66 Questions
What is the main function of the male gonads in the reproductive system?
Production of germ cells
Which hormone is predominantly secreted by the testes in males?
Testosterone
How does male gonadotropin secretion differ from females?
Noncyclical in nature
What happens to male gonadal function with advancing age?
Slowly declines
In terms of DNA, what is the main source from the male reproductive system?
Testes
Which hormone is masculinizing in its action in males?
Testosterone
What is the role of olfactory receptors in spermatozoa?
Aiding in chemotaxis towards the ovary
What is the function of P2X receptors in male ejaculation?
Mediate contractions of the vas deferens
Where do spermatozoa slow down and undergo capacitation?
Isthmus of the uterine tubes
What is the significance of maintaining testes at a lower temperature?
Facilitates spermatogenesis
What are the ligand gated cation channels that respond to ATP in male ejaculation?
P2X receptors
What is the main nutritional supply for spermatozoa?
Sugar
Where is the temperature of the testes normally maintained?
~32°C
Which hormone causes an increase in body hair but a decrease in scalp hair?
DHT
What is responsible for the fusion of epiphyses to the long bones?
Estrogens
What process results from testosterone binding to an intracellular receptor?
Transcription of genes
Which hormone limits the usefulness of testosterone as an anabolic agent in patients with wasting diseases?
Libido
What enzyme converts testosterone to DHT in some target cells?
5α-reductase
What is the role of androgen in the maturation of spermatids to spermatozoa?
Activating Sertoli cells
Which hormone acts on Sertoli cells to promote the last stages of spermatid maturation?
FSH
Where do spermatozoa acquire motility during their development?
Epididymis
What is the importance of motility for spermatozoa in vivo?
To enable them to move forward towards the ova
What proteins are responsible for the acquired motility of spermatozoa in the epididymis?
CatSper family proteins
What happens to sperm from knockout mice that do not express CatSper1-4?
They have altered motility and are infertile
What is the role of FSH in the male reproductive system?
Maintains gametogenic function of the testes
How does LH affect Leydig cells?
Stimulates testosterone secretion
What feedback mechanism does testosterone have on LH secretion?
Inhibits LH secretion
What is the impact of hypothalamic lesions on testicular function?
Leads to testicular atrophy
What is the role of inhibin in the male reproductive system?
Stimulates FSH secretion
What are the subunits that form inhibins in the male reproductive system?
βA and βB subunits
What is the function of the blood-testis barrier described in the passage?
Allows germ cells to remain in contact with Sertoli cells for survival
Which cell type forms cytoplasmic bridges with germ cells to ensure their survival?
Sertoli cells
What is the role of tight junctions between adjacent Sertoli cells near the basal lamina?
Create a barrier that prevents movement of large molecules from the interstitial tissue to the tubular lumen
What is the role of NO in the male reproductive system?
Promoting erection
What is one of the functions attributed to the paracrine activity between Sertoli and Leydig cells?
Promotes maturation of spermatozoa
How is erection terminated in the male reproductive system?
Sympathetic vasoconstrictor impulses
How do maturing germ cells navigate through the blood-testis barrier?
By undergoing coordinated breakdown of tight junctions above them
What initiates the process of ejaculation in males?
Touch receptors in the glans penis
What is the significance of germ cells needing to stay in contact with Sertoli cells?
To ensure survival and proper development
Which neurotransmitter is likely released by efferent parasympathetic fibers in the male reproductive system?
Vasoactive intestinal polypeptide (VIP)
What is the main effect of androgens on protein synthesis and breakdown?
Increase synthesis and decrease breakdown
What is the enzyme responsible for converting testosterone to DHT in some target cells?
5α-reductase
What is the effect of dihydrotestosterone (DHT) on hereditary baldness development?
Prevents baldness development
How do androgens impact the fusion of epiphyses to long bones?
Cause fusion of epiphyses
What limits the usefulness of exogenous testosterone as an anabolic agent in patients with wasting diseases?
Masculinizing effects
Which ion retention is caused by androgens due to their anabolic effects?
K+
What is the final stage of maturation for spermatids to become motile spermatozoa?
Spermiogenesis
Which hormone is the principal hormone of the testis and plays a key role in the development of male secondary sex characteristics?
Testosterone
What is the rate at which testosterone is synthesized by Leydig cells under the control of luteinizing hormone in adult males?
4–9 mg/day
Where is most of the testosterone found in the plasma after being synthesized?
Bound to albumin
What type of cell division occurs from a spermatogonium to a spermatid?
Incomplete division
What is the primary function of inhibin B in adult men and women?
Inhibit FSH secretion
Where are inhibins and activins primarily produced in males and females?
Gonads
What is the function of activins in the bone marrow?
Facilitate white blood cell development
How does castration impact FSH and LH secretion?
Increases both FSH and LH secretion
In the male reproductive system, what is the direct effect of inhibin on the anterior pituitary?
Inhibits FSH secretion
What is the role of the heterodimer βAβB in the male reproductive system?
Promote FSH secretion
What is the final stage of maturation for spermatids?
Spermiogenesis
Where is testosterone synthesized in the male reproductive system?
Leydig cells
What is the principal hormone of the testis?
Testosterone
Which hormone controls the secretion of testosterone from Leydig cells?
Luteinizing hormone (LH)
What is the main function of testosterone in the male reproductive system?
Development of male secondary sex characteristics
How is testosterone primarily transported in the plasma?
Bound to albumin
At what rate is testosterone synthesized by Leydig cells in adult males?
$4-9$ mg/day
What type of cell division occurs from a spermatogonium to a spermatid?
Incomplete division
What is the role of testosterone in spermatogenesis?
Maintains male secondary sex characteristics
Explore the male reproductive system and the process of chemotaxis involving spermatozoa. Learn about the ejaculation of spermatozoa and how P2X receptors play a role in fertility. Discover the interaction between olfactory receptors and odorant-like molecules in the reproductive system.
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