1. erection, ejacultion and copulation Flashcards
list muscles of the penis and their anatomical locations/functions
- paired ischiocavernosus muscle: originates at ischial arch and inserts on root of penis. forces glood into the corpus cavenosum and corpus spongiosum
- urethralis and bulbospongiosus: surrounds some of urethra and transports semen
- paired retractor penis muscle: originates at caudal vertebrae and inserts on sigmoid flexure or distal penis. allows retraction/protrusion of the penis
what is libido
behavioural manifestation of sexual interest
what is intromission
entrance of penis into the vagina
what is erection
firming and enlargement of the penis
what is emission
movement of accessory gland fluid into male urethra to mix with sperm
what is ejaculation
reflex expulsion of sperm from male reproductive tract
outline the sequence of events in precopulatory behaviour
- search for sexual partner
- courtship
- sexual arousal
- erection
- penile protrusion
overall erection requires
- elevated arterial blood inflow
- dilation or corporal sinusoids
- restricted venous outflow
- elated intra-penile pressure
- relaxation of the retractor penis muscle
explain the mechanism behind erection
- erectile tissue is surrounded by a heavy capsule of varying thickness called tunica albuginea
- connective tissue trabeculae penetrate the erectile tissue and break up the space into sinusoids
- sinusoids are lined by endothelium
- engorgement of cavernous tissue causes a blockage of venous return
- ischiocavernosus muscle contraction compresses penile veins
- intermittent contractions causes pump like action at base of penis
- blood build up in corpus cavernosum and exceptionally high pressures
what happens to blood vessels and nerves in flaccid penis
helicine arteries empty into venous sinuses but
- lumen of helicine arteries obliterated by sympathetic tone of muscles in the vessel walls
- adrenergic nerves secrete norepinephrine
- norepinephrine causes vasoconstriction of helecine arteries so no filling of blood into sinuses
how does the nervous system induce erection
- parasympathetic fibres inhibit (relax) longitudinal muscle fibres in helecine arteries
- blood flows into the central sinusoids
- swllelling
- results in compression of oblique veins
- further penile swelling
what is essential for erection in the dog
contraction of vestibule muscles in the female
what is the principle neurotransmitter involved in the erectile process
nitric oxide