Reproductive System Flashcards
What does the Scrotum do?
Suspend testes outside body
What is the skin like on scrotum?
Rugose
Contains dartos muscle (smooth muscle)
Midline raphae
Divided by septum
What is each testis surrounded by?
Tunica albuginea
Why is each testis suspended in septum?
To keep cool
2-3 degrees below core temp.
Where do sperm pass from?
From seminiferous tubules to epididymis
What structures add nutrients to semen?
Bulbourethral gland and seminal vesicle
What do Gonads do?
Produce ‘seed’ cells or gametes
Male gonads produce sperm by spermatogenesis
What structures are part of the male gonad?
Testis and Epididymis
Where does spermatogenesis occur?
Seminiferous tubules
What do leading cells do?
Steroid synthesis
What do serotonin cells do?
Nurse cells for sperm
Help sperm develop
Continuous + have tight junctions
What are the Gonadal hormones?
FSH - follicle stimulating hormone
LH - Luteinizing hormone
Testosterone (regulated by FSH and LH)
Spermatogenesis:
Spermatogonia
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Primary spermatocytes
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Secondary spermatocytes
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Spermatids
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SpermatozoaWhat’s spermatogenesis regulated by?
FSH and testosterone
What’s in head of sperm?
Acrosomal cap - enzymes to aid penetration of ovum
Nucleus - genetic material
What’s in the mid piece of sperm?
Mitochondria around filamentous core
Energy for tail
What’s the tail of sperm like?
Specialised flagellum - movement
Where are testicular endocrine functions?
Leading and Sertoli cells
Importance of LH in Testis:
Stimulates Leydig cells to produce testosterone
What happens to testosterone in testis?
Diffuses across BM into Sertoli cells
Regulates spermatogenesis
What can Sertoli cells do to Leydig cells?
Regulate gene expression in Leydig cells - reduce testosterone production
Explain what happens between testosterone and estradiol in the testis?
Testosterone diffuses from Leydig cell to Sertoli cell
Aromatise converts testosterone to estradiol
Estradiol diffuses back to Leydig cell
What HDTV’s HPT axis stand for?
Hypothalamic Pituitary Testicular axis
What happens in HPT axis?
GnRH is released from preoptic + arcuate nucleus of hypothalamus
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Anterior pituitary gonadotropes secrete LH and FSH
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Leydig cell responds to LH and produces testosterone
Sertoli cell responds to FSH and produces inhibin B
Effect of testosterone and Inhibin B in HPT axis:
Negative feedback effect on hypothalamus and anterior pituitary gonadotropes
Comparison of HPT axis to pathways in ovaries:
1 primary hormone in HPT axis (testosterone)
2 hormones in ovaries (oestrogen and progestins)
No role of activins has been established
Effect of testosterone in bone:
Growth
Effect of testosterone on muscle:
Growth
Effect of testosterone in reproductive organs:
Growth + development of structures
Growth of facial, axillary + pubic hair
Growth of larynx - deeper voice
Spermatogenesis
Effect of testosterone on skin:
Increase in sebaceous gland size + secretions
Shape of uterus:
Pear
Purpose of uterus:
Central pelvic organ for implantation of fertilised ovum
Growth of foetus
Structure of uterus:
Anteflexed between cervix + body
Anteverted at entry to vagina
Position of ovary:
On lateral pelvic wall
Where does ovulation happen?
Into peritoneal cavity
What happens to ovum in ovulation?
Picked up by fimbriae Ed end of uterine tube
What are the female gonads?
Ovaries
What do female gonads produce?
Oocytes by oogenesis
Where does oogenesis take place?
In follicle
What cells are in follicle?
Theca and Granulosa cells
What gonadal hormones are involved in oogenesis?
FSH
LH
Oestrogen and Progestins
When does oogenesis begin?
Foetal stage of females
Oogenesis:
Primordial germ cells (oogonia) increase in number
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Oogonia mature into oocytes
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20 weeks gestation = max oocyte number
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Oocyte numbers declineWhat do oocytes contain?
Follicles in various stages of development (folliculogenesis)
Primordial, primary, secondary, tertiary, mature (Graafian) follicles
Purpose of endocrine ovaries:
Primarily related to latter follicles
Theca and granulosa cells
Work cooperatively to synthesis + secrete oestradiol
Structure of theca cells:
Superficial layer of follicle
LH receptors
What do Theca cells do?
Convert cholesterol into progenolone
Produce androstenedione and testosterone
Structure of Granulosa cells:
Deep compared to theca
LH and FSH receptors
What do Granulosa cells do?
Convert cholesterol into pregnolone
Activate aromatase
What does HPO axis mean?
Hypothalamic Pituitary Ovarian Axis
What are the main hypothalamic areas involved in ovarian control?
Preoptic and supraoptic nucleus
Significance of GnRH in HPO axis:
Peptide hormone and produced as prohormone
Modified to active form
Secreted into hypophysis portal system
Why is GnRH release pulsatile in HPO axis?
Less energy needed
Doesn’t desensitise target tissue receptors
What does LH (secreted by anterior pituitary gonadotropes) do in HPO axis?
Stimulate Theca cell
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Produce progestins and estrogens (negative feedback effect)
What does FSH (secreted by anterior pituitary gonadotropes) do in HPO axis?
Stimulate Granulosa cell
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Produces Inhibins and Activins
How do progestins and estrogens operate in HPO axis?
Negative feedback with hypothalamus and anterior pituitary gonadotropes
How do inhibins and activins operate in HPO axis?
Inhibins = negative feedback with anterior pituitary gonadotropes
Activins = positive feedback with anterior pituitary gonadotropes
What are the 3 main Oestrogens?
Oestradiol
Oestrone
Oestriol (during pregnancy)
Effects of oestrogens on bone:
Growth via osteoblasts
Effect of Oestrogens on endocrine:
Increase in progesterone responses
Effects of Oestrogens on Liver:
Increase in clotting factors
Increase in steroid-binding proteins
Decrease LDL
Increase HDL
Effects of Oestrogens on reproductive organs:
Uterine, vaginal and fallopian tube growth
Breast growth
Increase cervical mucus secretion
Increase number of LH receptors on granulosa cells
What are progestins?
Progesterone
Produced in theca and granulosa cells
Effects of Progestins on breast:
Increase in lobular development
Decrease milk production
Effects of Progestins on reproductive organs:
Decrease endometrial growth but increase secretions
Thicker mucosal secretions
Effects of Progestins on temperature:
Increase internal temp
Hormonal regulation of lactation:
Stimulus from sucking stimulates production of prolactin
Prolactin stimulates milk production
Decrease in GnRH production - inhibits ovarian cycle
What does continuous administration of GnRH cause?
Suppression of gonadotrophin secretion
What’s endometriosis?
Growth of endometrial tissue outside uterine cavity
Results in pain + infertility
How can GnRH be used in endometriosis?
Continuous administration reduces oestrogen levels - reduced endometriosis tissue
Give examples of therapeutic uses of GnRH:
Endometriosis
IVF
Different types of birth control pill:
Fixed combination
Varying-dose
Progestin only
How do contraceptive pills work?
Suppress LH and FSH secretion
No ovulation as no follicular development / LH surge
Progestin inhibits sperm penetration + reduces chances of implantation
