Testosterone Notes

Testosterone Production

  • Produced by:
    • Females:
    • Ovaries
    • Placenta
    • Males:
    • Testes
    • Both genders:
    • Zona reticularis of adrenal gland

Regulation of Testosterone

  • Mechanism:
    • Regulated through negative feedback involving:
    • Luteinizing hormone (LH)
    • Follicle-stimulating hormone (FSH)
    • Gonadotropin-releasing hormone (GnRH)
    • Effects of hormone levels:
    • Rising levels of LH and FSH: stimulates testosterone production
    • Falling levels of LH and FSH: inhibits testosterone production

Target Organs and Functions of Testosterone

  • General Functions:

    • Stimulates secondary sexual characteristics and libido.

  • Specific Target Organs and Related Functions:

    • Testes:
    • Stimulates sperm production
    • Muscles:
    • Enhances muscle development
    • Brain:
    • Influences behaviors related to territorialism and aggressiveness
    • Larynx:
    • Causes thickening/lengthening of vocal folds

  • Circadian Rhythm:

    • Blood levels of testosterone peak near sunrise and follow a 24-hour circadian rhythm.

Effects of Low Testosterone Levels

  • Consequences of Low Levels:
    • Mood disturbances
    • Increased body fat
    • Decreased muscle mass and metabolism
    • Loss of body hair
    • Sexual dysfunction
    • Memory and sleep difficulties

Effects of Prolonged Elevated Testosterone Levels (e.g., from anabolic steroids)

  • Consequences of Elevated Levels:
    • Testicular atrophy
    • Infertility
    • Decreased libido
    • Breast development
    • Irritability
    • Liver damage

Impact of High Testosterone in Females

  • High levels of testosterone in females lead to:
    • Masculinizing effects
    • This can include traits such as increased body hair and changes in body composition.