Reproductive Physiology Flashcards
Label the male reproductive tract
Check notes
What are the regulatory hormones of the male reproductive system and where are they produced
Gonadotrophin releasing hormone (GnRH) - Hypothalamus
luteinising hormone (LH) - anterior pit.
Follicle stimulating hormone (FSH) - anterior pit.
Testosterone (T) - testis
Describe the regulation/feedback systems of the male reproductive system
- Release of GnRH
- Release of FSH and LH
- LH stimulated testosterone release from Leydig cells
- Testosterone and FSH induce spermatogenesis
- Inhibit from spermatogenic cells and testosterone from Leydig cells induce -ve feedback on the pituitary glandd + hypothalamus
Explain the process of spermatogenesis
- Germ cell divides by mitosis to produce spermatogonia which become primary spermatocyte
- Spermatogonia undergo the first meiotic division to produce secondary spermatocytes
- Second meiotic division to produce spermatids
- maturation of spermatids -> sperm
Describe male reproductive function (age changes)
Starts at puberty
Functions continually
Normally continues throughout the rest of life
Sperm quantity and quality generally decreases with increasing age
Which cells support spermatogenesis occur in and which hormones are involved
Sertoli cells support spermatogenesis
LH stimulates testosterone production
FSH and testosterone sustain Sertoli cell function
Describe female reproductive function (age changes)
Starts at puberty
Functions cyclically
Normally operates until ~45 years of age
Egg quality generally decreases with increasing age
Describe the role of FSH and LH in reproductive function
FSH stimulates (some) development of ovarian follicles + 17b-estradiol synthesis LH stimulates progesterone production The steroids regulate uterine endometrium
Describe the regulation/feedback systems of the female reproductive system
- Hypothalamus releases GnRH/LHRH to stimulate the pituitary
- LH and FSH release form pituitary
- Progesterone and oestrogen release from the ovaries
- -ve feedback
Describe the changes in the female hypothalamus-pituitary axis during the menstrual cycle
Follicular - GnRH, FSH and LH release, ovaries release oestradiol -> -ve feedback
Midcycle - GnRH, Surge in LH + FSH, oestradiol -> +ve feedback
Luteal - Progesterone release from the ovaries -> -ve feedback
Draw a graph to show the changes in circulating hormones in a female
Refer to notes
What are the changes in tissue structures during the normal human menstural cycle
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Describe the process of folliculogenesis
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Describe oogenesis
Ovulation = release of mature oocyte (egg) from the ovary
Oocyte is 2n at this stage, in meiotic arrest (metaphase II)
Enters the Fallopian tube
Needs to be fertilised within 24 hours, as it degenerates after this
What occurs after fertilisation
- Meosis of maternal chromosomes resumes, forming female pronucleus (23 chromatids), and 2nd polar body.
- Sperm chromosomes decondense to form male pronucleus (23 chromatids).
- Chromatids in both pronuclei are duplicated
- They align on the mitotic spindle, and are separated into 2 identical ‘daughter’ cells (1st cleavage division of the embryo).
What are the important structures in the testis
Seminiferous tubules
Leydig cells
Sertoli cells
What is the function of the Seminiferous tubules
Produces sperm
Describe the Leydig (interstitial) cells
Secrete testosterone
LH responsive
Important for sexual differentiation and spermatogenesis
Describe Sertoli cells
“Nurse cells”
FSH responsive
Support spermatogenesis
Regulate the internal environment of the seminiferous tubules
What occurs in the epididymis
Sperm are released from the testis and stored here prior to ejaculation
What occurs at ejaculation
At ejaculation, sperm are released into the contractile Vas Deferens then pass through urethra.
During ejaculation sperm are mixed with fluid from the seminal vesicles and the prostate gland.
What are the two cycles of the menstrual cycle
Ovarian - follicular, ovulatory, luteal
Endometrial - menstrual, proliferative and repair, secretory
Describe what occurs in the follicular phase of the ovarian cycle
Development and growth of several follicles (although only one is selected to ovulate)
Stimulated by FSH
Leads to increased production of oestrogen which inhibits FSH and LH secretion
Describe what occurs in the ovulatory phase of the ovarian cycle
Follicle continue to grow, producing more oestrogen.
Dominant follicle is selected for ovulation
Oestrogen begins to stimulate secretion of LH and FSH of pituitary leading to LH surge in ovulation
Describe what occurs in the luteal phase of the ovarian cycle
After ovulation, follicle develops into corpus luteum
Corpus luteum produces progesterone (and some oestrogen)
Describe the menstrual phase of the endometrial cycle
Day 1-5 of cycle
Shedding of blood and endometrial lining of uterus
Remaining basal endometrium very thin
Describe the proliferative and repair phase of the endometrial cycle
Day 5-14 of cycle
Stimulation of endometrial cell proliferation, increase in thickness, increase in number and length of glands, increased in length of arteries
Describe the secretory phase of the endometrial cycle
Day 15-28 of cycle
Production of nutrients and other factors
Epithelial glands widen, endometrium thickens, increased coiling of spiral arteries o Endometrial lining maintained by progesterone
Importance of PROGESTERONE
What occurs in the secretory phase of the endometrial cycle when there is no pregnancy vs if there is pregnancy
If there is no pregnancy, progesterone falls and endometrium sheds →
If there is a pregnancy, corpus luteum will continue to maintain progesterone levels → no menses
Describe the process of fertilisation up to capacitation
- Sperm enters female tract near cervix following intercourse
- Cervical mucus is normally hostile to sperm which changes mid cycle to allow sperm entry into uterus
- Passage of sperm through uterus to fallopian tube
- Survival of the fittest so fertilization window is a few days
Describe the process of fertilisation from capacitation
- Capacitation
- Fusion of egg and sperm within ~24hrs post ovulation
- ACROSOME REACTION
- CALCIUM INFLUX
- Initiation of embryo mitotic cleavage following fusion of maternal and paternal pro nuclei
What occurs in capacitation
Mediated by progesterone release from oocyte, leading to increased motility of sperm and chemotaxis
What occurs in the acrosome reaction
Digests zona pellucida to allow sperm entry
Hardening of zona pellucida to prevent polyspermy
What occurs during calcium influx during fertilisation
Resumption of meiosis
Release of second polar body
