Flashcards in Reproductive system Deck (44):
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?
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?
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?
Inhabin - provides negative feedback to the anterior pituitary to reduce the production of LH and FSH.
Explain the menstrual cycle
1.The hypothalamus produces GnRH early in the cycle. This is used to communicate with the pituitary gland and start production of FSH.
2.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.
3.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.
4.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.
5.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.
6.Progesterone also causes the uterus to prepare for possible implantation.
7.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?
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?
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?
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?
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
What part of the nervous system controls penile erections and what substance do they release to make this happen?
Parasympathetic nervous system
Name the structures sperm pass through before being outside the body.
- Seminiferous tubes
- Ductus deferens
- Seminal vesicles (attached to the ductus deferens releases viscous fluid)
- Ejaculatory duct
- Prostate produces fluid
- Bulbourethral glands produces fluid
Which structure of the male reproductive system release fluid into semen and what percentage to they release?
- Seminal vesicles releases viscous fluid 60%
- Prostate produces fluid 30%
- Bulbourethral secretions 5%
- Epididymal secretions 5%
What Is the name of immature non motile sperm?
Sperm arrive at the epididymis as immature, non motile spermatozoa. How long do they take to move through the epididymis?
20 days before they can swim
Where are immature sperm stored?
tail of the epididymis for several months
When a male has a vasectomy which tube do they cut?
The ductus deferens
What happens when seamen ejaculated?
- bladder sphincter muscle constricts
- reproductive ducts and accessory glands contract
- bulbospongiosum muscle contracts
1. The hypothalamus releases gonadotropin-releasing hormone (GnRH)
2. GnRH signals the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary
3. FSH stimulates spermatogenesis by ensuring that cells involved in sperm production are receptive to testosterone
4. LH signals to Leydig cells to produce testosterone
5. Increased testosterone levels negatively feeds back to inhibit GnRH and FSH/LH release
6. Inhibin is also produced during spermatogenesis and has negative feedback effects on FSH and GnRH
In the absence of GnRH, LH and FSH, the testes will atrophy and
sperm and testosterone production cease
What are the three layers of the uterine wall?
¤ Perimetrium - outermost layer
¤ Myometrium - bulky, muscular middle layer contracts to expel baby
¤ Endometrium - mucosal inner layer
- allows for implantation of the fertilised egg
- is made up of 2 layers:
- Functional layer: cyclic changes
- Basal layer: Unresponsive to ovarian
Which cells of the male reproductive system produces testosterone?
Leydig cells (interstitial cells)
What are the two phases of the ovarian cycle?
What are the steps that occur during the two stages of the ovarian cycle?
1- Primordial follicle to primary follicle
- Follicular cell grows
- Oocyte enlarges
- Stimulated by FSH
2- Primary follicle to secondary follicle
- Follicular cells from double layer and take on name "granulosa cells"
- Granulosa cells send signals for oocyte growth
3- Secondary follicle to late secondary follicle
- A layer of cells surround the follicle called the theca
- Granulosa and theca cells produce estrogens
- Oocyte produces thick glycoprotein layer called zona pellucida
4- Late secondary follicle to vesicular follicle
- Fluid accumulates to form the antrum and separates the oocyte from granulosa cells
- Follicle reaches 2.5cm and bulges out of the ovary
1- Corpus Luteum in formed
- Ruptured follicle takes on new role of corpus lutem
- CL secretes progesterone and some estrogen
2a- Corpus Luteum degenerates
- In absence of fertilisation the CL degenerates into scar tissue and endometrial sloughing occurs
2b- Corpus Luteum can persist
- If oocyte is fertilised, the corpus luteum can persist for 3 months, until the placenta in ready to take over hormone production
3- The cycle starts again
- Decreased levels of progesterone and estrogen (due to degraded CL) stimulates the release of GnRH and thus, LH and FSH ... back to the follicular stage
What are the phases of the uterine cycle or the mistral cycle and what occurs in each phase?
Day 1-5: Menstrual phase (menses)
¤ shedding of the functional layer of the endometrium
n estrogen and progesterone are low
n dysmenorrhoea – painful menstruation
Day 6-14: Proliferative (pre-ovulatory) phase
¤ rebuilding of the functional layer of the endometrium
¤ cervical mucous becomes less viscous and sticky – allow entry of sperm
n stimulated and sustained by ovarian estrogens
n ovulation occurs at the end of this phase
Day 15-28: Secretory (post-ovulatory) phase
¤ begins immediately after ovulation
¤ endometrium prepares for implantation (glands enlarge, arteries elongate, nutritious glycogen is secreted)
n stimulated by progesterone and estrogens from corpus luteum
n if fertilisation does not occur, CL degenerates. Low progesterone leads to spasm of arteries, and low oxygen levels – blood enters fragmented capillaries and menses begins again
What do estrogen and progesterone work together to do?
¤ regulate uterine cycle and changes in cervical mucus
¤ maintain pregnancy and stimulate breast growth etc
NB: during pregnancy, the placenta makes most of the estrogen and progesterone
What is the difference between haploid and diploid cells?
Haploid cells have half the number of chromosomes as a normal body cell (23)
Diploid have the usual number of chromosome (46 or 23 pairs)
How are haploid cells produced?
They are formed during meiosis which is the nuclear division of chromosomes
The DNA is first replicated and then halved.
- Produces 4 daughter cells
- Genetic variation
How many sperm are produced on a daily basis?
How long does It take for each sperm to mature?