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What is the primary action of the hormone targeting the anterior pituitary gland?
What is the primary action of the hormone targeting the anterior pituitary gland?
Which receptors primarily convey information to the spinal cord during the ejaculation reflex?
Which receptors primarily convey information to the spinal cord during the ejaculation reflex?
What process directly leads to the termination of an erection?
What process directly leads to the termination of an erection?
What neurochemical mediators are involved in initiating an erection?
What neurochemical mediators are involved in initiating an erection?
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Which anatomical structures are primarily involved in the engorgement of the penis during erection?
Which anatomical structures are primarily involved in the engorgement of the penis during erection?
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What is the initial physiological response that leads to the engorgement of the penis?
What is the initial physiological response that leads to the engorgement of the penis?
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During ejaculation, what is the term for the movement of semen into the urethra?
During ejaculation, what is the term for the movement of semen into the urethra?
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Which of the following statements is true regarding the role of neurotransmitters in erection?
Which of the following statements is true regarding the role of neurotransmitters in erection?
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Which hormone is primarily responsible for stimulating testosterone secretion from Leydig cells?
Which hormone is primarily responsible for stimulating testosterone secretion from Leydig cells?
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What percentage of testosterone remains unbound in the plasma to exert its effects?
What percentage of testosterone remains unbound in the plasma to exert its effects?
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Which hormone produced by Sertoli cells is involved in the regulation of spermatogenesis?
Which hormone produced by Sertoli cells is involved in the regulation of spermatogenesis?
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What is the primary function of Follicle-stimulating hormone (FSH) in the male reproductive system?
What is the primary function of Follicle-stimulating hormone (FSH) in the male reproductive system?
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Which compound is NOT produced by Leydig cells?
Which compound is NOT produced by Leydig cells?
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What physiological role does testosterone play during male development?
What physiological role does testosterone play during male development?
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Which of the following factors could have an impact on spermatogenesis?
Which of the following factors could have an impact on spermatogenesis?
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What is the primary source of the majority of testosterone in males?
What is the primary source of the majority of testosterone in males?
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What role does inhibin play in the regulation of spermatogenesis?
What role does inhibin play in the regulation of spermatogenesis?
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Which of the following is NOT a function of testosterone?
Which of the following is NOT a function of testosterone?
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How does testosterone exert its negative feedback effect on the hypothalamus?
How does testosterone exert its negative feedback effect on the hypothalamus?
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What initiates the secretion of GnRH at the time of puberty?
What initiates the secretion of GnRH at the time of puberty?
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What is the primary role of FSH in male reproductive physiology?
What is the primary role of FSH in male reproductive physiology?
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Which circumstance leads to an increase in FSH secretion from the anterior pituitary?
Which circumstance leads to an increase in FSH secretion from the anterior pituitary?
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What is a significant effect of testosterone on metabolism?
What is a significant effect of testosterone on metabolism?
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Why does FSH secretion diminish when spermatogenesis is proceeding too rapidly?
Why does FSH secretion diminish when spermatogenesis is proceeding too rapidly?
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What is the primary function of the bulbocavernosus muscle in male reproductive physiology?
What is the primary function of the bulbocavernosus muscle in male reproductive physiology?
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Which condition is characterized by the inability to achieve pregnancy after 12 months of regular unprotected intercourse?
Which condition is characterized by the inability to achieve pregnancy after 12 months of regular unprotected intercourse?
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What underlying cause accounts for 20-25% of infertility cases that is not clearly identifiable?
What underlying cause accounts for 20-25% of infertility cases that is not clearly identifiable?
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Which term refers to decreased testosterone levels and associated symptoms of androgen deficiency?
Which term refers to decreased testosterone levels and associated symptoms of androgen deficiency?
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Which factor is NOT commonly associated with erectile dysfunction?
Which factor is NOT commonly associated with erectile dysfunction?
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Which type of hypogonadism originates in the hypothalamus or pituitary gland?
Which type of hypogonadism originates in the hypothalamus or pituitary gland?
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What is a common medical intervention for treating infertility?
What is a common medical intervention for treating infertility?
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Which of the following is NOT a potential cause of male infertility?
Which of the following is NOT a potential cause of male infertility?
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What is the primary purpose of In Vitro Fertilization (IVF) in assisted reproductive techniques?
What is the primary purpose of In Vitro Fertilization (IVF) in assisted reproductive techniques?
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Which infertility causes can IVF address?
Which infertility causes can IVF address?
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What role does controlled ovarian stimulation (COS) play in IVF?
What role does controlled ovarian stimulation (COS) play in IVF?
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What is preimplantation genetic testing (PGT) typically used for during IVF?
What is preimplantation genetic testing (PGT) typically used for during IVF?
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What is one function of cryopreservation in assisted reproductive techniques?
What is one function of cryopreservation in assisted reproductive techniques?
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Which assisted reproductive technique directly bypasses the fallopian tubes?
Which assisted reproductive technique directly bypasses the fallopian tubes?
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What is one procedural step that follows oocyte retrieval in the IVF process?
What is one procedural step that follows oocyte retrieval in the IVF process?
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In which circumstances is Intracytoplasmic Sperm Injection (ICSI) commonly performed?
In which circumstances is Intracytoplasmic Sperm Injection (ICSI) commonly performed?
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Study Notes
Male Reproductive Physiology - Lecture 2
- Objectives: Students will be able to identify hormones involved in spermatogenesis, describe hormonal control of the male reproductive system, understand testosterone functions, describe erection and ejaculation, identify causes of male/female infertility, and understand infertility treatment options and ARTs.
Hormones Involved in Spermatogenesis
- Gonadotropin-Releasing Hormone (GnRH) is released from the hypothalamus, stimulating Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) release from the anterior pituitary gland.
- LH stimulates Leydig cells in the testes, producing testosterone, along with other sex hormones such as dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), and estradiol.
- Testosterone can be converted into estrogen by aromatase and dihydrotestosterone by 5α-reductase.
- FSH stimulates Sertoli cells in the testes, regulating and supporting spermatogenesis. Sertoli cells produce inhibin, androgen-binding protein (ABP), and anti-Müllerian hormone (AMH).
- Other hormones like growth hormone, prolactin, thyroid hormones, and glucocorticoids can also affect spermatogenesis and male reproductive hormones.
Testosterone
- Testosterone is the primary androgen in males, produced by Leydig cells. Testicular testosterone concentrations are much higher than systemic levels.
- A small amount is produced by adrenal glands in both sexes.
- Ninety-eight percent of testosterone binds to either sex hormone-binding globulin (SHBG) or albumin in the blood. The unbound portion enters cells to exert its effects.
- Testosterone is essential for male development, including penis and scrotum formation and descent of testes.
- It regulates spermatogenesis and sexual desire.
- It contributes to secondary sex characteristics (body hair, voice, skin, acne).
- It also affects muscle development, bone density, red blood cell production, and electrolyte balance.
Hormonal Control of Spermatogenesis
- At puberty, GnRH secretion increases, initiating the release of LH and FSH.
- FSH primarily acts on Sertoli cells to promote spermatogenesis and production of hormones like inhibin.
- LH acts on Leydig cells to stimulate testosterone production.
- Testosterone has a negative feedback effect on the hypothalamus and anterior pituitary, decreasing FSH and LH secretion.
- Inhibin from Sertoli cells directly inhibits FSH secretion.
- Low sperm production increases FSH while high sperm production decreases FSH.
Physiology of Erection
- Erection involves engorgement of the penis with blood, facilitated by dilation of arterioles and relaxation of sinusoids within the erectile tissue (corpora cavernosa and corpus spongiosum).
- Intact anatomical, neurovascular, hormonal, and molecular factors are necessary for erection.
- Intact nerves and blood vessels are essential for this process. Mediators of this response include acetylcholine, vasoactive intestinal polypeptide (VIP), and nitric oxide (NO).
Physiology of Ejaculation
- Ejaculation is a two-part spinal reflex (emission and ejaculation proper).
- Emission involves transport of semen into the urethra.
- Ejaculation is a complex process involving the propulsion of semen through contraction of specific muscles.
- The spinal cord coordinates and integrates commands from the lower regions of the body for emission and ejaculation.
Abnormalities of the Male Reproductive System
- Infertility is the inability to achieve pregnancy after 12 months of unprotected intercourse and has various potential causes.
- Unrelated causes, anatomical problems, genetic factors, infections, hormonal issues, and lifestyle/environmental factors are possibilities.
Hypogonadism
- Hypogonadism is decreased testosterone production and related symptoms. It's important to distinguish between primary (testes-based) and secondary (hypothalamus/pituitary-based) hypogonadism.
Erectile Dysfunction
- Persistent inability to achieve or maintain an erection is erectile dysfunction (ED).
- Various factors contribute to ED, including diabetes, hypertension, and psychological issues.
Treatment of Infertility
- Infertility treatments address identified causes (when possible) medically, surgically, or via Assisted Reproductive Technologies (ARTs).
Assisted Reproductive Technologies (ARTs)
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ARTs are technologies used when natural conception is difficult or impossible, including Intrauterine Insemination (IUI), In Vitro Fertilization (IVF), Intracytoplasmic Sperm Injection (ICSI), and others.
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They involve handling eggs, sperm, and embryos outside the body and/or surgical approaches.
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IVF, a common procedure in these cases, involves ovarian stimulation to obtain eggs for fertilization in the lab and transfer of resultant embryos into the uterus.
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Other techniques for sperm retrieval and embryo transfer can also be used.
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Description
This quiz covers essential aspects of male reproductive physiology, focusing on hormones involved in spermatogenesis and their regulatory functions. Students will explore hormonal control of the male reproductive system, testosterone's roles, and factors affecting male and female infertility. Additionally, treatment options and assisted reproductive technologies (ARTs) will be discussed.
