Repro Session 7 Flashcards Preview

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Flashcards in Repro Session 7 Deck (195):
1

What stimulates formation of the blood-testis barrier?

Testosterone and androgen-binding protein of Sertoli cells

2

Is LH necessary for spermatogenesis?

No

3

Which two hormone cans initiate spermatogenesis in the absence of LH?

FSH and testosterone

4

What is the action of oestrogen secreted by Leydig cells?

Increase sperm viability

5

Which cells secrete inhibin in the male?

Sertoli

6

What does a spermatid become after spermiogenesis?

Spermatozoon

7

What happens in the head of a spermatid during spermiogenesis?

Nuclear condensation

8

How is the acrosome of a spermatid formed?

Golgi apparatus secrete lysozyme like enzymes into vesicle

9

What is the function of the acrosome?

Future penetration of an ovum

10

Where is the acrosome of a spermatid found?

In the head

11

Describe the mid-piece of a spermatid.

Mitochondria become packed around contractile filaments

12

How does the tail of a spermatid develop?

Centriole arises and micrtobules grow from it to form axoneme

13

What is the axoneme?

Shaft of flagellum with 20 micro tubules arranged in 9 doublets and 2 singlets

14

What happens to excess cytoplasm during spermiogenesis?

Removed with excess organelles by testosterone

15

What does LH act on to cause testosterone secretion?

Leydig cells

16

What surface molecules are found on a spermatozoa?

Proteins and carbohydrates

17

Describe the maturity and motility of spermatozoa.

Mature but lack motility

18

How are spermatozoa released?

Via spermation from Sertoli cells into lumen of seminiferous tubule

19

What do Sertoli cells release in addition to spermatozoa?

Testicular fluid

20

What is the function of testicular fluid?

Carry spermatozoa via peristaltic contractions to the epididymis

21

What are the surface proteins of spermatozoa covered in when they reach the epididymis?

Seminal plasma proteins

22

What happens to spermatozoa in the epididymis?

Gain motility, become fertile and be stored

23

Does storing spermatozoa for several months have an impact in fertility?

No

24

What happens to spermatozoa that are not released within a few months of arrival at the epipdidymis?

Phagocytosed by epididymal epithelial cells

25

What are the stages involved in maturation of the oocyte nucleus?

Meiosis I, nuclear membrane disappears, 1st polar body formed, Meiosis II, stop in metaphase II

26

Where does the 1st polar body formed during oocyte nuclear maturation go?

Perivitelline space

27

What process are involved in oocyte cytoplasm maturation?

Organelle distribution, protein and lipid synthesis and cytoskeleton dynamics

28

What happens during organelle redistribution in oocyte cytoplasm maturation?

Mitochondria and ER form granules

29

What do protein and lipid synthesis during oocyte cytoplasm maturation form?

Cortical granules and lipid drops

30

What cytoskeleton dynamics take place during oocyte cytoplasm maturation?

Movement of microfilaments to the cortex

31

How are dizygotic twins formed?

2 eggs are ovulated and fertilised

32

What happens during the excitement phase of coitus in both the male and female?

Sensory and psychological stimulation activate the limbic system

33

What is the limbic system?

Instinct and mod part of the brain that initiates sex drive

34

What are the neural consequences of activation of the limbic system?

Activation of sacral parasympathetic nerves and inhibition of thoracolumbar sympathetic nerves

35

What are the consequences of activation of the sacral parasympathetic nervous system in the female?

Vasocongestion causing vaginal lubrication, clitoris engorgement, uterine elevation, increased muscle tone, increased HR, increased BP and vaginalis elongation and expansion

36

How is nitric oxide synthase activated in the male excitement phase of coitus?

ACh acts on M3 receptors of endothelial cells causing an increase in calcium

37

What is the consequence of NO production from stimulated eNOS in the excitement phase of the male?

Causes arteriolar vasodilation in corpora cavernosa to increase penile bloodflow

38

What happens in penile filling?

Latency period with increased blood but no erection

39

What are the end results of the male excitement phase?

Penile tumescence (erection), scrotal skin thickens and tenses, testes elevate and engorge

40

What is the effect of continued stimulation on muscle tone, HR and BP in the female plateau phase of coitus?

Further increased

41

What change is visible in the labia minora in the plateau phase?

Deepens in colour

42

Where is the orgasmic platform found?

Lower 1/3 of vagina

43

What does the clitoris do during the plateau phase?

Draws under its hood

44

What is the function of Bartholin mucus secretion in the plateau phase ?

Lubricate vestibule for penis entry

45

Describe the positions of the uterus and vagina in the plateau phase.

Uterus fully elevated. Inner 2/3 of vagina fully distended

46

How does activation of the sacrospinous reflex impede venous return in the male plateau phase?

Contracts ischiocavernosus causing compression of the crus penis

47

What decreases arterial inflow in the male plateau phase?

Intracavernous pressure rising towards systemic circulatory levels

48

What is the function of stimulation of the Cowper's and Littre's glands in the male plateau phase?

Secretions lubricate distal urethra and neutralise urine

49

What does the thoracolumbar sympathetic reflex cause in the male emission phase?

Contraction of ductus deferens, ampulla, seminal vesicle and prostate

50

Why do the urethral sphincters contract in the male emission phase?

Prevent retrograde ejaculation

51

Where does semen pool during the male emission phase?

Urethral bulb

52

What are the two stages of the male orgasm phase?

Emission and ejaculation/expulsion

53

What is the neural involvement in the ejactulation phase?

Spinal reflex, cortical control, SNS L1 and 2

54

What is the action of neural activity in the ejaculation phase?

Contraction of smooth muscles in glands and ducts

55

What stimulates the pudendal nerve in the ejaculation phase?

Internal urethral filling

56

What does stimulation of the pudendal nerve cause in the ejaculation phase?

Contractions of genital organs, ischio- and bulbocavernosus

57

What happens to the orgasmic platform in the female orgasmic phase?

Rhythmically contracts 3-15 times

58

What does pudendal nerve stimulation in the female orgasm phase cause?

Uterus (fundus to cervix) and anal sphincter contract

59

What happens to the clitoris in the orgasm phase of coitus?

Remains under hood

60

Does the inner 2/3 of vagina move during the orgasm phase of coitus?

No, remains motionless

61

Are multiple orgasms possible?

Yes but only in the female

62

What are all visible changes in the breast during coitus due to?

Venous engorgement and increased arterial flow

63

What changes are seen in the breasts during coitus?

Increased breast size, nipples erect, distinct veins, increase in areolar size and sex flush on breasts and upper abdomen

64

What is the G spot?

Grafenberg spot = area of erotic sensitivity on anterior vaginal wall similar to male prostate tissue

65

What happens when the G spot is stimulated?

Small amount of fluid released that is enzymatically similar to prostatic secretions

66

What neural activity brings about the male and female resolution phase?

Activation of thoracolumbar sympathetic pathway

67

What are the effects in the vasculature of the resolution phase of coitus?

Contraction of arteriolar smooth muscle and increase venous return

68

What are the results of the male resolution phase?

Detumescence, flaccidity, refractory period, testes descend and scrotum wrinkles

69

What are the results of the female resolution phase?

Clitoris descends, labia regress and vagina shortens and narrows

70

What is the oust common cause of sexual dysfunction and has an increasing incidence?

Desire

71

What two categories can sexual dysfunction due to desire be divided into?

Hypo- and hyperactive

72

Describe sexual dysfunction due to hypoactive desire.

Little or no interest in sex, can lead to revulsion or fear of one or all aspects of process

73

What is hypoactive desire in sexual dysfunction often a result of?

Abuse or assault

74

How does the severity of sexual dysfunction due to hyperactive desire vary?

From abnormally high interest in sex to nymphomaniac

75

What is Klüver Bucci syndrome?

Pts with bilateral medial temporal lobe lesions from trauma, metastases etc display hyperphagia, hypersexuality, hyperorality, visual agnosia and docility

76

What changes due to female ageing can lead to reports of desire and arousal?

Decreased vasocongestion, loss of vaginal and urethral elasticity, decreased length and width of vagina, fewer orgasmic contractions and more rapid resolution

77

How does decreased vasocongestion cause a reduction in desire and arousal?

Loss of vaginal lubrication

78

What is the normal number of sperm in 2-4 ml of semen?

20-200 X 10^6 per ml

79

What proportion of sperm in 2-4 ml swim forward vigorously?

>60%

80

What usually happens to semen within an hour of expulsion?

Become gelatinous and reliquefy

81

What proportion of the ejaculate do the seminal vesicles secrete?

60%

82

What is semenogelin?

Clotting factor released by the seminal vesicles

83

What are the components of the seminal vesicle fluid part of ejaculate?

Alkaline fluid, fructose, prostaglandins, clotting factors

84

What is the function of prostaglandins from seminal vesicle secretions?

Increase spermatozoa motility and increase female genital smooth muscle contraction

85

What proportion of the ejaculate is formed by prostatic secretions?

25%

86

What are the components of the prostatic secretions in the ejaculatory fluid?

Milky acidic fluid, proteolytic enzymes citric acid, acid phosphatase

87

What is the purpose of proteolytic enzymes from the prostatic secretions?

Re-liquefaction of semen

88

What is the citric acid found in prostatic secretions contributing to ejaculatory fluid used for?

Krebs cycle

89

What proportion of the ejaculatory fluid is due to bulbourethral gland secretions?

5%

90

What abnormal morphology can sperm display?

Giant, macro, double headed, double tailed, long head, rough head or abnormal mid-piece

91

What is the problem in sexual dysfunction to to female sexual arousal?

Persistent recurrent inability to lubricate in response to swelling

92

What is sexual dysfunction due to male arousal called?

Impotence

93

What is the most common cause of impotence?

Psychological due to descending inhibition of spinal reflexes due to cortical control

94

What are the physical origins of impotence?

Tear in fibrous tissue of corpus cavernosa, atherosclerosis, diabetes, alcohol, beta-blockers, diuretics

95

How does Viagra treat impotence?

Inhibit cGMP breakdown therefore increasing NO action

96

What are the 8 stages of fertilisation?

Semen deposition and transport; spermatid penetration of oocyte; block to polyspermy; syngomy; cleavage; compaction; hatching; implantation

97

When must semen deposition be timed so that fertilisation occurs?

Needs to be 3-0 days prior to ovulation

98

Why must the deposition of sperm be relatively tightly timed?

Sperm can survive up to 5 days but the oocyte is phagocytosed within 6-24 hours

99

When is the fertile time of the menstrual cycle?

Days 11.5-16

100

What happens to the oocyte upon fertilisation?

Takes 3-4 days to travel from ovary to body of uterus

101

What does failure of the fertilised oocyte to travel to the uterus cause?

Ectopic pregnancy leading to a non-viable embryo

102

How many spermatid reach the site of fertilisation in the female repro tract?

300

103

What is the action of oxytocin on the uterine body?

Stimulates uterine contraction

104

Where is semen deposited in the female repro tract?

Junction of vagina and cervix

105

How does the cervical mucus appear when oestrogen only is present?

Abundant and non-viscous

106

How does the cervical mucus appear when oestrogen and progesterone are acting?

Thick, sticky plug

107

What is the function of the oestrogen and progesterone stimulated cervical mucus?

Protects conceptus from infection

108

How many sperm are sacrificed to disperse the zona pellucida?

299

109

What does the sperm need to penetrate to facilitate fertilisation?

Corona radiata and zona pellucida

110

What is the corona radiata?

Layer of follicular cells around oocyte

111

What allows binding of sperm to ZP3 proteins on the oocyte?

Exposure to female repro tract removing seminal plasma coatings and some spermatid surface molecules exposing proteins

112

What does binding of sperm to ZP3 cause?

Acrosome reaction

113

What happens in the acrosome reaction?

Intracellular calcium signalling causes acrosomal enzymes to digest the zona pellucida

114

Where on the oocyte does the sperm bind?

Region rich in microvilli not region over metaphase chromosomes

115

When does the oocyte become a zygote?

Once the sperm has moved into the cytoplasm

116

How does sperm tail movement change during penetration of the oocyte?

Changes from beat to whip-like action

117

What are the two blocks to polyspermy and how do they differ?

Fast (temporary) and slow (permanent)

118

What happens in the fast block to polyspermy?

Electrical change to oocyte RMP from -75 mV to +20 mV due to sodium channel opening

119

Where does the wave of depolarisation in fast block polyspermy start?

Site of sperm entry

120

What happens in the slow block to polyspermy?

Calcium from ER causes wave of granule exocytosis

121

Why does granule exocytosis occur in a wave in the slow block to polyspermy?

Enzymes released stimulate adjacent granules

122

What does the cortical matrix modify?

Existing extracellular matrix

123

What is syngomy?

Union of male and female pronuclei to form diploid zygote

124

What happens to the oocyte during syngomy?

Completes meiosis II and expels second polar body

125

What happens during the cleavage stage of fertilisation?

Rapid mitotic divisions and metabolic changes amusing increasing number but not size of cells

126

What happens if two separate cell masses develop during cleavage?

Monozygotic twins

127

Why does the size of cells not increase in cleavage?

No new cytoplasm or organelles are formed

128

Why does each cell during cleavage have to be totipotent?

Needed to increase nuclear/cytoplasm ratio as one cannot transcribe enough RNA

129

How can the division in cleavage be described?

Asynchronous

130

When does compaction occur?

8-cell stage

131

What happens during compaction?

Polarisation and tight junction formation to crest inner embryo environment

132

What happens during hatching in fertilisation?

Enzymes from trophoblast cells digest ZP opposite to inner cell mass

133

Why is the ZP opposite the inner cell mass digested in hatching?

Reduce risk of enzymatic damage to embryo

134

What happens to the conceptus between ovulation and implantation?

Nourishment in intrauterine fluid for 2-3 days

135

When does implantation occur with respect to ovulation?

6 days later

136

What allows the trophoblast overlying the inner-cell mass to adhere to the progesterone primed endometrium in implantation?

It is sticky

137

Does the blastocyst display totipotency?

No

138

What is polyploidy?

3 or more pronuclei due to polyspermy or failure of second polar body extrusion

139

How long does it take for the zygote to become a blastocyst?

7 days (days 14-21)

140

What are the 3 methods of 'natural' contraception?

Abstinence, coitus interruptus, rhythm methods

141

Why is pt education needed in coitus interruptus?

Need to know sperm is present in pre-ejaculate

142

What does the rhythm method of contraception require?

Regular cycle

143

If a regular mestrual cycle lasts 28 days, when is the fertile period?

Days 7-16

144

What is vasectomy?

Bilateral split of vas deferens to prevent spermatid entering ejaculate

145

Is coitus affected by vasectomy?

No

146

Can vasectomy be reversed?

Yes

147

Why must the ejaculate be tested before relying on vasectomy for contraception?

Risk of residual sperm in ligated vas deferens

148

What are the 3 barrier methods of contraception?

Condoms, diaphragm and cap

149

What is used in addition to barrier methods to make the most effective?

Spermicide

150

What additional advantage does condom use have other than contraception?

Protects against STDs

151

Describe how diaphragms are used in contraception.

Lies diagonally across cervix to hold sperm in acidic vagina to reduce survival time

152

Why does diaphragm use as a contraceptive require aureate fitting?

Does not occlude passage of sperm

153

How does a cap work as a contraceptive?

Physical barrier to sperm across the cervix

154

How can alteration of the cervical mucus be used as a contraceptive method?

Progesterone can be used to mediate the production of thick 'hostile' mucus to inhibit sperm passage

155

How can progesterone be administered as a contraceptive?

Combined OCP, depot progesterone, implant/pill

156

What methods can be used to prevent ovulation in contraception?

Combined OCP, depot progesterone or progesterone only implant/pill

157

How does the combined OCP prevent ovulation?

Oestrogen causes loss of mid-cycle +ve feedback so no LH surge. Together with progesterone causes -ve feedback on HPA axis to inhibit follicular development

158

How does depot progesterone prevent ovulation?

Given IM every 3 months causes -ve feedback of HPA axis

159

How long is the progesterone-only implant effective for?

5 years

160

What is the main mechanism by which progesterone only implant/pill prevents conception?

Alsatian of cervical mucus (may inhibit ovulation at low dose)

161

How does female sterilisation serve as a contraceptive?

Clips/rings/ligation used to occlude Fallopian tubes

162

What are the problems with using female sterilisation for contraception?

Not very reversible and may recanalise

163

How can implantation be inhibited as a method of contraception?

Hormones such as OCP, POP, depot, progesterone implant directly affect receptivity of endometrium and indirectly via absence of corpus luteum causing endometrial preparation

164

How does post-coital contraception work?

Combined high dose oestrogen and progesterone or progesterone only make lining unfavourable for implantation up to 72 hours after intercourse

165

Why is post-coital contraception most effective within 72 hours of intercourse?

Embryo stays in uterine tubes in this time

166

What are the problems associated with post-coital contraception?

May disrupt ovulation +/- luteal function impairment

167

How does an intrauterine copper device act as a contraceptive?

Interferes with endometrial enzymes and possibly sperm transport by inducing a foreign body reaction

168

Why does IUCD not lead to PID?

Copper is inert

169

Which IUD carries a slightly higher infection risk?

Copper

170

When is an IUCD used for contraception?

For pure contraception with normal menstruation

171

How does a progesterone IUD act as a contraceptive?

Interferes with implantation

172

What additional benefits can a progesterone IUD give with contraception?

Easing of fibroid and endometriosis symptoms

173

When is a progesterone IUD used [unlicensed] and why?

Menorrhagia as after a year of use periods are light/absent

174

What is there a risk of if fertilisation occurs despite POP use?

Ectopic pregnancy

175

Why is the efficacy of OCP, POP, implants and depot good for contraception?

Multi-action

176

What is the definition of infertility?

Failure to conceive within 1 year

177

What proportion of couples are affected by infertility?

~15%

178

How is infertility due to female, male and unexplained cause split?

20-25% male, 45-60% female, 20-30% unexplained

179

What is male primary infertility?

No children by any partner

180

What is primary female infertility?

No conception ever

181

What is secondary infertility?

Failure to conceive following previous pregnancy whether this pregnancy was successful or not

182

What are three female causes of infertility?

Coital problems, anovulation and tubal occlusion

183

How do coital problems cause infertility?

Spasms of vaginalis muscle make coitus painful/impossible

184

When is anovulation normal in female reproductive life?

At start and end

185

What can cause anovulation during reproductive life?

Weight loss, hyperprolactinaemia, exercise, stress, pituitary tumours, pituitary necrosis, ovarian failure, menopause, radio or chemotherapy, PCOS

186

What is Sheehan's syndrome?

Hypopituitarism due to post-partum haemorrhage

187

How does PCOS cause anovulation?

Uncertain pathogenesis causes high androgens, raising LH/FSH ratio, causing insulin resistance and cyst formation

188

What are the treatment options for anovulation?

Anti-oestrogen, FSH, pulsatile GnRH agonists

189

How can anovulation be diagnosed?

Look at hormones and anti-Müllerian hormone for follicle number

190

How can tubal occlusion cause infertility?

Sterilisation or scarring prevents passage of conceptus

191

How is tubal occlusion diagnosed?

Hysterectosalpinography

192

What are the treatment options for tubal occlusion?

Reanastomosis or assisted contraception

193

How can abnormal/absent production arise?

Testicular disease causing abnormal production, infection or vasectomy causing obstruction of ducts, hypothalamic/pituitary dysfunction

194

How can infertility due to abnormal/absent production be identified?

Semen analysis shows motility +/- morphology will be low

195

Why does semen analysis require a period of abstinence and regular interval between analyses?

Spermatogenesis is cyclic