Repro 2 Flashcards Preview

ESA 4 - 2017 - Incomplete/Some errors > Repro 2 > Flashcards

Flashcards in Repro 2 Deck (53)
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1
Q

What 4 events are needed for successful reproduction?

A

Fertilisation
Support of conceptus, embryo and foetus
Birth at the correct time
Support of the neonate

2
Q

What is the HPG axis?

A

The interaction between the hypothalamus, pituitary gland and the gonads

3
Q

What does the HPG axis regulate?

A

Development
Reproduction
Ageing etc.

4
Q

What does the hypothalamu-pituitary part of the HPG regulate/control?
Hint: 3 glands 4 processes

A
Thyroid
Adrenals
Reproductive glands
Somatic growth
Lactation
Milk secretion 
Water metabolism
5
Q

Where is the pituitary gland situated?

A

Base of brain, below hypothalamus but connected by stalk with nerve fibres/blood vessels

6
Q

In which specific structure is the pituitary located in the skull?

A

Sella Turcica

7
Q

What are the other names for the anterior and posterior lobes of the pituitary?

A

Anterior - pars distalis

Posterior - pars nervosa

8
Q

What is the visual differentiating feature between the anterior and posterior lobes of the pituitary?

A

Staining - the anterior is darker

9
Q

What structural features differentiate the anterior and posterior lobes of the pituitary?

A

Tissue composition - Anterior is glandular while posterior is nervous

10
Q

What does the posterior lobe of the pituitary (neurohypophysis) secrete?

A

ADH & Oxytocin

11
Q

What is the origin of the posterior pituitary?

A

Hypothalamus - the lobe is an outgrowth of it, allowing neurons to pass through the stalk (median eminence)

12
Q

What is the origin of the anterior pituitary gland?

A

Rathke’s pouch

13
Q

What connects the anterior lobe of the pituitary to the hypothalamus?

A

Hypophyseal artery

14
Q

Which 6 peptide hormones are secreted by the anterior pituitary?

A
Prolactin
GH
TSH
ACTH
FSH
LH
15
Q

How does the hypothalamus control the anterior pituitary?

A

Hormone releasing hormone -> Hypophyseal-portal circulation -> pituitary releases hormones -> these negatively feedback to hypothalamus

16
Q

What are the characteristics of hypothalamic releasing hormones?
Hint: 6

A

Secreted in pules related to “body clock”
Transduced via 2nd messengers
Stimulate release of already stored pituitary hormones
As well as synthesis of these hormones
Stimulate hyperplasia AND hypertrophy of target cells
Regulate their own receptors

17
Q

Name and action of the hypothalamic releasing hormones please
Hint: 7, most of which do what they say on the tin

A
CRH - ACTH secretion 
TRH - TSH and prolactin secretion 
GHRH - GH secretion
Somatostatin - inhibits GH
GnRH - LH & FSH secretion 
PRH - prolactin secretion 
Dopamine - inhibits prolactin secretion
18
Q

What are gonadotrophs?

A

Anterior pituitary cells (5-10% of them) that secrete LH&FSH

19
Q

How do FSH&LH exert their effect?

A

Gs-PCReceptors

20
Q

Briefly describe the secretory mechanisms of GnRH

Hint: 4 main steps

A

Hypothalamus secretes GnRH -> Anterior pituitary secretes FSH&LH -> Gonads secrete steroids -> Steroids act on reproductive tract or +ly/-ly feedback on pituitary or hypothalamus

21
Q

Which male gonadal hormone(s) act on GnRH secretion and how?

A

Testosterone - reduces GnRH secretion

22
Q

Which female gonadal hormone(s) act on GnRH secretion and how?

A

Oestrogen - action is different at varying titres
Moderate titres: -ve feedback
High titres: +ve feedback

23
Q

What is the significance of high levels of oestrogen?

A

Causes LH surge

24
Q

On the other hand, what does progesterone do regarding GnRH in females?

A

Increases inhibitory effect of moderate oestrogen

Prevents +ve feedback of high oestrogen

25
Q

What, then, is the significance of progesterone?

A

Prevents the LH surge

26
Q

Which male gonadal hormone(s) act on the pars distalis and how?

A

Testosterone - reduces LH&FSH secretion

27
Q

Which female gonadal hormones act n the pars distalis and how?

A

Oestrogen - again varying effects as titres change
Moderate titres - reduces LH&FSH secretion
High titres - increases LH&FSH secretion

28
Q

Which hormone, present in both sexes, also acts on the pars distalis and how?

A

Inhibin - selectively reduces FSH secretion & is related to developing gametes

29
Q

Describe the actions of LH in the male

A

Stimulates Leydig cells in testcles to produce testosterone

30
Q

Describe the actions of FSH in the male

A

Stimulates Sertoli cells to produce androgen binding globulin & inhibin

31
Q

Describe the function of androgen binding globulin in the male

A

Keeps testosterone bound in seminiferous tubules

32
Q

Describe the function of inhibin in the male

A

SUpports spermatogenesis and inhibits the production of LH, FSH and GnRH

33
Q

What do increased levels of testosterone and inhibin cause in the pituitary and hypothalamus?

A

Negative feedback

34
Q

The hormone levels in the male HPG axis must remain constant in the long term, how and why is this?

A

Spermatogenesis is continuous - the male reproductive system must be ready at all times
It is achieved by negative feedback loops

35
Q

Briefly describe the negative feedback of inhibin and testosterone

A

Both from the gonads
Inhibin effects the pars distalis
Testosterone effects the hypothalamus

36
Q

What do LH&FSH stimulate the production of in the female?

A

Oestrogen & inhibin

37
Q

Define Ovarian cycle and Uterine cycle

A

Ovarian - preparation of the gamete

Uterine - preparation of the endometrium

38
Q

Briefly describe the hormone profile at the start of the menstrual cycle
Hint: some not present at all, some low and some on the rise

A

No ovarian hormone production
Low steroid and inhibin levels
FSH on the rise

39
Q

Decribe the changes to the follicle (and its surroundings) as FSH binds

A

FSH binds to granulosa cells
Theca interna appears
Follicle can now secrete oestrogen
Inhibin secretion begins

40
Q

Which two processes are vital to the mid-follicular phase?

A

Increased LH from +ve feedback of follicular oestrogen

Follicular inhibn rises selectively reducing FSH production at pars distalis

41
Q

What hormone changes occur in preparation for ovulation?

Hint: 4 hormones

A

Circulating oestradiol and inhibin rise rapidly (osetradiol production no longer dependent upon FSH)
LH surge
Progesterone production begins

42
Q

Following progesterone production what change occurs in the granulosa cells?

A

They become responsive to LH

43
Q

What does the luteiniesed follicle secrete?

Hint: 3

A

Inhibin

Oestrogen & progesterone (in large quantities)

44
Q

What phase is established after the follicle is luteinised and how?

A

Waiting phase - LH is suppressed by progesterone secretion

45
Q

What is the luteal phase?

A

When the corpus luteum develops

46
Q

What does the corpus luteum produce?

A

Progsterone, oestrogens and inhibin

47
Q

What happens to the corpus luteum in the absence of an LH rise?

A

Spontaneous regression

48
Q

What follows the regression of the corpus luteum?

A

Fall in gonadal hormones
relief of negative feedback
Resetting of the cycle

49
Q

If fertilisation occurs, what maintains the luteinising effect and how?

A

Syncytiotrophoblast via human chorionic gonadotrophin production

50
Q

What arte the timelines of the uterine and ovarian cycles?

A

Ovarian; Follicular - days 0-14, Luteal - days 14-28 (0)

Uterine; Proliferative - days 4-14, Secretory - days 14-28

51
Q

How long is the menstrual cycle?

A

21-35 days (+/- 1 week from 4)

52
Q

WHat causes variation in cycle duration?

A

Variation in length of follicular phase

53
Q

List some factors affecting the menstrual cycle

Hint: 4

A

Pregnancy (obviously)
Lactation
Emotional stress
Low body weight