Physiological functions of testosterone, one of the most important sex hormones in both males and females
What Is Testosterone?
- Testosterone is a steroid hormone in the androgen family.
- It is primarily produced in:
Testes (Leydig cells) in males
Ovaries and adrenal glands in females - It plays key roles in development, reproduction, metabolism, and behavior
Formula: C₁₉H₂₈O₂
Synthesized from: Cholesterol → DHEA → Androstenedione → Testosterone
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Physiological Functions of Testosterone
Sexual Differentiation and Development
- Fetal stage: Drives development of male internal and external genitalia
- Promotes testis descent, penis and scrotum formation, and Wolffian duct development
Puberty and Secondary Sexual Characteristics
Initiates:
- Deepening of the voice
- Facial and body hair
- Muscle mass increase
- Bone growth and density
- Increased libido
- Penile and testicular growth
Spermatogenesis and Fertility
- Supports sperm production by stimulating Sertoli cells in the testes
- Works with FSH to maintain normal sperm counts
Spermatogenesis and Fertility
Influences:
- Sex drive (libido)
- Aggression
- Cognitive function and memory
- Mood regulation (deficiency can cause depression or fatigue)
Anabolic Effects
Increases:
- Muscle protein synthesis
- Strength and endurance
- Bone mineral density (prevents osteoporosis)
Metabolic Regulation
Helps regulate:
- Fat distribution
- Insulin sensitivity
- Red blood cell production via erythropoietin stimulation
Functions in Females
- Produced in smaller amounts (ovaries, adrenals)
- Supports:
- Libido
- Bone health
- Muscle strength
- Precursor to estradiol (via aromatase)
Summary Table
Function
Effect
Sexual development
Male genitalia formation in fetus
PubertyEffect
Secondary sex traits (voice, hair, growth)
Reproduction
Sperm production and fertility
Behavior
Libido, mood, aggression
Anabolic
Muscle, bone density, protein synthesisEffect
MetabolicEffect
Fat balance, RBC production
Female roles
Libido, estradiol precursor, bone health