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MEDSCI 142 > Module 4 - Reproductive > Flashcards

Module 4 - Reproductive Flashcards

1
Q

hypothalamus

A

homeostatic regulator for reproduction, stress, body temp, hunger, thirst, sleep
- neuroendocrine organ

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2
Q

neuroendocrine organ

A

processes both neural and hormonal info

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3
Q

neurosecretory neurones

A
  • aggregated into nuclei
  • possess long axon tracts that lead into posterior pituitary
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4
Q

posterior pituitary - neurosecretory peptide hormones

A

synthesised in hypothalamus -> bind to carrier proteins -> travel down to axon terminals -> stored as secretory vesicles (in posterior pituitary)
nerve impulse -> trigger exocytosis of secretory vesicles -> peptide hormone release

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5
Q

posterior pituitary hormones released

A

oxytocin, antidiuretic hormone (ADH) / vasopressin

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6
Q

oxytocin

A
  • major effects on smooth muscle contraction (e.g milk ejection, uterus contraction during childbirth)
  • secretion in response to stimulation of nipples / uterus distension
  • used to induce labour
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7
Q

anterior pituitary - releasing/inhibiting hormones

A
  • synthesised by neurosecretory neurones in their cell body -> vesicles -> axon terminus
  • nerve impulse -> hormones secreted into linking hypophyseal portal vessels
  • act on specific anterior pituitary secretory cells arranged in clumps at termini of portal vessel
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8
Q

anterior pituitary hormones released

A

gonadotrophs:
- follicle stimulating hormone (FSH)
- luteinising hormone (LH)

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9
Q

FSH

A
  • act on ovaries to stimulate growth/development of gametes
  • act on testes to stimulate production of gametes
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10
Q

LH

A
  • act on testes to promote synthesis of testosterone
  • act on ovaries to trigger ovulation and promote synthesis/release of ovarian hormones
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11
Q

reproductive hormones - water soluble

A

peptides and proteins
- gonadotrophin releasing hormone (GnRH)
- follicle-stimulating hormone
- luteinising hormone
- oxytocin

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12
Q

GnRH site of secretion

A

hypothalamus

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13
Q

FSH site of secretion

A

anterior pituitary

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14
Q

LH site of secretion

A

anterior pituitary

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15
Q

oxytocin site of secretion

A

posterior pituitary

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16
Q

reproductive hormones - lipid soluble

A

steroid hormones
- androgens
- oestrogens
- progestagens

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17
Q

androgen site of secretion

A

testes

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18
Q

oestrogens site of secretion

A

ovary

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19
Q

progestagens site of secretion

A

ovary

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20
Q

hormone regulation

A

by homeostatic mechanisms involving positive and negative feedback loops

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21
Q

pulsatile release

A

hypothalamic secretions released in discrete bursts separated by period of little/no secretion
- prevents receptor desensitisation/downregulation

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22
Q

endocrine relationships

A

complex systems of amplification controlled by a series of feedback loops

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23
Q

-ve feedback control often involves

A

signalling between hypothalamus, pituitary, target organ

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24
Q

ovaries function

A
  • oogenesis
  • regulation of menstrual cycle
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25
Q

testes function

A

sperm maturation

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26
Q

two main functions of gonads

A

1) gametes
2) reproductive hormones

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27
Q

reproductive hormones function

A
  • begin process of sexual development
  • reinitiation of puberty
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28
Q

regulation of pituitary secretory cells (GnRH feedback loop)

A

hypothalamus: GnRH -> anterior pituitary: gonadotrophs -> FSH and LH -> gonads: sex hormones -> -ve feedback to both hypothalamus and anterior pituitary

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29
Q

sex steroids

A
  • androgens
  • oestrogens
  • progestagens
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30
Q

androgen types

A
  • testosterone
  • 5 alpha dihydrotestosterone
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31
Q

testosterone

A
  • main secretory product of testis
  • associated with development/maintenance of male characteristics/fertility
    => sertoli cells, DHT, secondary sexual characteristics
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32
Q

5 alpha dihydrotestosterone (DHT)

A
  • more active than testosterone
  • stronger (twice as potent) variant of testosterone
  • important in development of secondary sexual characteristics
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33
Q

androgen key properties

A
  • male sex development
  • spermatogenesis
  • sexual behaviour
  • muscle development
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34
Q

oestrogen types

A
  • oestradiol
  • oestrone
  • oestriol
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35
Q

oestradiol

A

most potent

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36
Q

oestrone

A
  • main source of oestrogen for males
  • important after menopause
  • produced by adipose tissue
  • weakest type of oestrogen
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37
Q

oestriol

A
  • weaker
  • softens cervix for labour
  • produced by placenta prior to labour
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38
Q

oestrogen main role

A

development/maintenance of female characteristics/fertility

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39
Q

oestrogen main site of production

A

granulosa cells of growing follicle

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40
Q

oestrogen key properties

A
  • important in both females and males (females just produce more)
  • female sex development (not as much in males)
  • regulation of menstrual cycle
  • growth of endometrium
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41
Q

endometrium

A

lining of uterus
- important for implantation of fertilised embryo

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42
Q

progestagen type

A

progesterone

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43
Q

progesterone

A
  • major steroidal hormone of corpus luteum/placenta
  • only in females
  • associated with prep/maintenance of pregnancy
  • produced only during menstrual cycle
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44
Q

sex determination - bipotential

A

commitment of bipotential gonad to a testis or an ovary (mesoderm -> bipotential gonad -> testis/ovary)
- early gonad has potential to become both male/female
- once decision made, testes/ovary produces applicable sex hormones

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45
Q

sex determination - control

A

genetically controlled in mammals
- other by temp, behaviour etc.

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46
Q

sex-determining region (SRY gene)

A
  • on Y chromosome
  • provides pathway for testes to develop
  • presence of testis determines sexual fate of embryo against basic feminine trend
  • absence/mutation in SRY => embryo develops into female
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47
Q

sex differentiation

A

phenotypic development of genital structures due to action of hormones produced by gonad

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48
Q

internal genitalia

A
  • mullerian duct: female
  • wolffian duct: male
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49
Q

testis =>

A
  • sertoli cells
  • leydig cells
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50
Q

sertoli cells =>

A

anti-mullerian hormone -> mullerian duct regression

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51
Q

leydig cells =>

A

testosterone -> wolffian duct development -> internal male genitals

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52
Q

internal male genitals

A
  • vas deferens
  • seminal vesicle
  • epididymis
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53
Q

ovary =>

A

oestrogens, progestagens
mullerian duct development -> internal female genitals
wolffian duct regression

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54
Q

internal female genitals

A
  • fallopian tube
  • uterus
  • upper third vagina
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55
Q

female differentiation

A
  • 10 weeks: wolffian duct begins to regress slowly
  • mullerian ducts persist/develop to give rise to uterine (fallopian) tubes, uterus, cervix, upper vagina
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56
Q

male differentiation - testes

A

testis descends from internal position to scrotum usually after 7th month of pregnancy
- if not, infertile but can manually/chemically make them drop

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57
Q

external genitalia - female differentiation - labioscrotal swellings

A

urethral folds/labioscrotal swellings remain separate => labia minora and majora formed (respectively) which protect opening of urethra/vagina

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58
Q

external genitalia - male differentiation - labioscrotal swellings

A

labioscrotal swellings fuse in the midline => scrotum formed

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59
Q

external genitalia - female differentiation - genital tubercle

A

genital tubercle (glans area) forms clitoris

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60
Q

external genitalia - male differentiation - genital tubercle

A

genital tubercle (glans area) expands forming glans penis

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61
Q

external genitalia - male differentiation - urethral folds

A

fusion of urethral folds => urethral tube enclosed => shaft of penis formed

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62
Q

androgen insensitivity syndrome

A

mutation in androgen receptor gene
=> prevents androgen function
=> external genitalia appear female
=> XY/has testes but genital ducts and/or external genitals are female

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63
Q

puberty

A

physical, emotional, sexual transition from childhood -> adulthood
- transition is gradual and punctuated by well-defined events/milestones

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64
Q

rewakening of reproductive system =>

A

full secondary sexual maturation with capacity for reproduction

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65
Q

plasma levels of gonadotrophins

A

very low in childhood until initiation of events leading to puberty (first endocrine sign of puberty)

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66
Q

increased GnRH release =>

A

increased plasma levels of LH => increased sex steroids

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67
Q

plasma gonadotrophin levels - early puberty

A

both LH/FSH secretion occurs at night during sleep

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68
Q

plasma gonadotrophin levels - late puberty

A

daytime LH pulses increase

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69
Q

secondary sexual characteristics

A
  • characteristics develop at different chronological ages in different individuals
  • sequence of change occurrence is characteristic for each sex
  • males: enlargement of male sex organs, aggressiveness, libedo, hair growth, baldness
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70
Q

tanner stages

A
  • criteria for staging development of secondary sexual characteristics
  • allows abnormalities to be detected
  • allows comparisons to be made between individuals
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71
Q

secondary sexual characteristics - female order of occurrence

A

1) breast development
2) sexual hair development
3) growth spurt
4) menarche

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72
Q

breast development

A
  • age ~10-11: first physical sign of secondary sexual maturation
  • oestrogen secretion => appearance of breast bud => formation of breast mound
  • ovulation + subsequent progesterone secretion => full breast development
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73
Q

sexual hair development

A
  • age ~10-12: usually within 6 months of breast bud appearance
  • due to exposure of hair follicles to androgens
  • axillary hair follows ~1 year after pubic hair
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74
Q

growth spurt

A
  • age ~11-12
  • growth: stimulated by steroid hormones (oestrogen and androgen)
  • epiphyseal closure (bony ends): stimulated by oestrogen
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75
Q

menarche + trend

A
  • age 12-13 on average
  • trend towards earlier menarche due to attainment of critical weight caused by improvements in nutrition, healthcare, social living conditions => shows sufficient storage required to sustain pregnancy/lactation
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76
Q

first ovulation

A

6-9 months after menarche
- positive feedback mechanisms of oestrogen (involving LH hormone) have not developed
- regular ovulatory cycles: established 1-2 years after menarche

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77
Q

secondary sexual characteristics - male order of occurrence

A

1) testicular enlargement
2) sexual hair growth
3) penile enlargement
4) height spurt
5) spermarche

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78
Q

testicular enlargement

A
  • 10-13.5 years old
  • first signs of secondary sexual development
  • leydig cells enlarge/secrete testosterone => increased testicular size
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79
Q

sexual hair growth - males

A
  • 6 months after beginning of testicular enlargement
  • axillary hair begins ~18 months later
  • facial hair later
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80
Q

penile enlargement

A

elongation/enlargement of penis begins within 1 year of testicular enlargement

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81
Q

spermarche

A
  • first spermatogenesis event
  • motile sperm seen in urine at ~13-14 years
  • first ejaculation: soon after
  • ability to produce sperm is earlier than ovulation in females
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82
Q

body shape in males/females

A

determined by differential effects of androgen and oestrogen

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83
Q

body shape - males

A
  • more muscular
  • heavier
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84
Q

body shape - females

A
  • more fat (breasts, around reproductive area)
  • pelvis easier for childbirth
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85
Q

precocious puberty

A

appearance of physical/hormonal signs of puberty before:
- 7 yrs in girls
- 9 yrs in boys
usually GnRH dependent problem
often extreme cases due to hypothalamic tumour

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86
Q

delayed puberty

A

lack of appearance of physical/hormonal signs of puberty:
~13 yrs in girls
~14 yrs in boys
- occurs when gonadotrophin signals from pituitary are inadequate for sex steroid hormone secretion
- more common in boys than girls

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87
Q

menopause

A
  • consequence of ovaries running out of follicles that respond to hormonal stimulation
  • occurs between 50-52 yrs of age
  • last episode of natural menstrual bleeding signifies end of reproductive life (post menopause > reproductive life)
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88
Q

number of follicles by age

A
  • fetal development: ~7 million follicles develop
  • birth: number of follicles declined to ~1-2 million
  • steady decline in follicles
  • puberty: ~400 000
  • menopause: < 1000 follicles
    400 oocytes released throughout lifetime
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89
Q

pre-menopause

A

age ~40 years to end of regular cycles (~46 years)

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90
Q

menopausal transition

A

end of regular cycles (~46 years) to menopause (~50-52 years)
- of variable duration (tend to be longer)
- typically 4-5 years

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91
Q

peri-menopause

A
  • around time of menopause
  • many symptoms occur here
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92
Q

post-menopause

A

after menopause (~50-52 years) - viewed retrospectively

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93
Q

ovarian senescence

A
  • takes 1-2 years as even without eggs, still produce hormones
  • ovary essentially ceased producing hormones
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94
Q

postmenopausal oestrogen production

A
  • reduces to < 1/10 of previous
  • oestrogen produced now is oestrone (arises mainly from production in stromal cells of adipose tissue)
95
Q

perimenopausal symptom features

A
  • most women experience a variety of clinical symptoms of oestrogen deprivation
  • most symptoms may be prevented/arrested by oestrogen treatment (menopausal hormone therapy)
    BUT increased exposure to oestrogen is associated with risk of breast cancer/hormonal diseases
96
Q

perimenopausal symptoms

A

1) vasomotor
- hot flushes
- night sweats
2) genitourinary symptoms
- vaginal dryness
3) bone metabolism
- increased risk osteoporosis
4) behavioural/psychological changes
- depression, tension, anxiety, mental confusion, libido

97
Q

ovaries vs. testes

A

ovaries:
- cyclical activity from puberty to menopause
- ability to incubate foetus
- few oocytes released (~400)
- mature oocyte released every ~28 days

98
Q

female reproductive organs

A
  • vagina
  • uterus
  • uterine (fallopian) tube/oviduct
  • ovaries
99
Q

vagina

A

elastic muscular 7.5-9.0 cm tube extending from cervix to exterior of body

100
Q

vagina function

A
  • passageway for the elimination of menstrual fluid
  • receive penis during sexual intercourse + hold spermatozoa before passing into uterus
  • form lower portion of birth canal through which fetus passes during delivery
101
Q

uterus

A
  • small, pear-shaped organ
  • weighs ~30-40 g
102
Q

uterus function

A
  • pathway for sperm transport
  • provide mechanical protection, nutritional support, waste removal for developing embryo/fetus
  • contractions in muscular wall (myometrium) important in ejecting fetus at time of birth
  • source of menstrual fluid
103
Q

endometrium subdivided into

A

1) inner functional zone (stratum functionalis)
2) outer basilar zone (stratum basalis)

104
Q

inner functional zone (stratum functionalis)

A

contains most of uterine glands

105
Q

outer basilar zone (stratum basalis)

A
  • adjacent to myometrium
  • attaches endometrium to myometrium
106
Q

anteflexion/retroflexion

A

~20% women have retroflexed uterus
- may cause some pain during menstruation/intercourse

107
Q

uterine (fallopian) tube/oviduct

A
  • fertilisation typically occurs in ampulla
  • provide rich, nutritive environment containing lipids/glycogen for spermatozoa, oocyte, developing embryo (number of different secretions)
108
Q

fimbriae

A
  • partially cover ovary
  • draws oocyte into uterine tubes following ovulation
109
Q

epithelium lining of uterine tube

A

both ciliated and nonciliated secretory columnar cells

110
Q

mucosa of uterine tube

A

surrounded by concentric layers of smooth muscle
- allows movement of oocyte/embryo via peristaltic contraction

111
Q

transport along uterine tube =

A

combination of ciliary movement + peristaltic contractions

112
Q

ectopic pregnancy

A

when fertilised embryo is implanted in tissue other than uterine wall
- most occur in uterine tube (tubal pregnancy)

113
Q

ectopic pregnancy risk factors

A
  • smoking: cilia beating not as strong
  • advanced maternal age
  • prior tubal damage
114
Q

ovaries

A
  • oval, weight ~5-10 g
  • often yellowish with bumps (follicles)
  • comprised of 3 distinct regions
115
Q

3 distinct regions of ovaries

A

1) outer ovarian cortex
2) central ovarian medulla
3) inner hilum (hilus)

116
Q

outer ovarian cortex

A
  • outer shell
  • contain ovarian follicles
117
Q

central ovarian medulla

A
  • soft tissue
  • consist of ovarian stroma
  • consist of steroid producing cells
118
Q

inner hilum (hilus)

A
  • point of entry/exit for nerves/blood vessels
119
Q

predicting fetal growth - before ultrasound

A
  • fundal height
  • top of uterus to pubic bone
  • number of cm ≈ number of weeks gestation
  • increased with: twins, breech birth, gestational diabetes
  • decreased for: small for gestational age, intrauterine growth restriction
120
Q

follicular development

A

1) primordial follicle
2) primary follicle
2.5) follicle development
3) secondary follicle
4) mature (Graafian/pre-ovulatory) follicle

121
Q

primordial follicle

A
  • formed by oocyte once surrounded by single layer of follicular cells which develop into granulosa cells
  • sits largely dormant for up to 50 yrs
122
Q

primary follicle

A

aka pre-antral follicles
- follicles grow
- flat squamous cells become cuboidal (metabolically active)
- immature primary follicles consist of only one layer of granulosa cells
- oocyte secretes glycoproteins -> forms zona pellucida
- beginning of condensation of ovarian stromal cells (thecal cells) around follicle

123
Q

zona pellicuda

A

translucent acellular layer
- just protein no calcium

124
Q

follicle development

A

FSH -> some follicles get layer -> produce many layers of granulosa cells surrounding oocyte

125
Q

secondary follicle

A

aka antral follicles
- granulosa cells proliferate -> produce viscous follicular fluid: coalesces to form singular follicular antrum

126
Q

corona radiata

A

formed from 3-4 cell thick inner layer of granulosa cells firmly attaching to zona pellucida

127
Q

cumulus oophorus

A

mass of loosely associated granulosa cells

128
Q

theca develops into

A

1) theca interna
- inner glandular
- highly vascular
2) theca externa
- surrounding fibrous capsule

129
Q

mature (Graafian/pre-ovulatory) follicle

A

follicular antrum grows in size
- oocyte becomes suspended in fluid
- connected to rim of peripheral granulosa cells by thin stalk of cells

130
Q

ovulation

A
  • slow/controlled process that involves lots of hormones
  • increased pressure from follicular fluid
  • increasing size of follicle + position in cortex of ovarian stroma
  • bulge out from ovarian surface
  • follicle ruptures carrying oocyte + surrounding mass of cumulus cells
  • oocyte collected by cilia on fimbria which sweep cumulus mass into uterine tube
131
Q

corpus luteum

A

yellow body
- empty follicle becomes one of most important endocrine glands in the body for the embryo
- antrum breaks down
- basement membrane between granulosa/thecal layers break down
- blood vessels invade

132
Q

luteinisation

A
  • transformation of granulosa cells -> large lutein (yellow pigment) cells
  • associated with increasing secretion of progestagens (primary progesterone in pregnancy as it’s important for maintenance of endometrium)
133
Q

corpus albicans

A

white body
- whitish scar tissue remaining
- absorbed back into stromal tissue of ovary over weeks-months
- if no fertilisation, cycle restarts

134
Q

fertilisation

A

if oocyte fertilised + begins to divide, corpus luteum persists past normal 2 week life span
- rescued from degeneration by human chorionic gonadotropin (hCG) hormone

135
Q

hCG

A
  • produced by chorion of embryo beginning ~8 days after fertilisation
  • presence of hCG in maternal blood/urine is an indicator of pregnancy (detected by home pregnancy tests)
136
Q

two phases in ovarian cycle

A

1) follicular phase
- day 1 to ovulation
2) luteal phase
- ovulation to menstruation

137
Q

three phases in uterine/menstrual cycle

A

1) menstruation (menstrual phase)
2) proliferative phase (preovulatory phase)
3) secretory phase (postovulatory phase)

138
Q

length of menstrual cycle

A

average 28 days
variation in length due to:
- variable length of follicular phase (changes as women age)
- luteal phase usually 14 days

139
Q

reason for menstrual cycle

A

humans are one of few animals that have it
female reproductive tract has two main functions:
- produce oocyte + reproductive hormones
- incubate embryo

140
Q

menstruation =>

A

no fertile cycle

141
Q

menstrual cycle - 1

A
  • corpus luteum regresses
  • oestrogen/progesterone levels: low
  • FSH: increased
142
Q

menstrual cycle - 2

A

FSH stimulation -> increased follicular growth

143
Q

menstrual cycle - 3

A

~day 6-7: selection of dominant follicle from primary follicles to develop into single secondary follicle
- increased oestradiol

144
Q

menstrual cycle - 4

A

oestradiol suppressed FSH (and LH) production in pituitary

145
Q

menstrual cycle - 5

A

oestrogen levels rise
~day 12: oestradiol threshold concentration exceeded
- if very high oestradiol levels is maintained for ~36 hrs, temporary switch from -ve to +ve feedback effect on hypothalamus/anterior pituitary
=> 6)

146
Q

menstrual cycle - 6

A

GnRH/LH secretion increased

147
Q

menstrual cycle - 7

A

LH surge brings about ovulation

148
Q

menstrual cycle - 8

A

corpus luteum develops progesterone increased

149
Q

menstrual cycle - 9

A

elevated progesterone -> GnRH inhibition -> decreased FSH/LH (-ve feedback loop)

150
Q

menstrual cycle - 10

A

demise of corpus luteum

151
Q

seminiferous tubule of testes

A
  • site of spermatogenesis
152
Q

seminiferous tubule - interstitial cell

A

leydig cells
- produce progesterone/testosterone => located outside tubules close to blood vessels in interstition between seminiferous tubules

153
Q

sustentacular/sertoli cell

A
  • supporting
  • create blood-testis barrier (tight junction)
  • important in development of spermatocytes => close proximity to seminiferous tubules
  • inside seminiferous tubules in direct contact with spermatogonia
    => sperm, androgen binding protein, inhibin
154
Q

spermatogenesis + no. sperm produced

A
  • only occurs after puberty (different to females who are born with)
  • huge numbers of sperm produced constantly by mature male (300-600 sperm/gram of testis tissue/second ≈20,000 sperm per sec)
155
Q

three phases of spermatogenesis

A

1) mitotic division: as in somatic cell
2) meiotic division: reproductive
- only in oocyte/presperm cell
3) cytodifferentiation: shape change from round to elongated sperm cell

156
Q

testes at brith

A

firm with no sperm

157
Q

spermatogenesis process

A

primary germ cells reactivated => spermatogonial stem cells => divide by mitosis => 1 undifferentiated daughter cell + 3 daughter cells that continue to divide by mitosis (differentiated spermatogonia) => primary spermatocytes => meiosis 1 => secondary spermatocytes => meiosis 2 => spermatids => spermiogenesis => spermatozoa

158
Q

spermatogonia

A
  • sit on basement membrane of seminiferous tubule
  • move between adjacent sertoli to adluminal compartment of seminiferous tubules by squeezing through tight junctions
  • 2n
159
Q

primary spermatocytes

A
  • adluminal compartment
  • 2n
160
Q

secondary spermatocytes

A
  • n with 2 chromatids each
161
Q

spermatids

A
  • round cells/morphology
  • begin to cytodifferentiate in adluminal compartment
162
Q

spermiogenesis

A
  • final process in spermatogenesis
  • round spermatids differentiate shape and become spermatozoa (sperm)
163
Q

spermiogenesis forms

A
  • tail
  • mid piece
  • head
164
Q

sperm mid piece

A

engine of sperm: packed with mitochondria to produce energy (help sperm swim through female reproductive system)

165
Q

sperm head

A
  • contains DNA
  • covered by acrosome
166
Q

acrosome

A

compartment filled with enzymes required for egg/zona pellucida penetration

167
Q

residual body

A
  • excess cytoplasm of spermatid is lost into this structure
  • phagocytosed by sertoli cells after sperm leaves
168
Q

reason for residual body

A

excess cytoplasm not needed as only job in sperm’s life is to swim and fertilise egg => shed off for more efficient swimming

169
Q

spermatogonia do not develop into sperm without

A

testosterone

170
Q

kisspeptin

A

hormone
- sits on top of hypothalamus
- binds to gonadotrophin receptors
- regulates release of GnRH

171
Q

inhibin

A

regulates FSH independently of LH

172
Q

androgen binding protein

A

traps some testosterone inside seminiferous tubule to prevent escape (maintains high level)
- helps lipid based hormone (androgens) travel through blood

173
Q

male infertility

A
  • 1/6 to 1/4 couples are infertile
  • have many causes
  • common feature of infertile men is reduced sperm count (<20 million/ml)
174
Q

male infertility types

A
  • oligospermia
  • azoospermia
  • immotile sperm
175
Q

oligospermia

A

some sperm in ejaculate (not production)

176
Q

azoospermia

A

complete lack of sperm in ejaculate

177
Q

immotile sperm

A

can’t swim

178
Q

cryptorchidism

A

absence of one or both testes from scrotum
- if testes don’t descend
- one of most common anatomical anomalies
- 3% of term male babies (coming out of womb)
- cryptorchid individuals are infertile

179
Q

male infertility alternatives

A

1) in vitro fertilisation (IVF)
2) IntraCytoplasmic Sperm Injection (ICSI)

180
Q

IVF

A
  • oocytes harvested (one per droplet) + fertilised ex vivo (in petri dish)
  • requires ~50,000 motile sperm
  • in vitro: cell culture outside the organism
181
Q

ICSI

A
  • single sperm injected directly into oocyte using microfine pipettes
  • sperm doesn’t need to be motile
  • sperm collected by biopsy of testes can be used (sperm can be directly taken from testes)
  • petri dish, oocyte held by holding pipette
182
Q

orchidectomy

A

removal of a testis

183
Q

testes location

A

scrotum
- testes move to scrotum from pelvis during pregnancy (in humans)

184
Q

pathway of sperm

A

testes -> rete testis -> epididymis -> vas deferens - seminal vesicles - prostate -> urethra -> penis

185
Q

epididymis structure

A
  • comma shaped organ that runs around testicle
  • as you move down from head -> tail, tubes converge into a single tube => all sperm in one tube to go into epididymis
  • sperm move slowly (10-14 days) through epididymis
186
Q

epididymis function

A

sperm acquires ability to:
- be motile
- fertilise by changing structure
=> biopsy of sperm from head/tail is different
reabsorbs liquid from around sperm making it more concentrated

187
Q

how does sperm move through epididymis

A

sperm movement through seminiferous fluid -> epididymis is mediated by mass flow of fluid and a little peristalsis

188
Q

vas deferens

A
  • 45 cm long
  • runs from epididymis -> up and around bladder -> down to join ejaculatory duct (passes through prostate)
  • major site of sperm storage in humans (may be stored for several months)
189
Q

accessory glands

A

1) seminal vesicle
2) prostate

190
Q

seminal vesicle

A

secretory glands (not storage areas) that empty into ejaculatory duct
- directly after sperm is ejected from vas deferens
- washes sperm down ejaculatory duct
- seminal fluid is last component of ejaculate

191
Q

ejaculatory duct

A

joins urethra at prostate

192
Q

mucoid (sticky) substance secreted by seminal vesicle is:

A
  • alkaline
  • contains fructose: energy source for sperm to swim
  • contains prostaglandins
  • contains clotting proteins
193
Q

prostaglandins

A

hormone that may induce smooth muscle contractions in female reproductive tract to help sperm swim/push them along the tract

194
Q

clotting proteins in seminal fluid

A
  • similar to proteins causing causing blood to clot
  • clot keeps ejaculate in vagina during intercourse (prevents leaving)
195
Q

prostate

A
  • donut shaped organ about size of golf ball (urethra passes through)
  • secretes prostatic fluid into urethra (and ejaculatory duct) ahead of sperm during ejaculation
196
Q

prostatic fluid is:

A
  • slightly acidic (pH 6.5)
  • contains citrate (for ATP)
  • milky colour (partly because P and Ca - insoluble in H2O)
  • contains phosphate and calcium
  • contains prostate specific antigen (PSA) protein + other enzymes
197
Q

significance of acidic prostatic fluid

A

acidity of prostatic fluid is neutralised in semen by alkaline seminal vesicle fluid => buffer to physiological pH

198
Q

significance of PSA

A

breaks down post ejaculation coagulum (clot) otherwise sperm stays trapped (can’t swim)

199
Q

urethra

A
  • ~20 cm long
  • runs from bladder -> through prostate -> end of penis
200
Q

3 major structures of penis

A

1) corpora cavernosa (x2)
2) corpus spongiosum
3) penile urethra

201
Q

corpora cavernosa

A
  • main erectile tissue
  • essentially blood vessels (blood-filled spaces)
202
Q

corpus spongiosum

A
  • surround penile urethra
  • prevents occlusion during erection
203
Q

penile urethra

A

conducts semen + urine

204
Q

how does sperm move through male reproductive systm

A

pushed through by fluid (do not swim)

205
Q

erection

A

sexual stimulation => activation of parasympathetic autonomic nervous system => release of vasodilators: nitric oxide (NO) / prostaglandin E1 => Guanosine Monophosphate (cGMP) pathway => reduced intracellular calcium => smooth muscle relaxation in corpora cavernosa => blood fills cavernous spaces more easily (engorgement) => occludes blood drainage => reduces venous outflow => adds to engorgement

206
Q

blood volume of erect vs flaccid penis

A

erect penis has 8 times increased blood volume as flaccid penis

207
Q

no bones in human penis =>

A

erection caused entirely by hydrostatic/hydronamic pressure in the two corpora chambers within penis

208
Q

viagra - sildenafil

A

inhibits phosphodiesterase type 5 (PDE5) => increased cGMP => relaxation of arteries supplying corpora cavernosa/erection => erection

209
Q

PDE5

A

enzyme that breaks down cGMP

210
Q

semen

A

ejaculated fluid

211
Q

semen composition by volume

A

seminal vesicle fluid: 60%
prostate fluid: 30%
sperm: 10%
other secretions: small amounts

212
Q

semen components order of secretion

A

prostate fluid -> sperm -> seminal fluid
- all empty content into ejaculatory duct

213
Q

semen pH

A

~7.5

214
Q

semen total volume

A

2-5 mls in humans
- varies greatly in volume/content between species (e.g boar ejaculate: 500 mls)

215
Q

semen sperm content

A

at least 20 million sperm/ml

216
Q

benign prostatic hyperplasia (BPH)

A

not cancerous prostate overgrowth

217
Q

BPH consequences

A

excess growth of prostate => occludes urethra (prostate can’t grow/expand outwards due to surrounding tissue => grows inwards into urethra) => difficulty voiding bladder => eventually weakens bladder => urinary infections + ascending infection => kidney problems

218
Q

incidence of men requiring treatment for BPH

A

<40: rare
50-59: 17%
60-69: 27%
70-79: 35%
>85: 90% => very common disease

219
Q

BPH treatment options

A
  • selective 5 alpha-reductase inhibitor(s) => stops prostate enlargement/cause shrinking
  • surgery
  • others
220
Q

selective 5 alpha-reductase inhibitor(s)

A
  • finasteride: short half life of 5-7 hrs
  • dutasteride: long half life of 5 weeks
221
Q

5 alpha-reductase

A

converts testosterone -> dihydrotestosterone (DHT)

222
Q

prostate cancer

A

detection increasing due to PSA testing but deaths also increasing

223
Q

PSA testing

A

men can be screened for elevated levels of PSA => early detection but also overdiagnosis

224
Q

what to do about positive PSA screen

A
  • prostate biopsy
  • treat cancer
225
Q

autopsy cancer

A

most (66% of) men who die with prostate cancer don’t know they had prostate cancer

226
Q

is it right to screen for prostate cancer considering…

A

high false positive PSA test results + autopsy cancer

227
Q

prostate cancer treatment

A
  • watchful waiting
  • androgen depletion
    – 5 alpha reductase inhibitors (finasteride)
    – castration
    – inhibitors of androgen synthesis
  • inhibition of testosterone action: block androgen receptor
  • surgery: prostatectomy
  • others
228
Q

prostatectomy

A
  • 1% die as a consequence of operation
  • 20-80% have erectile dysfunction
  • 4-21% have urinary incontinence as a result of operation
229
Q

progesterone levels max during menstruation

A

late in postovulatory phase
- corpus luteum formed, increased secretion to prepare endometrium in time for arrival of fertilised ovum

230
Q

initiation of menstruation

A

triggered by declining levels of progesterone

231
Q

repair of ovary surface after ovulation

A

LH is responsible

232
Q

prolactin

A

causes breast growth + milk production during pregnancy/after birth
- produced by anterior pituitary

233
Q

mucus

A

produced by glands in cervix (lower part of uterus)

234
Q

oestrogen in men

A

produced by leydig cells + germ cells

MEDSCI 142 (8 decks)

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