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BRS: Endocrinology > The reproductive system > Flashcards

The reproductive system Flashcards

1
Q

What does seminal fluid consist of?

A
  • Fructose
  • Citric acid
  • Bicarbonate (used to neutralise the acidic environment of the vagina)
  • Fibrinogen
  • Fibrinolytic enzymes
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2
Q

Describe the spermatic cord.

A

Formed at deep inguinal ring

Contains several structures including:

  • Testicular artery
  • Pampiniform plexus (v)
  • Autonomic & GF nerves
  • Lymph vessels
  • Vas deferens
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3
Q

Describe the penis.

A
  • 2 x Corpora Cavernosa
  • 1 x Corpora Spongiosum
  • Erection due Parasympathetic stim
  • Ejaculation due Sympathetic stim
  • Point and Shoot

(see diagram 4/68)

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4
Q

What is the arterial blood supply for the testes?

A
  • testicular arterties from the aorta via the spermatic cord
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5
Q

Which lymph nodes do the tests drain to?

A

para-aortic lymph nodes

see diagram 5/68

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6
Q

Where are the ovaries?

A

Ovaries inside peritoneal cavity (remainder outside)

see diagram 6/68

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7
Q

What is the arterial blood supply for the ovaries and uterus/vagina?

A

ovaries: ovarian arteries (from aorta)

uterus/vagina: uterine arteries (from internal iliac a)

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8
Q

Which nervous system stimulates erection?

A

para-sympathetic nervous system

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9
Q

Which nervous system stimulates ejaculation?

A

sympathetic nervous system

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10
Q

Which are the lymphatic drainage systems for the ovaries and the uterus/vagina?

A

Ovaries: para-aortic LNs

Uterus/Vagina: iliac, sacral, aortic and inguinal LNs

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11
Q

What is the gametogenesis?

A

production of gametes from reproduction

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12
Q

What are the two functions of the gonads?

A
  1. gametogenesis

2. reproductive hormone production

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13
Q

When does gametogenesis begin?

A

at puberty

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14
Q

Describe the Germ cells in males across a lifespan.

A
  • Gametogenesis begins at puberty
  • Spermatogonia undergo differentiation and self-renewal -> pool available for subsequent spermatogenic cycles throughout life (continuous fertility)
  • Produce ~1,500 mature sperm/second

(see diagram 9/68)

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15
Q

What happens to the germ cells before birth in females?

A
  • Multiplication of Oogonia to ~ 6 million/ovary
  • Form 10 Oocytes within ovarian follicles (= primordial follicle) -These begin meiosis (halted in prophase)
  • Some primordial follicles degenerate (atresia).
  • At birth ~2 million/ovary remain
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16
Q

What happens to the germ cells by puberty in females?

A

-By puberty <0.5 million/ovary remain (due further atresia)

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17
Q

What is the name for gametogenesis in males?

A

spermatogenesis

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18
Q

Define spermatogenesis.

A

production of mature spermatozoa

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19
Q

What is the Vas deferens surrounded by?

A

muscle (for ejaculation)

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20
Q

Is the vagina sterile or non-sterile?

A

non-sterile

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21
Q

What do the fallopian tubes have?

A

• Fallopian tubes have cilia and spiral muscle

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22
Q

Where does fertilisation occur?

A

• Fertilisation in ampulla (wider part of Fallopian tube)

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23
Q

What is the uterus supported by?

A

• Uterus supported by tone of pelvic floor (levator ani & coccygeus) and ligaments (broad, round, uterosacral)

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24
Q

When is the endometrium shed?

A

• Endometrium shed at menses due to vasoconstriction of arterioles

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25
Q

Where is the ureter in relation to the cervix?

A

• 1cm lateral to cervix is ureter

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26
Q

Which areas of the female reproductive system are sterile?

A

• All areas superior to cervix are sterile (shedding, thick

mucus, narrow os, pH<4.5)

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27
Q

How many mature sperm are produced per second?

A

1500

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28
Q

Describe spermatogenesis.

A

Spermatognium (44XY) -> [mitosis] primary spermatocytes (44XY) -> [1st meiotic divison] secondary spermatocytes (22X or 22Y) -> [2nd meiotic division] spermatids (22X or 22Y) -> [differentiation] spermatozoa (22X or 22Y)

(see diagram 13/68)

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29
Q

Describe the seminiferous tubules.

A
  • Sertoli cell inside
  • Leydig cell outside

(see diagrams 14-15/68)

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30
Q

What are the main reproductive hormones in males?

A

androgens:

  • testosterone
  • dihydrotestosterone
  • Androstenedione

inhibin + activin

oestrogens (from androgen aromatisation)

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31
Q

Where are the sertoli cells?

A

within seminiferous tubules

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32
Q

Which receptors do the sertoli cells have?

A

FSH receptors

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33
Q

What are the functions of sertoli cells?

A 
Support developing germ cells
• Assist movement of germ cells to tubular
lumen
• Transfer nutrients from capillaries to
developing germ cells
• Phagocytosis of damaged germ cells

Hormone synthesis
• Inhibin & Activin (-ve or +ve on FSH)
• Anti-Mullerian Hormone (AMH)
• Androgen-Binding Protein (ABP)

Enrico Sertoli 1865

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34
Q

Where are the Leydig cells?

A

between seminiferous tubules

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35
Q

What receptors do the Leydig cells have?

A

LH receptors

Leydig cells have a pale cytoplasm as they are cholesterol-rich

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36
Q

What are the functions of Leydig cells?

A 
Hormone synthesis
• On LH stimulation, secrete androgens:
- Testosterone (oestrogens)
- Androstenedione
- Dehydroepiandrosterone (DHEA) (can be aromatised to oestrogens)
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37
Q

What is the name for gametogenesis in females?

A

oogenesis

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38
Q

What is the definition of oogenesis?

A

production of mature oocytes

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39
Q

Describe oogenesis.

A

in 2nd trimester of pregnancy, all oogonia in foetus develop into primary oocytes (forming primordial follicles):
oognium (44XX) -> [mitosis] primary oocytes (44XX)

Menarche:
primary oocytes (44XX) -> [1st meiotic division] secondary oocytes (22X)
(shedding of polar body)

Sperm fusion occurs around the 2nd meiotic division.

secondary oocytes (22X) -> [2nd meiotic division] ootids (22X) -> [differentiation] ova (22X)

(see diagram 22/68)

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40
Q

What is menarche?

A

first menstrual cycle

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41
Q

What does sperm fusion cause?

A

the final stage of differentiation of the ova

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42
Q

What is folliculogenesis?

A

follicle development

43
Q

Describe folliculogenesis.

A
  1. Primordial follicle (10 Oocyte at birth)
  2. Primary (=Preantral) follicle
    - 10 Oocyte and layers of granulosa cells and outer theca cells
  3. Secondary (=Antral) follicle
    - Fluid-filled cavity (antrum) develops
    - FSH and LH receptors
  4. Mature (=Graafian/Preovulatory)
    follicle
    - Forms due to LH surge
    - 20 Oocyte formed
  5. Ruptures surface of ovary

6-7. Corpus Luteum

  • Progesterone & oestrogen (stim by LH/HCG)
  • In pregnancy, progesterone & oestrogen production taken over by placenta

(see diagram 24/68)

44
Q

Describe the mature follicle.

A

Mature follicle = Graafian follicle = Preovulatory follicle

contains the ovum

(see diagram 25/68)

45
Q

What are the main female reproductive hormones?

A

Oestrogens:

  • Oestradiol
  • Oestrone
  • Oestriol

Progestogens:
- Progesterone

Androgens:

  • Testosterone
  • Androstenedione
  • DHEA (but not DHEAS which is made in adrenals)

Relaxin

Inhibin

46
Q

What are the Theca cells associated with?

A

outer part of ovarian follicles

47
Q

What are the functions of the Theca cell?

A

Support folliculogenesis
• Structural & nutritional support of growing
follicle

Hormone synthesis
• LH stimulates synthesis of androgens
- Overactivity -> high androgen levels

48
Q

What are the Granulosa cells associated with?

A

inner part of ovarian follicles

49
Q

What are the functions of the Granulosa cell?

A

Hormone synthesis
• FSH stimulates granulosa cells to convert
androgens to oestrogens (by aromatase)
• Secrete Inhibin & Activin (effects on FSH)

After ovulation
• Turn into granulosa lutein cells that produce:
- Progesterone (-ve feedback, promote pregnancy by maintaining endometrium)
- Relaxin (helps endometrium prepare for pregnancy and softens pelvic ligaments/cervix)

50
Q

What are the gonadal sex steroid hormones?

A

oestradiol
+
testosterone

both chemicals are very similar

in men, all of human steroidgenesis occurs in the Leydig cells, but in females it depends.

(see diagram 31-32/68)

51
Q

Describe the Hypothalamic-Pituitary-‘Gland’ (HPG) Axis for reproduction.

A

Kisspeptin -> [Hypothalamus] GnRH -> [pituitary] LH/FSH -> [glands/targets] Gonads -> [Target hormones] Oestrogen, Progesterone, Androgen

Oestrogen and progesterone can feedback to act on the hypothalamus and the pituitary

(see diagram 34-35/68)

52
Q

How many hormones are produced by the anterior pituitary gland?

A

6

53
Q

How many hormones are produced by the posterior pituitary gland?

A

2

54
Q

What effect can hyperprolactinaemia have on kisspeptin neurons?

A

Hyperprolactinaemia inhibits Kisspeptin Neurons

55
Q

When are testosterone levels highest for men

A

in morning

56
Q

Describe Hyperprolactinaemia.

A

Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus -> Inhibits kisspeptin release.

  • > Decreases in downstream GnRH/LH/FSH/T/Oest
  • > Oligo (>35d menses) or amenorrhoea (3-6m no menses)/Low libido/Infertility/Osteoporosis

(see diagram 36/68)

57
Q

What the menstrual cycle comprise of?

A

Ovarian Cycle & Uterine Cycle driven by hormonal level changes

58
Q

What are the phases in the Ovarian Cycle

A
  • Follicular Phase
  • Ovulation (=pre-ovulatory phase)
  • Luteal Phase
59
Q

What is the typical duration of the menstrual cycle?

A

28 days

60
Q

What are the phases in the Uterine Cycle? (Endometrial cycle)

A
  • Menstrual Phase
  • Proliferative Phase
  • Secretory Phase
61
Q

What is the menstrual cycle driven by?

A

feedback loops involving:

  • Hypothalamic Kisspeptin & GnRH
  • Pituitary LH & FSH
  • Ovarian Oestrogen, Progesterone, Activin, Inhibin
62
Q

Describe the menstrual cycle.

A

Day 1:
First day of bleeding (Blood & cellular debris from necrotic endometrial lining)

Ovulation:
~Day 14 (with surge of LH)

Length:
Average 28d (21-35)
>35 days = oligomenorrhoea

on the day after ovulation, body temperature increases by at least 0.5*C (due to progesterone)

(see diagram 38-39/68)

63
Q

What does tubular fluid reabsorption result in?

A

concentration (induced by oestrogen)

64
Q

What is secreted into the epididymal fluid?

A

Nutrients (e.g. fructose) and glycoproteins secreted

Induced by androgens

(See diagram 43/68)

65
Q

How far does spermatozoa travel?

A

100,000 times its length from testis to Fallopian tube

Equivalent to 150km for a 1.5m human

66
Q

What is semen made out of?

A

Spermatozoa (15-120 million/ml)

Seminal fluid (2-5ml)

Leucocytes

Potentially viruses (e.g. hep B, HIV)

67
Q

What fraction of spermatozoa in ejaculate enter the cervix?

A

1/100

68
Q

What fraction of spermatozoa in ejaculate gets through the cervix to the ovum?

A

1/10,000

69
Q

What fraction of spermatozoa in ejaculate reach ovum?

A

1/million

70
Q

What does seminal fluid contain?

A
  • Fructose
  • Citric acid
  • Bicarbonate
  • Fibrinogen
  • Fibrinolytic enzymes
71
Q

Where is seminal fluid secreted from?

A

Mainly from accessory sex glands:

  • seminal vesicles
  • prostate
  • bulbourethral glands

Small contribution from:
- epididymis/testis

(See diagram 46/68)

72
Q

What is the capacitation of sperm?

A

To achieve fertilising capability in the female reproductive tract

Occurs in the female reproductive tract

73
Q

How is the capacitation of sperm achieved?

A
  1. Loss of glycoproteins ‘coat’
  2. Change in surface membrane characteristics
  3. Develop whiplash movements of tail

(See diagram 47/68)

74
Q

What is required for the capacitation of sperm?

A
  • Takes place in ionic & proteolytic environment of the Fallopian tube
  • Oestrogen-dependent
  • Ca2+-dependent
75
Q

Describe the acrosome reaction.

A
  • sperm binds to ZP3 (sperm receptor)
  • Ca2+ influx into sperm (stimulated by progesterone)
  • release of hyaluronidase + proteolytic enzymes (from acrosome)
76
Q

What happens as the result of the acrosome reaction?

A

Spermatozoon penetrates the Zona Pellucida

See diagram 48-49/68

77
Q

Where does fertilisation occur?

A

Fallopian tube

78
Q

What reaction does fertilisation trigger?

A

Cortical reaction

79
Q

What happens in the cortical reaction?

A
  • cortical granules release molecules which degrade Zona Pellucida (e.g. ZP2 +3)

Therefore preventing further sperm binding as there are no receptors

Goes from haploid to diploid

(See diagram 50/68)

80
Q

Describe the development of the conceptus.

A
  • continues to divide as it moves down the fallopian tube to the uterus (3-4 days)
  • received nutrients from uterine secretions

This free-living phase can last for 9-10 days until implantation.

(See diagram 52/68)

81
Q

List the phases in implantation.

A

Attachment phase
Decidualisation phase

(See diagram 54-56/68)

82
Q

What is the attachment phase?

A

Outer trophoblast cells contact uterine surface epithelium

83
Q

What is the decidualisation phase?

A

Changes in underlying uterine stromal tissue (within a few hours)

84
Q

What does implantation require?

A

Progesterone domination in the presence of oestrogen

85
Q

What two key molecules are involved in the process of attachment?

A

Leukaemia inhibitory factor (LIF)

Interleukin-11 (IL11)

There are others involved (e.g. HB-EGF)

86
Q

What is the role of LIF?

A

LIF from endometrial cells stimulates adhesion of blastocyst to endometrial cells

87
Q

What is the role of IL11?

A

IL11 from endometrial cells is released into the uterine fluid, and may be involved in attachment

88
Q

What occurs in decidualisation?

A

Endometrial changes due to progesterone

  • glandular epithelial secretion
  • glycogen accumulation in stromal cell cytoplasm
  • growth of capillaries
  • increase vascular permeability (can lead to oedema)
89
Q

Which factors are involved in decidualisation?

A

IL11, histamine, certain prostaglandins, TGF-beta (which promotes angiogenesis)

90
Q

What is angiogenesis?

A

Formation of new blood vessels

91
Q

Which hormone is only present in pregnancy?

A

hCG (human chorionic gonadotropin)

(can only be produced by the placenta)

measured in blood or urine

92
Q

What are the key hormones in pregnancy?

A

hCG
oestrogen (mainly oestriol)
human placental lactogen
progesterone

(see diagram 60/68 for hormone changes and effects during pregnancy)

93
Q

Describe the progesterone and oestrogen production during pregnancy during the first 40 days.

A

produced in corpus luteum (in maternal ovary)
- stimulated by hCG (produced by trophoblast) which acts on LH receptors

essential for developing fetoplacental unit

inhibits maternal LH and FSH (-ve feedback)

(see diagram 62/68)

94
Q

What happens to progesterone and oestrogen production from day 40 of pregnancy?

A

placenta starts to take over

95
Q

Which maternal hormones increase during pregnancy?

A 
ACTH
Adrenal steroids
Prolactin
IGF1 (stimulated by placental GH-variant)
Iodothyronines
PTH related peptides
96
Q

Which maternal hormones decrease in pregnancy?

A 
Gonadotrophins
Pituitary GH (due to placenta making its own growth hormone)
TSH (due to placenta producing hCG; which has a similar action as TSH)
97
Q

What is parturition?

A

labour

98
Q

What cells does oxytocin affect in partruition?

A

myometrium and endometrial cells

99
Q

What does oxytocin do (with some action from oestrogen and progesterone)?

A
  • uterine contraction
  • cervical dilation
  • milk ejection

(see diagram 65/68)

100
Q

What is prolactin for?

A

milk synthesis

101
Q

Where is oxytocin made?

A

posterior pituitary gland

102
Q

What is lactation?

A

breastfeeding

103
Q

Describe the endocrine control of lactation.

A

suckling (stimulus) -> neural pathways -> hypothalamus -> pituitary

posterior pituitary -> [neurohypophysis] oxytocin

anterior pituitary -> [adenohypophysis] prolactin

therefore milk ejection and milk synthesis

(see diagram 67/68)

104
Q

What is hyperprolactinemia?

A

galactorrhea due to high/excess prolactin

BRS: Endocrinology (10 decks)

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