Erection and Ejaculation – Commensal Organisms

Question 1

Define: libido, intromission, erection, emission,ejaculation

Answer 1

Libido – behavioural manifestation of sexual desire
Intromission – entrance of the penis into the vagina
Erection – firming and enlargement of the penis
Emission – movement of accessory gland fluid into male urethra to mix with sperm
Ejaculation – reflex expulsion of sperm from male reproductive tract

Question 2

• Where is spermatozoa produced, matured & stored?

Answer 2

Testis – production, Epididymis – maturation & storage

Question 3

• Which species has a urethral process?

Answer 3

Ram

Question 4

• What are the three main parts of the penis?

Answer 4

Crura, body, glans

Question 5

• Which part of the penis enlarges to form the glans penis?

Answer 5

Corpus spongiosum

Question 6

• What is the function of the paired ischiocavernosus muscle?

Answer 6

Forces blood into corpus cavernosum and corpus spongiosum

Question 7

• Which muscle allows retraction/protrusion of the penis?

Answer 7

Paired retractor penis muscle

Question 8

• What is required to achieve erection?

Answer 8

Elevated arterial blood inflow, dilation of corporal sinusoids, restricted venous outflow & relaxation of the retractor penis muscle

Question 9

• What does engorgement of cavernous tissue cause?

Answer 9

A blockage of venous return

Question 10

• What is the state of helicine arteries in the flaccid penis?

Answer 10

Lumen of helicine arteries obliterated by sympathetic tone of muscles in the vessel walls

Question 11

• What initially causes erection?

Answer 11

PSNS inhibits longitudinal muscle fibres in helicine arteries, allowing blood to flow into central sinusoids

Question 12

• What is the principle neurotransmitter that drives the erectile process?

Answer 12

NO, stimulates guanylate cyclase which converts guanylate triphosphate (GTP)  cyclic guanosine monophosphate (cGMP), cGMP causes smooth muscle of helicine arteries to relax

Question 13

• How does sildenafil citrate (Viagra) work?

Answer 13

Blocks the action of PDE5, PDE5 breaks down cGMP -> GMP

Question 14

• What happens during erection of a fibroelastic penis?

Answer 14

Length increases by straightening of sigmoid flexure as a result of relaxation of retract penis muscle

Question 15

• Which nerve stimulates ejaculation?

Answer 15

Internal pudendal nerve

Question 16

• What are the features of ejaculate in the dog?

Answer 16

Pre sperm fraction from prostate, sperm rich fraction, prostrate derived fraction delivered with greater force

Question 17

• What may injury in the pelvic region result in?

Answer 17

Semi-permanent erection (priapism) and paraphimosis (penis won’t return to prepuce)

Question 18

• How can sperm quality be assessed?

Answer 18

Total sperm output, percentage of normal sperm motility, percentage of normal morphology sperm

Question 19

• What is the term used to describe organisms transmitted at mating?

Answer 19

Venereal transmission

Question 20

• What is the most common commensal organism found in the sheath of the dog?

Answer 20

E. coli – 47%

Question 21

• What are the effects of campylobacter fetus?

Answer 21

May result in uterine infection, infertility or early pregnancy loss

Question 22

• What commensal is found in up to 30% of cows and 80% of bulls?

Answer 22

Haemophilus somnus

Question 23

• What tests may be used to monitor herds or individuals?

Answer 23

Fluorescent antibody testing & serological testing