Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
What is SHBG? What is Megalin? how do the two interact?
|
Sex Hormone Binding Globin binds to sex hormones allowing for their circulation in blood. SHBG binds to Megalin which is a receptor on reproductive tissue that internalizes the bound SHBG and causes the sex hormone to be free once in the cell.
|
|
|
What is the SRY gene? what does it produce and what is its product's functions?
|
SRY is a gene on the Y chromosome which determines maleness and produces TDF (testes determination factor) causes the Medullla of the devolping gonad to be well developed and the cortex to be degenerate leading do the testes' formation.
|
|
|
What is the origin of the testes?
|
The endodermal cells of the primitive gut.
|
|
|
What are the sperm cords formed from and how?
|
They're formed on top of the coelom by upward movement and enclosing around primordial germ cells (sperm).
|
|
|
What is the initial step in the testes' development?
|
The formation of fibrous connective tissue to separate sex cords from the surface epithelium.
|
|
|
(Testes' Development) What is the Mesoenpheric duct? What does it interact with? what does it form?
|
The mesoenpheric duct (aka wolffian duct) connects to the rete testes to form the epididymus. Its presence is maintained by test secretions from Leydig cells.
|
|
|
(Testes Development) What are seminiferous cords' function and what are they composed of?
|
They are made of sertoli cells which secrete Anti Mullerial Hormone to inhibit the formation of mullerian ducts.
|
|
|
What is DHT? how is it formed (precursor) and where is it formed?
|
5-alpha Dihydrotestosterone is formed from testosterone by 5 alpha reductase inside of target organs.
|
|
|
What male delopmental characteristic does testosterone control? What about DHT?
|
Testosterone regulates male internal genital development: vas defference, epididimus, seminal vessicle. DHT regulates external male genital development: Genitalia and further development of testes (secondary male characteristics).
|
|
|
What is the missing link hypothesis for puberty? what is the gonadostat hypothesis for puberty?
|
Missing link suggests that something is missing from the HPG axis prior to puberty. Gonadostat assumes puberty occurs because of a decreased sensitivity to gonadal steroids
|
|
|
What is the autocrine GnRH hypothesis? what types of "pulses" does it include?
|
An intrinsic pulse generator consisting of fast pulses which the GnRH neuron fires and causes a Ca influx and activates A. Cyclase which stimulates more GnRH secrtions. And slow pulses which occur when local GnRH levels are high causing a change from Gs activity to Gi, interrupting the GnRH rise.
|
|
|
What is the role of estrogen in the development of the male fetus?
|
Testosterone is converted by aromatase to estrogen in fetal brain cells which binds to DNA and initiates masculinizing gene expression.
|
|
|
(Testes Development) What is the mesenchyme? what does it do? what is it made of?
|
Mesenchyme is undifferentiated mesoderm that seperates the seminiferous cords . Mesenchyme will go on to produce Leydig cells which produces testosterone.
|
|
|
What is the structure of Progesterone? What is the Structure of dehydroepiandrosterone?
|
Dehydroepiadnrosterone is a C19 steroid with a ketone on C17 and a OH group on C3. Progesterone is a C21 steroid with an Acyl group on C17 and keytone on C3.
|
|
|
What are the activities of 17 alpha hydroxylase? Which molecules does it react with?
|
It converts progesterone 17 alpha hydroxyprogesterone. It also converts pregnenolone to 17 alpha hydroxypregnenolone.
|
|
|
What is the structure like for 17 alpha ketosteroids? what and where are they formed?
|
They have C17 ketone groups and C3 OH groups. Theyre formed from testosterone in the liver.
|
|
|
What is the effect Testosterone had on the Hypothalamic Pituitary Gonadal Axis?
|
Test negatively feeds back on the hypothatlamus and pituitary, decreasing GnRH pulsatility and FSH/LH release.
|
|
|
What is the first step that occurs when LH binds to Leydigs cells? what is the end result/final product produced?
|
LH binds, signals through a cAMP pathway and causing the conversion of cholesterol to pregnenolone, a precursor in the production of testosterone.
|
|
|
What is the function of inhibin? and what is its structure?
|
Inhibin is secreted by sertoli cells to inhibit FSH release from the pituitary. Inhibin A: subunit 1) alpha subunit 2) Beta a. Inibin B: subunit 1) alpha subunit 2) Beta b.
|
|
|
What is the function of activin? and what is its structure?
|
Activin stimulates FSH and augments sperm population (spermatiogenesis). Activin A: subunit 1) Beta a subunit 2) Beta a. Activin AB: Subunit 1) Beta a Subunit 2) Beta b. Activin B: Subunit 1)Beta b Subunit 2) Beta b.
|
|
|
What are FSH effects on testes/testosterone production?
|
It binds to sertoli cells using a cAMP pathway to initiate the synthesis of androgen binding protein which binds to testosterone to initiating spermatogenesis forming spermatid in the seminiferous tubule, which then travel to the epidydimus to mature.
|
|
|
What are the effects of Estrogen in Males? What causes the presence of estrogen?
|
Estradiol interferes with Testosterone synthesis and spermatogenesis. E2 is converted from testosterone by aromatase, inhibits testosterone production in leydig cells. E2 (converted by aromatase) in sertoli cells inhibits spermatogenesis.
|
|
|
What are the two types of Androgen Insensitivity?
|
Receptor negative androgen resistance: a mutation in the androgen receptor preventing the steroid from binding.
Receptor positive androgen resistance: a mutation preventing the androgen receptor from binding to the androgen receptor DNA response element. |
