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Rob's RDA > Reproductive physiology > Flashcards

Reproductive physiology Flashcards

1
Q

Where GnRH, LH, FSH and Testosterone released

A

Gonadotrophin releasing hormone (GnRH)
Hypothalamus

Luteinising hormone (LH)
Anterior pituitary

Follicle stimulating hormone (FSH)
Anterior pituitary

Testosterone (T)
Testis

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2
Q

Where do inhibin and testosterone negatively feedback

A

Inhibin from sertoli cells (in response to FSH) feed back on ant. pituitary to reduced FSH

Testosterone from Leydig cells (in response to LH) feed back on hypothalamus and anterior pituitary to reduce LH

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3
Q

Outline the chromosome number in each of the following cells from spermatogenesis:

Primordial germ cell

Spermatogonium

Primary spermatocyte

Secondary spermatocyte

Spermatids

Mature sperm

A

all 46 until secondary spermatocyte

secndary spermatocyte onwards has 23

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4
Q

What are spermatogonium

A

The spermatogonium come from mitotic division of primordial germ cells

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5
Q

Testes are the source of what

A

Sperm

Testosterone

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6
Q

Function of human male reproductive tract

When is testosterone important

A

Ihe two main functions are the provision of androgens (primarily testosterone) to initiate and sustain the necessary male phenotype,

and the production of mature sperm.

Testosterone importnat for IU growth of males but not importnat until age 12 for puberty

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7
Q

Does the name of the hormones affecting male reproductive tract (FSH and LH) reflect its action

A

In the testes there are no follicles. The hormone names are derived from information obtained on the female reproductive system

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8
Q

Waht is the pattenr of LH and FSH release

A

Pulsatile (more pulsatile for LH)

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9
Q

Where are the leydig cells

A

In the interstitium

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10
Q

What is the release of teststerone like

A

Cyclic

It acts locally at the site of production in the testes then is released into the circulation, from where it can affect the whole body.

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11
Q

What is sertoli cell funtion based on

A

FSH and testosterone (both required)

ABP (androgen binding protein very important)

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12
Q

Compartments of the testes

A

Seminiferous tubles

Interstitial

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13
Q

Where are the mature sperm in the seminiferous tubles

A

In the lumen

The lumen leads to epidiymis

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14
Q

Outline the divisions taking place in sperm cell division

A

Mitotic division first (to create a large enough pool)

Then late stages meiotic division to develop 4 haploid cells

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15
Q

When does male reproductive function start

When does it function

A

Starts at puberty

Functions continually

and throughout the rest of life

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16
Q

Does sperm quality or quantity decrease with age?

A

Sperm quantity and quality generally decreases with increasing age

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17
Q

Differentiate the function of males and female reproducitve system

A

Male functions continuously

Female functions CYCLICALLY

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18
Q

Does egg quality decrease with age>

A

Yes

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19
Q

Function of FSH and LH in women

A

FSH stimulates (some) development of ovarian follicles &; 17b-estradiol synthesis

LH stimulates progesterone production

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20
Q

What is difference between LHRH and GnRH

A

Same thing

GnRH is very pulsatile LH release is matched to this

But FSH less pulsatile

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21
Q

Function of steroids in females

A

Act on reproductive tract

And act on the uterus too

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22
Q

What happens with GnRH, FSH and LH and oestradiol effect in folluclar phase, midcyle and luteal phase

A

In follicula rphase, estradoil is reducing GnRH release from hypothalamus and FSH/LH from the ant pit.

In the midcycle, oestradiol is then positively feedbacking on hypothalamus and ant pit to increase GnRH and FSH/LH

In the luteal phase, same as follicular phase BUT the main steroid being produced by ovary is progesterone not estradiol

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23
Q

T/f only progesterone is present in the luteal phase

A

F…. also moderately high oestrogen production.

For implantation, progesterone dominance in the presence of oestrogen required

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24
Q

What is the average menstrual cycle length

A

28 days

on average… stress can change things

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25
Q

If the menstrual cycle changes in length, which part does this

A

The luteal phase increases in length (follicular phase constant)

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26
Q

What is the thickness of endometrium at minimum (ie. after menses) to maximum (high progesterone)

A

2-4mm at min.

7-16mm at max

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27
Q

What hormones are important for which stage of the menstrual cycle (uterus)

A

ESTROGEN –> proliferative stage

PROGESTERONE DOMINANCE with oestrogen –> secretory phase

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28
Q

How long does corpus luteum make steroids for

A

Arond a week to ten days following ovulation

GnRH falls towards the end of the cycle, and so will LH. So progesterone also falls towards end of secretory phase

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29
Q

How are eggs developed

A

Primordial follicle (developed during intrauterine life…. born with millions)

MINORITY mature into:
Primary follicle

30
Q

t/f primordial follicle and primary follice both contain primary oocyte

A

True…

31
Q

Structure of follice

A

It has an antrum (fluid filled space) with the primary oocyte in the middle and the luteal cells around the side

32
Q

T/f the development of follicles occurs over 1 month period

A

F…. actually 3 months

33
Q

Differentiate the development of oogonia nad spermatogonia

A

SPERMATOGONIA DEVELOPED BY MITOSIS DURING LIFE

OOGONIA LAID DOWN IN INTRAUTERINE LIFE AND NO MORE PRODUCED THROUGHOUT LIFE

34
Q

Outline folliculogenesis

A

Over 3 months,

so various stages of follicle development at any time

Dominant follicle selected

35
Q

What is metaphase II arrest

A

Ovulation = release of mature oocyte (egg) from the ovary

Oocyte is 2n at this stage, in meiotic arrest (metaphase II)

36
Q

How long do eggs last and when can fertilisation occur

A

Enters the Fallopian tube

Needs to be fertilised within 24 hours, as it degenerates after this
(luckily sperm can surivive for 3 days so intervourse near time of fertilisation is sufficient for pregnancy)

37
Q

Outline fertilisation

A

Egg is chemoattractant for sperm

Sperm release enzyme to break down zona peluida

38
Q

What happens to chromosomes in the sperm after fertilisation

A

Develop into the male pronucleus

DNA decondense (was packed into the sperm)

39
Q

What happens to male and female pronuclei

A

The nuclei approach each other (approximation)

As soon as pronuclei are near each other, the nuclear membrane breaks down and spindle fibres immediately form so that a division immediately takes place to form 2 identical cells

I.E. THERE IS NO FUSION OF MALE AND FEMALE PRONUCLEUS

40
Q

What happens to DNA in the pro-nuclear stage

A

replication of the haploid DNA occurs

There is no diploid nucleus formed by combination of the two pronuclei…… replication occurs and then division happens

Chromatids in both pronuclei are duplicated
They align on the mitotic spindle, and are separated into 2 identical ‘daughter’ cells (1st cleavage division of the embryo).

41
Q

What occurs in maternal chromosomes after fertilisation

A

Meosis of maternal chromosomes resumes, forming female pronucleus (23 chromatids), and 2nd polar body.

Then there is replication of the DNA

42
Q

How frequenty are eggs released from each ovary

A

Supposed to be alternating (left ovary one month and right ovary the next)

BUT

if ovary is removed then it will take place every month from one egg

43
Q

What is epididymis function.

A

One within each scrotal sac. Sperm are released from the testis and stored here prior to ejaculation.

44
Q

Journey of sperm at ejaculatin

A

From epidiymis, At ejaculation sperm pass through the two Vas Deferens (which are contractile), and are mixed with fluid from the seminal vesicles. The fluid then leaves the ejaculatory duct, and passes into the urethra where it mixes with secretions from the prostate gland.

45
Q

How many sperm produced per day

A

The overall production of sperm from both testes is estimated to up to 200 million sperm per day.

46
Q

Which cells are there within a follicle

A

Oocyte (middle)
Around the outside:
thecal cells and granulosa-luteal

47
Q

what are thecal cells and granulosa-luteal cells responsible for

A

thecal cells of the developing follicles are responsible for the production of estrogens, and the granulosa-luteal cells produce estrogens and progesterone during the second half of the ovarian cycle.

48
Q

Differentiate the proliferative and secretory phase of the endometrial cycle and the days at which is occurs

A

Menstrual phase is until day 5

Proliferative- day 9

  • Stimulation of endometrial proliferation
  • increase in thickness
  • number of glands, and length of arteries increases

Secretory- day 13

  • production of nutrients and other factors
  • epothelial glands widen, endometrium thickens and increased coiling of spiral arteries
49
Q

What cuases proliferative stage and what causes secreotry phase

A

Proliferative: E2

Secretory: progesterone dominnce with presence of E2

50
Q

When exactly does oestrogen act as postive feedback and when does it act as negative feedback on the hypothalamus and pituitary

A

Negative feedback in early & mid follicular phase, as well as luteal phase (E2 &P)

Positive feedback in the late follicular phase

51
Q

When does oestrogen peak

A

A few dyas before ovulation (so a few days before day 14)

52
Q

When does basal body temperature change during mesntual cycle

A

the basal body temperature rises slightly (about 0.5°C) around the time of ovulation

53
Q

What stimulates the oocyte to complete meiosis 1.

When does meiosis II occur

A

The first meiotic division is completed during the formation of the secondary follicle, linked to the LH surge. Meiosis I starts during embryonic development, but halts at the diplotene stage of prophase I (primary follicle); this persists until puberty when meiosis resumes as secondary follicles develop

Meiosis II follows immediately after this, but pauses in metaphase II

54
Q

What causes completiiton of meiosis II

A

Fertilisation

55
Q

T/f babies are already born having had lots of their oocytes died

A

T

Contain ~6 million primordial follicles at ~20 weeks of development.
By delivery of the infant, this has fallen to ~1 million per ovary.

56
Q

How many follicles ovulate during reroductive life

A

400ish

57
Q

What is sexual reproduction

A

Produces offspring that differ genetically from both parents.

58
Q

Which other brain pathways involved in reproduction

A

Nigrostriatal tract

Mesolimbic dopaminergic system (pathway for reward and pleasure)

59
Q

Control of penile erection

A

Brain (limbic system) –> spinal cord –> efferent

Or tacile system can activate afferent system via pudendal nerve. Still involves spinal cord

60
Q

Explain how erection occurs

A

Increased PNS to smooth muscle of pudendal artery

Increases NOS, more NO.

Increases cGMP, causing arterial SM dilation , counteracting SNS myogenic tone

Increased blood flow in corpus cavernosum

Compresses dorsal vein, restricting outflow of blood.

61
Q

Why is the urehtera protected from the high presures of the corpus cavernosum during penil erection

A

The urethra is protected from increased pressure by surrounding corpus spongiosum (less turgid)

62
Q

What is the mechanism of action of viagra

A

Cyclic GMP is normally de-activated by a phosphodiesterase enzyme (so reverses erectin)

Viagra inhibits the phosphodiesterase, thus potentiating the effects of cyclic GMP.

63
Q

What equivalent tissue in females is erectile

A

Clitorus, using same cGMP mecahnism

64
Q

What changes occur to cervical mucosa mid-cycle

A

Cervical mucus is normally hostile to sperm
This forms a physical barrier to sperm
Cervical mucus changes at mid-cycle
This change permits sperm to enter uterus

65
Q

What happens once sperm has entered th uterus

A

Passage of sperm through uterus
Passage of sperm into Fallopian tube
Swim from there to Fallopian tube ampulla

66
Q

What is capacitation

A

Capacitation is essential preparation before the sperm meet the oocyte (see endo)

67
Q

What happens to the egg when the sperm enters

A

Rapid membrane depolarisation

Cortical reaction, leads to hardening of zona pelucida and exclusin of other sperm and inactivation of ZP3 receptors

68
Q

t/f the cumuls cells are surrounding the oocyte and are within the zona pellucida

A

F…. they are outside the zona pellucia

figure 2.13

69
Q

What must occur before formation of pronucleus

A

Maternal chromosomes separate and form 2nd polar body and female pronucleus

There are now 2 pronuclei (one from sperm one from egg) whihc are both haploid

70
Q

In order for the now fertilised egg to divide to start forming embryo, the now diploid cell must divide. Outline how this occurs

A

So there was haploid pronuclei –> 23 chromosomes in each (and these are not replicated)

Now the two pronuclei are in the same cell, so there are 46 chromosomes, unreplicated.

We now need 2 daughter cells.

Note that there is no formation of a diploid nucleus in the egg.

Simply, before mitosis, the 23 chromosome from each pronucleus divides, dissolves plasma membrane, and then mitosis occurs.

All the replicated chromosomes will line up in one line as is customary in mitosis, and so each daughter cell will receive all the maternal and all the paternal chromosomes

71
Q

When do the maternal and paternal chromosomes mix for the first time

A

Maternal and paternal chromosomes mix for the first time, as the metaphase plate of the first cleavage division is formed

Rob's RDA (10 decks)

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