1.1 Puberty Flashcards
(44 cards)
How does TRH affects gonadotrophin levels?
high TRH levels): stimulates prolactin production → stimulates dopamine release → inhibits GnRH → limits gonadotrophin (LH, FSH, oestrogen, progesterone) levels
Effect of TSH?
Stimulates T3 and T4 production
Effect of prolactin?
Stimulates milk production
Effect of GH?
Stimulates growth (in children) & maintains bone strength (in adults)
Effect of FSH?
Stimulates oestrogen production and oocyte development
Effect fof LH?
Stimulates oestrogen and progesterone production
Effect of ACTH?
Stimulate cortisol and androgen production
Effect of vasopressin?
Regulates osmolality & blood volume
Effect of oxytocin?
Triggers uterine contractions during labour
Each mature ovarian (Graafian) follicle is formed from an outer ___________ layer, and inner ___________ layer and a fluid-filled central cavity (antrum):
• Theca layer produces androgens which are converted to oestrogens in the granulosa layer (mainly oestradiol and oestrone)
As the secondary follicle grows under the influence of FSH, fluid (follicular liquor) accumulates between the granulosa cells → become confluent and forms the antrum:
• Oocyte becomes surrounded by several layers of granulosa cells, and is attached to the wall of the follicle by the ___________
• Thecal cells outside the basal lamina of the granulosa cells differentiate into the inner theca interna (pale, larger) and outer theca externa (appears like regular stroma)
• Progesterone is only produced later by the corpus luteum (after ovulation)
theca;
granulosa;
cumulus oophoricus;
What functions do oestrogens have?
- Stimulate breast development
- Promote growth and maturation of bone and pubertal growth spurt
- Increases binding globulin formation in the liver (e.g. SHBG, TBG)
- Increases HDL and reduces LDL (cardioprotective function)
- High levels stimulate LH production → triggers ovulation
What is the function of progesterone?
Progesterone is mainly involved in maintaining the pregnancy:
• Encourages secretory changes in the endometrium and encourages endometrial proliferation
• Thickens the cervical mucus to prevent sperm penetration (after fertilisation)
• Prevents uterine contractions (and other smooth muscles including in the lactiferous glands to prevent lactation during pregnancy)
where is oestrogenn synthesized and what is the synthesis mediated by?
- Peripheral conversion of androgens in adipose tissue → mediated by FSH release (in a negative feedback loop)
- Oestradiol synthesis in the ovary requires CYP450 and HSD (hydroxysteroid dehydrogenase) enzyme families
where is progesterone synthesized?
Produced by the ovaries, adrenal glands, placenta (from conversion of cholesterol → pregnenolone → progesterone) and stored in the adipose tissues
which receptors do progesterone bind to?
intracellular progesterone receptor and mineralocorticoid receptors (with greater affinity than aldosterone and cortisol → strong inhibitor)
what does thelarche means?
Start of breast development
What does pubarche means?
Development of pubic hair
what does adrenarche means?
Development of secondary sexual hair and sebaceous gland formation in the axilla and skin → sweat, body odour and skin oiliness (may cause acne)
• Due to adrenal zona reticularis maturation → androgen production (adrenal source; not gonadal source)
What does menarche means?
Onset of menstrual bleeding
How is the breast and pubic hair like at stage I puberty in girls?
- breast: only papillae elevated
- no pubic hair
How is the breast and pubic hair like at stage II puberty in girls
- Areola and breast elevated as a small mound (areola enlarged)
- Sparse downy, slightly pigmented hair mainly growing along the labia
How is the breast and pubic hair like at stage III puberty in girls
- Further enlargement of breast and areola with smooth contours
- Longer coarser hair (mostly curly) over the junction of the labia
How is the breast and pubic hair like at stage IV puberty in girls
- Areola and papilla form a contour above the breast tissue
- Pubic hair: Adult in appearance but smaller area covered and no spread to medial surface of thighs
How is the breast and pubic hair like at stage V puberty in girls
- Areola flattens in line with breast contour and only papilla elevated
- Pubic hair: Adult in appearance and quantity with spread to medial surface of thigh
