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
What is secondary infertility?
Failure to conceive within 1 year, with a history of a pregnancy, whether it was successful or not
Name 4 problems associated with infertility
- Coital problems
- Anovulation
- Tubal occlusion
- Abnormal or absent sperm production
Discuss causes anovulation, with respect to infertility
- some anovulatory cycles are normal, especially at the extremes of reproductive life
- ovarian failure
- radio or chemotherapy
- Sheehan syndrome (pituitary necrosis or tumours)
PCOS (dealt with separately)
What is Sheehan syndrome?
Decreased functioning of the pituitary gland due to ischaemic necrosis due to hypovolaemic shock and blood loss during or after child birth.
Describe the blood supply to the anterior pituitary and explain Sheehans syndrome
- low pressure portal system
- during pregnancy, lactotrophs hypertrophy and hyperplasia occurs without corresponding increase in blood supply
- during peri or post partum, if a major haemorrhage and hypotension occurs, necrosis will occur of the AP.
Why does the posterior pituitary not undergo necrosis?
It has its own direct arterial supply and not supplied by the low pressure venous system.
Describe SYMPTOMS of PCOS
Weight gain
Acne
Hirsutism
Irregular menstrual cycles
Describe features of PCOS
Insulin resistance - metabolic problems High LH:FSH ratio High androgen and testosterone in circulating blood Multiple ovarian cysts Anovulation
Describe the 2 features that must be present for the diagnosis of PCOS.
2 of the following 3 are required to diagnose PCOS
- Hx of not getting pregnant or amenorrhea
- Hirsutism or high testosterone
- Classical picture on ultrasound in one or both ovaries
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MoD 1 - Cell Injury26
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MoD 2 Acute Inflammation18
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MoD 3 Chronic Inflammation14
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MoD 4 - Healing and Repair15
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MoD 6 Atheroma10
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MoD 5 - Haemostasis, Thrombosis And Embolism15
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MoD 7 Cell Adaptations26
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MoD 8 Neoplasm I19
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MR 118
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MR 216
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MR 310
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MR 415
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MR 513
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MR 612
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MR 712
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MR 89
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Repro 149
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Repro 216
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Repro 317
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Repro 431
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Repro 530
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Repro 627
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Repro 735
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Repro 842
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MoD 10 Neoplasia III18
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Repro 949
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Cardiovascular 112
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Cardiovascular 220
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Cardiovascular 219
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MR 1015
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Carduovascular 427
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MSK - 112
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MSK 214
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Cardiovascular 52
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MSK 329
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MSK 413
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MSK 53
