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penis

  • contains a root, a shaft, and an enlarged tip called glans penis

  • erectile tissue consists of

    • 2 corpora cavernosa and 1 corpus spongiosum which contains the glans penis (enlarged tip)

  • longest of sections

<ul><li><p>contains a root, a shaft, and an enlarged tip called glans penis</p></li><li><p>erectile tissue consists of</p><ul><li><p>2 corpora cavernosa and 1 corpus spongiosum which contains the glans penis (enlarged tip)</p></li></ul></li><li><p>longest of sections </p></li></ul><p></p>
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accessory glands

  • 3 accessory glands produce secretions that combine with sperm to five semen

    1. seminal vesicles

    2. prostate glands

    3. bulbourethral gland

<ul><li><p>3 accessory glands produce secretions that combine with sperm to five semen</p><ol><li><p>seminal vesicles</p></li><li><p>prostate glands</p></li><li><p>bulbourethral gland</p></li></ol></li></ul><p></p>
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seminal vesicles

  • paired glands found at the base of the urinary bladder

  • produces seminal fluid → alkaline fluid that protects sperm from the acidic environment of the vagina

  • also contains fructose used as energy source for the sperm

  • accounts for 60% of total semen volume

<ul><li><p>paired glands found at the base of the urinary bladder</p></li><li><p>produces <strong>seminal fluid</strong> → alkaline fluid that protects sperm from the acidic environment of the vagina</p></li><li><p>also contains<strong> fructose</strong> used as energy source for the sperm</p></li><li><p>accounts for 60% of total semen volume</p></li></ul><p></p>
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prostate gland

  • unpaired gland the encircles the urethra (wraps around)

  • produces a milky, slightly acidic fluid

    • neutralized by alkaline fluid

  • also contains enzymes and nutrients needed to feed and activate sperm (aggressive swimming)

  • accounts for 30% of total semen volume

<ul><li><p>unpaired gland the encircles the urethra (wraps around)</p></li><li><p>produces a milky, slightly acidic fluid</p><ul><li><p>neutralized by alkaline fluid</p></li></ul></li><li><p>also contains enzymes and nutrients needed to feed and activate sperm (aggressive swimming)</p></li><li><p>accounts for 30% of total semen volume</p><p></p></li></ul><p></p>
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bulbourethral gland

  • a paired gland located in the urogenital diaphragm

  • produces a fluid that neutralized urine present in the urethra (bad stuff stored in urine)

  • accounts for 5% of total semen volume (last part to leave)

<ul><li><p>a paired gland located in the urogenital diaphragm</p></li><li><p>produces a fluid that neutralized urine present in the urethra (bad stuff stored in urine)</p></li><li><p>accounts for 5% of total semen volume (last part to leave)</p></li></ul><p></p>
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semen

  • consists of sperm, testicular fluid, and secretions from the prostate gland, the bulbourethral glands, and the seminal vesicles

  • semen is slightly alkaline → pH 7.3-7.7

    • modest, close to neutral

  • acts as a transport medium that also nourishes and protects the sperm present in semen

    • “ocean water” so they can move

  • 2.5-5.0mL of semen are released upon ejaculation (frequency, last time you cum)

  • there are 50-150 million sperm per mL of semen

    • infertility becomes an issue when there are fewer than 20 miion sperm per mL of semen