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Erection - Anatomy & Physiology (view source)
Revision as of 11:18, 10 July 2008
, 11:18, 10 July 2008→Sensory Input and Local Vascular Response
* Must be appropriate sensory stimuli (tactile, visual, olfactory, auditory) in order for the central nervous system to be stimulated for efferent events to cause erection.
* Must be appropriate sensory stimuli (tactile, visual, olfactory, auditory) in order for the central nervous system to be stimulated for efferent events to cause erection.
** Extrinsic stimuli are called '''erotogenic stimuli'''.
** Extrinsic stimuli are called '''erotogenic stimuli'''.
* Stimuli cause afferent sensory nerves to fire.
* Stimuli cause afferent sensory nerves to fire.
* Terminals synapse with neurons in the ''''behaviour centre'''' in the [[Endocrine_System_-_Hypothalamus_-_Anatomy_%26_Physiology#Hypothalamus|Hypothalamus]].
* Terminals synapse with neurons in the ''''behaviour centre'''' in the [[Endocrine_System_-_Hypothalamus_-_Anatomy_%26_Physiology#Hypothalamus|Hypothalamus]].
** Release nitric oxide (NO) from their terminals.
** Release nitric oxide (NO) from their terminals.
** NO is the principle neurotransmitter that drives the erectile process.
** NO is the principle neurotransmitter that drives the erectile process.
** NO activates the enzyme guanylate cyclase.
** Guanylate cyclase converts guanylate triphosphate (GTP) into cyclic guanyosine monophosphate (cGMP).
* Causes corporal smooth muscle relaxation (vasodilation) and results in erection.
* Under nonerotogenic conditions, cGMP is acted upon by PDE5 (phosphodiesterase 5).
* PDE5 promotes conversion of cGMP to GMP.
* Breakdown causes increased vascular tone.
** Tonic contraction of arterial and corporal smooth muscles.
** Outflow of blood from '''corpora cavernosa'''.
* Loss of erection and return to usual flaccid state.
'''''Local Vascular Component'''''
'''''Local Vascular Component'''''