4.8 Endocrine male Flashcards
5 significant hormones of male reproduction?
1) testosterone
2) follicle stimulating hormone
3) luteinising hormone
4) human chorionic gonadotropin
5) inhibin
testosterone chemical neture and source?
- steroid
* Leydig cells of testes= ‘interstitial cells’ between seminiferous tubules
for the first 40 days (6 weeks) an embryo has ______ gonads
undifferenciated
at six week either:
– development of cortex= no TDF =ovaries
– devel of medulla= yes TDF = testes
what gene serves as a testes-determining factor (TDF)?
SRY (sex-determining region) on Y chromosome serves as testes-detemining factor
absence of TDF means?
ovaries will develop
1) testosterone secretion begins?
2) peaks?
3) declines
4) levels rise again?
1) begins as early as 8 weeks after conception
2) peak at 12-14 weeks
3) declines to very low levels at 25 weeks
- -when delivered, equal for both genders
4) rise again at puberty
what is testosterone 2 main functions?
1) sex differentiation (SRY and TDF)
2) descent of testes (later inpregnancy
1) must have testosterone for development of normal?
2) if absenct in male then devel of ___
3) if absent in male than devel of _____
genetalia
2) female genetalia
3) male genetalia
how is genetic sex determined?
by fertilization of ovum with sperm possessing Y or X chromosome
present of absense of ____ chromosome determiens if gonads are?
Y chromosome determines is gonads are testes or ovaries
17alpha hydroxylase is required for?
conversion of cholesteral to testosterone
*otherwise you’d have under-developed male infants
descent of testes promoted by?
testosterone and other factors like organs pushing testes down
testes must be at cooler temps such as 35 C instead of 37 why?
for spermatogenesis
define chryptorchidism
undescended testes = no spermatogenesis
*crypt= hidden; orchid= testes
undescended testes happen how often?
10% (usually 1) and higher in premies
- -2% by age 2
- -0.3% by puberty
why is treatment important for undescended testes?
1) for both spermatogenesis (sperm devel)
2) avoid heath complications like tumors
why must ndescended testes be surgically moved early?
after puberty, higher temps will cause irreverssible damage to spermatogenic epithelium AND increase risk of malignant tumors
3 main functions of testosterone at puberty?
1) primary sex characteristics (devel of egnetalia for reproduction)
2) secondary sex characteristics (muscularity, hairy, low voice)
3) maturation of spermatozoa (mature and mobile sperm)
what are primary sex characteristics?
growth and maturation of sex organs
secondary male sex characteristics?
1) muscular hypertrophy (making contractile proteins)
2) skeletal growth (and EPIPHYSEAL UNION)
3) haryngeal hypertrophy and vocal cord thickening (deeper)
4) pubic hair
5) eccrine (sweat) and sebaceous (oil) glandular activity
WHAT INITIATES PUBERTY?
hypothelamus
hypothalamus maturation acts as biological clock to all puberty processes such as?
GnRH= releasing factors to affect Ant Pit
FHA= circoli cells of testes to make sperm
LH= testosterone production
*adrenal cortex has a pre-puberty peak of androgens that MAY play a role in preparing testes to produce more testosterone and sperm
describe mature sperm?
happy mature motile spermatozoa
testosterone mechanisms of action?
steriod; so it enters cell, cell nucleus, turns on genes
*anabolic= build things, promote AA uptake, increase protein synthesis
name the 3 gonadotropins
1) follicle stimulating hormone (FSH)
2) Luteinizing hormone (LH)
3) human chorionic gonadotropin (hcg)
what gonadotropin is ONLY present during fetal development?
human chorionic gonadotropin (hcg)
-comes from tropoblast portion of tropocyst (part that implants inuterus)
gonadotropins sources
- ant pit > FSH and LH (after puberty aks after maturation of hypothalamus)
- trophoblast and placenta > hCG during fetal development
trophoblast eventuarlly becomes?
placenta
FSH function?
stimulates sertoli cells of testes > spermatogenesis
1) primary spermatocyte
2) add FSH
3) secondary spermatocyte (non-motile immature sperm)
4) testoseterone
5) mature motile sperm
LH function?
stimulates Leydig cells of testes to make testosterone
1) LH aka
2) Leydig cellsaka
1) LH aka ICSH because
2) Leydig cells aka interstitial cells
hypothalamus secretes releasing factors to ant pit thru?
portal system that stimulates gonadotrophs to stimulate FSH and LH (for male)
what has actions like LH?
hCG
function of hCG?
like LH
**stimulates Leydig cells= testosterone during FETAL development
variation of hormone secretion prier to puberty
=incomplete development of hypothalamus
- little or no pituitary gonadotropin secretion
- only time testosterone secretion is high is when hCG is present to stimulate testosterone secretion
- no timulus for testosterone secretion between birth and puberty
variation of hormone secretion at puberty
=development of hypothalamus and neurons responsible for GnRH production and secretion
- -increase FSH (spermatogenesis for secondary sperm)
- -increase LH (testosterone production to make mature motile sperm)
variation of hormone secretion after age 20
***how is this different from females?
VERY GRADUAL decline inleydig cell function of testosterone secretion
- young male= 7mg/day
- 70 year old male= 4 mg/day
- ** female gonadotropin levels sky-rocket at menopuase when their estrogen and progesterone levels drop
What is unique about FSH and LH control mechanism?
they are controlled independently even through both are produced in same cell
**castration causes increase in FSH and LH, but addition of testesterone ONLY causes LH to go back to normal
testosterone inhibits ___ production and secretion? where?
LH
*at both the hypothalamus and pituitary
inhibin is produced by?
sertoli cells of testes
inhibiin inhibits?
FSH production and secretion at the pituitary only
hypogonadism (eunuchism) causes? symptoms?
- causes are castrasion and underdeveloped testes
* symptoms are child-like sexual development, DELAYED epiphyseal plate closure, and muscular weakness
hypergonadism (eunuchism) causes? symptoms?
- cuases are Laydig cell tumor and excessive adrenal androgens
- symptoms are early sexual development, EARLY epiphyseal plate closure and muscular hypertrophy
do we notice hypergonadism more in woman or men?
notice in women and children more!
