Puberty, menstrual cycle and menopause/ later life Flashcards
When do boys start puberty?
age 10-14- lasts an avg of 3 yrs
When do girls start puberty?
age 9-13- lasts an avg of 2.5 yrs
What is the first sign of puberty in boys and in girls?
Boys= pubic hair growth and testis descent/ enlargement Girls= pubic hair growth and breast bud development (thelarche)
What is the crucial weight for girls to start puberty?
47kg
How can you asses what stage of puberty someone is at?
The tanner scale
What drives pubic hair growth in men and women?
Testosterone- however in women it is lower and suppressed by carrier proteins which inactivate it
What causes earlier epiphyseal fusion in girls?
Oestrogen- this is why they end up being smaller
What effect will precious puberty have on height?
your growth plates will fuse earlier so youll be shorter
What can cause precious puberty?
Adrenal, pituitary or testicualr tumours, brain or spinal injuries, hypothyroidism, obesity and meninigits
However, 90% of the time in females it is idiopathic
What triggers the start of puberty? (common to both M and F)
Gradual increases in gonadotrophin releasing hormone (GnRH) from the hypothalamus- leptin and photoperiod have been shown to increase this release. The GnRH is released in a pulsatile fashion to the ant pituitary which releases FSH and LH in response. This will cause testosterone and oestrogen release (in boys too- as the testosterone is converted to oestoradiol), this will have a positive feedback on growth hormone release, which causes the growth spurt.
Why might leptin be important in stimulating GnRH release?
It is released from adipose tissue, and so may be indicating to the body that it has enough fat/ energy stores for puberty to start.
How does the time of day affect GnRH release?
GnRH release increases at night
What happens in males when FSH and LH release increases at the start of puberty?
LH stimulates leydig cells to produce testosterone.
Sertoli cells will react to FSH by increasing sperm production, they also produce inhibin which starts to regulate the LH and FSH production.
What affect does the rise in FSH and LH at the start of puberty have on female hormones?
FSH causes granulosa cells of follicles to release oestrogen and inhibin and start follicular development for the menstrual cycle to start.
LH acts on theca interna cells to release androgens such as progesterone which also drive puberty and development.
What is the most common cause of delayed puberty?
Constitutional delay- they just have low GnRH, FSH and LH
What 3 processes cause genetic variation of gametes?
- crossing over: homologous chromosones exchange regions of DNA in prophase 1
- independant assortment: random alignment of homologous chromosomes in metaphase 1
- random segregation: random distribution of alleles among the 4 gametes
Where does spermatogenesis occur?
Within gaps in between sertoli cells within seminiferous tubules. The sertoli cells provide nutrients for sperm growth and development from spermatogonium and also form tight junctions to form a barrier from the blood.
What is the difference between spermatogenesis and spermiogenesis?
spermatogenesis is the whole process from permatogonium to spermatozoa, spermiogenesis is just the maturation from spermatid to spermatozoa.
Where do spermatogonium come from?
Primordial germ cells of the yolk sac
How much fluid is produced in each ejaculate? What is the normal sperm count?
2-4 ml// 20- 200 million per ml
Describe the process of spermatogenesis?
- From puberty, Ap spermatogonium in the basal membrane start to divide by mitosis but produce a primary spermatocyte and another spermatogonium
- Ad spermatogonium dont divide, but act like a reserve
- The primary spermatocyte divide by meiosis into secondary spermatocytes and then again into spermatids
- Spermatids are released into the seminiferous tubules
- They remodel as they pass through the seminiferous duct and rete testis until they get to the epididermis, they’re non motile at this stage and are moved by peristalsis
What is a spermatogenic cycle and how long is it?
The time taken for one group of cells along the seminiferous tubule to get back to the same stage of spermatogenesis- takes approx 16 days. This is because differnt parts of the seminiferous tubule are at differnt stages to ensure constant production of sperm
What is a spermatic wave?
The distance between the two regions of the seminiferous tubule that are in the same stage of the spermatic cycle
What triggers capacitation?
Progesterone and other hormones from the ovum and vagina
What occurs during capacitation?
G proteins in the sperm become activated which causes the sperm to loose its glycoprotein and cholesterol membrane on the head of the sperm
Describe the process of oogenesis before puberty
- primordial germ cells from the yolk sac colonise the gonadal cortex and differentiate into oogonia
- they proliferate rapidly by mitosis
- By the end of the 3rd month gestation they’re arranged in clusters with flat epithelial cells around them
- some differentiate to create a primary oocyte
- many oogonia and primary oocytes degenerate because theyre not perfectly formed
- The primary oocytes are stuck in meiosis 1
What is the primordial follicle made up of?
the oocyte and the follicular cells (the flat epithelial cells around it)
Describe the completion of oogenesis after puberty (4 stages)
- preantral stage- follicular cells become cuboidal and differentiate into granulosa cells, these secerete glycoprotein onto the ovum to form the zona pellucida
- antral stage- air filled spaces form between granulosa cells which come together to make one large space called the antrum. The outer layer of granulosa cells differentiates into the theca externa and theca interna
- preovulatory stage: surge in LH induced the preovulatory stage, this is where meiosis 1 completes to form the polar body and secondary oocyte
- the secondary oocyte starts meiosis 2 but arrests in metaphase
What effect do LH and FSH surges have on the follicle before ovulation?
Rapid proliferation to from the graafrian follicle. LH increases collagenase activity and prostaglandins cause local muscle contraction, these help the oocyte break free of the ovary walls
Describes what happens to the follicle after ovulation? State what happens if fertilisation does and does not take place
The remaining granulosa and theca cells become vascularised. They then develop a yellow pigment and become lutein cells which secrete oestrogen and progesterone. If HcG is released form an embryo, the corpus luteum continues to grow and form the corpus luteum graviditatis which continues to secrete progesterone until the placenta takes over. If no fertilisation, it degenerates and forms a fibrotic scarcaled corpus albicans
How long does a normal menstrual cycle last?
between 21 and 35 days
Which phase of the menstrual cycle is more variable depending on stress, loss of weight ect?
The follicular phase (developing follicle) can change but the luteal phase is less variable- almost always 14 days
Brefily outline how the menstrual cycle is controlled?
- FSH increase
- Binds to granulosa cells & causes follicles to develop and the theca interna to start secreting oestrogen and inhibin
- This inhibits FSH and LH and causes endometrial proliferation
- Granulosa cells keep building up and secrete more oestrogen until the critical limit of oestrogen is met where it starts to positively feedback on LH
- LH spike causes ovulation
- Corpus luteum develops and starts to secrete oestrogen, progesterone and inhibin in large quantities
- this inhibits FSH and LH and causes development of glands in endometrium (starts the secretory phase)
Which hormone does inhibin inhibit?
FSH
From where is human chorionic gonadotrophin released from?
Syncitiotrophoblast, which appears approx 14 days post fertilisation
How does the endometrium change throughout the menstrual cycle?
The oestrogen will interact with the basal layer and cause it to proliferate and create a functional layer. When progesterone starts to be produced, glands will become more dense and more coiled.
If progesterone stimulation is removed it will degenerate
What effects on the body does progesterone have?
- thickening of endometrium into secretory form
- thickening of myometrium but reduction in motility
- secretion of thick, acidic mucus at the cervix to stop sperm and infection entry
- increased body temp
- metabolic changes
What effects does oestrogen have on the body?
- endometrium proliferation
- growth and proliferation of myometrium
- secretion of thin, alkaline mucus at the cervix
- skin, hair and metabolic changes
How can giving GnRH tablets help endometriosis, fibroids and hyperprolactinaemia??
Giving constant GnRH desensitises you to it (as release is normally pulsatile), so you stop producing LH, FSH and so oestrogen.
What is primary and secondary amenorrhea?
Primary= no menses before age 16 Secondary= no menses for more then 6 months
What structural defects may cause amenorrhea?
- agenesis of uterus, vagina ect
- imperforate hymen
Where may defects be to cause amenorrhea?
- hypothalamus
- pituitary
- ovaries
- uterus
Looking at hormone levels may indicate the level of the pathology
What is menorrhagia?
excessively heavy periods
What could cause menorrhagia?
- endometrial cancer
- polyps
- fibroids
- hypothyroidism
- copper coil
- bleeding disorders
- drugs such as warfarin
What is dysmenorrhoea?
painful periods
Give 2 primary and 2 secondary causes of dysmenorrhoea?
primary= idiopathic, uterus producing prostaglandins casing painful contractions secondary= endometriosis or obstruction
What is premenstrual syndrome?
severe cyclical pain, w/ irritability, low mood, anxiety, breast tenderness, bloading ect 1 or 2 weeks before a period. The severe form is pre menstaul dysphoric disorder
What could cause irregular bleeding?
- STIs
- cervical cancer (usually post coital bleeding)
- endometrial polyps/ cancer
- hormonal contraception esp minipill
Define menopause
The time when there has been no mestruation for 12 consecutive months and no other physiological/ pathological cause can be identified
When is early menopause?
menopause before age 45
What is surgical menopause?
menopause occuring due to bilateral oophorectomy
When should menopause occur?
between 45-55 (avg 50)
What is pre menopause?
The follicles are degenerating leading to irregular cycles, the follicular phase tends to be shorter and ovulation does always occur. Oestrogen production steadily reduces.
Why does FSH rise more than LH in premenopause?
there is less oestogen and inhibin due to less follicular development. Less oestroegn= more LH and FSH but also less inhibin means FSH can rise further
What is perimenopause?
the transition phase where the drop in oestrogen is staring to cause noticeable changes - flushings, irritability ect.
Why are oestrogen levels dropping not used to diagnose menopause?
Because some oestrogens are still being produced by adipose tissues
What changes/ signs occur in early menopause/ premenopause?
hot flushes, sweating, insomnia, menstural irregularities, psychological symptoms
What changes occur in intimidate menopause (55-65)?
vaginal atrophy
painful sex/ lack of lubrication
skin atrophy
mixed incontinance as pelvic floor weakens
What changes are seen in late menopause (65+)
oesteoporsis
atherosclerosis
alzheimers disease
Why does dysfunctional uterine bleeding sometimes occur during menopause?
some oestorgens are still produced by adipose tissues but no progesterones as no corpus luteum means no maintainance
What psychological changes occur in menopause?
More irritable, insomnia, low libido, fatigue, headache, depression. These are probably due to hormones and fact they cant sleep well due to hot flushes
What visible/ physical changes occur in menopause and why?
- wrinkles- elastin degrades
- fat deposition around hips and buttocks
- hair becomes dry, coarse and thin
- voice deepens
- breast tissue flattens and shrivels
- fat in labia majora decreases
- pubic hair decreases as testosterone decreases
Why does menopause cause constipation and bloating?
motor activity in the gut decreases
Why are androgens other than oestrogen such as testosterone often high in early menopause?
low oestrogens= high GnRH= high stimulation of other androgens
How can adverse affects of menopause be treated non- hormonally?
Lifestyle changes: reduce fat intake and increase exersize to stop fat gain, wear thin clothing, avoid caffine, spicy foods and alcohol to avoid hot flushes
How can hormone therapy be used in menopause?
HRT is a combination of oestrogen (to reverse anti oestrogen affects) and progesterone. It may prevent/ reverse/ limit some effects of menopause whether given before, after or during menopause. It may limit osteoporosis but is not recommended as first line.
What adverse effects does HRT have?
increases cancer risk, increases coagulability
Why is progesterone also given in HRT unless they’ve had a bilateral hysterectomy?
It inhibits the proliferative effects of oestrogen at the uterus to reduce cancer risk.
What is hypergonadotrophic hypogonadism? How will it present?
Where your gonads fail to respond to LH/FSH to produce testosterone. As a consequence, you will have delayed puberty and no negative feedback leading to high levels of GnRH, FSH and LH.
What is the most common cause of delayed puberty when GnRH and/or LH & FSH is low?
This is hyPOgonadotrophic hypogonadism. It could be an anterior pituitary or hypothalamus defect in not producing the GnRH,LH or FSH yet, but more likely it is constitutional delay (esp if GnRH is low), and given time puberty will occur eventually.
What is kallman syndrome?
Abnormal development of GnRH releasing neurones- olefactory neurones also tend to be affected.
What affect can meningitis have on puberty?
Cause early or precocious puberty
What hormone is responsible for the increase in basal body temp after ovulation?
Progesterone
give 3 primary causes of anovulation?
hyperprolactinaemia, polycystic ovarian syndrome, pregnancy, emotional stress,
Give 3 secondary causes of anovulation?
Dysgenetic gonads, hypothalamic dysfunction, hypothyroidism, kallmans syndrome
