Human Reproductive System - 14.3 Flashcards
When is the chromosomal sex or genetic sex determined?
At fertilization
What is the sex chromosome combination for a male?
XY
What is the sex chromosome combination for a female?
XX
How long are male and female embryos anatomically identical?
Until about 7th week of development
When does the development of male sex organs begin?
Before birth
What does the Y chromosome carry in males?
Testis determining factor gene (TDF)
What does TDF do?
Triggers the production of male sex hormones
What is another word for male sex hormones?
Androgens
What does the presence of Androgens cause?
Initiates the development of male sex organs and ducts in the fetus
What is puberty?
Period in which the RS completes its development and becomes fully functional
When do most boys enter puberty?
Between ages 10 and 13 years old
What are the changes that puberty causes?
*Final development of the sex organs
- Final development of the secondary characteristics
What does GnRH cause the anterior pituitary to secrete?
*FSH
*LH
What do FSH and LH cause in males?
Cause the testes to begin producing sperm and to release testosterone
What does FSH cause in males?
- Causes the interstitial cells in the testes to produce sperm
- Causes the cells in the seminiferous tubules to produce inhibin
What does inhibin do?
Acts on the anterior pituitary to inhibit the production of FSH (negative feedback loop)
What happens when FSH levels drop?
Testes release less inhibin
Decrease in inhibin causes the anterior pituitary to secrete more FSH
What does LH cause in males?
Causes the testes to release testosterones - promotes changes in muscle development and the formation of facial hair
What happens when there are high levels of testoserone in the body?
Acts on the anterior pituitary to inhibit the release of LH
What are side affects of antibiotic steroids?
Shrinking testicles, low sperm county, loss of body hair, growth of breasts
What is andropause?
When testosterone levels decline in males (around age 40)
What are symptoms of andropause?
Fatigue, depression, loss of muscle/bone mass. drop in sperm production
When does puberty happen in girls?
Between ages 9 to 13 years old
What do FSH and LH cause in the female RS?
Act on the ovaries to produce the female sex hormone: estrogen and progesterone
What is the pattern in the female reproductive system called?
The menstrual cycle
What does the menstrual cycle ensure?
It ensures that the ovum is released at the same time that the uterus is most receptive to a fertilized egg
How long does the menstrual cycle last?
About 28 days - cycle ends with menstruation and ends with the starts of the next menstruation period
What cycle of the menstrual cycle takes place in the ovaries?
Ovarian cycle
What cycle of the menstrual cycle takes place in the uterus?
The uterine cycle
What controls the the ovarian and uterine cycle?
estrogen and progesterone
What happens when a follicle matures and releases an ovum?
It develops into the corpus luteum
What is the first stage of the ovarian cycle?
The follicular stage
What is the second stage of the ovarian cycle?
The luteal stage
What happens in the follicular stage?
- FSH stimulates follicle to mature
- As follicle develops it secretes progesterone and estrogen
*Rising levels of estrogen in blood acts on the anterior pituitary to to inhibit the release of FSH
*Estrogen triggers hypothalamus to secrete GrNH
*anterior pituitary secretes Lh which triggers ovulation - follicle bursts releasing ovum
What happens in the luteal stage?
*LH causes the follicle to develop into a corpus luteum
- Corpus luteum secretes sone progesterone and some estrogen
- As corpus luteum degenerates there are low levels of sex hormones - anterior pituitary secretes hormones again - cycle starts again
What happens to levels of estrogen and progesterone if ovum is fertilized?
They remain high under stimulus of hCG - released by embryo supporting membranes
What does the continued presence of estrogen and progesterone do?
*Progesterone - maintains the endometrium to support developing follicles
- Estrogen - stops the ovarian cycle so no additional follicles mature
What day does ovulation take place?
Day 14 - halfway through the ovarian cycle
How long does the ovum survive after ovulation?
24 hours
What does the uterine cycle ensure?
That the uterus is prepared to receive and nurture a new life.
Does the uterine cycle begin on the first day of mensturation?
Yes - this day the luteum has degenerated and the sex hormones in the blood are low
What causes a rapid thickening of the endometrium?
The release of progesterone by the corpus luteum
What happens if fertilization does not occur?
- Corpus luteum degenerates
- Level of sex hormones are low
- Endometrium breaks down
- Mensuration begins again
What is the complete end of the menstural cycle called?
Menopause
What is menopause?
When a woman is no longer fertile and is no longer able to produce ova
What are symptoms of menopause?
*Blood vessels alternately constrict and dilate
* Change in mood
* Cholesterol levels rise
*Diminishing bone mass
* Increased uterine, breast, and heart cancer
What can one consider during menopause?
To get hormone replacement therapy (prescription of low levels of estrogen with or without progesterone)
What are the risks of hormone replacement theory?
*Increased coronary heart disease, strokes, and blood clots
*Increase breast cancer and colorectal cancer
*Increased risk of dementia
