Brainscape's Knowledge GenomeTM

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


See full index

Sex and Reproduction > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

Reproductive Development:

A

the formation, from conception to adulthood, of sexual characteristics specific to the sex of an individual

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

Sexual Characteristics(2)

A

Primary = gonads
Prenatal

Secondary = all other sexually dimorphic characteristics
Internal and external genitalia
Variation in body structure, physiology, function
Two major stages of development
Pre- and postnatal
Pubertal

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

Sexual Dimorphism(3)

A

Morphism: the form of a structure or substance

Dimorphism: having two different forms

Sexual Dimorphism: having two different forms, one for each of two sexes

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

Sexual Differentiation

A

Differentiation: the process of going from a non-specific state (monomorphic) to a specific state

Sexual Differentiation: the process of going from a sexually monomorphic state to a sexually dimorphic state

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

Undifferentiated (Bipotential) Fetal Reproductive Structuresat Approximately Six Weeks Development

A

IMAGE

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

Primary (Gonadal) Sex Determination is Chromosomal

A

Y chromosome = SRY gene = ♂ = testes

No Y chromosome = no SRY gene = ♀ = ovaries

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

Many Genes on Different Chromosomes are involved in Primary Sex (gonadal) Differentiation (short list)

A

X = ATRX; Dax1

Y = SRY

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

Overview of Genetics of Gonad Formation

A

Testes form around week seven.

Ovaries form around week sixteen.t

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

SRY present?

A

If SRY is present, TESTES form around week seven. The testes begin to produce and secrete TESTOSTERONE. If no SRY is present, OVARIES form. Ovaries form around week sixteen.

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

Proper Development of the Ovary Needs Autosomal Genes

A

Genes needed

Wnt4 (Chromosome 1) to prevent male characteristics in gonad

Gdf9 (Chromosome 5) and FoxL2 (Chromosome 3) are required for proper follicular development

Two copies of DAX1 (X-Chromosome) yield ovaries even in the presence of SRY

Two X-chromosomes are needed for fully functional ovaries

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

Differentiation of Bipotential Gonad

A

Primordial Germ Cells become Oogonia or Spermatogonia

 Primordial Germ Cells (PGCs) develop OUTSIDE of the embryo, but migrate to (invade) the gonad once gonadal sex is determined.

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

Hormones of Sex Differentiation

A

Androgens

Testosterone: secreted by Leydig cells of testis

5α-Dihydrotestosterone (DHT): testosterone is converted to DHT at the cells on which it acts

AntiMüllerian Hormone (AMH); aka Müllerian Inhibiting Hormone (MIH, MIS, MRF): secreted by Sertoli cells

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

If Androgens & AMH present….

A

If androgens and AMH are present, structures are male.If no androgens or AMH, structures are female.

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

SRY & DAX1?

A 
SRY = testis determining factor
DAX1 = 2 copies are needed to form ovaries
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Anatomical Homologies

A

Structures are “homologous” in two different sexes (or two different species) if they develop from the same embryonic tissue/structure.

In two different species, they represent common ancestry.

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

Some final words on prenatal development… descent of the testes.

A

Gonads form at the posterior body wall of the abdominal cavity. Both ovaries and testes descend. But only testes navigate through the pelvic floor.

17
Q

Descent of the testes

A

Descent occurs in two stages:
Transabdominal descent (cranial suspensory ligament and gubernaculum)
Inguinal-scrotal descent (androgen dependent)

18
Q

Puberty

A

Puberty begins approximately ten to twelve years following birth.

19
Q

Steroid Hormones(2)

A

Androgens
Testosterone
DHT (5α-dihydrotestosterone)
Androstenedione

Estrogens
Estradiol
Estriol
Estrone

20
Q

Puberty is? Changes?

A

The period marking the end of childhood and the attainment of sexual maturity.

Somatic changes = changes in non-reproductive tissues

Reproductive changes = development of secondary sexual characteristics

21
Q

Major Events(4)

A 
Adrenarche:  adrenal gland activation results in steroid hormone synthesis
  produces weak androgens
  promotes pubic and axillary hair growth
Gonadarche:  enlargement of gonads
  more significant in testes
  marks beginning of male puberty
Thelarche:  breast enlargement
  not significant in males
  marks beginning of female puberty
Menarche:  onset of menstrual cycle
  exclusive to females
  last obvious stage of female maturation
22
Q

GnRH Pulse Generator signals the onset of puberty in both males and females

A

GnRH: gonadotropin releasing hormone
quiescent since birth
triggers LH and FSH secretion by the pituitary

23
Q

GnRH activation is…

A

GnRH Activation is an orchestration of internal and external signals

24
Q

Factors implicated in pubertal activation of GnRH are divided into two groups

A

Permissive signals: allow puberty to proceed
Integration of multiple signals may or may not be required

Independent “Master” signal is probably an innate developmental clock

25
Q

Permissive signals implicated in pubertal activation of GnRH – may be different in males and females:

A

adequate nutritional intake
adequate fuel reserves
available calories
bottom line may actually be “energy balance” (less important in males)
adequate body size
circadian clock activity (nocturnal melatonin increases)

26
Q

Developmental Clock is now thought to involve two important signaling hormones directly related to energy balance. (2)

A

Leptin = adipose (fat) derived hormone that controls energy intake and expenditure
signals nutritional status

Kisspeptin = protein expressed in neurons of control regions in hypothalamus
functions through GPR54 receptor
no GPR54 receptor – NO PUBERTY!!!
neurons express kisspeptin production at GnRH producing cells
many kisspeptin neurons have leptin receptors

27
Q

Adrenarche is NOT controlled by GnRH:

A

Since pubertal onset and duration varies between boys and girls, control of activation of GnRH may differ in males and females
There are probably more signals, besides leptin, acting through the Kisspeptin pathway regulating the variation in males and females

28
Q

Male Secondary Sex Characteristics of Puberty in order of appearance (time span ~8 years)

A

Initiation of androgen production
Fat deposition begins
Skeletal growth begins; spontaneous erections; seminal vesicles and prostate grow larger
Spontaneous nocturnal ejaculations
Growth of vocal cords & deepening of voice; axillary, pubic and upper lip hair grow

29
Q

Male Secondary Sex Characteristics of Puberty in order of appearance (time span ~8 years)(continued)

A

First fertile ejaculation
Appearance of chest, body and facial hair; sweat and oil glands increase production; loss of body fat
Muscle growth; increase of muscle strength; broadening of shoulders
Adult height may be reached (sometimes growth continues into 20s)

30
Q

GRAPHS

A

Understand graphs!

31
Q

Female Secondary Sex Characteristics of Puberty in order of appearance (time span ~5 years)

A

Growth spurt and deposition of fat
Widening of pelvis
Growth and maturation of uterus, uterine tubes and vagina
Growth of pubic and axillary hair
Skeletal growth increases then decreases; sweat and oil glands increase production; first ovulation occurs
Voice deepens slightly
Adult height is reached

32
Q

Differences in LH & FSH

A

GRAPH!

33
Q

Estrogens Fluctuations through life in femal

A

graph!!

34
Q

Effects of LH & FSH on Estrogen & Progesterone

A

Graph!

35
Q

Range of Ages of Onset of Puberty (on 4)

A

Adrenarche is prepubertal

Menarche = 8.5 to 17 years of age

Thelarche = 8 to 14 years of age

Gonadarche = 8.5 to 16

36
Q

Variation in individuals at puberty stages.

A

All females in image are 12.75 years old. All males are 14.75 years old.

Sex and Reproduction (7 decks)

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