Endocrine Control of Reproduction and Spermatogenesis

This flashcard set covers the endocrine regulation of the male reproductive system, including hormone pathways, the cellular mechanics of meiosis and spermatogenesis, and related clinical outcomes.

When does the onset of puberty lead to the production of GnRH, and which organ produces it?

The hypothalamus produces GnRH (Gonadotropin-Releasing Hormone) at the onset of puberty.

Which two hormones are classified as gonadotropins?

$FSH$ (Follicle-Stimulating Hormone) and $LH$ (Luteinizing Hormone).

What are the specific targets and products of FSH in the male reproductive system?

FSH targets the sustentacular cells of the testes to stimulate the production of Inhibin and ABP (Androgen-Binding Protein).

What is the primary role of LH in the male testes?

LH targets interstitial cells to stimulate the production of testosterone.

How does testosterone exert negative feedback on the brain?

High testosterone levels decrease the secretion of GnRH, $LH$, and $FSH$ by the hypothalamus and pituitary gland.

What is the specific function of Androgen-Binding Protein (ABP)?

ABP concentrates testosterone in the testes to support sperm production.

How does Inhibin regulate sperm production without affecting testosterone levels?

Inhibin selectively inhibits only $FSH$ secretion, which reduces sperm production without modifying testosterone production.

At what age does testosterone production typically peak and when does it begin to decline?

Production peaks around age $20$ and begins to decline around age $30$.

What are the three major events that occur during spermatogenesis and meiosis?

$1$. Division of a germ cell into $4$ mobile sperm; $2$. Reduction of the chromosome number by half; $3$. Genetic shuffling.

What is the difference in chromosome count between somatic cells and gametes?

Somatic cells are diploid with $46$ chromosomes ($23$ pairs), while gametes are haploid with $23$ chromosomes.

During which phase of Meiosis I does crossing-over occur?

Prophase I.

What is the result of Meiosis I in terms of chromosome count and structure?

Each cell is haploid with $23$ double-stranded chromosomes.

What is the final product of Meiosis II?

$4$ haploid cells with $23$ single-stranded chromosomes in each cell.

What is the chromosomal cause of Trisomy 21 (Down’s Syndrome)?

A zygote ends up with $47$ chromosomes because the $21 ext{st}$ chromosome failed to separate (nondisjunction) during meiosis.

According to the NCLEX review, what is a primary side effect of the 5-alpha reductase inhibitor finasteride (Proscar)?

The patient's interest in sexual activity (libido) may decrease while taking the medication.

How many potential embryos can result from independent assortment alone?

$70$ million.

In the comparison of mitosis and meiosis, which process results in genetic variation in daughter cells?

Meiosis results in significant genetic variation, whereas mitosis results in none.