Testicular and Ovarian Function Flashcards
What are the two main functions of reproductive organs?
gametogenesis and secretion of hormones
Where is testosterone produced in the testis?
in the Leydig cells in the interstitial tissue
What is the role of mitotic division in gametogenesis?
to increase the number of germ cells
What are primary spermatocytes?
the product of mitotic division of spermatogonia
What are secondary spermatocytes?
the product of meiotic division of primary spermatocytes
What are spermatids?
the product of meiotic division of secondary spermatocytes
What are spermatazoa?
mature spermatids
When does spermatogenesis begin?
puberty
Why does one spermatogonia remain on the outside of the seminiferous tubule?
to maintain the germ cell line
When does oogenesis begin?
in fetal life
At what stage of division are primary oocytes arrested?
at prophase 1 of the first meiotic division
When does the primary oocyte complete its first meitotic division and what are the products?
at puberty in each menstrual cycle a few primary oocytes will complete their first meiotic division to become the secondary oocyte and the first polar body
When does the secondary oocyte begin and complete its second meiotic division and what are the products?
the second meiosis begins when the egg is released from the ovary - it divides into a mature ovum and a second polar body - however the second meiosis isnt completed until fertilisation occurs
How many mature ovum do you get from one primary oocyte?
1
How many mature spermatazoa do you get from one primary spermatocyte?
4
How many primary spermatocytes do you get from one spermatogonium?
4
What reproductive hormone is released from the hypothalamus?
GnRH
What reproductive hormones are released from the anterior pituitary from stimulation by GnRH?
LH and FSH
What peptide hormones are produced by the gonads?
inhibin and activin
What enzyme converts testosterone to DHT?
5 alpha reductase
What enzyme converts testosterone to estradiol?
aromatase
What is the role of sertoli cells?
to surround and support the sperm and regulate their development
What is the role of Leydig cells?
to secrete testosterone
What is the role of LH in males?
signals to the Leydig cells to produce testosterone
What is the role of FSH in males?
signals to the sertoli cells to release paracrine signals for spermatogenesis
How often is GnRH released?
it is constantly released in a pulsatile way
What is the role of inhibin?
negatively feedsback on FSH
Where does the mucus in semen come from?
the bulbourethral gland
Where do the buffers in semen come from?
the prostate and bulbourethral gland
Where does the fructose and vitamin C in semen come from?
the seminal vesicles
Where does the citric acid in semen come from?
the prostate gland
Where does the carnitine in semen come from?
the epididymis
Where do the enzymes for clotting and liquefying semen come from?
the seminal vesicles and prostate
Where do the prostaglandins in semen for smooth muscle contraction to aid transport come from?
the seminal vesicles
What does testosterone have negative feedback on?
LH and GnRH
What is the role of testosterone in sex specific tissues?
promotes spermatogenesis and growth and maturation of the reproductive system
What are the two phases of the menstrual cycle?
the follicular/proliferative phase and the luteal/secretory phase
Which secondary sex characteristics are controlled by oestrogen?
breast growth and fat deposition
Which secondary sex characteristics are controlled by adrenal androgens in females?
pubic and axillary hair, libido
Which phase of the menstrual cycle is variable in length?
the follicular phase - the luteal phase is always the 14 days following ovulation as this is the lifespan of the corpus luteum
Describe the changes in the uterus in the menstrual cycle?
the menstrual cycle begins with menses where the endometrium is shed, then the proliferative phase begins and the new endometrium is built up, then in the secretory phase the endometrium develops coiled blood vessels and a secretory glandular structure to promote implantation
What happens to basal body temperature in the menstrual cycle?
basal body temperature increases after ovulation under the control of progesterone
What is the role of FSH in females?
FSH stimulates follicle development
What are the two types of cells in the follicle and what are their roles?
granulosa cells and thecal cells - granulosa cells produce oestrogen and thecal cells produce androgens which are converted to oestrogen in the granulosa cells by aromatase
In the early to mid follicular phase what is the feedback role of oestrogen?
oestrogen has positive feedback on the follicle to increase maturation and negative feedback on FSH and GnRH
What is the role of LH in females?
LH stimulates thecal cells to produce androgens
In the late follicular phase what is the feedback role of oestrogen?
oestrogen switches to positive feedback on GnRH whch causes a surge of FSH and LH
What is the role of inhibin in the late follicular phase?
inhibin has negative feedback on FSH to prevent maturation of another follicle
What stimulates ovulation?
the LH surge triggered by GnRH
What happens to the follicle after ovulation?
it becomes the corpus luteum - an endocrine organ of its own which releases progesterone and oestrogen
What hormone causes proliferation of the endometrium and expression of progesterone receptors in the endometrium?
oestrogen
What is the role of oestrogen and progesterone in the luteal phase?
maintain the endometrium, make the endometrium have a secretory structure and have negative feedback on GnRH, LH and FSH
What happens if there is no pregnancy?
the corpus luteum dies, the oestrogen and progesterone levels drop, the GnRH goes back to tonic secretion, LH and FSH rise, a new follicle will begin to develop and the cycle will start again
What is the trigger for menses?
the removal of the supportive role of oestrogen and progesterone will make the endometrium slough off
What happens to cervical mucous throughout the menstrual cycle?
in the proliferative phase the cervical mucous is thin and watery, at ovulation it becomes thin and stringy under the influence of oestrogen to facilitate the entrance of sperm, after ovulation it becomes a thick mucous plug (under the influence of progesterone) to stop the entrance of sperm
What happens in menopause?
ovaries stop responding to LH and FSH, there are low levels of oestrogen and progesterone, there is cessation of egg development
What are the symptoms of menopause?
hot flashes, increased osteoporotic risk
How long does sperm live in the reproductive tract?
48 hours
How long does an ovulated secondary oocyte live?
24 hours
Where does fertilisation happen?
in the fallopian tube
What is the acrosomal reaction?
where the sperm releases digestove enzymes to digest the zona pellucida around the ovum
What blocks polyspermy?
the cortical reaction
What is a zygote?
an egg and sperm nuclei fused
When does the blastocyst enter the uterus?
day 4-5
When does implantation occur?
day 5-9
What is the decidua?
the endometrium during pregnancy
At what stage is early pregnancy?
weeks 1-2
At what stage is the embryonic period?
weeks 2-8
At what stage is the zygotic period?
weeks 9-38
What is the pregnancy suceptible to in early pregnancy?
chromosomal abnormalities and failure to implant
What is the pregnancy susceptible to in the embryonic period?
teratogens
What kind of defects occur due to problems in the embryonic period?
structural defects
What kind of defects occur due to problems in the fetal period?
physiological defects
What are the different methods of contraception?
block ovulation, block sperm and ovum transport or block implantation
How does the OCP work?
small amounts of oestrogen and progesterone have negative feedback so doesnt allow sufficient FSH for follicular development, and there is no LH surge so ovulation doesnt occur, and progesterone is too low to allow the endometrium to develop so if fertilisation does occur it wont be able to implant
