Reproductive system Flashcards
Which hormone is released from the anterior pituitary gland at the beginning of the cycle?
FSH (follicle stimulating hormone)<— stimulates follicle to develop.
On what organ does FSH act upon?
ovaries
What event does FSH hormone trigger?
follicle growth and maturation
During the follicular phase the thecal cells of the developing follicle secrete estrogen. What effect do rising estrogen levels have on the endometrium of the uterus and the anterior pituitary gland?
Building up of the functional layer.
On what day of the ovarian cycle does ovulation usually occur?
14
What triggers ovulation?
LH (luteinising hormone)
After ovulation what happens to the ruptured follicle?
After ovulation, the released egg travels along the Fallopian tubes, where fertilisation by sperm can occur. The ruptured follicle left behind after ovulation forms the corpus luteum which secretes progesterone, the hormone responsible for the rise in body basal temperature (BBT) that signals ovulation. It also suppresses the ripening of further follicles, induces closing of the cervix and the thickening of cervical mucus. The corpus luteum is then degraded with the onset of menstruation.
Which three hormones does the corpus luteum secrete and what effect do these hormones have on the hypothalamus and anterior pituitary?
Progesterone
Estrogen
Inhabin - provides negative feedback to the anterior pituitary to reduce the production of LH and FSH.
Explain the menstrual cycle
- The hypothalamus produces GnRH early in the cycle. This is used to communicate with the pituitary gland and start production of FSH.
- In response to GnRH, the pituitary gland begins production of FSH. This hormone stimulates the ovaries and causes an ovarian follicle to begin to mature.
- As the follicle matures, FSH levels decrease. The maturing follicle produces estrogen which feeds back to the hypothalamus. The GnRH production changes frequency and causes the pituitary gland to begin producing lutenizing hormone.
- A surge in LH levels causes the mature follicle to release its egg. This event is known as ovulation. The egg proceeds down the fallopian tube awaiting possible fertilization.
- The portion of the follicle that remains after ovulation is the corpus luteum. It produces progesterone which feeds back to the brain to reduce LH levels.
- Progesterone also causes the uterus to prepare for possible implantation.
- Unless pregnancy results and HCG is produced, both progesterone and estrogen levels fall as the corpus luteum degenerates. This causes the body to prepare for menstruation and the start of another cycle if pregnancy does not result.
What happens to the corpus luteum if the oocyte is not fertilized?
Becomes the corpus albacans and dies
What happens to the corpus luteum if the oocyte has been fertilized?
It remains and HCG maintains the corpus luteum in order for it to produce progesterone
Explain the role of progesterone in the first 3 months of pregnancy.
Progesterone increases blood supply to the uterus and the lining thickens with additional fluid and nutrients.
Essential for implantation of a developing embryo.
Progesterone levels stop the proliferation of endometrial cells.
Progesterone matures the stroma and glands, turning them into cells that can nourish and support a developing embryo.
If an embryo doesn’t implant, the corpus luteum stops producing progesterone and begins to degenerate after around 14 days.
A woman undergoing IVF treatment is told by her doctor that she must use progesterone pessaries for the first 3 months after the blastocyst is transferred to her uterus. Why must this woman use artificial source of progesterone during the first 3 months of pregnancy?
Because she doesn’t have a corpus luteum to produce progesterone to stop the deterioration of the uterus lining.
A woman undergoing IVF treatment is told by her doctor that she must use progesterone pessaries for the first 3 months after the blastocyst is transferred to her uterus. What might happen to the blastocyst if progesterone passaries were not used?
The blastocyst would be expelled during the next period.
The blastocyst wont implant
What process does testosterone facilitate via its action on sustenocytes (Sertoli, Nurse or sustentacular cells)?
meiosis –> spermatogenisis
What are some actions of testosterone?
- Maintain sex organs
- hair growth
- deep voice
- stimulate libido
- muscle growth
What hormone is produced and secreted by sustenocytes?
Inhibin
What is the action of Inhibin in males?
Negative feedback on FSH and effect on hypothalamus (GnRH)
What fluid is produced and secreted by sustenocytes and what is the function of this fluid?
Testicular fluid
To transport cause they cant swim and also to nourish
Sarah and Gerry had been trying to get pregnant for over 12 months, Upon further investigation, Gerry was diagnosed with Kallmann syndrome, A disorder characterised by low GnRH, LH, FSH and testosterone levels. Given the hormonal evaluation, what endocrine organ do you think Kallmann syndrome affects?
hypothalamus
Sarah and Gerry had been trying to get pregnant for over 12 months, Upon further investigation, Gerry was diagnosed with Kallmann syndrome, A disorder characterised by low GnRH, LH, FSH and testosterone levels. How will this hormone profile affect fertility?
It will cause a low sperm count because testosterone is needed to make sperm
Sarah and Gerry had been trying to get pregnant for over 12 months, Upon further investigation, Gerry was diagnosed with Kallmann syndrome, A disorder characterised by low GnRH, LH, FSH and testosterone levels. What could be done to overcome the infertility issues in the couple?
Give Gerry doses of FSH and LH
What hormone does a pregnancy test test for?
HCG
What regulates the temperature of the testes?
There are two muscles that regulate temperature: Dartos muscle (smooth muscle) - contracted makes scrotum wrinkled and thick Cremaster muscle (skeletal muscle) - contracted brings testes and scrotum closer to body.
Both muscles contract in cold and relax in warm temperatures
