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26 Cards in this Set
- Front
- Back
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Sexual Reproduction |
- The process by which organisms produce offspring by making germ cells called gametes - After the male gamete (sperm cell) unites w/ the female gamete (secondary oocyte)─an event called fertilization─the resulting cells contain one set of chromosomes from each parent |
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The male and female reproductive organs can be grouped by function. |
- The gonads─testes in males, ovaries in females─produce gametes and secrete sex hormones - Various ducts then store and transport them, and accessory sex glands produce substances that protect the gametes and facilitate their movement - Supporting structures, such as penis and uterus, assist the delivery of gametes |
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Gynecology and Urology |
- Gynecology - the specialized branch of medicine concerned w/ the diagnosis and treatment of diseases of the female reproductive system - Urology - The study of the urinary system |
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Urologists and Andrology |
- Urologists - Diagnose and treat diseases and disorders of the male reproductive system - Andrology - Deals w/ male disorders, especially infertility and sexual dysfunction |
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Male Reproductive System Includes: |
- Testes (male gonads) - produce sperm and secrete hormones - A system of ducts (epididymis, ductus deferens, ejaculatory ducts, and urethra) - transports and stores sperm, assists in their maturation, and conveys them to the exterior |
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Male Reproductive System Includes: |
- Accessory sex glands (seminal vesicles, prostate, and bulbourethral glands) - Semen contains sperm plus the secretions provided by accessory sex glands - Several supporting structures: • Penis - delivers sperm into the female reproductive tract • Scrotum - supports the testes |
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The Scrotum 1 |
- The supporting structure for the testes; Consists of loose skin and underlying subcutaneous layer that hangs from the root (attached portion) of the penis - Externally, it looks like a single pouch of skin separated into lateral portions by a median ridge called the raphe |
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The Scrotum 2 |
- Internally, the scrotal septum divides the scrotum into 2 sacs, each containing a single testis - The septum is made up of a subcutaneous layer and muscle tissue called the dartos muscle, which is composed of bundles of smooth muscle fibers |
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The Scrotum 3 |
- Associated w/ each testis in the scrotum is the cremaster muscle, a series of small bands of skeletal muscle that descend as an extension of the internal oblique muscle through the spermatic cord to surround the testes - The location of scrotum and contraction of its muscle fibers regulate the temp. of the testes |
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The Scrotum 4 |
- Normal sperm production requires a temperature of about 2-3ºC below core body temp.; This lowered temperature is maintained w/in the scrotum b/c it is outside the pelvic cavity - Contraction of dartos muscle causes scrotum to become tight, which reduces heat loss; Exposure to warmth reverses these actions |
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The Testes |
- Paired oval glands in the scrotum (5cm long, 2.5cm in diameter); Each testis has a mass of 10-15g - They develop near the kidneys and usually begin their descent into the scrotum through the inguinal canals during the latter half of the 7th month of fetal development |
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Tunica Vaginalis |
- A serous membrane, which is derived from the peritoneum and forms during the descent of the testes, partially covers the testes - A collection of serous fluid in the tunica vaginalis is called a hydrocele; It may be caused by injury to the testes or inflammation of the epididymis |
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Internal to the tunica vaginalis is ______ |
- A white fibrous capsule composed of dense irregular connective tissue, the tunica albuginea - It extends inward, forming septa that divide the testis into a series of internal compartments called lobules |
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Each of the 200-300 lobules contains one to three tightly coiled tubules, ____________ |
- The seminiferous tubules, where sperm are produced (spermatogenesis) - Seminiferous tubules contain 2 types of cells: spermatogenic cells (the sperm-forming cells) and Sertoli cells (several functions in supporting spermatogenesis) |
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Spermatogonia |
- Stems cells that develop from the primordial germ cells that arise from the yolk sac and enter the testes during the 5th week of development - In embryonic testes, prim. germ cells differentiate into spermatogonia, which remains dormant during childhood and actively begin producing sperm at puberty |
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Toward the lumen of the seminiferous tubule, are layers of progressively more mature cells. |
- In order of advancing maturity, these are primary spermatocytes, secondary spermatocytes, spermatids, and sperm cells - After a sperm cell (or spermatozoon) has formed, it is released into the lumen of the seminiferous tubule |
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Embedded among the spermatogenic cells in the seminiferous tubules are large __________ |
- Sertoli cells (or sustentacular cells), which extend from the basement membrane to the lumen of the tubule - Internal to the basement membrane and spermatogonia, tight junctions join neighboring Sertoli cells to one another |
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These junctions form an obstruction known as ____________ |
- The blood-testis-barrier b/c substances must first pass through the Sertoli cells before they can reach the developing sperm - By isolating the developing gametes from the blood, the b-t-b prevents an immune response against the spermatogenic cell's surface antigens, which the immune system recognizes as "foreign" |
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Sertoli cells support and protect developing spermatogenic cells in several ways. |
- They nourish spermatocytes, spermatids, and sperm; phagocytize excess spermatid cytoplasm as development proceeds; and control movements of spermatogenic cells and the release of sperm into the lumen of the seminiferous tubule - Also produce fluid for sperm transport, secrete the hormone inhibin, and regulate the effects of testosterone and FSH |
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In the spaces between adjacent seminiferous tubules are clusters of cells called _________ |
- Leydig (interstitial) cells - These cells secrete testosterone, the most prevalent androgen - Androgen - a hormone that promotes the development of masculine characteristics |
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Spermatogenesis |
- Takes 65-75 days; Begins w/ spermatogonia, which contain the diploid (2n) # of chromosomes - Types of stem cells; when they undergo mitosis, some remain near basement membrane of seminif. tubule in an undifferentiated state to serve as a reservoir of cells for future cells division and subsequent sperm production |
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The rest of the spermatogonia lose contact w/ the basement membrane, squeeze through the tight junctions of the blood-testis barrier, undergo developmental changes, and differentiate into ________________ |
- Primary spermatocytes - Like spermatogonia, they are diploid (2n, 46 chromosomes) - Shortly after it forms, each prim. sperm. replicates its DNA and then meiosis begins |
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The two cells formed by meiosis I are called ____________ |
- Secondary spermatocytes; each has 23 chromosomes, haploid number n - Each chromosome w/in a sec. sperm. is made up of 2 chromatids (2 copies of the DNA) still attached by a centromere |
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The four haploids resulting from meiosis II are called ____________ |
- Spermatids - A single primary spermatocyte therefore produces 4 spermatids via 2 rounds of cell division (meiosis I and II) |
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The final stage of spermatogenesis, _______ |
- Spermiogenesis, is the development of haploid spermatids into sperm - No cell division occurs in spermiogenesis; each spermatid becomes a single sperm cell |
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Finally, sperm are released from their connections to Sertoli cells, an event known as _______________ |
- Spermiation - Sperm then enter the lumen of the seminif. tubule - Fluid secreted by Sertoli cells pushes sperm along their way, toward the ducts of the testes. At this point, sperm are unable to swim |
