week 4 hormones

Question 1

how does hormones enter the blood?

Answer 1

released by neurosecretory cells in the hypothalamus which enter capillaries and travel to anterior pituitary gland where secretion of hormones is controlled. hormones of the posterior pituitary gland are produced in the hypothalamus and are carried by vesicles during axoplasmic transport

Question 2

what’s the process where hormones travel to gonads?

Answer 2

• the hypothalamus released gonadotropin-releasing hormone (GnRH) which travels to pituitary gland
• the anterior pituitary releases gonadotropins which go into the blood stream
• gonadotropins travel to gonads
• gonads produce sex hormones

Question 3

what Is GnRH

Answer 3

acts like a messenger and travels to the pituitary gland

Question 4

what are gonads

Answer 4

ovaries, testes

Question 5

name the 2 types of gonadotropins?

Answer 5

1. LH (luteneizing hormone)
2. FSH (follicle-stimulating hormone)

Question 6

what is LH

Answer 6

helps trigger ovulation (release of egg) and helps make testosterone in males

Question 7

what is FSH

Answer 7

helps with development of egg and sperm production

Question 8

what do gonads release

Answer 8

estrogen, androgen or progesterone

Question 9

when is puberty or sexual maturation initiated?

Answer 9

when the hypothalamus secretes GnRH which stimulates release of gonadotropic hormones by the anterior pituitary gland

Question 10

up to 6 weeks of development what is significant about primordial gonads and reproductive ducts?

Answer 10

no difference in male or female gonads

all fetuses have the antecedents of both wolfian and mullerian reproductive ducts

Question 11

what happens if the baby is xx after 6 weeks of conception

Answer 11

the outer layer (cortex) of the gonad develops which becomes the ovary

in the absence of testosterone, the mullerian system develops into female reproductive ducts, and wolfian system does not develop

Question 12

what happens if the baby is XY after 6 weeks of contraception

Answer 12

the inner part of gonad (medulla) develops, becomes testis

testosterone makes the wolfian system develop

mullerian-inhibiting substance makes the mullerian system degenerate

Question 13

what does wolfian system mean

Answer 13

male reproductive system

Question 14

what does mullerian system mean

Answer 14

female reproductive system

Question 15

why is dihydrotestosterone different to testosterone

Answer 15

it has 2 extra water molecules

Question 16

what leads to external genitalia

Answer 16

conversion of testosterone to dihydrotestosterone by 5a-reductase 2 enzyme

Question 17

what is one area of the hypothalamus that is structurally different in males and females

Answer 17

media preoptic area

Question 18

what did Rhees et al 1990 find about the medial preoptic area of the hypothalamus in male and female rats?

Answer 18

• studied the SDN-POA (sexually dimorphic nucleus of the preoptic area) which is responsible for sexual behavior
• in male rats the SDN-POA is large and normal
• in females its much smaller
• when a female rat was injected with testosterone after birth, the SDN-POA grew much larger

shows testosterone in critical period of day 18 of pregnancy and day 5 after birth is important for shaping the brain

Question 19

what did De Jonge et al 1989 find about damaging the SDN-POA

Answer 19

reduces masculine sexual behavior

Question 20

what is aromatization

Answer 20

process of converting a non-aromatic ring into an aromatic ring to let the substance cross the blood brain barrier, so converting androgens eg testosterone into estrogens eg estradiol by the enzyme aromatase

Question 21

what did Warne & Zajac 1998 say about the causes of differences of the brain due to aromatization?

Answer 21

masculinizing of the brain is due to aromatization of testosterone into estradiol

blocking aromatization blocks masculinity

human females protected from mothers estradiol by placenta

Question 22

difference between organizational and activation effects

Answer 22

organizational are permanent and occur early in development, eg testosterone in developing male fetus, activational is transient and happens throughout life eg puberty

Question 23

what is androgen insensitivity syndrome

Answer 23

XY with this disorder are not sensitive to testosterone so wolffian system does not develop

they are sensitive to anti-mullerian hormone (not an androgen), so mullerian system does not develop either

external genitalia not sensitive to dihydrortestosterone but female genitalia does develop

Question 24

turners syndrome

Answer 24

abnormal sex chromosme - XO

neither ovaries or testes develop

Question 25

what did Shabir et al 2015 say impairs the differentiation of external genitalia?

Answer 25

deficiency of the 5a-reductase 2 enzyme

Question 25

persistant mullerian duct syndrome causes

Answer 25

either failure to produce anti-mullerian hormone or absence of receptors for it - Wayne and Zajac 1998 both sets of internal sex organs develop but presence of female organs interferes with normal function of male organs

Question 26

maternal stress can cause release of

Answer 26

cortisol

Question 27

describe leplante et al 2009 ice storm study

Answer 27

children exposed to high levels of stress and cortisol in utero, had lower IQ, verbal IQ and language ability

Question 28

what did vom Saal and Bronson 1980 find about pre-natal hormonal control of aggression in females

Answer 28

being next to a male fetus increases female blood levels of testosterone 2 M females (male either side) are more likely to engage in inter-female aggressiveness. effects most pronounced with additional activational effect of testosterone

Question 29

what does oxytocin do

Answer 29

increases reactivity of reward centers - eg just after sex oxytocin increases memory for faces i.e. pair bonding

Question 30

what did Bartels and Zeki 2004 fMRI study show with mothers

Answer 30

mothers looking at pictures of their infants, showed increase oxytocin receptors activity