(M) Lec 5: Reproductive Function (Males) Flashcards
Familiarize yourself with the 6 sources of reproductive hormones
- Gonads (testes and ovaries)
- Hypothalamus
- Pituitary Gland
- Adrenal Gland
- Peripheral non-gladular tissues
- Placenta
What are the 3 sex steroids?
- Androgens
- Estrogens
- Progesterone
Sex Steroids
- The sex steroids are synthesized from ____
- The adrenal ____ synthesizes weak androgens
- Cholesterol (the CPPP ring)
- Cortex
Sex Steroids
What are the 3 weak androgens?
- Dehydroepiandrostenedione (DHEA)
- DHEA sulfate (DHEAS)
- Androstenedione
Note: They have weak affinities to their receptors
Sex Steroids
What are the 3 estrogens?
- Estrone
- Estradiol
- Estriol
Sex Steroids
- The testis converts adrenal androgens into ____
- Through the enzyme, ____, it will become ____ which is more androgenic (10x) than the first product
- The ovary converts testosterone to ____ and androstenedione to ____
- The conversions in the ovary are through the enzyme, ____
- Testosterone
- 5-alpha-reductase; dihydrotestosterone (DHT)
- Estradiol; Estrone
- Aromatase
Sex Steroids
If 5-alpha-reductase is absent, there will be a failure to convert testosterone to dihydrotestosterone which results in?
Conversion into a type of estrogen instead resulting in female features
Sex Steroids
If aromatase is absent, there will be a failure to convert testosterone to estrogens which results in?
Male features on a female patient
Binding Proteins
- 45% of the androgens, testosterone, and estrogens are strongly bound to this
- This transports both progesterone and glucocorticoids
- 50% are loosely bound and will dissociate to become available for interaction with target cells
- Sex Hormone-Binding Globulin (SHBG)
- Corticosteroid-Binding Globulin (CBG)
- Albumin
Binding Proteins
- Makes up 1-2% (or 2-3%) of the hormones
- Are biologically active and can exit the vascular system by diffusion to interact with target cells
Free/Unbound
- Paired, ovoid organs that hang from the inguinal canal by the spermatic cord
- Consists of seminiferous tubules and the interstitium
- Functions in the production of sperm and reproductive steroid hormones
Testes
Testes (analogy)
- Seminiferous tubules are to ____ & ____ cells
- The interstitium is to ____ cells
- Germ Cells and Sertoli Cells
- Leydig Cells
Regulation of Male Reproduction
- The hypothalamus will release the ____ hormone in a ____ pattern
- This will stimulate the anterior pituitary gland to release ____ and ____
- Gonadotropin-Releasing Hormone (GnRH); pulsatile
- Follicle-stimulating Hormone (FSH) and Luteinizing Hormone (LH)
Regulation of Male Reproduction
- The ____ targets the Leydig cells to produce testosterone
- The ____ targets the Sertoli cells to produce androgen-binding proteins (ABP)
- TOF: The testosterone binds to the ABP to aid the survival of sperm cells
- LH
- FSH
- True
Regulation of Male Reproduction
- As spermatogenesis progresses and sperm production increases, the Sertoli cells release ____ which inhibits the release of FSH only (negative feedback)
- With decreased FSH levels, the stimulation of the testes to produce more sperm is ____
- The Sertoli cells also secrete an anti-____ hormone
- Inhibin
- Reduced
- Mullerian
Regulation of Male Reproduction
- When a fetus is already 8 months old, it harbors 2 ducts namely, ____ and ____
- Which duct develops into female internal genitalia?
- Which duct develops into male internal genitalia?
- Paramesonephric Duct and Mesonephric Duct
- Paramesonephric (or Mullerian) Duct
- Mesonephric (or Wolffian) Duct
Regulation of Male Reproduction
- In male embryogenesis, the developing testes produce ____ to cause regression of the ____ ducts and maintain male characteristics
- In female embryogenesis, the absence of ____ results in the development of the ____ ducts to maintain female characteristics
Both numbers (Anti-Mullerian Hormone and Paramesonephric Ducts)
A group of 19-carbon compounds wherein testosterone is the principal hormone of this classification
Androgens
Androgens
- The primary precursor of natural estrogens
- Converted to testosterone and other androgens; also the parent structure of estrone
- Is converted to testosterone
- A metabolite of testosterone but is more potent (most androgenic androgen)
- Dehydroepiandrosterone (DHEA)
- Androstenedione (A4)
- Androstenediol (A5)
- Dihydrotestosterone (DHT)
What makes up the bioavailable testosterone?
Free testosterone + testosterone loosely bound to albumin
Levels of Testosterone
- Testosterone is present as HCG stimulates its release
- There is a little amount which declines at age 1 and becomes absent during the childhood years
- There is a surge stimulated by LH up until adulthood
- Testosterone levels decline as well as spermatogenesis
- Fetal
- Postnatal
- Puberty
- Andropause
Puberty
- This refers to the cell awakening of the adrenal glands wherein it begins secreting sex hormones
- This refers to the maturation of the gonads/enlargement of the genitalia
- An enhanced linear skeletal growth due to increased testosterone
- Adrenarche
- Gonadarche
- Growth Spurt
Puberty
What is the earliest sign of puberty in males and females (2)?
- Males: Testicular enlargement
- Females: Breast enlargment
Puberty
Refers to the failure of the testes to descend due to lack of testosterone
Cryptorchidism