Reproduction and Development Flashcards
Describe testes
-Male gonads which produce male sex hormones and sperm.
-Held outside the body in the scrotum.
-Composed of: seminiferous tubules: location of spermatogenesis, and interstitial cells: secrete testosterone.
Describe the scrotum
-Pouch of skin located below the pelvic region.
-Sperm will not develop at body temp (37) - scrotum is at a lower temp (35).
-The testes do not re-enter because a thin membrane forms over the canal where the testes descend.
Describe the inguinal hernia
-Rupture of the thin membrane causing a segment of the small intestine to be forced in the scrotum.
What is the vas deferens (ductus deferens)?
-Tubes that conduct sperm towards the urethra.
-Any blockage will prevent the movement of sperm from the testes to the external environment.
-Vasectomy: Vasectomy deferens cut/tied -> if male doesn’t want kids -> surgery voluntary -> sperm still gets made.
What is the ejaculatory duct?
-Regulates the movement of sperm and fluids into the urethra.
What is the urethra?
-Common chamber for expelling semen and urine.
-A sphincter regulates the voiding of urine from the bladder.
-Both functions work independently but are never open at the same time.
What happens during sexual excitement with the penis?
-During sexual excitement, the erectile tissue within the penis fills with blood.
-Stimulation of the parasympathetic nerve causes the arteries to dilate thereby increasing blood flow.
-As blood flows towards the penis, the veins carrying blood away become blocked.
What is impotency?
-Caused by damages to the parasympathetic system.
-Other causes include hormone imbalance and stress.
-Difficulty achieving or sustaining an erection.
Describe sperm
-Sperm is built for speed.
-Only use a small amount of cytoplasm to function.
-High concentration of mitochondria near flagellum (tail).
-Nucleus that holds DNA in the head.
-At body temp only last 24-72 hours.
What are Sertoli cells?
-Support cells which nourished the sperm cell.
What are acrosome?
-Filled with enzymes that dissolve the outer coating of the egg.
What are seminiferous tubules?
-Coiled ducts found within testes.
-Lined with sperm producing cells.
What is epididymis?
-Located along the posterior border of the testis.
-Sperm are stored here and mature.
-Develop flagellum and begin swimming motions within 4 days.
What is seminal fluid
-Sperm are mixed with fluid along the ductus deferens.
What are the fluids that help the sperm get to the female and where do they come from?
-Seminal vesicles: secrets —> fructose: provides a source of energy
-Prostate gland secrets —> buffers (alkaline fluid): protects sperm from acidic vagina
-Cowpers gland secrets —> pre-ejaculate fluid: fluids may protect the sperm from acids found in the urethra from urine, assist sperm movement.
What are the prostag Landins?
-Triggers rhythmic contraction of the smooth muscle in the uterus.
What is TDF?
-Y chromosome contains the TDF (testes determining factor) gene.
-Triggers the production of male sex hormones.
What is GnRH?
-Gonadotropin releasing hormone.
-Puberty begins when the hypothalamus increases its production of GnRH.
What are anabolic steroids?
-Mimic the action of testosterone.
-Disrupt the reproductive hormone feedback systems.
-Side effects: shrinking testicles, low sperm count, loss of body hair, development of breasts.
What is andropause?
-The gradual decline after age 40 for males where they become infertile.
-Prostate gland often grows leading to some discomfort.
Describe the ovary
-Responsible for production of ova and female sex hormones.
-During development, the ovaries migrate but remain in the pelvic region.
-Egg cells are called ovum (singular) and ova (plural).
-Composed of fibrous connective tissue and follicles.
-Site of oogenis (production of ova).
Describe the fallopian tubes (oviduct)
-Passageway through which an ovum moves from the ovary to the uterus or womb.
-Egg enters through the ends called fimriae and moves through via cilia (on fallopian tube walls).
-Fertilization occurs here.
-Ovum deteriorates within 48 hours.
Describe the uterus
-The female organ in which the fertilized ovum normally become embedded and in which the embryo and fetus develop.
What is the myometreum?
-Muscular outer lining of the uterus, provided support for the embryo and helps in uterine contractions.
What is the endometrium?
-Glandular inner lining (contains blood vessels).
-Provides nourishment for the embryo.
-Shed during menstruation.
What is the cervix?
-Separates the vagina from the uterus.
-Circular band of muscle.
-Dilates during birth to allow the fetus to enter the birth canal.
-During a Pap smear, physicians use a swab to collect epithelial cells from the cervix to look for abnormalities.
Describe the vagina (vaginal canal)
-Connects the uterus with the outer environment.
-Also serves as the birth canal.
-Highly acidic in an attempt to be inhospitable to microbes.
What is menopause?
-Marks the termination of the female reproductive years.
What is the menstrual cycle?
-Approximately every 28 days from puberty until middle age.
What are follicles?
-Structures in the ovary that contain the egg and secret estrogen.
-Composed of two cell types: primary oocyte and granulosa cells.
-400 000 follicles are present at puberty but only 1000 follicles develop.
-In an ovarian cycle, one follicle will mature, release an ovum, and form into a corpus luteum.
-Genetic defects in children produced by older females has been suggested to be due to the age of the follicles.
What is the follicular stage in the ovarian cycle?
-Development of follicle leading to ovulation.
-Begins with an increase in FSH.
-Maturing follicles release estrogen (+some progesterone).
-Estrogen acts on the anterior pituitary to inhibit the release of FSH but positively.
Feedbacks on the hypothalamus triggering a sudden release of GnRH.
LH production increases triggering ovulation.
What is the luteal stage of the ovarian cycle?
-Development of the corpus luteum.
-After ovulation, LH causes the follicle to form the corpus luteum.
-Secrets progesterone (+some estrogen) which inhibits release of FSH/LH.
-As the corpus luteum degenerates, secretion of estrogen and progesterone slows.
-FSH levels begin to rise and the cycle begins again.
-An implanted embryo (fertilized egg) secrets hCG which causes the corpus luteum to maintain high levels of estrogen and progesterone.
What does LH do?
-Production of sex hormones (testosterone, estrogen and progesterone).
-Stimulates ovulation.
What does FSH do?
-Sperm and egg production.
What does estrogen do?
-Development of secondary sex characteristics.
What does progesterone do?
-Helps prepare the endometrium to receive and support a fertilized egg.
-If pregnancy occurs, it continues to support the uterine lining to prevent shedding (menstruation).
-Inhibits uterine contractions during pregnancy to prevent uterus from contracting early.
-Also inhibits ovulation contractions.
When does endometrium development stop?
-Stops at a menopause, or when the corpus luteum degenerates.
Where is testosterone released?
-Primarily released by cells in the insterial tissue, in the testes.
