Flashcards in Reproductive System Deck (106)
What are the 3 lipid soluble hormones?
What are the 4 water soluble hormones and where are they secreted from?
Gonadotrophin releasing hormone (GnRH) - hypothalamus
Follicle stimulating hormone (FSH) - anterior pituitary
Luitinising hormone (LH) - anterior pituitary
Oxytocin - posterior pituitary
Describe the neurosecretory neurons:
They connect the hypothalamus to the pituitary and they can conduct a nerve impulse but also synthesise and carry and release neurosecretory peptide hormones. They are aggregated into nuclei and have long axon tracts.
Describe how oxytocin and ADH are released from the pituitary gland and what their functions are:
They are synthesised in the hypothalamus, travel bound to carrier proteins down the axon terminals and are then stored as secretory vesicles. Nerve impulses travel along the axon to trigger exocytosis of the secretory vesicles, releasing the hormones
1. Oxytocin - a reproductive hormone that has major effects on smooth muscle contraction - milk ejection - contraction of uterus - secreted in response to nipple stimulation - used to induce labour
2. Antidiuretic hormone (ADH) - works on kidneys to retain water
Describe how gonadotrophs (LH and FSH) are released from the pituitary gland?
Neurosecretory neurons synthesise releasing and inhibiting hormones in their cell bodies into vesicles which travel to the axonal terminus in response to nerve impulses they are secreted into the hypophyseal portal vessels in the anterior pituitary.
1. Gonadotrophs - produce FSH and LH
Why are hypothalamic secretion released in a pulsatile release?
They are released in bursts separated by periods of time of no secretion. This prevents receptor desensitisation and down-regulation.
How does FSH and LH cause changes in the gonads?
By binding to receptors on the outside and promoting the synthesis of sex steroid hormones and gametogenesis.
What does FSH do in a female?
Promotes growth of ovarian follicles
What does FSH do in a male?
Promotes growth of spermatazoon
What does LH do in a female?
Secretion of female sex hormones and stimulates ovulation
What does LH do in a male?
Stimulates production of testosterone
Describe an antiflex uetrus:
The uterus is suspposed to be at 90 degrees facing the back, but some women have it facing the front which is called a retroflex uterus and this is usually corrected after the first baby
Describe the structure of the vagina:
An elastic muscular 7.5cm to 9cm tube extending from the cervix to the exterior of the body
Describe the structure of the uterus:
It is a small pear shaped organ that weighs 30-40g. The endometrium can be divided up into inner functional zone (stratum functionalis) that contains most of the uterine glands and the outer basal layer (stratum basalis) which attaches the endometrium to the myometrium.
Describe the structure of the fallopian tubes:
The epithelium lining of the uterine tube has both ciliated and non-ciliated secretory columnar cells. The mucosa is surrounded by a concentric layers of smooth muscle. Transport along the tube requires both ciliary action and peristalsis.
Describe the structure of the ovaries:
They are oval shaped and weigh about 5-10g. They are comprised of 3 distinct regions: the outer ovarian cortex containing the ovarian follicles, the central ovarian medulla consisting of ovarian stroma and steroid producing cells and the inner hilum which acts as a point of entry for nerves and blood vessels
Describe the function of the uterine tubes:
Fertilization usually occurs at the ampulla. The tubes provide a rich nutritive environment containing lipids and glycogen for the spermatazoa, oocyte and developing embryo.
Describe the function of the uterus:
It is the pathway for sperm transport. Provides mechanical protection, nutritional support and waste removal for the developing embryo ad foetus. Contractions in the muscular wall is important in ejecting the foetus. It is also the source of menstrual flow.
Describe the function of the vagina:
It serves as a passageway for the elimination of menstrual fluids, receives penis during intercourse, holds the sperm before they pass into the uterus and forms the lower part of the birth canal
What is the order of follicular development?
Primoridal follicle, primary, secondary, mature, ovulation, corpus luteum, corpus albicans.
Describe this stage of follicular development: primordial follicle
The oocyte is surrounded by a layer of follicular (granulosa) cells
Describe this stage of follicular development: primary follicle
The follicles grow and become more columnar and are now called primary. The oocyte secretes glycoproteins which form a translucent layer known as the zona pellucida. Condensation of ovarian stroma cells begin to form the thecal layer. In response to FSH some follicles may grow more layers of granulosa cells
Describe this stage of follicular development: secondary
As the granulosa cells proliferate they produce a viscous follicular fluid that forms a cavity known as the antrum. The inner most cells of the granulosa layer becomes firly attached to the zona pellucida and is called the corona radiata. Mass of loosly associated granulosa cells is called the cumulus oophorus. The theca develops to become the inner glandular highly vascular theca interna and externa. The theca interna and granulosa cells work together to make oestrodiol.
Describe this stage of follicular development: mature follicle
As the follicular antrum grows, the the oocyte becomes suspended in fluid and is connected to the rim of the peripheral granlosa cells by a thin stalk of cells. It bulges out of the ovarian surface.
Describe this stage of follicular development: ovulation
The follicle ruptures, carrying with it the oocyte and the surrounding mass of cumulus cells. The oocyte is collected by cilia on the fimbriae which sweep it down the fallopian tube.
Describe this stage of follicular development: corpus luteum
The antrum breaks down and the basement membrane between the granulosa and thecal layers breaks down and blood vessels invade. The granulosa cells form large lutein cells. This transformation os called luitenisation and is associated with an increasing secretion of progestagens.
Describe this stage of follicular development: corpus albican
The whitish scar tissue left is absorbed back into the stromal tissue of the ovary over weeks to months.
What happens to the corpus luteum if the oocyte is fertilised?
It persists past its normal 2 week life span and is rescued from degeneration from the presence of hCG which is a hormone produced by the chorion of the embryo about 8 days after fertilisation.
When taking a pregnancy test at home, what is the hormone present?
hCG in the urine.