Endocrine L4: Reproduction Flashcards
Sex determined by chromosomes – XX, XY from fertilisation – ‘_____’
genetic sex
What are genetic sex?
Sex determined by chromosomes – XX, XY from fertilisation
All embryos have ‘______’ gonads, Wolffian ducts & Müllerian ducts
bi-potential
Not gender specific –> Can turn into male or female Initially –> gonads have both sex –> turn into one
If male, gonads differentiate into testes from seventh week of gestation, ovaries form after ninth week – ‘_____’
gonadal sex
What is gonadal sex?
If male, gonads differentiate into testes from seventh week of gestation, ovaries form after ninth week
When does gender get developed = after 9 weeks The baby either develops as a male or stay as a female If you have no changes –> develop into a female (eg. didn’t have changes or it didn’t work) Only when things change, start to develop into a male Default development = ____ (female/male)
female
After 8 weeks gestation testosterone production by testes causes development of Wolffian ducts into male internal reproductive organs, dihydrotestosterone (DHT) causes masculinisation of external genitalia - ‘______ ‘
phenotypic sex
What are phenotypic sex?
After 8 weeks gestation testosterone production by testes causes development of Wolffian ducts into male internal reproductive organs, dihydrotestosterone (DHT) causes masculinisation of external genitalia
_____ (testes/ovaries) become dormant after birth, _____ (testes/ovaries) quiescent until onset of puberty
Testes; ovaries
Onset of puberty influenced by _____, _____, ______ and ______
bodyweight/obesity, genetics, health, melatonin
- Need to reach a certain body weight –> puberty is getting earlier now because children are growing quicker and have high body weight
- Severe obesity can delay puberty
- If parents went into puberty early
Pre-pubertal increase in pulses of ________ trigger production of gonadotrophins (LH & FSH) from anterior pituitary, which trigger gonadal activity
gonadotrophinreleasing hormone (GnRH)
____ and _____ are the same hormones for males and females and work on testes or ovaries
FS; FSH
Production of ____ steroids cause development of secondary sexual characteristics and fertility
sex
Produced within gonads = secondary changes (body shape, voice changes and fertility)
Growth spurt associated with increase ____/_____ and sex steroids
growth hormone/IGF-I
Why does growth hormone affect puberty?
Will stop you growing = cause epiphyses to close = stop you from getting taller (initially get growth spurt)
How does the control of reproduction occur?
- Hypothalamus (centrally controlled) produces pulses of GnRH
- Stimulates pulsatile release of LH and secretion of FSH
How does the negative feedback control work?
How does the male reproduction of hormones work?
What does testis structure and spermatogenesis?
What are 2 types of cells in testicular function?
- Leydig cells
- Sertoli cells
What are Leydig cells?
produce testosterone and small amounts of other steroids
- eg oestradiol &dihydrotestosterone (DHT) in response to LH
What is the function of testosterone?
either acts on adjacent Sertoli cells or is released in the blood, actions outside testes
What are Sertoli cells?
(with support from testosterone & FSH)
- maintain tight junctions (to create seminiferous tubules)
- nourish germ cells & support spermatogenesis (Maturation of sperm)
- secrete androgen binding protein (ABP)
- secrete inhibin
- convert testosterone to DHT or oestradiol (Lipophilic hormone (carried around on a binding protein))
What is the mechanism of actions for androgens?
Problems with liver = less binding proteins = more testosterone floating around in the liver
For males, once they get going, they keep going (eg. produced for the rest of their lives)
- Can be fertile well into their 90s
What are the 5 actions of the action of androgens?
- Sex determination in foetus
- At puberty: growth spurt, closure of epiphyses
- Development & maintenance of male secondary sexual characteristics - external genitalia, deep voice, hair growth pattern, skin, body shape (lean muscle mass, low body fat)
- Development & maintenance of accessory sex organs & libido
- Anabolic actions, effects on brain & bone
What are 5 characteristics of the female sexual development?
- Just prior to puberty GnRH pulse generation begins, LH & FSH are released from anterior pituitary - ‘awakens’ ovary – start of follicular development
- Developing follicles release oestrogens – development of female secondary characteristics, eg fat deposition, growth & maturation of reproductive tract
- Growth of auxiliary hair, libido and pubertal growth spurt due to pubertal rise in adrenal androgens
- When sufficient GnRH, LH & FSH to support full follicular development to ovulation first ‘period’ - menarche – menstrual cycles commence
- Oestrogens cause closure of epiphyses
Just prior to puberty GnRH pulse generation begins, ___ and ____ are released from anterior pituitary - ‘awakens’ ovary – start of follicular development
LH; FSH
Developing follicles release _______ which cause the development of female secondary characteristics, eg fat deposition, growth & maturation of reproductive tract
oestrogens
Enlargement of ovaries
Growth of auxiliary hair, libido and pubertal growth spurt due to pubertal rise in adrenal _____.
androgens
When sufficient GnRH, LH & FSH to support full follicular development to ovulation first ‘period’ - menarche – _______ cycles commence
menstrual
First period (menarche): First follicles gets big enough to ovulate
In females, ______ cause closure of epiphyses
oestrogens
Bones stop getting longer
What are 6 characteristics of the menstrual cycle (follicular development)?
- At birth primordial follicles are present in ovary (2 million) Most of them don’t survive and left if 200, 000 when puberty starts
- Every day small numbers begin development & grow, but most die (atresia), at puberty ~200,000 remain
- To grow through to ovulation a follicle must receive correct level of gonadotropins (LH & FSH), each cycle 15-20 follicles develop but only one continues to ovulation – the rest die
- LH & FSH have a cyclic pattern of release Allows one of the follicles to continue to develop
- Once a follicle becomes fully developed requires LH surge to cause ovulation – follicle then becomes corpus luteum (CL)
- Both developing follicle and CL produce steroids, follicle = oestrogen, CL = progesterone
In females, you need ____ first –> once it turns into ____–> need ______
oestrogen; CL; progesterone
What do … look llike?
AAD
A
What does the levels of FSH and LH look like over a cycle?
A
What does the levels of FSH and LH look like when combined with ovulation in a cycle?
What does the levels of FSH and LH look like when combined with ovulation and estrogen and progesterone in a cycle?
What does control of follicular phase look like?
What does control of LH surge look like?
What does control of luteal phase look like?
What does the uterus look like throughout a cycle?
What does the overall cycle look like?
What does the overall cycle look like with timeline?
What are the 4 effects of female sex steroids?
- In normal cycle there is a brief “steroid free period” followed by sequential exposure to oestrogen then progesterone + oestrogen
- Oestrogen stimulates both E-receptor and P-receptor expression
- Alone progesterone has very few effects (its actions require oestrogen priming)
- Menopause - very low oestrogen and progesterone as menstrual cycles cease regression of reproductive tract reversed by treatment with oestrogen (HRT)
What are 4 characteristics of menopause?
Run out of eggs very low oestrogen and progesterone as menstrual cycles cease regression of reproductive tract reversed by treatment with oestrogen (HRT)
What are the principal functions of oestrogen?
cellular proliferation; growth of the tissues of sexual organs (soft and healthy); growth/modification of other tissues related to reproduction
What are the principal functions of progesterone?
prepares the reproductive tract (and other organs) for pregnancy, modifies or blocks (antagonises) the action of oestrogen
What does pregnancy and lactation look like in terms of the cycle?
AA
What do placental hormones look like in terms of a cycle?
What are 3 characteristics of lactation- development during pregnancy?
- During pregnancy oestrogen stimulates duct growth, progesterone stimulates alveolar lobule formation in breasts Also prolactin (from mother)
- Prolactin & human chorionic somatomammatrophin (aka hPL) promotes gland development and induces enzymes for milk production (from about 4 months of gestation breast capable of milk production) If a women has a mischarge after 4 months –> they can go into lactation (quite devastating)
- High levels of oestrogen & progesterone (from placenta) prevent initiation of lactation until after birth
What is oxytocin prior to birth?
High placental oestrogens in late pregnancy increase number of oxytocin receptors in uterus, oxytocin stimulates rhythmic uterine contractions in labour (through neuroendocrine reflex/positive feedback loop)
What happens to hormones after birth?
Decrease in oestrogen & progesterone (from placenta) permits lactation to commence
What was oxytocin after birth?
Stimulated by suckling, causes contraction of myoepithelial cells in breast promotes milk ejection
What is prolactin?
Suckling stimulus promotes release of prolactin, which acts on alveolar epithelial cells to increase milk secretion maintains milk production
What is an example of a reproductive disease?
Prolactinoma
What is prolactinoma?
Prolactinomas are the commonest pituitary adenomas, prolactin, also produce high levels of cause compression of pituitary and optic chiasm
What are the symptoms of prolactinoma?
caused either by increased prolactin levels (hyperprolactinemia) or by ‘mass’ effect (due to size of the tumour)
What are the 4 Hyperprolactinemia causes of prolactinoma?
- Amenorrhea (Done have normal menstruation)
- Galactorrhea (infrequent in men) (Milk production)
- Loss of axillary and pubic hair
- Hypogonadism, gynecomastia, erectile dysfunction (Development of breast tissue (even in men))
What are the 2 mass effects of prolactinoma?
- Bi-temporal hemianopsia (as optic chiasm compressed) (Visual effects –> can’t see periphery on other eyes (can see straight through only))
- Vertigo, nausea, vomiting
