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PowerPoint ® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PART A 16 The Reproductive System
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reproductive System Purpose is to promote survival of the species Gonads—primary sex organs Testes in males Ovaries in females Gonads produce gametes (sex cells) and secrete hormones Sperm—male gametes Ova (eggs)—female gametes
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Overview Testes Duct system Epididymis Ductus (vas) deferens Urethra
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Overview Accessory organs Seminal vesicles Prostate Bulbourethral glands External genitalia Penis Scrotum
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Figure 16.2a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Figure 16.2b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Function Exocrine- sperm producing function Endocrine- testosterone producing function Suspended in pouch called the scrotum Contains testes and epididymis Divided by a septum Keeps sperm 3 degrees Celsius below body temperature Subject to traumatic injury
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Coverings of the testes Tunica albuginea—capsule that surrounds each testis Septa—extensions of the capsule that extend into the testis and divide it into lobules
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Figure 16.1
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Each lobule contains one to four seminiferous tubules Tightly coiled structures Function as sperm-forming factories Empty sperm into the rete testis (first part of the duct system) Sperm travels through the rete testis to the epididymis Interstitial cells in the seminiferous tubules produce androgens such as testosterone
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Figure 16.1
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Duct System Epididymis Ductus (vas) deferens Urethra
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Epididymis Comma-shaped, tightly coiled tube Found on the superior part of the testis and along the posterior lateral side Functions to mature and store sperm cells (at least 20 days) during this time, they mature and gain the ability to swim Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Epididymis Figure 16.1
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Ductus Deferens (Vas Deferens) Carries sperm from the epididymis to the ejaculatory duct Passes through the inguinal canal and over the bladder Moves sperm by peristalsis Spermatic cord—ductus deferens, blood vessels, and nerves in a connective tissue sheath
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Ductus Deferens (Vas Deferens) Figure 16.1
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Ductus Deferens (Vas Deferens) Ends in the ejaculatory duct which unites with the urethra Expanded end is called the ampulla Ejaculation—smooth muscle in the walls of the ductus deferens create peristaltic waves to squeeze sperm forward Vasectomy—cutting of the ductus deferens at the level of the testes to prevent transportation of sperm
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Urethra Extends from the base of the urinary bladder to the tip of the penis Carries both urine and sperm, but not at same time Sperm enters from the ejaculatory duct and the bladder sphincter constricts
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Urethra Regions of the urethra Prostatic urethra—surrounded by prostate Membranous urethra—from prostatic urethra to penis Spongy (penile) urethra—runs the length of the penis
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Parts of the Urethra
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Urethra Figure 16.2b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Seminal vesicles Prostate Bulbourethral glands
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Figure 16.2b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Seminal Vesicles Located at the base of the bladder Produces a thick, yellowish secretion (60% of semen) Fructose (sugar) Vitamin C Prostaglandins Other substances that nourish and activate sperm
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Figure 16.2b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Prostate Doughnut shaped gland Encircles the upper part of the urethra Secretes a milky fluid Helps to activate sperm Enters the urethra through several small ducts
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Prostate Figure 16.2a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Prostate Gland Hypertrophy of Prostate Very common Makes urination difficult Leads to bladder and kidney infections Prostatitis Inflammation of the prostate Single most common reason for a man to consult a urologist
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Prostate Gland Prostatic Cancer Third most prevalent cancer Most common cancer in men Early detection is critical PSA test
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Bulbourethral Glands Figure 16.2a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Bulbourethral Glands Pea-sized gland inferior to the prostate Produces a thick, clear mucus Cleanses the urethra of acidic urine Serves as a lubricant during sexual intercourse Secreted into the penile urethra
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Semen Mixture of sperm and accessory gland secretions Advantages of accessory gland secretions Fructose provides energy for sperm cells Alkalinity of semen helps neutralize the acidic environment of vagina Semen inhibits bacterial multiplication Elements of semen enhance sperm motility Amount of ejaculation is about 1 tsp.
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Infertility Can be caused by obstruction of the duct system Hormonal imbalances Environmental estrogens Pesticides Excessive alcohol Antibodies made by some men against their own sperm
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Infertility First step in treatment is semen analysis Sperm count Need 20 million per mililiter Motility Morphology (shape and maturity) Semen volume Ph Fructose content
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Infertility Infertility- abnormally low ability to produce Sterility- complete inability to reproduce Oligospermia- decreased sperm count Oligospermia can be caused by Infection Fever Radiation Malnutrition High temperature in testes
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Scrotum Penis
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.2a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Scrotum Divided sac of skin outside the abdomen Maintains testes at 3°C lower than normal body temperature to protect sperm viability
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Penis Delivers sperm into the female reproductive tract Regions of the penis Shaft Glans penis (enlarged tip) Prepuce (foreskin) Folded cuff of skin around proximal end Often removed by circumcision
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.2a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Internally there are three areas of spongy erectile tissue around the urethra Erections occur when this erectile tissue fills with blood during sexual excitement
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.1
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Production of sperm cells Begins at puberty and continues throughout life Occurs in the seminiferous tubules
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3 (1 of 2)
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3 (2 of 2)
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty Follicle-stimulating hormone (FSH) modifies spermatogonia division One cell produced is a stem cell, called a type A daughter cell The other cell produced becomes a primary spermatocyte, called a type B daughter cell
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Primary spermatocytes undergo meiosis One primary spermatocyte produces four haploid spermatids Spermatids—23 chromosomes (half as much material as other body cells)
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Human Life Cycle Union of a sperm (23 chromosomes) with an egg (23 chromosomes) creates a zygote (2n or 46 chromosomes)
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Human Life Cycle Figure 16.4
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermiogenesis Late spermatids are produced with distinct regions Head Midpiece Tail Sperm cells result after maturing of spermatids Spermatogenesis (entire process, including spermiogenesis) takes 64 to 72 days
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Sperm Figure 16.5b
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Sperm Figure 16.5a
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of a Mature Sperm Cell The only human flagellated cell Head Contains DNA Acrosome—“helmet” on the nucleus, similar to a large lysosome Breaks down and releases enzymes to help the sperm penetrate an egg Midpiece Wrapped by mitochondria for ATP generation
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Threats to spermatogenesis Some common antibiotics can alter sperm production Radiation, lead, certain pesticides, marijuana, tobacco, and excessive alcohol can cause production of abnormal sperm Two- headed sperm or multi-tailed sperm
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testosterone Production The most important hormone of the testes Produced in interstitial cells During puberty, luteinizing hormone (LH) activate the interstitial cells In turn, testosterone is produced
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testosterone Production Functions of testosterone Stimulates reproductive organ development Underlies sex drive Causes secondary sex characteristics Deepening of voice Increased hair growth Enlargement of skeletal muscles Thickening of bones Helps close epiphyseal plate
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Hormonal Control of the Testis Figure 16.6
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testosterone Abnormalities If testosterone is not produced: Secondary sexual characteristics don’t appear Reproductive organs remain childlike, called sexual infantilism Effects of castration Interstitial cells do not produce testosterone Results in decrease in size and function of reproductive organs and a decreased sex drive Sterility occurs because testosterone needed for final stages of sperm production
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Disease Cryptorchidism Undescended testes Usually descend two months prior to birth Early treatment needed to prevent permanent sterility Testicular Cancer Most common between ages 25-35 Genetic predisposition
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Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Disease Impotence Inability to achieve an erection Commonly caused by anxiety or stress Temporarily caused by drugs or alcohol Can have other medical causes Inguinal Hernia Intestines push through a weak area of the abdominal wall and protrudes into the scrotum Can be congenital Present at birth
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