Module 19: The Reproductive System Flashcards
Testes
Each testis has 250 - 300 wedge-shaped compartments called lobules
Each lobule contains 1 to 4 tightly-coiled seminiferous tubules (“sperm factories”)
Leydig cells
In clusters between seminiferous tubules
Produce testosterone
Epididymis
Site for the maturation of the sperm cells
Sperm cells mature in 18 hours to 10 days
Stores sperm for up to two months
Vas (ductus) deferens
Direct continuation of the epididymis
Passes out of the scrotum and up into the abdominal cavity in the region of the urinary bladder
Contains three layers of muscle in its wall that uses peristalsis to move sperm through during ejaculation
Seminal vesicles
Two hollow glands found on the posterior surface of the urinary bladder
Each has a duct that joins with each vas deferens
Produce slightly alkaline viscous secretions, rich in nutrients (fructose), that are added to sperm to form semen to nourish the sperm
Ejaculatory ducts
Formed by the union of the vas deferens and the seminal vesicle duct
Open into the first part of the urethra
Prostate gland
A single, doughnut-shaped gland, about the size of a chestnut
Surrounds the urethra at the point where the ejaculatory ducts are formed
Adds alkaline secretions to semen - helps neutralize acidic vaginal fluid
High acid phosphatase gives “milky appearance”
Enhances motility as it acts as a liquefying agent
Bulbourethral glands (Cowper’s glands)
Paired glands, about the size of a pea, lying on each side of the urethra
Add alkaline secretions to semen that neutralizes acid in the urethra
Secretions help to lubricate urethra and end of the penis
Pathway of sperm
Seminiferous tubules Epididymis (sperm stored until ejaculated) Vas deferens Ejaculatory ducts Urethra
Testosterone
Synthesized from cholesterol in the testes
Responsible for the normal growth, development and function of the male sex organs, including sperm cell production
Voice change, beard growth, muscle development
Increases protein synthesis and decreases protein catabolism
Stimulates the descent of testes before birth
Infundibulum
Funnel-like end of the uterine tube
Fimbriae
Finger-like projections that sweep the ova into the uterine tube
Estrogens
Produced mainly by the follicular cells that surround a maturing ovum prior to ovulation
Promote the growth of the female reproductive organs
Induce ovulation
Cause thickening of uterine lining
Development of breasts, deposition of fat in thighs and buttocks, development of smooth, soft-textured skin
Progesterone
“Pregnancy hormone”
Secreted by the mature follicle (corpus luteum) after it has ruptured during ovulation
Prepares the lining of the endometrium of the uterus for implantation of a fertilized ovum
Inhibits ovulation during pregnancy
Causes enlargement of the mammary glands during pregnancy
Menstrual phase
First five days
Upon withdrawal of hormonal support from the endometrium, the lining that had developed during the preovulatory and progestational phases is shed
Proliferative phase
The next 10 days
Also called the preovulatory phase
Time between menstruation and ovulation
Several ova (about 20) and their surrounding follicles start to develop under the influence of FSH secreted by the anterior pituitary
Only one ovum and its follicle continue to develop the others are repressed
The cells of the developing follicle start to secrete estrogens, inhibition of GnRH, inhibition of FSH, endometrium increases in thickness
About 24 hours before ovulation, LH increases and induces ovulation, the cervical mucus becomes thin, stringy and crystalline, which allows sperm cells to pass through easier
Secretory phase
Days 15-28
Also called the progestational phase
Ovulation occurs between the proliferative and the secretory phase
Mature follicle ruptures
Ovum is released and starts to travel to the uterus via the
fallopian tube
Ruptured follicle stays in the ovary where it increases in size under the influence of LH from the anterior pituitary, to become the corpus luteum
Corpus luteum secretes some estrogens, but mainly progesterone - endometrium thickens and becomes more vascular
If fertilization does not occur, the corpus luteum begins to degenerate
Progesterone and estrogens decrease, GnRH increases
If fertilization does occur the corpus luteum is maintained
