Repro: Sexual Response

Question 1

Outline the human sexual response?

Answer 1

• Excitement phase (phychogenic and/or somatogenic stimuli)
• Plateau phase
• Orgasm phase
• Resolution phase (return to haemodynamic norm followed by a refractory period)

Question 2

What is the parasympathetic innervation of the penis?

Answer 2

• Pelvic nerves and pelvic plexus
• Cavernous nerve to corpora and vasculature
• Fibres from the lumbar and sacral spinal levels

Question 3

What is the neurophysiology of an erection?

Answer 3

• Inihibiton of sympathetic arterial vasoconstrictor nerve
• Activation of PNS
• Activaton of non-adrenergic, non-cholinergic, autonomic nerves to arteries to release Nitric Oxide

Question 4

How is NO made and what is the role?

Answer 4

• 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

Question 5

What are causes of erectile dysfunction?

Answer 5

• Psychological
• Tears in fibrous tissue of corpora cavernosa
• Vascular
• Drugs

Question 6

What is emission?

Answer 6

Emission

• Movement of semen into prostatic urethra
• Contraction of Smooth muscle in prostate, vas deferens and spinal vesicles

Question 7

What is ejaculation?

Answer 7

Expluson of semen

• Contraction of glands and ducts
• Bladder internal sphincter contracts preventing retrograde ejaculation
• Rhythmic striatal muscle contractions

Question 8

How does the cervical mucus vary through the menstrual cycle?

Answer 8

• Oestrogen leads to thin and stretchy mucus lining

- Oestrogen and progesterone form a thick and sticky plug

Question 9

What is the fertile windrow of oocytes and spermatozoa?

Answer 9

Spermatozoa - 48-72 hours

Oocytes - 6-24 hours

Question 10

What is acrosome?

Answer 10

• Organelle on the anterior half of of the head of the spermatozoa
• Derived from Golgi region of developing spermatid
• Contains enzymes
• Necessary for fertilisation

Question 11

What is the fertile period?

Answer 11

Sperm deposition up to 3 days prior to ovulation or day of ovulation

Question 12

What is the acrosome reaction?

Answer 12

• Sperm pushes through corona radiata
• Binding of sperm surface receptor to ZP3 glycoprotein of zona pellucida
• Triggers acrosome reaction
• Digestion of zona pellucida

Question 13

What is the cortical reaction?

Answer 13

If fertilisation occurs, there is a fusion of plasma membrane to block polyspermy

Question 14

How does the completion of meiosis 2 occurs when there is fertilisation?

Answer 14

• 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

Question 15

What is significant about a morula?

Answer 15

Each cells at this stage of development is totipotent

Question 16

How does the blastocyst form and hatch?

Answer 16

• 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

Question 17

How is implantation controlled?

Answer 17

• 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

Question 18

What are methods of contraception?

Answer 18

• Natural
• Barrier
• Hormonal
• Prevention of implantation
• Sterilisation
• Emergency contraception

Question 19

What are advantages and disadvantages of abstinence?

Answer 19

Advantages
-100% reliable method of contraception

Disadvantages
-No sex

Question 20

What are advantages and disadvantages of barrier contraceptions?

Answer 20

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

Question 21

What are barrier contraceptions?

Answer 21

• Male and female condoms

- Diaphragm caps

Question 22

What is the effect of lower dose of progesterone as a contraceptive pill?

Answer 22

-Thickens cervical mucus

Ovulation still likely

Question 23

What is the combined contraceptive pill and its action?

Answer 23

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

Question 24

What are advantages and disadvantages of combined oral contraceptive pill?

Answer 24

• 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

Question 25

What are methods of giving high dose progestogen as a contraceptive and its actions?

Answer 25

1. Intramuscular injections given at intervals 2. Progestogen pill 99% effective Action - Inhibits ovulation - Thickens cervical mucus - Prevent endometrial proliferation

Question 26

What are the advantages and disadvantages of the progestogen implant?

Answer 26

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

Question 27

What are the advantages and disadvantages of low dose progestogen only pill?

Answer 27

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

Question 28

What are method of inhibiting implantation?

Answer 28

-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

Question 29

What are the advantages and disavantages of IUD and IUS?

Answer 29

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

Question 30

What are methods of sterilisation?

Answer 30

- 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)

Question 31

What are methods of emergency contraception?

Answer 31

- Emergency IUD - Emergency pill with ulipristal acetate - Emergency pill with levonorgestrel

Question 32

What are advantages and disadvantages of progestogen injections?

Answer 32

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

Question 33

What are the principles of lactational amenorrhea method of contraception?

Answer 33

- 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

Question 34

What are advantages and disadvantages of lactational amenorrhea method of contraception?

Answer 34

Advantages -No hormone/contraindications Disadvantages - Unreliable - No STI prevention

Question 35

What are advantages and disadvantages of withdrawal method and fertility awareness methods?

Answer 35

Advantages -No devices/hormones Disadvantages - Not reliable (some sperm release in pre ejaculate, will power reliant) - No protection for STI's