Ch 80, 81, 82 Flashcards
What are 3 different ways of sexual differentiation?
genetic sex, gonadal sex, phenotypic sex.
What is genetic sex?
male- XY, Female- XX
What is gonadal sex?
Males- testies. Females- ovaries.
What is phenotypic sex?
Determined by action of hormones produced by gonads during fetal life.
What will the paramesonephric duct become in females?
Fallopian tubes, uterus and part of vagina.
In males what will the mesonephric ducts become?
Connections between testis and prostate: epididymis, vas deferens, semial vesicles.
What leads to the development of female genital tract and genitalia?
Lack of testosterone and MIS (which are produced by the fetal testies).
In females high levels of androgens before external genitals have differentiated can result in what?
Male phenotype or malformation.
Where is GnRH synthesized at?
In the hypothalamus.
How will the hypothalamus release GnRH?
In vesicles from the median eminence in a pulsatile fashion through the hypothalamohypophyseal portal blood.
GnRH reaches the anterior pituitary gland and binds to what?
membrane receptors on gonadotrophs.
How is synthesis and secretion of GnRH regulated?
By feedback control from gonadal hormones.
Besides gonadal hormones how will the synthesis and secretion of GnRH regulated?
stress, pheromones, light/dark cycles.
What is the general functions of the gondaotrophes (LH & FSH)?
Promote gametogenesis, and gonadal hormone secretion.
LH and FSH are active in who males or females?
Both.
What happens to levels of LH and FSH in a fetus and why?
We get a spike of these hormones so there are more gonadal hormones secreted to help with development.
What are levels of LH and FSH like in childhood?
Low with no spikes.
What are levels of LH and FSH like during puberty?
They gradually increase.
What are levels of LH and FSH like during the adult reproductive period?
Females- rises and falls monthly. Males- levels off.
What is Senescence?
Growing old or aging. The period after the adult reproductive period.
What are levels of LH and FSH like during senescence?
Females- rises fast and then levels off. Males gradually rises
During gestation GnRH is secreted when?
Week 4.
Secretion of GnRH starts during week 4 of gestation and remains low until when?
Puberty.
During gestation secretion of FSH and LH begins when?
Week 10-12.
Secretion of FSH and LH begins during week 10-12 of gestation and remains low until when?
Puberty.
What levels are higher in childhood FSH or LH?
FSH.
What is puberty?
Transition from non-reproductive to reproductive state.
Puberty is an essential event due to what?
Pulsatile secretion of GnRH.
During puberty what level is higher LH or FSH?
LH.
During puberty plasma levels in females increase with what?
Estrogen and inhibin.
During puberty plasma levels in males increase with what?
Testosterone and inhibin.
Responsiveness of target cells to gonadal hormones that increase at puberty leads to what?
Secondary sex characteristics.
The ovaries produce what during puberty?
Estradiol.
What is menarche?
Onset of menstrual cycles.
When will female growth spurts be at?
between 11-14 years old.
During male puberty what cells will proliferate?
Leydig cells.
What are the 3 major functions of the male reproduction?
- Regulation and synthesis and secretion of hormones. 2. speratomgenesis. 3. Sexual act.
What are the 2 jobs of the testes?
Produce sperm, and secrete hormones.
What hormone will the testes mainly secrete?
Testosterone.
What are the 2 compartment of the testes and what cells are found in the compartments?
- Connective tissue interstitium- leydig cells. 2. Seminiferous tubules- sertoli cells.
The Leydig cells found in the connective tissue intersitium of the testes do what?
They are the primary endocrine area.
What cells produce sperm?
Sertoli cells.
What is inner male genitalia?
The prostate.
How many lobes does the prostate have?
Five.
What will the prostate produce?
A thin alkaline milky fluid.
What is an out-pocketing of the vas deferens?
The semial vesicles.
What % of semen is from the semial vesicles?
70%.
What is the semen like that is secreted from the seminal vesicles?
Energy for sperm because it is rich in fructose, citric acid and prostaglandins.
What are the male hormones secreted by the testes called?
Androgens.
What is the major Androgen?
Testosterone.
Leydig cells make up what % of testes mass?
20%.
Testoternone and FSH leads to what?
Spermatogenesis.
What % of andorgens come from leydig cells and where else can they come from?
95% from leydig cells and 5% can come from adrenals.
Androgens are what type of compounds?
Steroid.
How is dihydrotestosterone synthesized?
From testosterone in some target tissues.
What is androstenedione?
a precursor of testosterone with 1/10th the activity.
Testosterone is released on a diurinal pattern and is high when and low when?
High- morning . Low-night.
What will testosterone levels be like as a fetus and why?
High to masculinize the external genitalia.
What happens to testosterone levels after birth?
They are low until puberty when they start to ramp up and then they level off as an adult and then start to decline around age 60.
What causes testosterone levels to drop off around 60 years of age?
The leydig cells lose responisveness to LH.
What are the results of testosterone levels droping off at age 60?
Loss of libido, but spermatogenesis still occurs.
What is an androgen?
A male sex hormone.
What % of androgens circulate in blood bound to proteins?
97-98 percent.
Since most of the androgens are bound to proteins in the blood how long will they last before they are transferred to target tissues or degraded?
30 minutes to several hours.
What is the major protein that the androgens will bind to?
Sex hormone-binding globulin, and some to albumin.
2-3 % of testosterone in the blood is unbound and is active and will be converted to what in target tissues by what?
Converted to dihydrotestosterone by 5-alpha reductase.
Excess testosterone is exreted how?
Through liver via bile or kidneys via urine.
What part of target cells will testosterone bind to?
Cytoplasmic receptors since it is a steroid hormone and can pass through the cell membrane.
Once testosterone binds to receptors in the cytoplasm of target tissues what happens?
Testosterone will then enter the nucleus and affects DNA-RNA transcription, translation and protein production.
Where will testosterone stimulate production of proteins?
Almost everywhere in the body.
What will the proteins do that were made by testosterone stimulation?
These proteins are then responsible for various actions of the androgens like primary and secondary sex characteristics.
Many target tissues of testosterone have enzymes that convert it to active metabolites. What will aromatase and 5 alpha-reductase convert testosterone into?
Aromatase- E2 (estradiol). 5-alpha reductase- dihydrotestoterone.
In utero what week will testosterone and metabolites start to be produced?
Week 7.
In utero what will stimulate the secretion of testosterone and metabolites?
hCG from the placenta.
What will stimulate the descent of the testis?
hCG that will increase the fetal secretion of testosterone and metabolites.
Testosteron is responsible for what during puberty?
Development of primary and secondary sex characteristics.
What will testosterone do to muscles during puberty?
Increase size by 50% at puberty.
What will make a males voice get deeper during puberty?
Tesosterone secretion that enlarges the larynx and thickens the vocal cord.
What will promote the secretion of male genital tract (prostate and seminal vesicles)?
Testosterone and metabolites.
What effects on the skin will testosterone and the metabolites have?
Increases thickness of skin over entire body.
What will testosterone do to the BMR?
Increase it up to 15%.
FSH most directly controls what?
Spermatogenesis.
In early fetal life the fetal gonadotropins transform primordial germ cells into what?
Speratogonia.
What type of receptors do spermatogonia have and what activates them at puberty?
They have FSH receptors and are stimulated by FSH.
What will testosteron do to inhibin?
Stimulate secretion in a minor role.
Sertoli cells envelop spermatogonia and then the spermatogonia does what?
Enlarges to become primary spermatocyte.
What happens to primary spermatocytes?
They undergo meiotic division to become secondary spermatocytes with 46 chromosomes.
What happens to secondary spermatocytes?
They divided and become spermatid with 23 chromosomes.
What will spermatid become?
Spermatazoa.
How long will the development from spermatogonia to spermatozoa take?
70 days.
How much sperm is produced each day by a male?
70-100 million.
Where and how long will it take sperm to mature?
2 weeks in the epididymis.
The number of sperm produced is directly related to what?
Number of sertoli cells.
What role will GH have in spermatogenesis?
Controls metabolic function of testis and aids in division of spermatogonia.
Semen is made of what % of fluids from where?
vas deferens-10%. Prostate- 30%. Seminal vesicles-60%.
What is the average pH of semen?
around 7.5
What will decrease viscosity of semen to increase motility?
Fibrinolysin from prostate gland.
What makes up the head of a sperm?
Condensed nucleus a thick cap (acrosome) filled with proteolytic enzymes to aid in fertilization.
What is the flagellum of sperm for?
Back and forth movement creating motility.
Sperm can be stored in the vas deferens of the testes for how long?
Up to 1 month.
How long can sperm live for in female?
24-48 hours.
Sperm can be frozen for how long?
Years.
Each month females develop an ova in the ovaries that goes where when?
Midcycle expulsion of this single ovum from ovary into ABDOMINAL CAVITY.
When will GnRH be released from the Hypothalamus?
pulses every 90 minutes in males and females.
How will GnRH secretions change during the monthly cycle?
It will not.
In females when will the anterior pituitary gland start to secrete FSH and LH?
At puberty.