Lecture 47: Coitus

Question 1

How is blood supplied to the penis?

Answer 1

Abdominal aorta —-> common iliac arteries —> internal iliac arteries —-> internal pudenal artery = main artery of perineum

Question 2

What is ejaculation?

• Describe the two phases?

Answer 2

= the process of expulsion of semen from the penis - under sympathetic control

1. Emission
   - sperm and fluid from the accessory glands move to the urethra in response to peristaltic contractions
2. Expulsion
   - Strong spasmodic contractions of urethral smooth muscles that eject the semen

• Pelvic floor smooth muscles contract in response to pudenal (sosmatic) nerve stimulation

Question 3

What is erectile dysfunction?

What are the possible causes?

Answer 3

- consistent inability to attain/maintain erection
possible causes:
- tears in corpus cavernosa capsule
- obstructions in penile arteries
- diabetes
- alcohol, drugs, smoking

Question 4

What is erection ?

Answer 4

Erection is a parasympathetic response
- a visual/mental or other stimulation is transmitted by the brain or by the internal pudendal nerve, causing efferent parasympathetic signals to be sent to the brain
- Nitric oxide is released by the endothelial cells lining the blood vessels, causing the deep arteries of the penis to dilate, filling the lacunae. In addition, the filling results in compression of the views in the penis, reducing venous drainage
= sequence of events causes the penis to become engorged with blood giving rise to erection

Question 5

What are the genital reflexes of the female sexual act?

Answer 5

• engorgement of corpora of clitoris, labia and vagina in response to autonomic stimulation
• entry of lubricating fluid through vaginal wall; secretion of mucus into vestibule
• Increased blood flow to vagina
• Increased width and length of vagina in response to tactile stimulation. Uterus elevates upwards
• Rhythmic contraction of vaginal, uterine and perineal muscles in response to pudendal nerve stimulation

Question 6

What are the various contraceptive methods?

Answer 6

• natural control methods
• artificial control methods
• surgical sterilisation
• mechanical barrier methods
• intrauterine devices
• women steroidal contraceptive
• male steroidal contraceptive