Repro: Sexual Response Flashcards
Outline the human sexual response?
- Excitement phase (phychogenic and/or somatogenic stimuli)
- Plateau phase
- Orgasm phase
- Resolution phase (return to haemodynamic norm followed by a refractory period)
What is the parasympathetic innervation of the penis?
- Pelvic nerves and pelvic plexus
- Cavernous nerve to corpora and vasculature
- Fibres from the lumbar and sacral spinal levels
What is the neurophysiology of an erection?
- Inihibiton of sympathetic arterial vasoconstrictor nerve
- Activation of PNS
- Activaton of non-adrenergic, non-cholinergic, autonomic nerves to arteries to release Nitric Oxide
How is NO made and what is the role?
- Post ganglionic fibres release ACh
- ACh bonds to M3 receptors on endothelial cells
- Rise in Ca2+ and activation of NOS and formation of NO
- Nitric Oxide diffuses into vascular smooth muscle and causes relaxation
- NO also released directly from nerves
What are causes of erectile dysfunction?
- Psychological
- Tears in fibrous tissue of corpora cavernosa
- Vascular
- Drugs
What is emission?
Emission
- Movement of semen into prostatic urethra
- Contraction of Smooth muscle in prostate, vas deferens and spinal vesicles
What is ejaculation?
Expluson of semen
- Contraction of glands and ducts
- Bladder internal sphincter contracts preventing retrograde ejaculation
- Rhythmic striatal muscle contractions
How does the cervical mucus vary through the menstrual cycle?
- Oestrogen leads to thin and stretchy mucus lining
- Oestrogen and progesterone form a thick and sticky plug
What is the fertile windrow of oocytes and spermatozoa?
Spermatozoa - 48-72 hours
Oocytes - 6-24 hours
What is acrosome?
- Organelle on the anterior half of of the head of the spermatozoa
- Derived from Golgi region of developing spermatid
- Contains enzymes
- Necessary for fertilisation
What is the fertile period?
Sperm deposition up to 3 days prior to ovulation or day of ovulation
What is the acrosome reaction?
- Sperm pushes through corona radiata
- Binding of sperm surface receptor to ZP3 glycoprotein of zona pellucida
- Triggers acrosome reaction
- Digestion of zona pellucida
What is the cortical reaction?
If fertilisation occurs, there is a fusion of plasma membrane to block polyspermy
How does the completion of meiosis 2 occurs when there is fertilisation?
- Series of calcium waves are activated following fusion of oocyte and sperm membranes
- Resumption of meiosis 2 occurs
- Pronuclei move together
- Mitotic spindle forms leading to cleavage
What is significant about a morula?
Each cells at this stage of development is totipotent
How does the blastocyst form and hatch?
- Differetation to form inner and outer cell mass
- Formation of blastocyst
- Blastocyst hatches from zona pellucida
- No longer constrained so now free to enlarge
- Can interact with uterine surface to implant
How is implantation controlled?
- Endometrium controls degree of implantation
- Transformation of endometrium into decidua In presence of the conceptus
- Decidual reaction provides the balancing force for the invasive force of the trophoblast
What are methods of contraception?
- Natural
- Barrier
- Hormonal
- Prevention of implantation
- Sterilisation
- Emergency contraception
What are advantages and disadvantages of abstinence?
Advantages
-100% reliable method of contraception
Disadvantages
-No sex
What are advantages and disadvantages of barrier contraceptions?
Advantages
- Reliable
- Protection from STIs
- Male condom is widely available
Diadvantages
- Disrupt romantic nature of sexual intercouree
- Reduces sexual pleasure
- Danger of expiring
- Allergy/Sensitivity to latex/Spermicide
What are barrier contraceptions?
- Male and female condoms
- Diaphragm caps
What is the effect of lower dose of progesterone as a contraceptive pill?
-Thickens cervical mucus
Ovulation still likely
What is the combined contraceptive pill and its action?
Synthetic oestrogen and progesteron taken for 21 days (+- 7 day placebo)
- Prevents ovulation
- Reduces endometrial receptivity to inhibit implantation
- Thickens cervical mucus to inhibit penetration of sperm
What are advantages and disadvantages of combined oral contraceptive pill?
- Can relive menstrual disorders
- Reduces risk of ovarian cancer and endometrial cancer
Disadvantages
- Interaction with other medications
- Contraidications and side effects
- Increased risk of breast cancer, cervican cancer, VTE, MI, Stroke
- No protection from STIs
What are methods of giving high dose progestogen as a contraceptive and its actions?
- Intramuscular injections given at intervals
- Progestogen pill
99% effective
Action
- Inhibits ovulation
- Thickens cervical mucus
- Prevent endometrial proliferation
What are the advantages and disadvantages of the progestogen implant?
Advantages
- Reliable
- LARC
- It can be useful for women who can’t use contraception that contains oestrogen
- Natural fertility return quickly when removed
Disadvantages
- Minor procedure to insert
- Side effects
- No STI protection
What are the advantages and disadvantages of low dose progestogen only pill?
Advantages
- Quickly reversible
- It does not interrupt sexual intercourse
- Can be used where the COCP is contraindicated
Disadvantages
- User dependant
- Menstrual problems are common
- Interacts with other medication
- Risk of ectopic pregnancy
- Does not protect from STI’s
What are method of inhibiting implantation?
-Intrauterine system
Progestogen-releasing plastic device that works for 3-5 years. It prevents impantating and reduces endometrial proliferation.
-Intrauterine device
Plastic device with added copper. Works for 5-10 years
Copper is toxic to ovum and sperm
Also causes endometrial inflammatory reaction to prevent implantation and changes the consistency of cervical mucus
What are the advantages and disavantages of IUD and IUS?
Advantages
- Convenient
- Long duration of action
Disadvantages
- Insertion may be unpleasant
- Risk of uterine perforation
- Menstrual irregularity
- Doesn’t prevent STI
- Displacement/expulsion may occur
What are methods of sterilisation?
- Vasectomy (the vas deferens is interrupted to prevent sperm entering ejaculate
- Tubual Ligation/Clipping (Fallopian tubes cut or blocked to stop ovum travelling from the ovary to the uterus)
What are methods of emergency contraception?
- Emergency IUD
- Emergency pill with ulipristal acetate
- Emergency pill with levonorgestrel
What are advantages and disadvantages of progestogen injections?
Advantages
- Reliable
- Does not interrupt sexual intercourse
- Can be useful for women who can’t use COCP
Disadvantages
- Appointment needed every 12 weeks
- Contraindications and side effects
- Delay in fertility returning
- No STI protection
What are the principles of lactational amenorrhea method of contraception?
- Breastfeedng delays the return of ovulation after childbirth
- Sucking stimulus disrupts release of GnRH
- Affect feedback cycle of HPG axis
- Relies on exclusive breast feeding and is only effect for up to 6 months after giving birth
What are advantages and disadvantages of lactational amenorrhea method of contraception?
Advantages
-No hormone/contraindications
Disadvantages
- Unreliable
- No STI prevention
What are advantages and disadvantages of withdrawal method and fertility awareness methods?
Advantages
-No devices/hormones
Disadvantages
- Not reliable (some sperm release in pre ejaculate, will power reliant)
- No protection for STI’s
