Session 7 Flashcards
What are the phases of Coitus?
Excitement phase
Plateau phase
Orgasmic phase
Resolution phase
What happens in the Excitement phase of Coitus?
Arousal by mechanical or psychological stimuli
Blood to erectile tissue in males
Blood engorgement to breast, clitoris and vaginal mucosa in females
What happens in the Plateau phase of Coitus?
The excitement levels off
What happens in the Orgasmic phase of Coitus?
More stimuli is needed
Glandular activity of the vagina occurs
+/- orgasm in females
What happens in the Resolution phase of Coitus?
Males have a physiological refractory period
Females have a psychological refractory period
Vascular changes return to normal
What causes an erection in males?
The parasympathetic nervous system
Vascular changes
What causes vasodilation for Tumescence? (Engorgement of blood)
Inhibition of sympathetic arterial vasoconstrictor nerves –> Vasodilation
Activation of the Parasympathetic nervous system
Activation of non-adrenergic, non cholingeric nerves to arteries - release Nitiric Oxide causing vasodilation
What causes muscle relaxation for Tumescence?(Engorgement of blood)
Post ganglionic parasympathetic nervous system releases Ach which binds to M3 receptors on endothelial cells
Rise in [Ca2+]i leading to activation of Nitiric Oxide synthase making Nitric oxide
NO diffuses into vascular smooth muscle to cause relaxation
NO released from nerves makes cGMP which causes Ca2+ to go into the Endoplasmic reticulum leading to decreased [Ca2+]i
What are the 2 layers of the penis with erectile tissue?
Corpora cavernosa (Rigid fibrous tissue outer layer. Stops blood draining away) Corpus spongiosum (Around urethra so not as rigid)
What can cause erectile dysfunction?
20% = psychological. (Descending inhibition of spinal reflexes)
Tears in fibrous tissue of Corpus cavernosa
Vascular issues eg diabetes
Drugs eg antidepressants, antihypertensives, things blocking NO
How does Viagra treat erectile dysfunction?
It maintains dilation of vessels by inhibiting phosphodiesterase 5 which breaks down cGMP
What is Emission?
Before ejaculation, movement of the ejaculate into the prostatic urethea - sympathetic nervous system (leakage can occur - why withdrawal method is unreliable)
Vas deferens peristalisis (Sympathetic nervous system)
Accessory gland secretions such as the bulbourethral gland
Quickly followed by ejaculation
What occurs in ejaculation?
Spinal and cerebral reflexes cause it, sympathetic nervous system control - L1, L2
1) Contraction of glands & ducts (Smooth muscle)
2) Bladder internal sphincter contracts (Stop semen going into the bladder)
3) Rhythmic striatal muscle contractions (Pelvic floor, ischiocavernosus, bulbospongiosus, hip & anal muscles) Big autonomic response
What is a dry orgasm?
No ejaculate comes out.
Due to the internal sphincter of the bladder not contracting properly so semen goes into the bladder.
Can be tested for by taking a urine sample post coitus
What do you look for in semen samples?
% of sperm swimming forward vigorously (60%)
Volume (2-4ml)
How many sperm per ml (20-200x10[6])