Neural Control of Pelvic Function 7

Question 1

What are some of the physical events that occur in male arousal?

Answer 1

• Penile erection mediated by vasodilation of erectile tissue, producing tumescence
• Contraction of striated penile muscles leads to rigid erection
• Arterial blood flow increases several fold during erection
  
  • arteries are responsible for tumescence, not veins
• Penile volume increases 80-200 mL - pressures can be as great as 1500 mmHg

Question 2

Describe the process of detumescence.

Answer 2

• Active process mediated by vasoconstriction
• Due to NE released from non-cavernous nerve sympathetic postganglionic fibers
  
  • caudal sympathetic chain

Question 3

What is the mechanism of vaginal lubrication in female arousal?

Answer 3

• First sign of sexual arousal in females
  
  • 5-15 seconds after stimulation begins
• Probably active transport driven
  
  • contains high K+, low Na+ compared to plasma
• Mechanism of production is unknown

Question 4

What is the mechanism of clitoral erection in female arousal?

Answer 4

• Similar to penile erection
• Vasodilation mediated by the cavernous nerve
  
  • striated muscle activity probably not important

Question 5

What is the mechanism of genital vasocongestion during female arousal?

Answer 5

• Tissue becomes greatly engorged with blood
• Due to great increase in blood flow (vasodilation) and maybe vasoconstriction
• Autonomic mechanisms are unclear
• Returns to basal state following orgasm

Question 6

What are the physical events that occur during the emission phase of male climax?

Answer 6

• Strong contraction of the internal and external urethral sphincter
• Fluids from the prostate, seminal vesicle, and ductus deferens enter into the prostatic urethra
• Pressure within the urethra increases due to fluid and contraction of both smooth and striated muscle contraction

Question 7

What are the phsyical events that lead to ejaculation in the male climax?

Answer 7

• Internal urethral sphincter remains closed
• When volume/pressure reaches a certain point, external urethral sphincter opens
  
  • either can be reflexively or volunterily
• Seminal fluids ejected into the urethral bulb
• Powerful, rhythmic contractions of the bulbospongiosus muscles eject the semen
• Simultaneous contractions of ischiocavernosus muscle and external anal and urethral sphincters

Question 8

What are the physical events that occur during the female climax?

Answer 8

• Consists of rhythmic (3-10) contractions of the perineal muscles
• In general, physiology very similar to males