UNIT B (REPRODUCTION AND DEVELOPMENT) Flashcards
Testes
The male gonads, or primary reproductive organs; male sex hormones and sperm are produced in the testes.
Scrotum
The sac that contains the testes. The temperature in the scrotum is a few degrees cooler than that of the abdominal cavity. The cooler temperatures are important, since sperm will not develop at body temperature. Should the testes fail to descend into the scrotum, the male will not be able to produce viable sperm. This makes the male sterile.
Vas Deferens
Tube that conducts sperm toward the urethra.
Ejaculatory Duct
A tubule formed at the union of the vasa deferentia
and the seminal vesicle ducts and opening into the urethra.
Semen
A secretion of the male reproductive organs
that is composed of sperm and fluids.
Seminal Fluid
The fluid part of semen, which is secreted by three glands.
What contracts during ejaculation?
The vasa deferentia, seminal vesicles, ejaculatory duct, and prostate gland contract, forcing the semen to the base of the penis.
Seminal Vesicle
Structure that contributes to the seminal fluid (semen), a secretion that contains fructose and prostaglandins. Fructose provides a source of energy for the sperm cell and prostaglandins act as a chemical signal in the female system, triggering the rhythmic contraction of smooth muscle and assisting the movement of sperm cells toward the egg.
Prostate Gland
Structure that contributes to the seminal fluid (semen), a secretion containing alkaline buffers that protect sperm cells from the acidic environment of the vagina.
Cowper’s (bulbourethral glands)
Structure that contributes a mucus rich fluid to the seminal fluid (semen).
Ejaculation Order
Seminiferous tubules
Epidydimus
Vas deferens (ductus deferens)
Ejaculatory duct
Nothing
Urethra
Penis
Spermatogenesis Order
Seminiferous tubules: Immature sperm cells divide and differentiate. The site of spermatogenesis.
Spermatogonia: The seminiferous tubules are lined with sperm-producing cells called spermatogonia.
Spermatogonia divide to form Spermacytes
Spermacytes differentiate into Spermatids (23 chromosomes)
Sertoli Cells (Within Seminiferous Tubules)
Nourish the developing sperm cells until they are mature. Produce FSH.
Epididymis
Where sperm cells mature and are stored.
Sperm Order
From each testis, epididymis, ductus deferens, ejaculatory duct, penis.
Acrosome
Sperm have a reduced amount of cytoplasm to help them move fast. Can also be a problem. The cap found on sperm cells, containing enzymes that permit the sperm cell to move through the outer layers that surround the egg.
Middle Piece
Contains mitochondria, energy for the movement of the tail
Tail
Propels the sperm with lashing movement.
Urethra
Carries semen during ejaculation, carries urine from the bladder to the exterior of the body
Primary Sexual Characteristics
Primary sexual characteristics are directly involved in reproduction and are present at birth.
Secondary Sexual Characteristics
External features of an organism that are indicative of its gender (male or female), but are not the reproductive organs themselves.
Distinguishing features, males
Y Chromosome carries the testis-determining factor (TDF) gene to have male sex hormones (androgens). Testes first develop in abdominal cavity and during the 3rd month begin to descend toward scrotum.
Testosterone
Male sex hormone produced by the interstitial cells of
the testes. Stimulates the maturation of the testes and penis and also spermatogenesis. Facial and body hair; the growth of the larynx, which causes the lowering of the voice, the strengthening of muscles. In addition, testosterone increases the secretion of body oils The increased oil production can also create body odour. Testosterone levels are also associated with sex drive and more aggressive behaviour.
Interstitial Cells (Leydig Cells)
Found between the seminiferous tubules within the testes and secrete testosterone.