Session 7 - Coitus and Conception Flashcards
Define sexual reproduction:
Formation of a unique individual from the gametes of two other individuals.
What is the rate of sperm production?
1000 spermatozoa per second
How long does it take spermatogonia to mature?
74 days
What are the 4 phases of coitus?
Excitement Phase
Plateau Phase
Orgasmic Phase
Resolution Phase (+/- Refractory Period)
What are the features of the female sexual response?
Blood engorgement and erection of: Clitoris, Vaginal Mucosa, Breast and Nipples Glandular Activity Sexual excitement \+/- orgasm No physiological refractory period
What are the features of the female sexual response?
Blood engorgement and erection of: Clitoris, Vaginal Mucosa, Breast and Nipples Glandular Activity Sexual excitement \+/- orgasm No physiological refractory period
Describe the steps involved in penile erection:
Stimulants can be psychogenic or tactile.
This causes efferents via the Pelvic nerve (PNS) and Pudendal nerve (somatic) to cause hameodynamic changes.
What is the overall mechanism of erection?
Smooth muscle in the arteries of the corpus cavernous dilate allowing more blood in. The bulbospongiosus and ischiocavernous muscles compress the veins restricting the drainage of blood.
What is the overall mechanism of erection?
Smooth muscle in the arteries of the corpus cavernous dilate allowing more blood in. The bulbospongiosus and ischiocavernous muscles compress the veins restricting the drainage of blood.
What specific changes occur which produce haemodynamic changes or tumescence?
Inhibition of sympathetic arterial vasoconstrictor nerves
Activation of the PNS
Activation of non-adrenergic, non-cholinergic nerves to arteries releasing NO
What is the action of NO on smooth muscle?
Post ganglionic PNS releases ACh
ACh binds to M3 on endothelial cells
This increases Calcium levels intracellular and activates NOS and NO is formed.
NO diffuses into smooth muscle and causes relaxation of vasodilation.
(NO can also be released directly from the non-adrenergic, non cholinergic nerves)
What is the action of NO on smooth muscle?
Post ganglionic PNS releases ACh
ACh binds to M3 on endothelial cells
This increases Calcium levels intracellular and activates NOS and NO is formed.
NO diffuses into smooth muscle and causes relaxation of vasodilation.
(NO can also be released directly from the non-adrenergic, non cholinergic nerves)
What are some of the causes of erectile dysfunction?
Psychological - descending inhibition of spinal reflexes
Tears in fibrous tissue of corpora cavernosa
Vascular - arterial and venous
Drugs
Factors that block NO - alcohol, anti-hypertensives, diabetes
How does viagra work?
Viagra blocks an enzyme that causes cGMP breakdown.
cGMP is needed to cause a reduction in intracellular calcium which is needed to cause vasodilation.
How does viagra work?
Viagra blocks an enzyme that causes cGMP breakdown.
cGMP is needed to cause a reduction in intracellular calcium which is needed to cause vasodilation.
What is emission?
Otherwise known as pre-ejaculate
Movement of ejaculate into prostatic urethra - caused by Vas deferens peristalsis
Accessory glands secretions (bulbourethral glands) may be involved
What is mechanism of ejaculation?
Under sympathetic nervous system control L1,L2
- Contraction of glands and ducts (smooth muscle)
- Bladder internal sphincter contracts
- Rhythmic striatal muscle contractions (pelvic floor, ischiocavernous, bulbospongiosus, hip and anal muscles)
What is mechanism of ejaculation?
Under sympathetic nervous system control L1,L2
- Contraction of glands and ducts (smooth muscle)
- Bladder internal sphincter contracts
- Rhythmic striatal muscle contractions (pelvic floor, ischiocavernous, bulbospongiosus, hip and anal muscles)
What is the volume of a normal ejaculate?
2-4ml
What is the sperm content of a normal ejaculate?
> 40 x 10(6) or 20-200ml per ml
What is the criteria for abnormal oligospermia?
What is the criteria for abnormal oligozoospermia?
What do seminal vesicles contribute to ejaculate and what volume does it constitute?
Alkaline fluid (neutralises the acid of the male urethra and female reproductive tract) Fructose Prostaglandins Clotting factors (semenogelin) 60% volume
What does the prostate contribute to ejaculate and what volume does it constitute?
Milky, slightly acidic fluid
Proteolytic enzymes - breakdown of clotting proteins - reliqueyfies semen in 10-20 minutes
Citric acid and acid phosphatase
25% volume
What do bulbourethral glands contribute to ejaculate and what volume does it constitute?
Alkaline fluid
Very small volume
Also produces a mucous that lubricates the end of the penis and urethral lining.
What do bulbourethral glands contribute to ejaculate and what volume does it constitute?
Alkaline fluid
Very small volume
Also produces a mucous that lubricates the end of the penis and urethral lining.