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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Overview  Testes  Duct system  Epididymis  Ductus (vas) deferens  Urethra

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Overview  Accessory organs  Seminal vesicles  Prostate  Bulbourethral glands  External genitalia  Penis  Scrotum

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Figure 16.2a

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Male Reproductive System Figure 16.2b

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Figure 16.1

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Testes Figure 16.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Duct System  Epididymis  Ductus (vas) deferens  Urethra

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Epididymis Figure 16.1

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Ductus Deferens (Vas Deferens) Figure 16.1

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

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Parts of the Urethra

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Urethra Figure 16.2b

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs  Seminal vesicles  Prostate  Bulbourethral glands

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Figure 16.2b

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Accessory Organs Figure 16.2b

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Prostate Figure 16.2a

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Bulbourethral Glands Figure 16.2a

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

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.

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

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia  Scrotum  Penis

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.2a

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.2a

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings External Genitalia Figure 16.1

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3 (1 of 2)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spermatogenesis Figure 16.3 (2 of 2)

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

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)

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)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Human Life Cycle Figure 16.4

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Sperm Figure 16.5b

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Sperm Figure 16.5a

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

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

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

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

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Hormonal Control of the Testis Figure 16.6

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

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  Genetic predisposition

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