Physiology of sex I

Question 1

what is the only form of human reproduction?

Answer 1

sexual reproduction

Question 2

what are the forms of animal reproduction? (2)

Answer 2

sexual and asexual

Question 3

how many pairs of chromosomes do humans have?

Answer 3

23 pairs 46 total. 22 autosomal pairs and 1 pair of sex chromosomes (XX OR XY)

Question 4

what is a gamete?

Answer 4

it is the neutral word for sperm or egg (sex cells)

Question 5

what is the difference between homogeneity and heterogeneity?

Answer 5

females are homo - two of the same sex chromosomes (XX)
males are hetero - two different sec chromosomes (XY)

Question 6

the condensed Y chromosome leads to what?

Answer 6

a chromosomal imbalance in males but also between males and females. in males, this imbalance creates a cascade of processes to make up for the imbalance

Question 7

X-inactivation in females

Answer 7

this counteracts the chromosomal imbalance because we have two of the same, one X chromosome is up regulated and the other is inactivated

these genes are likely competing with each other, this is the process we see with all cells (one gene becomes dormant so the other can be expressed)

Question 8

Testes - determining factor, what is it? (gene)

Answer 8

sex determining region on Y chromosome = SRY GENE

plays a huge role in the differences between sex related differentiation of the body and the brain

at this stage the bi potential gonad develops at 3-6 weeks after gestation and it has the potential to follow one of two developing pathways but has not been directed yet

Question 9

the bipotential gonad. describe both pathways

Answer 9

at this stage in development it has been decided what pathway development will follow:

müllerian duct - female (the gonad comes into a kidney bean shape (uterus) and it has tubes and these represent the fallopian tubes)
wolffian duct - male (gonad starts upward and the testes will eventually drop

Question 10

female determining pathway

Answer 10

everyone has an X chromosome and if there is no substance to push us further to an XY pair we are going to end up XX

Question 11

two hormones that are secreted from cells i the testes to continue male differentiation

Answer 11

testosterone

mullerian inhibiting hormone MIH or anti-mullerian hormone AMH

Question 12

MIH AND AMH as well as development of internal and external genetalia (weeks)

Answer 12

die to the presence of SRY the bipotential gonad will develop into the testes and from here they secrete hormones which are specific to males.

sex is determined at 20 weeks for certainty (can go at 15 but not as accurate)

internal genitalia develops at 7 weeks (males) and 8 weeks (females)

AMH is going to degenerate the ducts on female side because it is not needed, the absence of AMH develops the female pathway

we get testosterone and androgens which are important for males and females

Question 13

signs of pubertal development

Answer 13

rapid growth spurt, pubic hair growth, axillary hsir growth, body odour, oil production (greasy hair, face and acne), breast development (females)

Question 14

androgens and estrogens are:

Answer 14

lipids and fats derived from cholesterol

Question 15

what is a hormone?

Answer 15

a chemical that is sent from one part of the body to another for the purpose of causing bodily changes. these are secreted into the blood through the circulatory system

Question 16

endocrine hormones? what is paracrine?

Answer 16

endocrine hormones are secreted internally and they travel through the blood

paracrine: happens internally, produced in one spot and acts in that same spot (developed by a hormone and the adjacent cell absorbs it)

Question 17

endogenous vs exogenous hormones

Answer 17

endogenous: generated internally

exogenous: external (injecting or injecting)
- oral contraceptives, insulin etc.

Question 18

why do hormones have different potencies? (3)

Answer 18

• interaction with different receptors
• conversion to alternative forms within tissues
• breakdown processes with the body

Question 19

hormone breakdowns + enzymes

Answer 19

androstenedione-> aromatase -> estrone which has a bidirectional interaction with 17b-HSD -> 17b estradiol

androstenedione has a bidirectional interaction with 17b-HSD -> testosterone

testosterone -> aromatase-> 17b estradiol
testosterone-> 5a reductase-> DHT (100% potency)

Question 20

what do estrogens do:

Answer 20

include development of secondary sex characteristic

cyclic changes in reproductive physiology (menstruation)

Question 21

what do androgens do:

Answer 21

induces development of secondary sec characteristics

stimulates activity of sec glands (prostate)

Question 22

hormone receptions and connections

Answer 22

lock and key model: receptor and ligand

receptor specificity: distinguishing between specific hormones

receptor “promiscuity” hormones binding to the same receptors
- structurally related hormones
- closely related hormones (of the same “family” of steroids) e.g., testosterone and DHT

Question 23

agonist and antagonist

Answer 23

agonist: mimics the action of a ligand. binds and activates a receptor

antagonist: decreases or reverses the action of a ligand. binds and deactivated a receptor but it can also have no effect

Question 24

things that influence puberty (genetic and environmental)

Answer 24

stress
genes
nutrition
infection
race
obesity
weight-height ratio
ethnicity
BMI etc.

Question 25

what stages occur only before the peak or “central puberty”

Answer 25

thelarche and mini-puberty

Question 26

an individual who cannot produce estrogen or cannot receive estrogen tends to be short?

Answer 26

false. these tend to be taller because estrogen is responsible for epiphysesl fusion, without appropriate concentration of estrogen, the growth plates don’t fuse and growth continues longer than someone who does have estrogen production

Question 27

true or false? androgens have a fundamental role in male sexual development ONLY?

Answer 27

false

Question 28

what is the name of the system used to assess or measure pubertal development

Answer 28

tanner stage

Question 29

as the internal genitalia develops prenatally, the bipotential gonad becomes sex differentiated. during this process the female reproductive system retains the ___ and the male system retains the ___

Answer 29

mullerian duct and the wolffian duct

Question 30

the protein class of hormones that we covered in class includes:

Answer 30

liteinizing hormone