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Reproduction > 7) Conception & Contraception > Flashcards

7) Conception & Contraception Flashcards

1
Q

What are the 4 main places semen is produced?

A

Testes
Seminal vesicles
Prostate gland
Bulbourethral glands (Cowper’s glands)

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2
Q

What is the semen from the testes made up of?

A

20-200x10^6 sperm per ejaculate
>60% sperm swimming forward vigorously
<30% sperm have abnormal morphology

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3
Q

What is the normal volume of ejaculate?

A

2-4ml

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4
Q

What is the semen from the seminal vesicles made up of?

A

60% of volume
Alkaline fluid (neutralises acid in male urethra & female repro tract)
Fructose
Prostaglandins
Clotting factors (fibrinogen, holds sperm in place after ejaculation, before liquefaction)

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5
Q

What is the semen from the prostate gland made up of?

A 
25% of volume
Milky, slightly acidic fluid
Proteolytic enzymes (break down clotting factors, re-liquefying sperm in 10-20mins)
Citric acid
Phosphotase
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6
Q

What is the semen from the Bulbourethral (Cowper’s) glands made up of?

A

Very small volume
Alkaline fluid
Mucous (lubrication of end of penis & urethral lining)

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7
Q

How does the process of emission occur?

A

Peristalsis of vas deferens
Secretions from seminal vesicles
Move ejaculate into prostatic urethra before ejaculation

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8
Q

Describe the physiological processes involved in erection of the penis

A

Stimulants - psychogenic, tactile (sensory afferents)
Efferents - Somatic & autonomic, pelvic nerve (PNS), pudendal nerve (somatic)
lead to Haemodynamic changes

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9
Q

Describe the haemodynamic changes in erection

A
  • Inhibition of sympathetic arterial vasoconstrictor nerves
  • Activation of parasympathetic nervous system (pelvic nerve, formation of nitric oxide, NO)
  • Activation of non-adrenergic, non-cholinergic nerves to arteries releasing NO
  • NO diffuses into & causes relaxation of vascular smooth muscle (vasodilation)
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10
Q

What happens to the arteries in the corpa cavernosa during erection?

A

Central helicine arteries straighten
Enlarge lumen
Blood flows into & dilates cavernous spaces in corpora of penis

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11
Q

What happens to the arteries in the corpus spongiosum during erection?

A

Arteries dilate

Not very much - avoid compression & closing off of urethra

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12
Q

What is the role of the bulbospongiosus & ischiocavernosus muscles during erection?

A

Compress veins egressing from corpora cavernosa
Impede venous return
Corpora cavernosa engorged with blood (arterial dilation + venous constriction)
Erectile bodies become turgid (enlarged & rigid)
Erection

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13
Q

Name some causes of erectile dysfunction

A

Vascular problems (most common)
Psychological (inhibition of spinal reflexes)
Tears in fibrous tissue of corpa cavernosa
Factors blocking NO (alcohol, anti-hypertensives, diabetes)

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14
Q

What drug can be used to treat erectile dysfunction?

A

Viagra
Inhibits breakdown of cGMP
Maintains erection

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15
Q

What physiological changes take place in a female to facilitate coitus?

A

Vaginal lubrication
Swelling & engorgement of external genitalia
Internal enlargement of vagina
Cervical mucus
- Oestrogen - abundent, clear, non-viscous mucous
- Progesterone + Oestrogen - Thick, sticky mucous plug

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16
Q

Describe the mechanism of ejaculation

A

Spinal reflex
SNS control:
1. Contraction of glands & ducts (smooth muscle)
2. Bladder internal sphincter contracts (prevents entry of semen into bladder)
3. Rhythmic striatal muscle contractions (pelvic floor, ischiocavernosus & bulbospongiosus - pudendal S2-4, hip & anal muscles)

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17
Q

Describe sperm transport through the cervix & uterus

A
  • Immediately after ejaculation semen coagulates (clotting factors, prevents sperm being lost from vagina)
  • 10-20mins later semen re-liquefies (enzymes
  • Vast majority of sperm don’t enter cervix
  • Sperm in uterus travel 15-20cm to uterine tube (hours)
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18
Q

How is the transport of sperm facilitated?

A

Own propulsive capacity

Fluid currents caused by action of ciliated cells in uterine tract

19
Q

What changes do sperm undergo during their passage through the uterus to the uterine tube?

A

Maturational changes:
Capacitation
Acrosomal reaction
Both induced by influx of Ca & rise in cAMP in spermatozoa

20
Q

What is capacitation?

A

Further maturation of sperm in female repro tract (6-8hrs)
Removal of sperm glycoprotein coat to allow fusion with oocyte cell surface
Tail movement changes, Beat > Whip-like action
Sperm become responsive to signals from oocyte

21
Q

What is the acrosomal reaction?

A

Capacitated sperm come into contact with oocyte zona pellucida
Membranes fuse
Acrosome swells, liberates contents by exocytosis
Proteolytic enzymes & further binding facilitate penetration of zona pellucida by sperm (15mins)

22
Q

Describe what happens during ovulation

A

Ovum (primary oocyte) in ovulatory follicle has completed 1st meiotic division
- Secondary oocyte & 1st polar body
Secondary oocyte surrounded by follicular cells in gelatinous matrix released from ovulatory follicle
Picked up by fimbria of uterine tube to ampulla for fertilisation

23
Q

What happens to the zygote once it has formed?

A

Cleavage - mitotic divisions (few hours)
Forms morula (ball of cells)
Forms blastocyst (hollow structure)
Gradually transported along uterine tube to uterus
Blastocyte enters uterine cavity 4-5 days later
Implantation

24
Q

What is an ectopic pregnancy?

A

Failure of transport of egg
Embeds in uterine tube, ovary or abdomen
Embryo dies
Severe risk of maternal haemorrhage

25
Q

What is ‘natural’ conception? (contraception)

A

Abstinence
Coitus interruptus - sperm in pre-ejaculate (not effective)
Rhythm method

26
Q

What are the main contraceptive methods used?

A 
Barrier methods e.g. condoms
Hormonal contraception e.g. OCP, COCP, POP
Vasectomy/Sterilisation
Natural conception
Post-coital contraception
27
Q

What is a vasectomy and how does it work?

A

Division of vas deferens bilaterally

Prevent sperm from entering ejaculate

28
Q

What are the main barrier methods of contraception?

A

Condoms (+ STI protection)
Diaphragm (holds sperm in acidic vagina, reduces survival time)
Cap (across cervix)
Prevent sperm from reaching cervix

29
Q

What is the role of progesterone in hormonal contraception?

A 
Thick, 'hostile' cervical mucus plug
Prevents sperm entering uterus
-ve feedback to hypothalamus/pituitary:
Decreases frequency of GnRH pulses
Inhibits follicular development
30
Q

What is the role of oestrogen in hormonal contraception?

A

-ve feedback on anterior pituitary
Loss of +ve feedback mid-cycle
No LH surge

31
Q

What are the main types of hormonal contraceptives?

A

Combined Oral Contraceptive Pill (COCP)
Progesterone Only Pill (POP)
Depot Progesterone (3 monthly injections)
Progesterone Implants

32
Q

What contraceptive methods can be used to inhibit implantation?

A

Hormonal contraceptives (COCP, OCP, POP)
Post-coital contraceptives (Morning-after pill)
Intra-uterine contraceptive device (Copper coil)

33
Q

How do intra-uterine contraceptive devices (e.g. coil) work?

A

Inert copper
Interferes with endometrial enzymes & implantation
May interefere with sperm transport into fallopian tube
Progesterone impregnated

34
Q

How does post-coital contraception (morning-after pill) work?

A 
Combined oestrogen/progesterone or POP
High Dose
Up to 72hrs after intercourse
May disrupt ovulation
Blocks implantation
May impair luteal function
35
Q

What is the difference between primary and secondary infertility?

A

Primary - No previous pregnancy

Secondary - Previous pregnancy, successful or not

36
Q

What can be the causes of male infertility?

A

20-25% cases
Abnormal sperm production e.g. testicular disease
Obstruction of ducts e.g. infection, vasectomy
Hypothalmic/Pituitary dysfunction

37
Q

Describe a normal semen analysis for a male

A

Volume >2ml
Sperm count >20 million per ml
Motility >50%
Morphology >50%

38
Q

What can be the causes of female infertility?

A

45-60% cases
Anovulation
- usually very irregular periods
- Hypothalmic e.g. hyperprolactinaemia, weight loss, exercise, stress
- Pituitary e.g. tumours, necrosis
- Ovarian e.g. ovarian failure, radiotherapy, chemotherapy

39
Q

How would you differentiate the causes of female infertility?

A

Look at hormone levels
Menopause - High FSH & LH, Low oestrogen
Ovarian failure - High FSH & LH, Low oestrogen
Hypo/Pituitary - Low FSH, LH & oestrogen
PCOS - Increased ratio FSH:LH, Normal oestrogen

40
Q

How can ovulation be induced?

A 
Anti-oestrogen therapy
 - reduce -ve feedback to hypothalamus/pituitary
 - Increase GnRH & FSH
Gonadotrophins
 - FSH administration
GnRH Agonists
 - Pulsatile to mimic secretion
41
Q

What are the causes, diagnosis & treatment of tubal occlusion?

A

Causes - sterilisation, PID
Diagosis - Laparoscopy, Hysterosalpingogram
Treatment - Tubal surgery, Assisted conception

42
Q

What is polycystic ovarian syndrome? (PCOS)

A

Increased androgen secretion
Raised LH:FSH ratio
Insulin resistance
Multiple small ovarian cysts

Coital problems, unexplained 20-30% cases

43
Q

What questions would you ask when trying to manage infertility in a patient?

A

Regular, unprotected intercourse?
Ovulating? Regular menstrual cycle? Day 21 progesterone?
Patent tubes - infection/sterilisation?
Adequate sperm count?

44
Q

How can you treat infertility?

A 
Induce ovulation
Overcome tubal occlusion by surgery or IVF
If inadequate sperm :
 - artificial insemination by donor
 - Intra-cytoplasmic sperm injection

Reproduction (13 decks)

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