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Flashcards in Male Phys Deck (18):

describe the secretion of GnRH

  • released in median eminence of hypothalamus
  • secreted for a few minutes every 1-3 hours


describe the cell signaling pathway of GnRH

  • IP3 and DAG increases Ca which causes exocytosis of LH/FSH


describe the cell signaling pathway of LH

  • binds to Leydig cells receptors to increase cAMP
  • increases DNA transcription to produce testosterone from cholesterol


describe the cell signaling of FSH

  • binds to Sertoli cells receptors to increase cAMP
  • causes increase in DNA transcription of:
    • inhibin
    • aromatase
    • androgen binding protein
    • GFs


describe the function of ABP

  • helps maintain high levels of local concentrations of testosterone to help keep sperm viable 


describe the cell signaling pathway of testosterone

  • binds to intracellular receptor (it's a steroid)
  • testosterone is converted into DHT (via 5 alpha reductase)
  • DHT binds to receptor and causes modulation of gene expression


describe the function of testosterone in the fetus

  • forms penis and scrotum
  • accessory organs
  • testicular descent
  • female suppression 
    • if testosterone levels low, female genitalia may be present 


describe the function of testosterone in adults

  • promotes long bone fusion
  • increases BMR
  • increase in RBC mass


describe the secondary sexual characteristics caused by testosterone in adult males

  • deposition of protein
  • increase in muscle mass
  • increase in strength and size of bones


how does testosterone travel and how is it metabolized

  • travels bound (~97%) to:
    • sex-hormone binding globulin
    • albumin
  • free testosterone is coverted into the more active form by 5-alpha reductase into DHT
  • it is broken down in the liver and excreted by the kidneys


describe feedback mechanisms of LH and FSH

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describe the formation of the ejaculate

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describe the mechanism of an erection

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describe how Viagra/Cialis function

  • NO increases cGMP levels
  • Phosphodiesterase (PDE) degrades cGMP 
    • ED drugs inhibit PDE to inhibit cGMP degradation


describe effects of hypogonadism

  • non-functional testes in fetus
    • leads to development of female sex organs
  • loss of testes pre-puberty
    • maintain inftantile sex organs
    • bones less strong but longer


describe adiposogenital syndrome

  • inability of hypothalamus to secrete enough GnRH
    • also effects feeding center of hypothalamus
  • obese and hypogonadism