Brainscape's Knowledge GenomeTM

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


See full index

Reproductive System > 4 > Flashcards

4 Flashcards

1
Q

What is puberty?

A
  • a stage of morphological, physiological and behavioural development when sexual maturation and growth are completed and result in ability to reproduce
  • primary sexual characteristics established before birth
  • but reproductive system inactive until puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which gender starts and ends puberty first?

A

Girls

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

What secondary sexual characteristics develop in girls and when?

A
  • usually around 9 to 13 years
  • breast bud (thelarche)
  • pubic hair growth (thelarche)
  • begins (adrenarche)
  • growth spurt
  • onset of menstrual
  • cycles (menarche)
  • pubic hair at end stage (more coarse)
  • breasts at end stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define primary sexual characteristics

A
  • sexual characteristics at birth (i.e. before puberty has begun)
  • includes the anatomy of the internal and external genitalia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define secondary sexual characteristics

A

-characteristics that develop after puberty i.e. pubic hair, breast or genital development/enlargement, and menstruation in females

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is thelarche?

A
  • “breast bud” development

- first sign of puberty in girls

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

What influences the development of pubic hair?

A

Testosterone in both boys and girls

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

What is menarche?

A

Initiation of the menstrual cycle, with a girl’s first period

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

Describe the secondary sexual characteristics in males

A
  • start at around 10-14 years old
  • genital development; testicular volume enlargement
  • begin pubic hair growth
  • spermatogenesis
  • begin growth spurt
  • genital enlargement; testes and external male genitalia continue to increase in size and volume until adult external genitalia has developed
  • pubic hair; becomes much coarser
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the tanner scale?

A

Marks pre-puberty to adult scale

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

Describe the accelerated somatic growth in both sexes

A
  • occurs in both
  • depends on growth hormone, IGF-1, and sex steroids in both sexes
  • earlier and shorter in girls
  • men larger b/c growth spurt longer and slightly faster
  • genital development in boys depends on testosterone
  • ended in both sexes by epiphyseal fusion
  • oestrogen closes epiphyses earlier in girls
  • closing of epiphyseal plates is caused by oestrogen in both sexes
  • process is called aromatization and occurs in the periphery tissues
  • can convert testosterone into oestrogen in males
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why does puberty occur earlier nowadays?

A
  • Back then average age was 17 but now 13
  • in girls, critical weight is 47kg
  • if below 47kg then menstrual cycle will cease
  • body weight is an important factor: nutrition
  • leptin may be involved in signalling
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain the role of the HPG axis in puberty

A
  • hormonal changes occurs before physical
  • puberty initiated by the brain (hypothalamus)
  • leptin levels cause the initial stimulation of the hypothalamus to release GnRH
  • Nocturnal GnRH pulsatile release happens much earlier before physical changes
  • GnRH release causes realease of LH and FSH in the anterior pituitary
  • GnRH release from hypothalamus to pituitary is paracrine signalling
  • LH and FSH release from pituitary to gonad is endocrine signalling
  • FSH and LH stimulate Gonads to release oestrogen and androgens which drive the development of secondary Sertoli cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Even though most parts of the reproductive system can work before normal puberty age, why dont they?

A
  • low GnRH secretion

- not a substantial amount of the needed hormones

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

How can we remember the influence of FSH and LH on the genitalia anatomy?

A

Male

  • Sertoli cells produce Sperm under the influence of fSh
  • Leydig cells produce testosterone under the influence of Lh

Female

  • granuloSa cells respond to fSh
  • tHeca cells respond to lH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the characteristics of GnRH?

A
  • secretion in pulses tied to internal biological clock (synchronized by external signal i.e. by light)
  • act on specific membrane receptors
  • transduce signals via second messengers
  • stimulate release of stored pituitary hormones
  • stimulate synthesis of pituitary hormones
  • stimulates hyperplasia and hypertrophy of target cells
  • regulates its own receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What environmental factors influence puber

A
  • breeding is seasonal
  • new “puberty” each year
  • triggered by changes in day length
  • involvement of pineal gland
  • secretion of melatonin
  • pineal tumours can influence puberty in humans (pernicious puberty)
  • leptin important for sustaining reproduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the GnRH-1 gene

A
  • lack of this gene results in no puberty
  • primarily responsible for mammalian GnRH
  • GnRH-1 gene exclusively expressed in discrete population of neurons in the hypothalamus
  • treating prepubertal primates with pulsatile GnRH alone induces puberty
  • lack of gonadotrophin synthesis and secretion and reproductive development occurs if GnRH is BLOCKED
  • treatment of infertile male HPG-mice with synthetic GnRH induces spermatogenesis and in females similar treatment causes ovarian maturation and can lead to established pregnancy
  • therefore critical role of GnRH in reproductive maturation established
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is adenohypophysis (aka AP)

A
  • aka anterior pituitary
  • not nervous tissue
  • connected to the hypothalamus by superior hypophyseal artery
  • an amalgam of hormone producing glandular cells
  • AP produced 6 hormones: prolactin, GH, TSH, ACTH, FSH, LH
  • FSH, LH and prolactin most significant for reproduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does GnRH affect the anterior pituitary?

A
  • secretion of gonadotrpin-releasing hormone (GnRH) by the hypothalamus stimulates the AP gland gonadotrophs to secrete two gonadotropic hormones: FSH and LH
  • one releasing hormone: GnRH is a 10 AA peptide
  • GnRH release is pulsatile
  • released every 1-3 hours
  • intensity of GnRH stimulus is affected by frequency and intensity of release
  • GnRH travels to pituitary hypophysial portal system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Explain how LH and FSH increase during puberty

A
  • in young children, LH and FSH levels are insufficient to initiate gonadal function
  • between 9-12 years, blood levels of LH and FSG increase in pulses
  • amplitude of pulses increases, especially during sleep (nocturnal activity)
  • high levels of LH and FSH initiate gonadal development
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain the sleep dependent nocturnal rise in LH

A
  • in adolescent boys the sleep related LH increase
  • stimulates a nocturnal rise of testosterone
  • androgen levels increase could account for some of the early pubertal changes seen in males
  • similar pattern seen in females with concomitant (accompanied) increase in oestrogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Explain the negative feedback system between the AP and hypothalamus in regards to androgens and oestrogen

A
  • hypothalamus produces GnRH
  • GnRH causes pituitary to produce LH and FSH
  • LH and FSH causes gonads to produce androgens and oestrogen
  • androgens and oestrogens negatively act on the hypothalamus, preventing production of GnRH
  • in turn halts the whole cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain androgen production in males

A
  • LH stimulates Leydig cells in testis
  • produce steroid hormone (from cholesterol): testosterone
  • greatest amount produced from testis
  • once production starts in the medium, long term testosterone levels remain constant (doesn’t change for a long time)
  • there is an effect of circadian rhythm (levels highest in the early morning)
  • effects of environmental stimuli (both driven by brain)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do the testes produce testosterone?

A

-each lobule contains 1-4 tightly coiled tubules which are seminiferous tubules (ST)
-each ST is about 60cm long
90% of the testicular volume
Location for spermatogenesis
-ST cannot function without Leydig cells
-in between ST there is loose CT and blood vessels
-interstitial tissue contains interstitial cells (Leydig cells)
-LEydig cells produce testosterone
-they function independently of ST

26
Q

Describe the seminiferous tubule cells

A

-ST lined by complex epithelium made of 2 cell types
-Supporting cells (Sertoli cells)
-spermatogenic cells/germ cells
Sertoli cells
-provide nutrition and hormonal support to germ cells allowing sperm formation
-sensitive to FSH (increase sperm production)
-secreted inhibin (-) feedback on AP FSH
-Sertoli cells sensitive to FSH and act on negative feedback
-sometimes messed up sperm is made which we do not want in the ECF
-so double layer of cells helps to prevent that

27
Q

How does FSH and LH act on females?

A
  • acts primarily on gonads via Gas PCR to adenylyl earth cyclase
  • female: target cells, ovarian granulose cells, theca interna cells
  • stimulates sex hormone synthesis (steroidgenesis)
  • i.e. oestrogen, progesterone, inhibin
  • controls gamete production (folliculogenesis and ovulation)
  • granulosa cells respond to FSH
  • theca cells respond to LH
28
Q

What in the follicle releases progesterone?

A

Corpus luteum

29
Q

How does oestrogen and progesterone on GnRH?

A
  • moderate titres of oestrogen reduce GnRH secretion (negative feedback)
  • high titres of oestrogen alone promote GnRH secretion (positive feedback, LH “surge”)
  • LH surge: starts of as small concentration of oestrogen then surges to high concentration
  • small amount of oestrogen negatively feedbacks on GnRH
  • high concentration of oestrogen will increase GnRH (positive feedback)
30
Q

How does oestrogen and progesterone act on FSH and LH?

A
  • progesterone increases inhibitory effects of small amounts of oestrogen
  • progesterone prevents positive feedback of high oestrogen (no LH surge)
  • oestrogen reduces GnRH per pulse, progesterone frequency of pulses
31
Q

How does inhibin act on FSH?

A
  • comes from granulose cells of corpus luteum
  • inhibits the secretion of FSH (same as male)
  • has a small inhibitory effect on LH
32
Q

What hormonal changes do you see in a growth spurt?

A
  • GH secretion from pituitary
  • increases TSH
  • increases metabolic rate
  • promotes tissue growth
  • increase of androgens= retention of minerals in body to support bone and muscle growth
  • therefore you get growth spurt
  • IGF also helps with somatic growth
33
Q

What is the significance of leptin in puberty?

A
  • signalling molecule regarding energy
  • signals the median eminence for GnRH
  • leptin is an adipocyte-derived protein hormone
  • signals information about energy stores to CNS
  • important role in regulating neuron doctrine function
  • reproductive dysfunction associated with leptin deficiency
  • leptin can accelerate the onset of reproductive function
  • leptin has pulsatile release pattern significantly associated with the variations of LH
  • leptin can regulate GnRH levels, and its secretion may, in turn, be influenced by gonadal steroids but appears to be independent of LH control
34
Q

How does control of reproduction differ in males and females?

A
  • Male: continuous gamete production required
  • Female:
  • tract needs to prepare for implantation
  • need to build in a “waiting phase”
  • therefore gamete production needs to be periodic so that gamete can be nurtured and developed
35
Q

What is the hypothalamus-pituitary-ovary axis?

A
  • the female system
  • There is a cycle rather than continuous production of gametes
  • feedback is positive and negative depending on the stage of the cycle
  • GnRH produced by hypothalamus
  • acts on AP to release LH and FSH
  • gonadotrophins act on ovary to promote follicular development and to produce ovarian hormones such as steroid hormones and inhibin
  • controlled by effects of gonadal hormones positively and negatively
36
Q

How does the feedback of the hormones differ in males and females?

A

Male
-LH and FSH release causes increase of testosterone levels
-high levels of testosterone will have an inhibitory effect on the hypothalamus and anterior pituitary
Female
-small amounts of oestrogen or progesterone will cause a negative effect
-large amounts of oestrogen or progesterone will have a positive effect

37
Q

Describe the menstrual cycle

A
  • divided into ovarian and uterine cycle
  • preparation of the gamete (ovarian)
  • preparation of the endometrium (uterine)
  • ovulation: release of the gamete
  • waiting: pause, maintaining the endometrium until a signal is received to indicate that fertilization has happened
38
Q

How is the menstrual cycle controlled?

A
  • gonadotrophins: act on the ovary

- ovarian steroids: act on tissues of the reproductive tract, act to control the cycle

39
Q

Why is the pulsatile GnRH release so important?

A
  • intermittent GnRH receptor is an absolute requirement for fertility
  • if GnRH receptors are exposed to continuous presence of GnRH then the receptors become desensitized
  • as a result FSH and LH production stops
  • which in turn results in Gonadal steroid production stopping
40
Q

What is endometriosis and how can we treat it?

A
  • when lining of the uterus grows in other places such as Fallopian tubes, ovaries or along the pelvis
  • treatment: give GnRH agonist to relieve symptoms and pause cycle
41
Q

What two parts can we separate the ovarian cycle into?

A

Follicular phase and luteal phase

42
Q

Describe the follicular phase

A
  • start of the cycle
  • no ovarian hormone production
  • early development of follicles begins
  • low steroid and inhibin levels
  • little inhibition at the hypothalamus or AP
  • free from inhibition since no hormones to inhibit
  • FSH levels start to rise
  • as FSH rises it causes the number of granulosa cells to increase
  • also causes development of the theca interna and externa cells
  • follicle now capable of oestrogen secretion and these low levels will cause negative feedback at hypothalamus and AP
  • inhibin secretion begins
43
Q

What happens in the mid-follicular phase?

A
  • a dominant follicle must be nominate in order to prevent recruitment of any further follicles
  • dominant follicle known as the Graafian follicle with a large antrum, ready to be released at ovulation
  • as follicle develops oestrogen levels increase
  • can now exert a positive feedback on hypothalamus and AP
  • as a results GnRH levels rise which causes LH to rise NLY
  • as follicle develops, inhibin also rises to prevent FSH stimulating more than one dominant follicle
44
Q

What are theca interna and theca externa cells?

A

-make up the outer layer of the follicle

45
Q

What hormone changes occur in preparation for ovulation?

A
  • circulating oestradiol and inhibin rise rapidly
  • oestradiol production is no longer dependent on FSH
  • surge in LH production
  • progesterone production begins as granulose cells become responsive to LH
  • modulation of GnRH pulse generator
46
Q

What is the LH surge?

A
  • when there is a rapid increase in the amount of LH
  • high concentrations of oestradiol enhances sensitivity of AP gonadotrophs to GnRH
  • occurs in late follicular phase
  • key factor that drives ovulation
47
Q

What happens at ovulation?

A
  • meiosis 1 completes and meiosis 2 starts

- mature oocyte extruded through the capsule of the ovary

48
Q

What are the effects of LH after ovulation?

A
  • follicle is lutenised
  • secretes oestrogen and progesterone in large quantities
  • inhibin continues to be produced
  • but LH is now also suppressed because of negative feedback due to the presence of progesterone
  • further gamete development suspended (waiting phase established)
49
Q

Describe the luteal phase

A
  • happens after ovulation
  • waiting stage to see if fertilization and implantation occurs
  • lutein=yellow in regards to corpus luteum
  • function of corpus luteum is to produce progesterone and oestrogen from androgens
  • produces inhibin
  • promotes production of progesterone
  • regresses spontaneously in the absence of a further RISE in LH
  • high levels of oestrogen will cause a positive feedback but the high levels of progesterone causes a NEGATIVE feedback on oestrogen at hypothalamus and AP
50
Q

How long is the luteal phase and why?

A
  • typically 14 days because lifespan of corpus luteum is 14 days
  • without implantation, corpus luteal regresses and levels of oestrogen, progesterone and inhibin drop allowing the cycle to start again
51
Q

What two phases is the uterine cycle split into?

A

Proliferative phase and secretory phase

52
Q

Describe the uterine cycle

A
  • lining of the uterus, endometrium, is responsive to hormones produced by the ovary
  • endometrium is a specialized epithelium
  • responds to oestrogen by proliferating
  • responds to oestrogen and progesterone by secreting
53
Q

Describe the proliferative phase

A
  • myometrium is the muscular wall of uterus
  • endometrium is the epithelial lining of the uterine cavity
  • endometrium has a functional and basal layer
  • at start of cycle endometrium will proliferate and thicken in response to oestrogen produced by the ovary
  • simple, straight glands within the endometrium but as this part of the cycle continues and the endometrium continues to develop, the gland becomes coiled and the functional layer doubles in size
  • early proliferative: glands sparse and straight
  • late proliferative: functional layer has doubled, glands now coiled
  • phase caused by oestrogen
54
Q

Describe the function of the functional and basal layer in the endometrium

A
  • functional layer: sheds during menstruation

- basal layer: allows the regrowth at the start of a new cycle, never sheds

55
Q

Describe the secretory phase

A
  • occurs after ovulation
  • under influence of progesterone
  • when hormones from corpus luteum begin to fall, glands lose their structure and the endometrium becomes ready to shed its functional layer if implantation has not occurred
  • early secretory: endometrium is at max thickness, very pronounced coiled glands
  • late secretory: glands adopt characteristic “saw tooth” appearance
56
Q

What happens at the end of the uterine cycle if implantation doesn’t occur?

A
  • in the absence of a further rise in LH, corpus luteum regresses
  • dramatic fall in gonadal hormones
  • relieving negative feedback
  • resets to start again
57
Q

What happens if ferilisation does occur?

A
  • after 14 days, HCG will be produced by the synctiotrophoblast
  • acts the same as LH
  • will maintain the corpus luteum
  • will in turn maintain the pregnancy by producing oestrogen and progesterone
  • eventually placenta will take over this function
58
Q

What are the actions of oestrogen in the follicular phase?

A
  • Fallopian tube function
  • thickening of endometrium
  • growth and motility of myometrium
  • thin alkaline cervical mucus
  • vaginal changes
  • changes in skin, hair, metabolism
59
Q

What are the actions of progesterone in the luteal phase?

A
  • further thickening of endometrium into secretory form
  • thickening of myometrium, but reduction of motility
  • thick, acid cervical mucus
  • changes in mammary tissue
  • increased body temperature
  • metabolic changes
  • electrolyte changes
60
Q

What the normal duration for the cycle?

A

21-35 days

61
Q

What factors affect the menstrual cycle?

A
  • physiological factors (pregnancy, lactation)
  • emotional stress
  • low body weight

Reproductive System (11 decks)

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