Reproductive physiology Flashcards
Which neural pathway is dominant in the neuroendocrine control of reward and pleasure?
Mesolimbic dopaminergic
Which neural pathway is dominant in the neuroendocrine control of movement?
nigrostriatal tract
What is the dominant neural region involved in erection?
Limbic system
Recall the sequence of neuroendocrine events that lead to erection
PNS acts on SMCs of pudendal artery
NO increased
cGMP increased
Blood flow in corpus cavernosum increased
Recall the mechanism of action of viagra
Inhibits phosphodiesterase - a de-activator of cGMP
What is the functional equivalent of the penis in females?
Clitoris
Recall the main components of the testes
Seminiferous tubules
Leydig cells
What is the function and location of the epididymis?
One within each scrotal sac
sperm storage prior to ejaculation
Recall the points at which fluid enters the ejaculate along the vas deferens
- Epidydmis (sperm)
- seminal vesicles
- Prostate gland
Sperm are released from the testis and stored in epididymis prior to ejaculation. At ejaculation sperm pass through the two Vas Deferens (which are contractile), and are mixed with fluid from the seminal vesicles. The fluid then leaves the ejaculatory duct, and passes into the urethra where it mixes with secretions from the prostate gland.
What cells are found within the seminiferous tubules?
Sertoli cells
What cells are responsible for testosterone production and what is their stimulant?
Leydig cells
LH
What cells are responsible for spermatogenesis and what is their stimulant?
Sertoli cells
FSH
Where is inhibin produced, and upon which hormone does it negatively feedback?
Seminiferous tubules (sertoli cells) GnRH
Why are gonadotropins released in a pulsatile fashion?
Testosterone negatively feeds back on LH, so as one rises the other falls
What is the role of sertoli cells in spermatogenesis?
Provide nutritional and hormonal support
Recall the precursor cells leading to the production of a sperm cell, and at which point they become haploid
Spermatogonium undergoes mitosis Primary spermocyte undergoes 1st meiosis Secondary spermocyte (haploid) 2nd meiosis Spermatid (haploid) differentiates Spermatozoa
At what point in the male lifespan are germ cells present?
Always - sperm production continues throughout life
Recall 4 key structures in the fallopian tube?
From proximal to distal Isthmus Ampulla infundibulum Fimbriae
Recall the 3 layers of the uterus
perimetrium
Myometrium
Endometrium
By what part of the broad ligament is the ovary suspended?
Mesovarium
What is the name given to the primordial germ cell destined to become an egg cell?
Oogonium
At what point in the female lifespan are germ cells present?
By birth they have all developed into at least the oogonium stage - no germ cells present after birth
Recall the precursor cells leading to the production of an egg cell
Oogonium
Primary oocyte
Secondary oocyte and 1st polar body but paused in metaphase 2.
Does not complete meiosis 2 until fertilisation (paused in metaphase 2)
After fertilisation: release of 2nd polar body and ovum is made.
Recall the cells that respond to LH and FSH in the female reproductive system and each of their functions
FSH - Granulosa cells: stimulate conversion of androstenedione to oestrone using aromatases
LH - Thecal cells: stimulate androgen synthesis
Recall the phases of the ovarian cycle and their length
Follicular (14 days)
Luteal (14 days)
What is the function of the follicular stage of the ovarian cycle?
17-beta-oestradiol production
Produced by thecal and granulosa cells
What is the function of the luteal stage of the ovarian cycle?
Production of E2 and progesterone by corpus luteum
How is ovulation stimulated
E2 surge –> LH surge
LH triggers ovulation
Recall the approximate change in basal body temperature at ovulation
+0.5 degrees celcius
What is the normal range of the menstrual cycle?
21-35 days
What name is given to a girl’s first period?
Menarche
Recall the changes in oestrogen feedback on the adenohypophysis throughout the menstrual cycle
At low levels = neg feedback
At high levels = positive feedback
Recall the phases of the endometrial cycle and their lengths
Menstrual (5 days)
Proliferative (9 days)
Secretory (13 days)
What is the function of the secretory phase of the endometrial cycle?
Produce nutrients and other factors
Progesterone thickens endometrial lining for implantation which happens in mid secretory phase
How is ovulation coordinated between the ovaries?
Alternate release of follicle between 2 ovaries so that there is 56 days between release of each secondary oocyte from each ovary
When do follicles undergo their first meiotic division? By what are they stimulated
Initiated in embryonic development: the oogonia undergoes MITOSIS to become primary oocyte. Primary oocyte initiates meiosis I but FREEZES at prophase I.
During puberty, the primary oocytes complete meiosis 1 to become SECONDARY oocytes. SECONDARY oocytes go through meiosis 2 and are halted in metaphase 2. This will not continue until after fertilisation.
Around how many follicles will be ovulated in a woman’s full lifetime?
400
When a follicle is ovulated, in what stage of meiosis is it halted?
Metaphase 2 of meiosis 2. Will not progress until fertilisation
How long does it take for a primordial follicle to develop into a secondary oocyte?
Just over a month
Why are sperm most likely to be able to enter the uterus mid-cycle?
Cervical mucus is usually hostile to sperm, changes mid-cycle to permit sperm entry
What does sperm bind to on the secondary oocyte surface?
ZP3 glycoprotein
Recall the events following sperm binding to a secondary oocyte that lead to fertilisation
Calcium influx
Meiosis II resumed
Sperm releases hyaluronidase
Penetrates ovum
Zona pellucida hardens to prevent further sperm entry
Female pronucleus produced along with 2nd polar body
When do the maternal and paternal pronuclei first fuse in the fertilised egg?
First mitotic division
What must happen in order for maternal and paternal pronuclei to fuse?
Decondensation of nuclear material
