Misc Flashcards
What happens to the mesonephric and paramesonephric ducts in male development? What part of the male DNA allows these changes to occur?
Mesonephric - becomes vas deferens
Paramesonephric - obliterated by production of mullerian inhibiting substance in males
SRY genes on the Y chromosome
What are the mesonephric and paramesonephric ducts AKA?
Mesonephric - Wolffian duct
Paramesonephric - Mullerian duct
What occurs in Turner’s syndrome? When and how is it diagnosed? What is the chromsomal classification?
- 45,XO.
- Results in degeneration of ovaries at 15th week of gestation.
- Diagnosis only occurs post puberty, when a lack of a menstrual cycle and secondary sexual characteristics are revealed.
What is the function of hCG and hPL (human placental lactogen)?
HCG - Promotes progesterone release form corpus luteum
hPL - Decreases maternal insulin and glucose utlitisation. Increases lipolysis.
What is the name of the visceral layer that covers the testis?
Tunica Vaginalis
What occurs post puberty with regards to spermatogenesis? How long does spermatogenesis take? How long does it take for new groups of spermatogonia to arise? What occurs during copuluation? Where do spermatozoa mature?
- At intervals, A1 spermatogonia emerge from population of stem cells, marking beginning of spermatogenesis in that part of the tubule.
- The A1 spermatogonia divide to produce more type A (stem) cells or Type B cells
- Type B spermatogonium divides to produce 64 clones of primary spermatocytes all linked together by a cytoplasm bridge
- Chain of primary spermatocytes push out of lumen of tubule and begin meiosis, producing 256 sperms per A1 spermatogonium.
- After meiosis complete, spermatids remodelled to form sperm by spermiogenesis and the cytoplasmic bridges are broken down. They are then released into the tubule lumen and washed down the rete testis by fluid secreted from Sertoli cells.
- Spermatogenesis takes 70 days and new groups of spermatogonia arise every 16 days.
- Production of sperm is continuous as different sections of the tubule begin the process at different times, therefore some part is always released sperm – Spermatogenic wave of production.
- Spermatozoa mature during progress through epididymis.
- During copulation, contraction of vas deferens sweep sperm to be mixed with seminal and prostate secretions.
Stem cells –> A1 Spermatogonia –> Type B spermatogonia –> primary spermatocytes (linked) –> Spermatids –> sperms (unlinked)
Distinguish between a spermatogenic cycle and a spermatogenic wave
Spermatogenic cycle – Development of A1 spermatogonia through to 256 sperms. Time taken for the same stage of the cycle to reappear in the same segment of tubule.
Spermatogenic wave – Different parts of tubule start the spermatogenic cycle at different times, so a constant ‘wave’ of production of sperm occurs. This can be thought of as the distance between 2 parts of the tubule on the same stage in the spermatogenic wave.
What happens before birth in the ovarian cycle? What are the 3 stages that a follicle must go through to mature? Can a woman produce more oocytes, why?
- Primordial germ cells in the primordial gonad, AKA oogonia, proliferate by mitosis to form primary oocytes.
- Oogonia’s entry to meiosis 1 stimulated by mesonephric cells which surround the primary oocytes to form primordial follicles.
- Meiosis arrested at prophase due to oocyte maturation inhibitor (OMI) secreted by primordial follicles.
- A woman therefore has all the oocytes she will ever have at birth. The longer the oocytes remain in an arrested stage the increases chances there are of cell damage.
- A small number of follicles begin further development each day post puberty, formation of a mature gamete requires follicles to go through 3 stages.
3 stages are - primordial follicle, secondary follicle, pre-ovulatory follicle
What happens in the primordial follicle stage to form the primary follicle?
- The primary oocyte grows dramatically
- Squamous granulosa cells become cuboidal Granulosa cells
- Zona pellucida forms around oocyte
What happens to the primary follicle to get to the secondary follicle? What substance does the theca produce?
- Inner and outer theca forms
- Theca secretes oestrogens
- Fluid filled vesicles develop among granulosa cells
What happens in the secondary follicle stage? What cells do FSH and LH bind to?
- Fluid filled vesicles combine to make one antrum
- Continued development depends on reproductive hormones.
- FSH – Binds only to Granulosa cells
- LH – Binds only to Thecal cells
What happens in the pre-ovulatory stage? How many hours before ovulation does the phase start? After how many hours do unfertilised cells degenerate?
- Phase begins 37 hours before ovulation
- Oestrogen causes receptors for LH to appear on outer Granulosa cells
- LH surge stimulates these receptors, leading to rapid changes in the follicle
- Within 3 hours of the LH surge, the follicle restarts meiosis, and the first meiotic division is completed. This division is asymmetric; cytoplasm remains with one daughter cell and the other forms a condensed polar body.
- The secondary follicle then enters meiosis II and arrests again 3 hours prior to ovulation.
- LH stimulates collagenase activity leading to follicle rupture
- Ovum is carried out in the fluid and gathered up into the fallopian tube by fimbria
- Meiosis is not completed unless the ovum is fertilised
- Unfertilised cells degenerate 24 hours after ovulation
What would happen to an XY individual with genitalia that are insensitive to testosterone or DHT?
- Testes remain in abdomen but removed post puberty due to high risk of malignancy
- Well developed breasts, no pubic hair or menstruation
- Genital ambiguity
What would happen in an XX individual and excessive androgen secretion?
External appearance is male but genetically female with internal genitalia of both sexes
What would happen to an XY individual with resistance to MIH?
Genetically and gonadally male but internal genitalia of both sexes due to test promoting external genitalia and wolffian duct.
Testes will fail to descend
What are the glycoprotein hormones that the ant pit secretes? What cell type produces each hormone?
FSH – produced by gonadotrophs
LH - produced by gonadotrophs
TSH - produced by thyrotrophs
What are the polypeptide hormones that the ant pit secretes? What cell type produces each hormone?
GH - produced by somatotrophs
ACTH - produced by Corticotrophs
Prolactin - produced by lactotrophs
What are the hormones that the post pit produces?
ADH Oxytocin (important for reproduction)
What is the action of GnRH in males? What is the action of FSH and LH? What is inhibin secretion rate related to? What else can affect the production of testosterone?
- Testosterone reduced GnRH secretion
- Spermatogenesis occurs continuously and male must be ready for action at any time. Therefore, hormone levels constant in medium and long term, achieved by –ve feedback
- FSH binds to Sertoli cells
- LH binds to Leydig cells:
- Promotes testosterone release and spermatogenesis
- Inhibin secretion related to rate of spermatogenesis.
- Testosterone is higher in mornings due to circadian rhythms and can be affected by environmental stimuli
What does inhibin do in both sexes? What is inhibin secretion related to?
Inhibin from gonad reduces FSH secretion
Inhibin secretion related to developing gametes - More developed gametes release more inhibin
What is the action of LH during the luteal phase? What about progesterone? How do progesterone only contraceptives function?
LH maintains corpus luteum
Progesterone in this stage acts on oestrogen primed cells:
Further thickening of endometrium
Thickening of myometrium
Thick, acid cervical mucus – barrier against sperm and bacteria between uterus and vagina. This is how progesterone only contraceptives work.
Changes in mammary tissue
At the beginning of the menstrual cycle, what are the levels of progesterone and oestrogen? What happens here?
Low progesterone and oestrogen
FSH levels rise:
- Binds to granulosa cells
- Theca interna develops
- Secretes oestrogen stimulated by LH
- Secretes inhibin
What happens in the mid follicular stage?
- Oestrogen levels rising
- Inhibin levels rising – inhibit FSH, no new follicles can develop
- Oestrogen exerts +ve feedback at hypothalamus and pituitary
- LH levels rise but not FSH
What happens in the pre-ovulatory phase?
LH surge. Precise timing may be influenced by environmental factors
What happens after the luteal phase if there is a preganancy?
If pregnancy occurs, HCG released by placenta preserves corpus luteum. Corpus luteum secretes increasing amounts of steroids but placenta soon secretes even more and after 12 weeks corpus luteum no longer supports pregnancy.
Why does the menstrual cycle vary in length? How many days is it from ovulation to menses?
Variation in timing of ovulation. From ovulation to menses always takes 14 days
During what ages doees puberty occur for males and females?
Females: 8-13
Males: 9-14
What is the female process of puberty?
- Breast bud (thelarche)
- Pubic hair growth begins (adrenarche)
- Growth spurt
- Onset of menstrual cycle (menarche)
- Pubic hair adult
- Breasts adult
What is the male process of puberty?
- Genital development begins
- Pubic hair growth
- Spermatogenesis begins
- Growth spurt
- Genitalia adult
- Pubic hair adult
What are the effects on the body of menopause on oestrogen sensitive tissue? What about on bone? How can you reverse the changes done to bone?
Vascular changes – hot flushes, relieved by oestrogen treatment
On oestrogen sensitive tissues:
- Uterus – regression of endometrium, shrinkage of myometrium
- Thinning of cervix
- Vaginal rugae lost
- Involution of some breast tissue
- Changes in skin
- Changes in bladder
Bone:
- Bone mass reduces 2.5% per year
- Increased reabsorption relative to production
- Osteoporosis
- Limited by oestrogen therapy
Define amenorrhoea
absence of menstruation
Define menorrhagia
Heavy periods
Define dysmenorrhoea
Painful periods
Define oligomenorrhoea
Lots of small periods
Define cryptomenorrhoea
hidden periods
What is dyfunctional uterine bleeding (DUB)?
Excessively heavy, prolonged or frequent bleeding of uterine origin that is not due to pregnancy, pelvic or systemic disease
Anovulatory
Define primary amenorrhoea and secondary amenorrhoea. To what age group does secondary amenorrhoea usually occur?
Primary amenorrhea – Absence of menses by age 14 with absence of 2ndary sexual characteristics (SSC)
Secondary amenorrhoea: Where an established menstruation has ceased.
- 3 months in a women with a history of regular cyclic bleeding
- 9 months in a woman with a history of irregular periods
- Usually happens to women aged 40-55 (menopause)
Describe the pathophysiology of DUB
- Disturbance in the HPO axis thus changing in the length of menstrual cycle
- No progesterone withdrawal from an oestrogen-primed endometrium
- Endometrium builds up with erratic bleeding as it breaks down
How do you manage DUB?
- HCG, TSH
- Smear if appropriate
- Possible malignancy
- Oestrogen therapy
- Followed by cyclic progesterone for 10 to 12 days each cycle
What is menorrhagia?
Heavy bleeding that isnt DUB
Usually ovulatory
What is the pathophysiology of menorrhagia?
- Usually secondary to distortion of uterine cavity – heavy with or without prolongation
- Uterus unable to contract down on open venous sinuses in the zona basalis
How do you manage menorrhagia?
NSAIDS or combined oral contraceptibe pill
What are the disadvantages of HRT?
Increased risk of thromboembolism and breast cancer
What embryological structures fuse to form the uterus?
Mesonephric ducts
What is the internal lining of the uterus called? Which layer is subject to growth and shedding?
endometrium
Stratum functionalis
What are the 3 phases of the endometrium? What occurs to hormone secretion during each stage?
- Proliferative phase of endometrium – oestrogen secreted during folliculogenesis
- Secretory phase of endometrium – corpus luteum secretes progesterone which stimulates endometrial glands to secrete glycogen and encriching vascular supply to mucous membrane
- Menstrual phase – conceptus failes to implant. Withdrawal of hormones. Changes in vascular supply of endometrium and degeneration of bulk of upper endometrium
What is the position of the uterus in relation to the vagina and cervix?
AnteVerted – In relation to Vagina
AntifleXed – In relation to the cerviX
What are the 3 parts of the broad ligament?
mesovarium, mesosalpinx, mesometrium
What is the lining of the endocervix and exocervix?
Endocervix:
Lined by columnar epithelium
Exocervix:
Stratified squamous non keratinised epithelium.
What innervates the uterus and vagina?
Inferior 1/5th of vagina receives somatic innervation from pudendal nerve S2-S4
Superior 4/5ths of vagina and uterus receives innervation from uterovaginal plexus
Where does the pain refer in vaginal/uteral injuries?
Above pelvic pain line – pain refers back up
Below pelvic pain line – pain refers locally
What is salpingitis? What can it lead to and how? How can it result in ectopic pregnancies?
- Inflammation of uterine tube caused by MOs
- Causes fusions or adhesions of mucosa and can block its lumen leading to infertility
- Blocked or dysfunctional tubes may result in ectopic pregnancies
What is endometriosis? What are the symptoms?
- Ectopic endometrial tissue is dispersed to various sites along the peritoneal cavity and beyond
- Associated with severe period pain and/or infertility
Where is an endoetrial carcinoma likely to occur? What is a symptom?
- Junction between columnar cells of endocervix and squamous cells of exocervix is wher emost neoplasma form
- Major symptom Is abnormal uterine bleeding
What is vaginismus?
Reflex of pubococcygeus muscle makes vaginal penetration painful or impossible
What are the 3 layers of the uterus?
endometrium, myometrium, perimetrium
What are the 4 muscles located in the root of the penis? What is their action?
- Bulbospongiosus x2 – Found in the bulb. Contacts to empty spongy urethra of any residual semen or urine. Anterior fibres aid in maintaining erection by increasing pressure in the bulb of the penis.
- Ischiocavernosus x2 – Surrounds left and right crura. Contracts to force blood from cavernous spaces in the crura into the corpus cavernosa, helping to maintain an erection.
What is the suspensory ligament a condensation of? What does it connect?
condensation of deep fascia. Connects erectile bodies to pubic symphysis