Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL31561 > Lecture 3 - Menstrual cycle I > Flashcards

Lecture 3 - Menstrual cycle I Flashcards

1
Q

Menstrual cycle: what processes does it underdo?

A
  • Maturation of the female gamete (oocyte) in the ovary and its transport to the site of fertilisation (uterine tube, aka Fallopian tube or oviduct)
  • Preparation of the uterine endometrium as a suitable site for implantation of a developing embryo
  • Menstruation if no embryo implanting occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

HPG axis: what is it and what is the process?

A

hypothalamic-pituitary-gonadal axis

  • Kisspeptin neurons activate gonadotrophin-releasing hormone (GnRH) neurons in the hypothalamus
  • Hypothalamus releases gonadotrophin releasing hormone (GnRH)
  • GnRH causes Gn release (FSH/LH) from the anterior pituitary
  • FSH/LH affect the ovaries and cause oocyte development and ovulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Menstrual cycle: what two parts of it are there?

A
  • Uterine cycle
  • Ovarian cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Uterine cycle

A
  • Menstrual phase - ~5 days
  • Proliferative phase - ~9 days
  • Secretory phase - ~14 days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ovarian cycle

A
  • Follicular phase - ~14 days
  • Luteal phase - ~14 days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why does the uterus lining break down?

A

The lack of circulating progesterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What follows the drop of circulating sex hormones?

A

FSH levels start to rise - this is due to the decreased amount of negative feedback on the hypothalamus and anterior pituitary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

FSH: what is it, what produced it, and what does it do?

A

Follicle stimulating hormone

The hypothalamus/anterior pituitary

Causes maturation of secondary follicles into tertiary follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Follicles: what are they, how does their maturation work, and what hormone do they produce?

A

Small sacs found in the ovaries that contain eggs

  • Ovaries enter the follicular phase as the uterus layer breaks down - results in maturation to secondary follicles
  • Maturation to tertiary follicles arises in the presence of FSH

Oestrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What causes the shift from the menstrual phase to the proliferative phase of the uterus?

A

Circulating oestrogen arising from tertiary follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Circulating oestrogen: does it undergo negative or positive feedback and why?

A

It undergoes negative feedback unless a threshold is reached, at this point positive feedback occurs and a rise in FSH and LH occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Follicular phase of the ovaries: how long does it last, what causes progression into this phase, and what does it do?

A

~14 days

Menstruation

Matures follicles until a dominant follicle is ready to be released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Luteal phase of the ovaries: how long does it last, what causes progression into this phase, and what does it do?

A

~14 days

Release of the egg from the follicle

Produces oestrogen and large amounts of progesterone - builds up and maintains the uterus lining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Menstrual phase of the uterus: how long does it last, what causes progression into this phase, and what does it do?

A

~5 days

Lack of fertilised egg binding to uterus

Breaks down the lining of the uterus, including many cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Proliferative phase of the uterus: how long does it last, what causes progression into this phase, and what does it do?

A

~9 days

Circulating oestrogen produced by follicles

Builds up the lining of the uterus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Secretory phase of the uterus: how long does it last, what causes progression into this phase, and what does it do?

A

~14 days

Circulating progesterone produced from the luteal phase of the ovaries

Endometrial secretions occur which support an embryo until it is ready for implantation

17
Q

Estrous cycle: what is it and how does it operate in animals and humans?

A

Behavioural strategy to ensure mating occurs at time of ovulation

Animals:
* Sexual stimulus
* Accept advances more readily
* Enticing behavioural gestures

Humans:
* Men prefer the smell of women in the middle of their menstrual cycle - sexual stimulus?
* Provocative movements potentially?
* Androstenone better tolerated

18
Q

Puberty: what controls it

A
  • Genetic
  • External factors - adiposity, endocrine disrupting chemicals, intra-family relationships, stressful events, etc
19
Q

Adiposity: why is it suggested to affect puberty age?

A
  • Puberty age has decreased over time
  • Countries with sub-optimal socioeconomic status have puberty later
  • Delayed puberty in malnutrition and low weight
  • Moderate obesity is associated with advanced puberty
20
Q

Adiposity: by what mechanisms may it affect puberty age?

A

Leptin?
Adipose tissue may cause leptin secretion which binds to LepR in gonadotrophin releasing hormone (GnRH) neurones in the hypothalamus

This is wrong - GnRH neurones don’t express the leptin receptor

Kisspeptin?
This is regulated by leptin and fills the gap in the previous model - leptin stimulates kisspeptin neurones which secrete kisspeptin which binds to GnRH neurones which can then cause gonadotrophin release from the anterior pituitary

21
Q

Kisspeptin: what is it, where is it produced, what does it do, what is it regulated by, and what is its potential pathway for inducing puberty?

A

GPCR ligand

Produced in the hypothalamus:
* Arcuate nucleus - important in GnRH pulse generation
* Anteroventral periventricular nuclei - GnRH/LH surge and ovulation

Leptin

Leptin stimulates kisspeptin neurones which secrete kisspeptin which binds to GnRH neurones (GPR54) which can then cause GnRH release - this then reaches the anterior pituitary and causes Gn release

22
Q

What evidence suggests kisspeptin plays a role in puberty age?

A

Disruption of the gene results in failure of sexual maturation but treatment of juvenile rats with kisspeptin advances puberty timing

23
Q

GnRH: what is it, what is its structure, what does it do, and what types of GnRH release are there?

A

Gonadotrophin releasing hormone

Simple amino acid structure (10 aa’s)

Acts as a ligand for the GnRHR which signals through Gαq and PLC to result in transcription of Gonadotrophins

Pulses or surges

24
Q

GnRH pulses: why are they important and what do they do?

A

Promote the production of FSH

25
Q

GnRH surges: why are they important and what do they do?

A

Promote the production of LH

26
Q

FSH: what is it, what is its structure, what confers its specificity, what is its production stimulated by, where is it secreted from, and where is it packaged within the cell?

A

Follicle stimulating hormone

Dimeric protein with both an α and β subunit (α identical in LH)

β subunit

Slow pulses of GnRH

Anterior pituitary

Secreted through the constitutive pathway - little storage within the cell

27
Q

LH: what is it, what is its structure, what confers its specificity, what is its production stimulated by, where is it secreted from, and where is it packaged within the cell?

A

Luteinising hormone

Dimeric protein with both an α and β subunit (α identical in FSH)

β subunit

Fast pulses of GnRH

Anterior pituitary

Packaged in electron-dense granules, in association with storage protein secretogranin II

28
Q

How are FSH/LH secretions regulated?

A
  • GnRH binds to GnRHR
  • Causes activation of Gαq
  • Gαq activates PLC
  • PLC activates protein kinase C - PKC activated MAPK, promoting βLH, βFSH, and FSH/LHα subunit production
  • FSH is dimerised then constitutively released
  • LH is packaged near to the PM, often on cells near capillaries- secretion is activated by Ca²⁺ ??????????
29
Q

GPCRs: what are they, what do they do, what is their structure, and how many domains do they have?

A

G protein-coupled receptors

Bind with ligands, activating their attached G protein which can then do downstream signalling

Long protein that passes through the membrane (7 times) and has extracellular/intracellular compartments

Ectodomain (NH₂), transmembrane, and cytoplasmic domain (COOH)

30
Q

G proteins: what are they, what is their structure, how do they become activated, and how many α subunit families are there?

A

Guanine proteins

Heterotrimer - αβγ subunits

GPCRs induce a conformational change in the α subunit, causing a swap of GDP to GTP and α subunit dissociation

Gαq - activates phospholipase C
Gαs - activates adenylate cyclase
Gαi - inhibits adenylate cyclase
Gα12 - Rho family of GTPases

31
Q

PLC: what is it, what is its function, and what is its pathways?

A

Phospholipase C

Causes downstream signalling after being activated by Gαq

  • Converts PIP₃ into PIP₂ and IP₃ which binds to receptors on the ER and Ca²⁺
  • Activates PKC which causes activation of the MAPK pathway
32
Q

FSH/LH receptors: what G protein are they coupled to, what is activated, and what is the downstream signalling?

A

Gαs

Activated adenylate cyclase

  • Causes conversion of ATP to cAMP
  • cAMP caused activation of PKA
  • PKA phosphorylates of Ser/Thr motifs

BIOL31561 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions