Repro 7 Flashcards
What role does Nitric Oxide play in achieving an erection?
- NO is released when ACh binds to M3 receptors.
- NO causes an increase in cGMP specific protein kinase.
- cGMP SPK causes a reduction in calcium
- vasodilatation occurs and the penis becomes erect.
Which muscle maintains the blood in the penis, and prevents it from draining?
What would happen if the other muscle did this? (Name the muscle)
Corpus cavernosa maintains the blood
Corpus spongiosum is not involved in erection as it would impinge on the urethra and that would be pointless.
Name a drug that prevents the breakdown of CGMP, for the treatment of erectile dysfunction?
Viagra
This is a PDE 5 inhibitor.
PDE5 breaks down cGMP and hence there is less cGMP SPK causing a decreasing in calcium.
Inhibition of this enzyme will lead to more vasodilation.
During ejaculation, what prevents the ejaculate from entering the bladder?
The bladder internal sphincter contracts
In terms of sperm per mL of ejaculate, what is deemed normal and abnormal ?
20-200 x 10^6 = normal
What causes Tumescence, and how is it bought about?
Haemodynamic changes result in Tumescence.
There is inhibition of the sympathetic arterial vasoconstriction in the penis.
The parasympathetic NS is activated, which releases NItric Oxide.
What are the 7 methods of contraception?
- Natural method
- Prevent sperm from entering the ejaculate
- Prevent sperm from reaching the cervix
- Prevent ovulation
- Inhibit transport along the Fallopian tube
- Inhibit sperm passing through the cervix
- Inhibit implantation
Outline the ‘natural method’ of contraception
- abstinence
- coitus interruptus
- take penis out before ejaculating but there is some sperm in precum
- rhythm method
- avoid sex during the fertile period.
How is sperm prevented from reaching the ejaculate?
Vasectomy
- divide the vas deferens
- semen analysis is done to ensure there is no sperm in the section of the vas deferens which drains into the ejaculatory duct.
How do you prevent sperm reaching the cervix
- Condoms
- diaphragm - sits across the entrance of the vagina and holds sperm in acidic environment of the vagina
- cap
- spermicide
What methods are available to prevent ovulation?
COCP
- progesterone negatively feedbacks onto the HPG and so it reduces the GnRH and FSH/LH therefore there is no LH surge mid cycle, and so there is no ovulation occurring.
- oestrogen, at lower doses, also negatively feeds back on to HPG
Depot Progesterone
- an injection every 3 months.
- negatively feedback
POP
- relies on cervical mucus thickening and so acts a physical barrier too.
What methods inhibit transport along the Fallopian tube
Occlusion of the Fallopian tubes.
- ligation, rings and clips
- re canalisation may occur.
- usually results in an ectopic pregnancy
How is sperm inhibited from passing through the cervix?
Mainly affects the cervical mucus, which is thickened and acts as a hostile environment for sperm.
- OCP
- Depot progesterone
- PoP
- Implants
How can implantation be inhibited?
IUCDs - inert, copper or progesterone containing device.
- copper interferes with the endometrial enzymes and prevents implantation. - can be used 5 days post coitus.
Post-coital contraception (up to 72hrs or 120hours for some meds)
- blocks implantation
- combined oestrogen/progesterone high dose or prog alone
What is primary infertility?
Failure to conceive within one year, with no previous pregnancy