[SISTEMA ENDÓCRINO] TESTÍCULOS: TESTOSTERONA | MK Fisiologia

Summary

This video explores the production and function of testosterone, focusing on its synthesis in the testes. The process begins in the Leydig cells, which convert cholesterol into testosterone with the help of enzymes. Testosterone plays a key role in male development, including the differentiation of the reproductive system, puberty, and maintaining sperm production. It also influences secondary sexual characteristics like muscle mass, voice changes, and bone growth. The video also discusses conditions like hypogonadism (testosterone deficiency) and hypergonadism (excess testosterone), explaining their effects on the body. It highlights the regulation of testosterone synthesis through the hypothalamic-pituitary-gonadal axis and its impact on male health.

Takeaways

• 😀 Testosterona is the primary hormone produced and secreted by the testes, specifically by the Leydig cells.
• 😀 The testes consist of lobules containing seminiferous tubules where sperm production (spermatogenesis) occurs.
• 😀 Leydig cells, located in the interstitial space between seminiferous tubules, are responsible for testosterone synthesis.
• 😀 Testosterone is a steroid hormone derived from cholesterol, similar to the androgens produced by the adrenal glands.
• 😀 The synthesis of testosterone begins when cholesterol is transported to the mitochondria and is converted into pregnenolone, which eventually forms testosterone.
• 😀 The secretion of testosterone is regulated by LH (luteinizing hormone) from the pituitary, which stimulates Leydig cells to produce testosterone.
• 😀 Testosterone circulates in the blood, mostly bound to plasma proteins like SHBG (sex hormone-binding globulin) and albumin, with only 2% circulating freely.
• 😀 The free testosterone can diffuse into target cells, where it binds to androgen receptors, affecting gene transcription to modify cell function.
• 😀 Testosterone can be converted into more potent dihydrotestosterone (DHT) or estradiol, which have different effects on the body.
• 😀 The primary functions of testosterone include stimulating spermatogenesis, influencing sexual differentiation, increasing muscle mass, promoting bone growth, and enhancing red blood cell production.
• 😀 Imbalances in testosterone levels can cause various health issues such as hypogonadism (low testosterone) or hypergonadism (high testosterone), affecting sexual development and function.

Q & A

What is the main function of testosterone in the male body?

Testosterone is the primary male sex hormone responsible for the development and maintenance of male reproductive tissues, including the testes, prostate, and seminal vesicles. It also promotes secondary sexual characteristics such as muscle mass, deepening of the voice, and body hair growth.

Where is testosterone primarily produced in the male body?

Testosterone is primarily produced and secreted by the Leydig cells in the testes.

What is the role of Sertoli cells in the testes?

Sertoli cells provide structural support and nourishment to developing sperm cells during spermatogenesis. They are essential for the proper development of sperm within the seminiferous tubules.

How is testosterone synthesized in Leydig cells?

Testosterone synthesis in Leydig cells begins with cholesterol. Cholesterol is transported into the mitochondria, where it is converted into pregnenolone. Pregnenolone is then converted into testosterone in the smooth endoplasmic reticulum, a process involving specific enzymes like P450scc.

What regulates the synthesis of testosterone in the Leydig cells?

The synthesis of testosterone is primarily regulated by luteinizing hormone (LH), which is secreted by the pituitary gland. LH stimulates Leydig cells to produce and secrete testosterone.

How is testosterone transported in the bloodstream?

Testosterone is transported in the bloodstream mainly bound to plasma proteins, such as sex hormone-binding globulin (SHBG) and albumin. Approximately 98% of testosterone is bound to these proteins, while only 2% circulates in its free form.

What is the significance of free testosterone in the body?

Free testosterone, the small percentage of testosterone not bound to plasma proteins, is biologically active. It can diffuse into target cells, where it binds to androgen receptors and influences gene expression, leading to the development of male sexual characteristics and functions.

What are the two primary forms of testosterone in target cells?

In target cells, testosterone can either bind directly to androgen receptors or be converted into two more potent forms: dihydrotestosterone (DHT) or estradiol. DHT is more potent and plays a key role in the development of male characteristics, while estradiol is important for bone health.

What are the effects of dihydrotestosterone (DHT) on the male body?

DHT, a more potent derivative of testosterone, is responsible for the development of male external genitalia during fetal development, as well as promoting the growth of body and facial hair, and the enlargement of the prostate during adulthood. It is also associated with hair loss in certain individuals.

What happens if there is a deficiency of testosterone in males?

Testosterone deficiency, or hypogonadism, can lead to various issues. In childhood, it may result in incomplete development of male sexual characteristics. In adulthood, symptoms include reduced libido, erectile dysfunction, and a decrease in muscle mass. In extreme cases, it may also lead to infertility.

What are the potential consequences of excessive testosterone in males?

Excessive testosterone, or hypergonadism, can lead to premature sexual development in children, including adult-like genitalia and other secondary sexual characteristics. In adults, it can exacerbate traits such as hair loss, acne, and aggressive behavior. It can also increase the risk of prostate issues and contribute to muscle hypertrophy.