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X Physiology 1B > Reproductive System > Flashcards

Reproductive System Flashcards

1
Q

in humans what is sex determined by?

A

X and Y chromosomes

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2
Q

how many chromosomes are in diploid cells?

A

46 or 23 pairs

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3
Q

how many chromosomes are found in haploid gametes?

A

23 chromosomes including one of either X or Y

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4
Q

what is the role of the Y chromosome in sex determination?

A

determines sex

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5
Q

how are haploid gametes created?

A

meiosis

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6
Q

how does meiosis differ between spermatocyte and oocyte?

A

cell division in oocyte is uneven and produces one egg cell and the polar bodies to ensure egg receives all essential materials

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7
Q

what are 2 abnormalities of sex chromosomes?

A

Turners Syndrome

Klinefelter’s Syndrome

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8
Q

what is the genotype of someone with Turners Syndrome?

A

X0 - one X, no Y

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9
Q

what is the genotype of someone with Klinefelter’s Syndrome?

A

XXY - two X and one Y

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10
Q

what is the phenotype of someone with Turner’s syndrome?

A

female

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11
Q

what is the phenotype of someone with Klinefelter’s Syndrome?

A

male (male genitalia, may have feminine characteristics)

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12
Q

what does the Y chromosome determine?

A

maleness - presence of testis

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13
Q

what gene on the Y chromosome determines presence of testis?

A

SRY gene

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14
Q

what is the role of the SRY gene?

A

determines production of TDF

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15
Q

what is TDF?

A

testis determining factor

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16
Q

what is the role of TDF?

A

causes undifferentiated gonad to become testis

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17
Q

what is androgen insensitivity syndrome?

A

partial or complete inability to respond to androgens - genetic makeup is male but due to AIS there is female phenotype

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18
Q

what are sex hormones responsible for in development?

A

sex determination

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19
Q

what hormone is from the family prostagens?

A

progesterone

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20
Q

what hormone is from the family androgens?

A

testosterone

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21
Q

what hormone is from the family oestrogens?

A

oestrogen (oestrodiol 17beta)

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22
Q

what is the precursor to the sex hormones?

A

cholesterol

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23
Q

what type of hormones are sex hormones?

A

steroid

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24
Q

what are the main female sex hormones?

A

oestrogen (oestrodiol 17beta)

progesterone

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25
Q

what is the main male sex hormone?

A

testosterone

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26
Q

how are oestrogens produced?

A

cholesterol is converted to progesterone through enzyme action. Progesterone is converted to testosterone and then testosterone to oestrogens via enzyme action for both stages.

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27
Q

what occurs in the ampulla of the uterine tube?

A

fertilisation of the egg

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28
Q

what is the role of the fimbria?

A

uptake of the ovulated ovum from the ovary

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29
Q

what are the 2 main functions of the ovary?

A

gametogenic and endocrine

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30
Q

what is gametogenic function?

A

production of gametes

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31
Q

what is the purpose of the endocrine function of the ovaries?

A

ensures right environment for development of gametes

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32
Q

what is the oestrous cycle named after?

A

oestrus

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33
Q

what is oestrus?

A

behavioral changes associated with sexual receptivity (heat)

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34
Q

what is the oestrous cycle formed of?

A

physiological changes that occur between one oestrus and the next

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35
Q

what is the oestrous cycle known as in humans?

A

menstrual cycle

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36
Q

what is the importance of oestrus?

A

occurs just before ovulation and optimises the chance of successful fertilization

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37
Q

what occurs in the follicular phase of the oestrous cycle in the ovary?

A

primordial follicles grow and develop with the oocyte within them

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38
Q

what happens during pro-oestrus?

A

follicles develop

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39
Q

what happens during oestrus?

A

behavioral changes

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40
Q

what happens at ovulation?

A

oocyte is released from the follicle

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41
Q

when does metoestrus occur?

A

between ovulation and formation of the corpus luteum

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42
Q

what occurs during the luteal phase of the oestrous cycle?

A

corpus luteum is formed from the degraded follicle and then breaks down

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43
Q

what is the dominant hormone during the follicular phase of the oestrous cycle?

A

oestrogen

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44
Q

what is the dominant hormone during the luteal phase of the oestrous cycle?

A

progesterone

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45
Q

what oocytes are female mammals born with?

A

finite number of primary oocytes

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46
Q

what stage of development do primary oocytes remain in until ovulation?

A

arrested state of development in prophase of first meiotic division

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47
Q

when does the menopause occur?

A

when no oocytes remain in the ovary

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48
Q

what is the name of the fist oocyte found pre-birth?

A

oogonium

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49
Q

how is the primary oocyte created pre-birth?

A

growth of the oocyte from oogonium

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50
Q

when does the first meiotic division of oocyte occur?

A

ovulation

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51
Q

what does the first meiotic division of oocyte at ovulation produce?

A

secondary oocyte and a first polar body

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52
Q

when does second meiotic division of the oocyte take place?

A

fertilisation

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53
Q

what does the second meiotic division of oocyte at fertilisation produce?

A

ootid (ovum) and second polar body

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54
Q

what cells is the primordial follicle surrounded by?

A

flat cells

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55
Q

what happens during stage 1 of follicular development?

A

oocyte increases in size

granulosa cells switch from flat to cuboidal

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56
Q

what is formed in stage 2 of follicular development?

A

zona pellucida

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57
Q

what is the zona pellucida?

A

acellular glycoprotein layer around the oocyte

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58
Q

what happens to granulosa cells during stages 3-5 of follicular development?

A

mitosis to produce 4 layers around the zona pellucida

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59
Q

what happens to the cells around the follicles during stages 3-5?

A

blood capillaries invade cells surrounding follicles (theca interna)

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60
Q

what is the theca interna?

A

connective tissue layer surrounding the granulosa cells

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61
Q

what happens during stage 6 of follicular development?

A

fluid forms in between granulosa cells

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62
Q

what is the name for the fluid filled spaces created during stage 6 of follicular development?

A

antrum

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63
Q

what is the name of the follicle at stage 7?

A

Graafian follicle

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64
Q

what happens at stage 7 of follicular development?

A

liquor folliculi builds up to from antrum

oocyte is pushed to one side and is surrounded by cumulus oophorus

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65
Q

what is the name of the fluid that creates the antrum in follicular development?

A

liquor folliculi

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66
Q

what is the cumulus oophorus?

A

1-2 layers of granulosa cells which surround the oocyte after the formation of the antrum

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67
Q

what happens during stage 8 of follicular development?

A

innermost layer of cumulus oophorus becomes columnar and forms corona radiata

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68
Q

what happens during stage 9 of follicular development?

A

ovulation has occurred, corpus oophorus remains in place around oocyte. The follicle becomes corpus luteum

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69
Q

what is the corpus luteum formed from?

A

follicle that remains after ovulation

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70
Q

what stages of follicular development are hormone independent?

A

stage 1-5

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71
Q

what stages of follicular development are hormone dependent?

A

stage 6-9

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72
Q

what are cyclical events in the ovary coordinated by?

A

the hypothalamus and hormones from the pituitary gland

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73
Q

where do the coordinating hormones of the cyclical events in the ovary come from?

A

the pituitary gland

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74
Q

what part of the pituitary do coordinating hormones of the cyclical events in the ovary come from?

A

anterior pituitary

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75
Q

what hormones are released from the anterior pituitary which control cyclical events in the ovary?

A

follicle stimulating hormone (FSH)
luteinising hormone (LH)
prolactin (PL)

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76
Q

what are FSH and LH formed from?

A

glycoproteins

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77
Q

what cell are FSH and LH secreted from?

A

gonadotrophs in the anterior pituitary

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78
Q

what are FSH and LH known as collectively?

A

gonadatrophic hormones

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79
Q

what type of hormone is prolactin?

A

peptide

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80
Q

what cells is prolactin secreted by?

A

lactotrophs

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81
Q

what factor from the hypothalamus causes release of LH and FSH?

A

gonadotropin releasing factor (GnRH)

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82
Q

what is the effect of GnRH?

A

tonic or surge release of FSH or LH from the anterior pituitary

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83
Q

what is prolactin release controlled by?

A

prolactin inhibitory factor (PIF) from hypothalamus

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84
Q

what is prolactin inhibitory factor (PIF) made from?

A

dopamine

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85
Q

what does an increase in PIF lead to?

A

decrease of prolactin (PF)

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86
Q

how would the tonic release of GnRH be described?

A

pulsatile

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87
Q

in the follicular phase what does increase in frequency of GnRH pulses lead to?

A

increase of FSH and LH release

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88
Q

what does FSH promote?

A

development and differentiation of follicle

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89
Q

what does development and differentiation of follicle lead to the synthesis of?

A

increased amounts of oestrogen

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90
Q

how do the frequency of GnRH pulses differ in the luteal phase?

A

reduced frequency of GnRH pulses

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91
Q

what does a reduced frequency of GnRH pulses during the luteal phase lead to?

A

fall in FSH and LH secretion

increase in progesterone synthesis from corpus luteum

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92
Q

what hormone is synthesised by the corpus luteum?

A

progesterone

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93
Q

what effect does GnRH have on its own release?

A

negative feedback

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94
Q

what effect does LH and FSH have on GnRH release?

A

negative feedback

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95
Q

what effect does progesterone have on GnRH release?

A

negative feedback

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96
Q

what is the effect of inhibin on LH/FSH?

A

inhibition of LH/FSH

particularly FSH to allow LH surge for ovulation

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97
Q

what effect does progesterone have on GnRH?

A

negative feedback

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98
Q

what effect does oestrogen have on LH/FSH and GnRH?

A

negative feedback until just before ovulation where it switches to positive feedback in order to initiate surge release of LH

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99
Q

what is the effect of prolactin on PIF?

A

positive feedback - increased prolactin increases PIF production in order to reduce PIF levels

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100
Q

what external factors can influence GnRH production and so production of sex hormones?

A 
olfactory
visual
auditory
temperature
stress
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101
Q

is initial follicle development at all related to hormones?

A

no - there is continuous follicle growth in early stages irrespective of hormones

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102
Q

what leads a follicle to become dominant and lead to ovulation?

A

slightly increased FSH binding

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103
Q

what does increased FSH binding to a developing follicle lead to the secretion of?

A

increased IGF secretion from follicle which in turn increases FSH binding

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104
Q

what type of feedback is there on FSH binding and IGF production in the developing follicle?

A

positive

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105
Q

what hormone is synthesised due to increased FSH binding to a developing follicle?

A

oestrogen

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106
Q

what cells of the follicle secrete oestrogen?

A

granulosa

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107
Q

what type of feedback effect is seen in granulosa cells producing oestrogen in the developing follicle?

A

positive

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108
Q

what is ovulation induced by?

A

LH surge

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109
Q

what is ovulation induced by in spontaneous ovulators?

A

switch from negative to positive feedback of oestrogen on GnRH leading to surge of LH

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110
Q

what is ovulation induced by in induced ovulators?

A

surge of LH triggered by mating

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111
Q

what is positive feedback of oestrogen on GnRH induced by?

A

prolonged high levels of oestrogen leading to increase in GnRH pulses

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112
Q

what receptors does oestrogen act via?

A

alpha and beta

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113
Q

what oestrogen receptors are found in GnRH neurones within the hypothalamus?

A

beta

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114
Q

what is the role of beta oestrogen receptors on GnRH neurones?

A

mediate negative feedback of oestrogen on tonic GnRH release

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115
Q

what receptors does positive feedback of oestrogen on GnRH occur via?

A

alpha

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116
Q

are there alpha oestrogen receptors on GnRH neurones?

A

no - work through intermediate neurones

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117
Q

what neurones may be involved in inducing LH surge due alpha oestrogen receptors?

A

Kisspeptin - synapse onto GnRH neurones in hypothalamus

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118
Q

what does increased frequency of GnRH pulses lead to?

A

surge release of LH

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119
Q

what is the role of PGF 2a?

A

causes degeneration of the corpus luteum at the end of the luteal phase

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120
Q

what does polyoestrus mean?

A

continually cycles until pregnancy

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121
Q

what does seasonally monooestrus mean?

A

one cycle per season

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122
Q

what doe seasonally polyoestrus mean?

A

series of cycles in a certain season

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123
Q

what type of cycle do humans have?

A

polyoestrus

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124
Q

what causes menses?

A

support for endometrial lining is lost as progesterone level reduces so it is shed

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125
Q

what happens during the follicular phase?

A

endometrium lining grows and develops

follicle develops

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126
Q

what happens during the luteal phase?

A

endometrium lining grows and develops and is maintained by progesterone
corpus luteum releases progesterone

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127
Q

what changes during the oestrus cycle?

A

biosynthetic activities of follicles and corpus luteum

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128
Q

what is the hypothesis for the mechanism for switch from oestrogen to progesterone synthesis?

A

two cell hypothesis

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129
Q

what are theca cells?

A

those which surround the follicle

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130
Q

what are granulosa cells?

A

those which surround oocyte

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131
Q

in what 3 ways do theca and granulosa cells differ?

A

hormone receptors
steroidogenic (those which are involved in producing hormones) enzyme activity
micro-environment (e.g. blood supply)

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132
Q

what does prolactin influence?

A

switch of follicle to corpus luteum and so production of progesterone

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133
Q

how does the micro-environment of granulosa cells influence the hormones they can produce?

A

no blood supply so cholesterol is reduced - difficult to synthesise any hormones

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134
Q

what happens during ovulation?

A

oocyte is shed from primary follicle and meiosis is resumed

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135
Q

what is ovulation triggered by?

A

LH surge

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136
Q

what are the 2 types of ovulation?

A

spontaneous and induced

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137
Q

what does the primary oocyte become after ovulation?

A

secondary oocyte

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138
Q

what happens to the secondary oocyte after ovulation?

A

enters oviduct

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139
Q

what surrounds the secondary oocyte as it enters the oviduct?

A

corona radiata and cumulus oophorus

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140
Q

what is the movement of the secondary oocyte into the oviduct aided by?

A

the cilia on fimbria

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141
Q

what effects does LH have that lead to ovulation?

A

induces protease and collagenase activity in the follicle

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142
Q

what does increased protease and collagenase activity in the follicle lead to?

A

increase in follicular fluid and so thinning of granulosa cell layer

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143
Q

what is the role of the Stigma in ovulation?

A

blister which bursts and releases oocyte

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144
Q

what is the corona radiata formed from?

A

innermost granulosa cells

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145
Q

what makes up the cumulus oophorus?

A

all granulosa cells

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146
Q

where does the first polar body come from?

A

1st meiotic division of oocyte

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147
Q

what is the infundibulum?

A

open end of oviduct

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148
Q

what is the oviduct lined with?

A

cilliated and secretory epithelium

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149
Q

what is the movement of oocyte in the oviduct due to?

A

action of cilia within the ampulla and muscular contractions in the isthmus

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150
Q

what is the ampulla?

A

first section of the oviduct after the infundibulum

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151
Q

where is the oocyte held within the oviduct until fertilization?

A

ampulla/isthmus junction

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152
Q

what is found at the ampulla/isthmus junction which holds the oocyte until fertilisation?

A

physiological sphincter (no physical presence)

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153
Q

when is the ampulla/isthmus junction physiological sphincter closed?

A

when oestrogen is high

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154
Q

when is the ampulla/isthmus junction physiological sphincter open?

A

when progesterone is high

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155
Q

how long does the early embryo take to reach the uterus after fertilisation?

A

2-3 days

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156
Q

why is there a delay of 2-3 days between fertilization and implantation into the uterus?

A

to ensure that the hormone environment is correct before the embryo arrives and implants

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157
Q

what happens to the follicle once the oocyte has been released?

A

collapses and forms corpus luteum

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158
Q

what cells make up the corpus luteum?

A

granulosa cells and cells of theca interna

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159
Q

where do blood vessels invading the corpus luteum originate from?

A

theca interna

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160
Q

what hormone does the corpus luteum begin to synthesise?

A

progesterone

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161
Q

what happens during lutinization?

A

cells cease dividing and are transformed into lutein cells

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162
Q

what do lutein cells contain?

A

yellow pigment

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163
Q

what hormones do thecal cells produce in the corpus luteum?

A

progesterone and androgens

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164
Q

what are thecal cells?

A

smaller lutein cells

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165
Q

what is the role of progesterone released by the corpus luteum?

A

many roles including decrease in GnRH leading to no LH surges so no more ovulation

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166
Q

what do large lutein cells produce?

A

progesterone

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167
Q

in humans what else is produced by the corpus luteum?

A

oestrogens (particularly oestradiol 17beta)
inhibin
oxytocin

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168
Q

what is the role of inhibin released from the corpus luteum?

A

promotes progesterone synthesis and inhibits FSH/LH

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169
Q

what is the role of oxytocin produced by the corpus luteum?

A

has a role in luteolysis

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170
Q

what happens to teh corpus luteum if a pregnancy does not occur?

A

undergoes luteolysis

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171
Q

what does luteolysis enable?

A

another follicular phase to start

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172
Q

what is involved in luteolysis?

A

ischaemia, leading to progressive cell death. This leads to a fall in progesterone output

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173
Q

what is left of the corpus luteum after luteolysis?

A

whitish scar tissue remains

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174
Q

what is the name of the whitish scar tissue that remains after luteolysis?

A

corpus albicans

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175
Q

in non primate species what effect does hysterectomy have on the corpus luteum?

A

prolongs lifespan

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176
Q

in non primate species what effect does injection of homogenised endometrium have on the corpus luteum?

A

causes luteolysis

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177
Q

in sheep what is the effect on the corpus luteum of ligating blood vessels between the uterus and ovary?

A

prolongs lifespan

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178
Q

what factor is thought to trigger luteolysis in non-primates?

A

prostaglandin F2alpha

179
Q

how is luteolysis thought to occur in non-primates?

A

prostaglandin (PGF) is synthesised by the uterus and released into uterine veins. Due to the close proximity of the uterine artery to the uterine pedicle, PGF is picked up by the ovarian artery and delivered back to the ovary where it causes luteolysis

180
Q

where is prostaglandin F2alpha synthesised?

A

endometrium

181
Q

what is prostaglandin F2alpha production stimulated by?

A

oxytocin from corpus luteum

182
Q

is luteolysis in primates related to prostaglandin?

A

no

183
Q

what is the possible cause of luteolysis in primates?

A

low levels of LH in luteal phase are insufficient to maintain corpus luteum which slowly regresses

184
Q

what is the influence of oestrogens on the oviduct?

A

movement of oocyte:
increased secretions
increased cilia and increased activity
increased muscle activity

185
Q

what is the influence of progestagens (progesterone) on the oviduct?

A

no oocyte movement:
reduced secretions
cilia number and activity decline
reduced muscle activity

186
Q

what is the influence of oestrogens on the cervix?

A

allow passage of sperm:
relaxation of cervical muscle
thinner alkaline secretions - allow the penetration of sperm

187
Q

what is the influence of progestagens (progesterone) on the cervix?

A

stop passage of sperm:
cervix is ‘firmer’
thick acidic secretions - prevent secretion of sperm

188
Q

what is the influence of oestrogens on the mammary gland?

A

primes glandular tissue

189
Q

what is the influence of progestagens (progesterone) on the mammary gland?

A

stimulates growth of glandular tissue

190
Q

what is the influence of oestrogens on the uterus?

A

increased myometrium activity
increased number and size of endometrial glands
increased watery secretions
increases synthesis of progesterone receptors in endometrium

191
Q

what is the influence of progestagens (progesterone) on the uterus?

A

reduced myometrium activity
further glandular growth
increased thick glycoprotein/sugar/amino acid rich secretions
development of spiral arteries in stroma

192
Q

what is the purpose of increased thick glycoprotein/sugar/amino acid rich secretions from the uterus?

A

provides nutrition for the early embryo

193
Q

what are the 2 functions of the testis?

A

gametogenic

endocrine

194
Q

where are the 2 functions of the testis carried out?

A

seminiferous tubule

endocrine cells within connective tissue

195
Q

where does spermatogenesis occur?

A

seminiferous tubules

196
Q

what cells of the seminiferous tubules provide nourishment, control and coordination of spermatogenesis?

A

sertoli cells

197
Q

what are developing sperm engulfed by that is part of sertoli cells?

A

adluminal compartments

198
Q

where do developing sperm move from?

A

basal compartment

199
Q

where are developing sperm shed?

A

into the lumen of the tubule once they are fully differentiated

200
Q

what forms the blood testis barrier?

A

junctional complexes between Sertoli cells

201
Q

where does mitosis occur during spermatogenesis?

A

in basal compartment near basal lamina

202
Q

where does meiosis occur during spermatogenesis?

A

in the adluminal compartment, on the other side of tight junctions

203
Q

what are developing sperm protected from in the adluminal compartment?

A

immune system

204
Q

what does the adluminal compartment allow?

A

a different seminiferous tubular fluid micro-environment for the late stages of spermatogenesis

205
Q

is sperm production temperature sensitive?

A

yes

206
Q

how is the scrotal temperature maintained several degrees below core temperature?

A

testis is removed from body core in the scrotum

heat exchanger in blood supply before it enters the testis

207
Q

what function of the testicular artery makes it an efficient heat exchanger?

A

is superficial for a long distance

208
Q

what is the name of the muscle which raises and lowers the testicles in response to temperature changes?

A

cremasteric muscle

209
Q

what is the name of the products of meiosis 2 found in the adluminal compartments?

A

spermatid

210
Q

do spermatid look like sperm?

A

no

211
Q

what happens during spermiogenesis?

A

head, midpiece and tail of sperm are formed

212
Q

what is formed by spermiogenesis?

A

spermatozoa

213
Q

what happens to spermatozoa?

A

shed into the lumen of the tubule

214
Q

what are the 3 processed of spermiogenesis?

A

condensation of nucleus
acrosome formation
flagellogenesis

215
Q

what is the process of condensation of nucleus essential for?

A

transfer of genetic material

216
Q

what is the process of acrosome formation essential for?

A

enabling fertilisation

217
Q

what is flagellogenesis?

A

development of flagellum

218
Q

what is the flagellum of sperm essential for?

A

independent and rapid movement

219
Q

what are the 4 phases of spermiogenesis?

A

golgi phase
cap phase
acrosomal phase
maturation phase

220
Q

what happens during the golgi phase of spermiogenesis?

A

alignment of centrioles and golgi apparatus at either end of the nucleus.
Increase in activity within the cell
DNA becomes condensed

221
Q

what happens during the cap phase of spermiogenesis?

A

golgi apparatus expands to form a cap over nucleus

centriole elongates to form flagellum

222
Q

what happens during the acrosomal phase of spermiogenesis?

A

cap expands to form acrosome
mitochondria migrate to midpiece
residual cytoplasm is removed

223
Q

what is the acrosome?

A

enzyme filled sac

224
Q

what happens during the maturation phase of spermiogenesis?

A

last of unnecessary cytoplasm removed in residual bodies
tail begins to elongate
mitochondria wrap around proximal region of tail in midpiece

225
Q

what does the head of the spermatozoa contain?

A

nucleus with highly condensed chromatin covered by acrosomal cap

226
Q

what does the midpiece of the spermatozoa contain?

A

packed spiral of mitochondria

227
Q

what is the role of mitochondria in the midpiece of the spermatozoa?

A

provides ATP for movement of flagellum

228
Q

what is found in the tail of the spermatozoa?

A

9+2 microtubule arrangement for motility

229
Q

what is the 9+2 tubule arrangement in the spermatozoa tail for?

A

motility

230
Q

what is the key element that provides motility to spermatozoa?

A

dynein arms attaching to adjacent microtubules

231
Q

what is the activity of dynein arms in spermatozoa flagellum provided by?

A

Ca2+ dependent ATPase activity

232
Q

what does hydrolysis of ATP in the flagellum of spermatozoa cause?

A

microtubules sliding past each other due to a conformational change in dynein

233
Q

how does dynein cause flagella bending?

A

axoneme is fixed to the sperm head the microtubules sliding past each other due to a conformational change in dynein results in flagellar bending

234
Q

what generates the wave of bending in the spermatozoa flagellum?

A

sequential activation of dynein arms

235
Q

how long is the spermatogenic cycle in a man?

A

64 days

236
Q

when do stem cells start to divide in spermatogenesis?

A

every 16 days

237
Q

when does the cycle of spermatogenesis start in the seminiferous tubule?

A

at different times along the length of the seminiferous tubule

238
Q

what ensures sperm are produced constantly not periodically?

A

spermatogenic waves starting at different times along the length of the seminiferous tubule

239
Q

what is testosterone responsible for?

A

male characteristics

240
Q

what is testosterone secreted by?

A

Leydig cells

241
Q

where are Leydig cells located in the testis?

A

interstitial tissue between seminiferous tubules

242
Q

what is most testosterone converted to in tissues?

A

dihydrotestosterone

243
Q

what is 98% of blood testosterone bound to?

A

albumin or sex hormone binding protein (SHBP)

244
Q

what anterior pituitary hormone is testosterone release stimulated by?

A

LH

245
Q

what enhances testosterone?

A

prolactin

246
Q

where is prolactin released from?

A

anterior pituitary

247
Q

what does episodic release of LH peak lead to in the male?

A

release of testosterone 45 minutes later

248
Q

what hormone from the hypothalamus causes release of LH and FSH?

A

pulses of GnRH

249
Q

what effect does testosterone have on GnRH and LH release?

A

negative feedback

250
Q

what is the role of prolactin in the male?

A

enhances binding of LH to Leydig cells

251
Q

what are the 3 effects of testosterone on the foetus?

A

development of testis
development of genital tract
testicular descent

252
Q

what are the 3 effects of testosterone during puberty?

A 
increase in testosterone levels
enlargement of genital tract
anabolic effects
masculine behaviour including libido
secondary sexual characteristics (beard growth etc)
253
Q

what are the 3 effects of testosterone in adulthood?

A

maintenance of sexual activity
maintenance of genital tract
spermatogenesis

254
Q

what happens to testosterone in the seminiferous tubule?

A

converted to DHT

255
Q

where is there androgen receptors within the seminiferous tubule?

A

adluminal space where sperm are developing

256
Q

what else is located in the adluminal space?

A

androgen binding protein

257
Q

what is the role of androgen binding protein?

A

keeps more testosterone in the space where it is required

258
Q

what is the role of FSH in spermatogenesis?

A

increased levels of androgen binding protein in adluminal spaces which further focuses testosterone binding

259
Q

what is the role of inhibin?

A

negative feedback on FSH release

260
Q

what is inhibin produced by in the male?

A

sertoli cells in response to FSH

261
Q

what vitamin is an essential component of spermatogenesis?

A

vitamin A

262
Q

what state are sperm in when they are released from seminiferous tubules into the lumen?

A

immature and immobile

263
Q

what 2 mechanisms carry sperm in fluid to epididymis?

A

hydrostatic pressure in tubule from fluid produced by Sertoli cells
feeble peristalsis of seminiferous tubule

264
Q

where do sperm enter the epididymis from the seminiferous tubule?

A

head

265
Q

what is the role of the tail of the epididymis?

A

sperm storage and exit to ductus defrens

266
Q

what is the movement of sperm through the epididymis due to?

A

cilia and contractions of smooth muscle due to oxcytocin

267
Q

what are the 4 functions of the epididymis?

A

storage of spermatozoa until release
sperm concentration (removal of fluid)
maturation
phagocytosis of sperm in times of sexual abstinence or after vasectomy

268
Q

in what condition are sperm when they leave the epididymis?

A

motile and fertile

269
Q

what are the 3 E’s of transport of sperm through the male reproductive tract into the female reproductive tract?

A

erection
emission
ejaculation

270
Q

what is spermatozoa transported through after leaving the epididymis?

A

ductus (vans) defrens

271
Q

what transports spermatozoa along the ductus (vans) defrens?

A

smooth muscle contractions

272
Q

what is added to spermatozoa to make semen?

A

fluids from accessory glands

273
Q

what are the accessory sex glands?

A

prostate
seminal vesicles
bulbo-urethral

274
Q

what are the 7 constituents of seminal fluid?

A 
high concentration of fructose/sorbitol
buffer
glycoproteins
constituents to stimulate female reproductive tract
coagulants
leukocytes
infective agents (HIV/hepatitis)
275
Q

what is the role of fructose/sorbitol in seminal fluid?

A

energy source

276
Q

what is the role of glycoproteins in seminal fluid?

A

to coat sperm head

277
Q

what is the role of coagulants in seminal fluid?

A

after deposition semen may act like slow release gel or form a plug to prevent further penetration of sperm

278
Q

what does the penis provide the means for?

A

deposition of sperm into the female reproductive tract

279
Q

what type of response is erection?

A

reflex

280
Q

what makes up the erectile tissue?

A

2 corpus cavernosa and 1 corpus spongiosum

281
Q

what are the venous sinuses of the penis bound by?

A

fibroelastic tissue

282
Q

how does erection occur?

A

vasodilation of arteries lead to increased blood flow

veins become compressed causing sinuses to fill with blood and penis becomes turgid

283
Q

what type of nervous stimulation causes erection?

A

parasympathetic stimulation

284
Q

what are helicine arteries?

A

branches of main artery surrounded by smooth muscle

285
Q

what is vasodilation of helicine arteries in the penis due to?

A

stimulation by acetylcholine
vasoactive peptide
nitrous oxide

286
Q

what does nitrous oxide cause?

A

relaxation of the smooth muscle by increasing presence of cyclic GMP

287
Q

how does viagra have its effect?

A

inhibits phosphodiesterase type 5 (PDE5) enzyme and so prevents breakdown of cGMP so encouraging vasodilation to continue for longer

288
Q

what is the role of cGMP?

A

relaxation of smooth muscle - vasodilation

289
Q

what is the role of phosphodiesterase type 5 (PDE5)?

A

breakdown of cGMP leading to contraction of smooth muscle in arteries

290
Q

what is intromission?

A

thrusting behaviour that resembles a reflex - follows insertion of penis into the vagina

291
Q

what is seminal emission caused by?

A

increase in sympathetic outflow to:
tail of epididymis
vans defrens
accessory glands

292
Q

what happens during seminal emission?

A

contents of vans defrens are expelled into the pelvic urethra and provide stimulus for ejaculation

293
Q

what does sympathetic innervation of the neck of the bladder during seminal emission cause?

A

contraction and prevents urine mixing with semen

294
Q

what causes ejaculation?

A

further rhythmic contractions of the urethra under somatic control

295
Q

why is semen not mixed evenly?

A

overlap between emission and ejaculation

296
Q

what are the 3 different fractions of ejaculate?

A

pre-sperm
sperm
post-sperm

297
Q

where is the ovum held in the oviduct until fertilisation?

A

ampulla/isthmus junction

298
Q

what effect does age of the gamete have on the stability of the zygote?

A

older gamete makes zygote more unreliable

299
Q

where is the usual site of deposition of sperm?

A

vagina

300
Q

what is the pH of the vagina?

A

low/acidic

301
Q

what may happen to the ejaculate to protect it from acidic conditions within the vagina?

A

may be coagulated

302
Q

what may the ejaculate form to prevent backflow of sperm?

A

plug (rats/mice)

303
Q

what are the 2 speeds of sperm transport?

A

rapid (sperm may be seen in ampulla 5 mins after deposition)

sustained (sperm may be held up at different points)

304
Q

what is the cervix made of?

A

connective tissue and muscle

305
Q

what may happen to sperm in the crypts of the cervix?

A

may become held in crypts

306
Q

what are micelles in the cervix?

A

strands of mucus

307
Q

what is the role of micelles in the cervix?

A

help guide sperm through the cervix

308
Q

what does the fluid secreted by the cervix prevent?

A

infection

309
Q

what is fluid in the cervix like under the influence of oestrogen?

A

watery, alkaline, hospitable, formation of micelles

310
Q

what is fluid in the cervix like under the influence of progesterone?

A

thick, acidic, inhospitable

311
Q

what is transport of sperm through cervix aided by?

A

uterine muscular contractions creating negative pressure

312
Q

what is passage of sperm through the uterus achieved by?

A

own propulsion aided by currents of fluid set up by action of uterine cilia

313
Q

what is passage of sperm through the uterotubule junction regulated by?

A

intermittent sphincter

314
Q

what happens to sperm once in the isthmus of oviduct?

A

become immobile

315
Q

how are sperm attracted to isthmus/ampullary junction?

A

by chemo attractant from oocyte-cumulous oophorous mass

316
Q

what essential process must happen to sperm for fertilisation to occur?

A

capacitation

317
Q

what is capacitation due to?

A

exposure of sperm to environment of female reproductive tract

318
Q

what happens during capacitation?

A

changes in macromolecular structure of sperm membrane - enabling acrosome reaction
activation

319
Q

what is involved in activation of sperm?

A

changes in beating pattern of flagellum from wavelike to whiplash

320
Q

what are the 4 stages of fertilization?

A

get sperm to oocyte
sperm nucleus enters oocyte
activation of oocyte
fusion of pro-nuclei

321
Q

what happens during fertilization?

A

penetration of cumulus/zona pellucida by swimming action of sperm and acrosome reaction

322
Q

what is the corona radiata designed to do?

A

guide sperm to zona pellucida

323
Q

what do sperm release to aid attachment to zona pellucida?

A

hyaluronidase on sperm membrane

324
Q

what do ZP3 receptors do?

A

bind to proteins on sperm head leading to acrosome reaction

325
Q

where are ZP3 receptors located?

A

zona pellucida

326
Q

what does binding of sperm to ZP3 receptors cause?

A

acrosomal membrane and plasma membrane to fuse releasing acrosomal enzymes

327
Q

what does release of acrosomal enzymes cause?

A

digestion of zona pellucida to allow sperm to reach plasmalemma and attach

328
Q

what is the plasmalemma?

A

membrane surrounding oocyte

329
Q

what happens once the sperm reach the plasmalemma?

A

fusion of oocyte and acrosomal membrane so nucleus enters oocyte

330
Q

what process resumes when sperm penetrates zona pellucida with aid of acrosomal enzymes?

A

meiosis resumes

331
Q

what is the role of cortical granules in the cytoplasm of oocyte?

A

fuse with plasma membrane and enzymes cause changes in zona pellucida

332
Q

how is polyspermy prevented?

A

fusion of cortical granules with plasma membrane and action of enzymes

333
Q

what triggers second meiotic division?

A

fertilization

334
Q

what is sygamy?

A

formation of diploid nucleus by fusion of sperm and oocyte nuclei

335
Q

what is the role of the zona pellucida once the oocyte is fertilised?

A

prevents 2 embryos from sticking together

336
Q

what happens during compaction of the embryo?

A

cells flatten against each other within zona pellucida

337
Q

where in the fallopian tube does fertilization take place?

A

ampulla

338
Q

why is there a need for time delay between fertilization and arrival/implantation of embryo to endometrium?

A

need to ensure hospitable environment for embryo so progesterone levels need to rise due to corpus luteum

339
Q

what stage is the embryo at when it reaches uterus?

A

morula or blastocyst stage

340
Q

what does the time to implantation usually exceed?

A

life of corpus luteum

341
Q

how does the decline of corpus luteum affect the embryo?

A

leads to fall in progesterone levels so myometrium contractions increase which can lead to loss of the foetus

342
Q

what prevents luteolysis until the placenta is established?

A

factors produced by the early embryo

343
Q

what factor is produced by the embryo in humans which prevents luteolysis until the placenta has developed?

A

human chorionic gonadotrophin (HCG)

344
Q

what must happen to endometrium to allow implantation?

A

must be oestrogen primed

345
Q

what levels of hormone must be adequate at the time of implantation?

A

progesterone

346
Q

what is the role of progesterone in aiding implantation?

A

decreases myometrial activity, increases glandular secretions (proteins, carbohydrates, lipids, steroids and ions)

347
Q

what are the glandular secretions of the uterus essential for in early pregnancy?

A

early nutrition and implantation

348
Q

what happens to the trophoblast during implantation?

A

comes into contact with the endometrium

349
Q

what happens to the blastocyst in implantation in humans?

A

blastocyst penetrates epithelium of endometrium

350
Q

what is the name for the type of implantation which occurs in humans?

A

interstitial implantation

351
Q

what allows invasion of epithelium by embryo?

A

proteolytic enzymes from trophoblast and maternal epithelium

352
Q

what does implantation of the embryo lead to the formation of?

A

the placenta

353
Q

what happens during the adhesion phase of interstitial implantation of the placenta?

A

microvilli on embryo and epithelium interlock
proteases from endometrium and trophoblast are secreted and lead to the embryo invading through endometrium
increased permeability of blood vessels and oedema around blastocyst

354
Q

what is the decidual cell reaction?

A

membranes between the cells break down

355
Q

where on the embryo does the decidual cell reaction take place?

A

syncitiotrophoblast

356
Q

what cells come into direct contact with maternal blood?

A

trophoblast cells

357
Q

what is exchanged by the placenta?

A

nutrients, gases and foetal waste

358
Q

what is the role of the placenta as well as nutrient exchange?

A

immunological barrier to prevent rejection of foetus

359
Q

what 4 hormones are produced by the placenta?

A

human chorionic gonadotrophin
oestrogen
progesterone
human placental lactogen

360
Q

what is the role of human chorionic gonadotrophin?

A

prolongs life of cor[us luteum

361
Q

what is the role of oestrogen in the placenta?

A

stimulates uterine growth and development

362
Q

what is the role of progesterone released by the placenta?

A

stabilises uterus and prevents myometrial contractions

363
Q

what is the role of human placental lactogen released from the placenta?

A

growth hormone like activity

364
Q

what are the 5 main human maternal changes during pregnancy?

A 
uterus expands
blood volume increases
heart workload increases
kidneys filter more blood
woman gains on average 10-15kg of weight
365
Q

what are the 2 main requirements for parturition?

A

coordinated contractions of myometrium to expel foetus

softening and reduced resistance of cervix

366
Q

is the mechanism of parturition common to all mammals?

A

yes

367
Q

what aspect of parturition differs within species?

A

the trigger

368
Q

how is parturition initiated in the goat?

A

levels of circulating hormones change

369
Q

how do levels of hormones change in the goat to initiate parturition?

A

progesterone and oestrogen switch (progesterone increases, oestrogen decreases)
levels of prostaglandin rise

370
Q

is there change in hormone levels in humans to initiate parturition?

A

no change in oestrogen:progesterone ratio

prostaglandin levels do not change until well into labour

371
Q

describe the initiation of parturition in the goat

A

foetus produces steroids from adrenal gland
leads to increased oestrogen production in the placenta
PGF2alpha synthesis increases so myometrial excitability increases
oxytocin release is enhanced by distention of cervix and vagina

372
Q

what provides the initial stimulus for initiation of parturition in the goat?

A

the foetus

373
Q

what is the effect of increased oestrogen release from the placenta on the myometrium during labour?

A

increase in excitation and calcium
increased oxytocin receptors
increased PGF2alpha release

374
Q

what is the role of oxytocin?

A

amplifies effects of oestrogen on myometrium

375
Q

what is the effect of PGF2alpha?

A

softening of cervix

376
Q

what is thought to initiate parturition in humans?

A

changes in local receptor populations

377
Q

what happens during stage 1 of parturition?

A

overt uterine contractions
positioning of the foetus
dilation of the cervix
transition leading to stage 2

378
Q

what happens during transition to stage 2?

A

contractions of the myometrium change

379
Q

what happens during stage 2 of parturition?

A

expulsion of foetus

380
Q

when does stage 2 of parturition start?

A

full dilation of cervix

381
Q

what hormone is the uterus highly sensitive to during stage 2?

A

oxytocin

382
Q

what is oxytocin release enhanced by?

A

vaginal stimulation

383
Q

what happens during stage 3 of parturition?

A

expulsion of placenta

involution of uterus

384
Q

what is the goal of involution of the uterus?

A

prevents excessive blood loss

385
Q

what type of tissue are mammary glands formed of?

A

glandular tissue

386
Q

how is glandular tissue arranged to form mammary glands?

A

alveoli that in turn are arranged in clusters

387
Q

what are milk secreting cells formed of?

A

single layer of epithelial cells surrounded by myoepithelial cells

388
Q

what is the hormonal stimulus for lactation?

A

sudden decline in oestrogen and progesterone and increased secretion of prolactin

389
Q

where do epithelial cells secrete milk into?

A

alveoli/lumen

390
Q

what is lactation maintained and initiated by?

A

prolactin from anterior pituitary

391
Q

what is required to initiate and maintain lactation?

A

suckling to stimulate hormone release

392
Q

what is milk release stimulated by?

A

action of oxytocin on myoepithelial cells

393
Q

what happens during the milk ejection reflex?

A

contraction of myoepithelial cells to expel milk from alveoli

394
Q

where is oxytocin secreted from?

A

posterior pituitary

395
Q

what is milk ejection reflex and maintenance of lactation initiated by?

A

mechanical stimulation of nipple

396
Q

what does milk production require?

A

prolactin and suckling

397
Q

what does milk ejection require?

A

oxytocin

398
Q

can milk ejection occur without stimulation of the nipple?

A

yes - is a conditioned reflex

399
Q

define contraception

A

the prevention of pregnancy and disease

400
Q

what are the 2 main contraceptive options?

A

hormonal and barrier

401
Q

how does a lot of hormonal contraception work?

A

negatively feeds back on/inhibits GnRH and LH/FSH so that ovulation does not occur

402
Q

what is the mode of action of the combined pill?

A

negative feedback on gonadotrophins (GnRH) to inhibit ovulation

403
Q

what are the advantages of the combined pill?

A

high efficacy
regular/controlled menstruation
acne may improve

404
Q

what are the disadvantages of the combined pill?

A

low risk venous thrombosis
breast/cervical carcinoma
can’t be used while lactating as partially suppresses lactation

405
Q

why does the combined pill suppress lactation?

A

oestrogen inhibits milk production

406
Q

what is the mode of action of the progesterone only pill?

A

makes cervical mucous hostile to sperm

407
Q

what are the advantages of the progesterone only pill?

A

can be used in lactating women

408
Q

what are the disadvantages of the progesterone only pill?

A

less effective than combined pill

need for meticulous timing

409
Q

what is the mode of action of the morning after pill?

A

delays ovulation beyond lifespan of sperm

prevents sperm transport

410
Q

what are the advantages of the morning after pill?

A

95% success if used within 24 hours

411
Q

what are the disadvantages of the morning after pill?

A

lower success if delayed to 72hrs

provides no protection for rest of cycle

412
Q

what is the mode of action of progesterone devices (IUD, implant or injection)?

A

similar to progesterone pill but may also prevent ovulation

413
Q

what are the advantages of progesterone devices (IUD, implant or injection)?

A

high efficacy
cost effective
prevents ovulation

414
Q

what are the disadvantages of progesterone devices (IUD, implant or injection)?

A

requires medical intervention

prolonged amenorrhea may follow cessation

415
Q

what are the 2 main options for male contraception?

A

testosterone/progesterone combinations

blocking testosterone temporarily

416
Q

how would testosterone/progesterone combinations aid prevention of pregnancy?

A

suppression of gonadotrophins and prevention of sperm production

417
Q

how would blocking testosterone aid prevention of pregnancy?

A

inhibition of sperm production by lowering systemic testosterone

418
Q

what is a disadvantage of blocking testosterone to prevent pregnancy?

A

fails to suppress spermatogenesis in all men

419
Q

what is lactational amenorrhea?

A

breastfeeding can act as a contraceptive in 60-70% of lactating mothers

420
Q

how does lactation act as a contraceptive?

A

suppresses follicular development
disrupts pulsatile action of GnRH - no LH surge
interferes with corpus luteum function

421
Q

what is the mode of action of the copper coil?

A

prevents fertilization as toxic to sperm

422
Q

what is the mode of action of the hormonal coil?

A

local progesterone release impairs implantation and fertilization

423
Q

after what age does female fertility decline?

A

35

424
Q

what are the 3 main classes of disorder that contribute to most infertility cases?

A

disorders of female tract
disorders of ovulation
poor quality spermatozoa

425
Q

are many cases of infertility explained?

A

no - high proportion don’t have a known cause

426
Q

what is ART?

A

assistive reproductive technologies

427
Q

what does ART include?

A 
fertility drugs
intra uterine insemination
in vitro fertilisation
in vitro maturation
intracytoplasmic sperm injection
embryo testing
cryopreservation
428
Q

what are fertility drugs used to overcome?

A

anovulation

429
Q

what is the role of anti-oestrogens?

A

block oestrogen receptors in hypothalamus and pituitary which release negative feedback of oestrogen and so increases release of FSH and LH leading to increased likelihood of LH surge and ovulation

430
Q

what is the role of gonadotrophins?

A

stimulates follicular growth

431
Q

what are gonadotrophins often used in conjunction with?

A

IVF treatment cycles

432
Q

how is the natural cycle suppressed during IVF?

A

administration of GnRH agonist

433
Q

what is the role of the GnRH agonist in suppressing the natural cycle in IVF?

A

prevents endogenous LH surge and premature ovulation

434
Q

how does ovulation hyperstimulation occur during IVF?

A

using recombinant FSH followed by injection of LH or human chorionic gonadotrophin to mature follicles

435
Q

how are eggs collected for IVF?

A

needle passes through vaginal wall and into follicle to retrieve egg

436
Q

what happens when eggs are fertilized during IVF?

A

incubated in sperm harvested from male partner in vitro for 24-48 hours

437
Q

when does embryo transfer occur?

A

at 4 cell stage

438
Q

how is the embryo placed in the uterus?

A

transcervical catheter

439
Q

what is administered to aid egg implantation after embryo transfer?

A

progesterone

440
Q

what happens during cryopreservation?

A

any remaining fertilised oocytes/embryos may be frozen for later use

441
Q

what are the 2 key reasons for embryo testing?

A

preimplantation genetic screening to check for chromosome abnormalities
pre implantation tissue typing for saviour siblings

442
Q

what are the 4 main dangers of ART?

A

multiple births
ovarian hyperstimulation syndrome
lower birth weight
congenital abnormalities

443
Q

what is the purpose of mitochondria replacement?

A

targets diseases caused by faulty mitochondria

444
Q

what happens during pronuclear transfer?

A

parent and donor eggs are fertilized by father
parents nuclear material removed and transferred into donor egg (nuclear material removed) which is healthy
then implanted as with IVF

X Physiology 1B (5 decks)

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