Sperm storage and production of seminal fluid

Question 1

Sperm in seminiferous tubules in a large volume of fluid

Answer 1

• washes sperm into rete testis, vasa efferentia and epididymis

Question 2

If vasa efferentia blocked

Answer 2

seminiferous tubules and testis swells

Question 3

how long does it take to travel through vasa efferentia and epididymis

Answer 3

6-12 days

Question 4

Seminal fluid

Answer 4

Mainly formed in accessory glands

Provides nutrients etc to protect spermatozoa Exploited by infectious agents (e.g. Hep. B, HIV)

Question 5

Haemodynamic changes in the penis

Answer 5

–involves the corpora cavernosa
• singular = corpus cavernosum
• sinuses along most of the length of the penis

Question 6

Arousal can be produced by:

Answer 6

– erotic psychological stimuli (e.g. visual, olfactory)
– tactile stimuli at the level of the brain
– tactile stimuli can also mediate local spinal reflexes

Question 7

Sympathetic arousal

Answer 7

– lower thoracic and lumbar spinal segments

– maintains flaccidity

Question 8

Parasympathetic

Answer 8

– control centre in sacral spinal segments

– increased activity produces turgidity

Question 9

Tumescence of the penis

Answer 9

Erection centre in the sacral spinal cord mediates the erection reflex:

Question 10

what steps are involved in the erection of the penis

Answer 10

Dilatation of arterioles to
c. cavernosa and c. spongiosum
Closing of arteriovenous shunts that normally bypass the c. cavernosa
Probably also occlusion of veins draining the penis

Question 11

Parasympathetic relaxation of vascular smooth muscle

Answer 11

action involves ACh acting on vascular endothelial cells
Indirectly triggers release nitric oxide (NO)
NO causes relaxation of vascular smooth muscle

Question 12

Failure to obtain an erection can result from:

Answer 12

– mechanical damage to the c. cavernosa
– obstruction of the arteries to the penis
– drugs that block parasympathetic actions
– psychological factors

Question 13

Stress associated with high sympathetic

activity

Answer 13

– NA causes vasoconstriction of penile arterioles and so inhibits erection

Question 14

Sympathetic mediated ejaculation

Answer 14

– ejaculatory centre in lower thoracic and lumbar spinal cord
– signals to ducts of genital tract and to bulbocavernosus muscle at the base of penis

Question 15

Emission phase of ejaculation

Answer 15

– rhythmic contractions of penis and bulbocavernosus muscle

– ejects semen in spurts

Question 16

Composition of ejaculate is not uniform:

Answer 16

First component: Prostate
Rich in acid phosphatase and citric acid
Second component: Vas deferens Rich in spermatozoa
Third component: Seminal vesicle Rich in fructose