Podcast
Questions and Answers
What type of steroids do Leydig cells secrete?
What type of steroids do Leydig cells secrete?
- C18 steroids
- C25 steroids
- C21 steroids
- C19 steroids (correct)
What is the function of Müllerian inhibiting hormone secreted by Sertoli cells?
What is the function of Müllerian inhibiting hormone secreted by Sertoli cells?
- Enhances development of female accessory sex organs
- Inhibits development of female accessory sex organs (correct)
- Enhances development of male accessory sex organs
- Inhibits development of male accessory sex organs
What is the function of inhibin secreted by Sertoli cells?
What is the function of inhibin secreted by Sertoli cells?
- Stimulates LH release from the anterior pituitary
- Stimulates FSH release from the anterior pituitary
- Inhibits FSH release from the anterior pituitary (correct)
- Inhibits LH release from the anterior pituitary
What is the location of Leydig cells?
What is the location of Leydig cells?
What is the function of androgens in the body?
What is the function of androgens in the body?
What is the function of GnRH in the Hypothalamic-Pituitary-Testicular Axis?
What is the function of GnRH in the Hypothalamic-Pituitary-Testicular Axis?
What is the function of DHT?
What is the function of DHT?
What controls the secretion of Leydig cells?
What controls the secretion of Leydig cells?
What is the primary function of Luteinizing Hormone (LH) in the testes?
What is the primary function of Luteinizing Hormone (LH) in the testes?
Which of the following is NOT a function of androgens?
Which of the following is NOT a function of androgens?
What is the primary function of inhibin?
What is the primary function of inhibin?
Which of the following estrogens is involved in maternal behavior?
Which of the following estrogens is involved in maternal behavior?
What is the precursor to estrogens?
What is the precursor to estrogens?
Which of the following is a function of estrogens?
Which of the following is a function of estrogens?
What is the primary function of progesterone?
What is the primary function of progesterone?
Which of the following hormones is involved in the development of secondary sex characteristics?
Which of the following hormones is involved in the development of secondary sex characteristics?
What is the main function of inhibin?
What is the main function of inhibin?
What type of hormones are produced by the placenta?
What type of hormones are produced by the placenta?
What is the function of chorionic gonadotropin (CG/hCG) produced by the placenta?
What is the function of chorionic gonadotropin (CG/hCG) produced by the placenta?
During which phase of life is the Hypothalamic-Pituitary-Gonadal Axis dormant?
During which phase of life is the Hypothalamic-Pituitary-Gonadal Axis dormant?
What is the role of INSL3 in the reproductive system?
What is the role of INSL3 in the reproductive system?
What type of steroids are progestogens?
What type of steroids are progestogens?
During which phase of life does the Hypothalamic-Pituitary-Gonadal Axis become active again?
During which phase of life does the Hypothalamic-Pituitary-Gonadal Axis become active again?
What happens to the Hypothalamic-Pituitary-Gonadal Axis during old age?
What happens to the Hypothalamic-Pituitary-Gonadal Axis during old age?
What is the primary effect of oxytocin on uterine contractions?
What is the primary effect of oxytocin on uterine contractions?
What is the primary function of the pineal gland in mammals?
What is the primary function of the pineal gland in mammals?
What is the primary function of serotonin in the pineal gland?
What is the primary function of serotonin in the pineal gland?
Which hormone is involved in the regulation of epinephrine biosynthesis in the adrenal medulla?
Which hormone is involved in the regulation of epinephrine biosynthesis in the adrenal medulla?
What is the typical duration of a circadian rhythm in hormone secretion?
What is the typical duration of a circadian rhythm in hormone secretion?
What is the primary function of melatonin in the pineal gland?
What is the primary function of melatonin in the pineal gland?
Which type of hormonal secretion is characterized by the release of hormones in bursts or pulses?
Which type of hormonal secretion is characterized by the release of hormones in bursts or pulses?
What type of input regulates hormone secretion in the endocrine system?
What type of input regulates hormone secretion in the endocrine system?
What is the term for the changes in hormone secretion that occur across the year?
What is the term for the changes in hormone secretion that occur across the year?
What is the primary function of negative feedback in the endocrine system?
What is the primary function of negative feedback in the endocrine system?
What is the term for the changes in hormone secretion that occur across the lifespan?
What is the term for the changes in hormone secretion that occur across the lifespan?
What is the primary function of positive feedback in the endocrine system?
What is the primary function of positive feedback in the endocrine system?
What is an example of physiological end-products regulating hormone secretion?
What is an example of physiological end-products regulating hormone secretion?
Which of the following hormones is NOT regulated by a biological rhythm?
Which of the following hormones is NOT regulated by a biological rhythm?
What is the function of the pineal gland in non-mammalian vertebrates?
What is the function of the pineal gland in non-mammalian vertebrates?
What is the primary mechanism by which oxytocin stimulates uterine contractions?
What is the primary mechanism by which oxytocin stimulates uterine contractions?
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Study Notes
Leydig Cells
- Located outside seminiferous tubules
- Controlled by LH from anterior pituitary
- Secrete androgens (C19 steroids)
Androgens
- Functions:
- Spermatogenesis
- Genital tract maintenance
- Accessory sex organs
- 2nd-degree sex characteristics
- Metabolism
- Cognition
- Sexual behavior, aggression
- Mood
- Types:
- Testosterone
- Acts as a prohormone for DHT and estrogen
- Dihydrotestosterone (DHT)
- Strong androgen
- Can’t be aromatized to estrogen
- Androstenedione
- Weak androgen
- Testosterone
Sertoli Cells
- Located inside seminiferous tubules
- Controlled by FSH and testosterone
- Secrete:
- Müllerian inhibiting hormone (protein)
- Inhibits development of female accessory sex organs early in development
- Inhibin (protein)
- Inhibits FSH release from anterior pituitary
- Müllerian inhibiting hormone (protein)
Hypothalamic-Pituitary-Testicular Axis
- Hypothalamic hormone: GnRH
- Binds to receptors on anterior pituitary
- Stimulates anterior pituitary to synthesize and secrete gonadotropins (LH and FSH)
- Anterior pituitary hormone: LH
- Binds to receptors on Leydig cells
- Stimulates growth of Leydig cells
- Stimulates synthesis and secretion of androgens
- Anterior pituitary hormone: FSH
- Binds to receptors on Sertoli cells
- Stimulates growth and activity of Sertoli cells
- Stimulates synthesis and secretion of inhibin
- Testicular hormones: Androgens
- Feed back to hypothalamus and pituitary to regulate GnRH, LH, and FSH secretion
- Influence development, structure, and activity of body and brain
Estrogens
- Synthesized from androgens
- Functions:
- Genital tract maintenance
- 2nd-degree sex characteristics
- Water retention
- Ca++ metabolism
- Cognition
- Sexual behavior
- Maternal behavior
- Types:
- 17β-Estradiol (E2)
- Estrone (E1)
- Estriol (E3)
Progesterone
- Function: Pregnancy maintenance in mammals
- Also involved in sexual behavior and maternal behavior
Inhibin
- Function: Inhibits FSH release from anterior pituitary
Placenta
- Temporary organ
- Protein hormones:
- Chorionic gonadotropin (CG/hCG)
- Placental lactogen (PL)
- Chorionic corticotropin (CC)
- Chorionic thyrotropin (CT)
- Steroid hormones:
- Estrogens
- Progestogens
- Corticosteroids
- Androgens
Hypothalamic-Pituitary-Gonadal Axis Across the Lifespan
- Active during prenatal period and infancy
- Dormant during childhood (prepubertal hiatus)
- Becomes active during puberty (reawakening)
- Active during adulthood
- Declines during old age (reproductive senescence)
Pineal Gland
- Photoreceptive in non-mammalian vertebrates
- Endocrine gland in mammals
- Produces indoleamines (derivatives of tryptophan):
- Serotonin
- Melatonin
- Melatonin:
- Produced in dark
- Circadian rhythms
- Sleep/wake cycle
- Reproductive effects (seasonal breeding)
Regulation of Endocrine Function
- Regulation of hormone secretion by:
- Neural input
- Hormones
- Physiological end-products
- Negative feedback
- Positive feedback
- Regulation of hormone biosynthesis
- Biological rhythms (circadian, pulsatile, circannual, and changes across the lifespan)
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