reproductive behavior

Question 1

Define sexual dimorphism

Answer 1

condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organ

Question 2

In humans, biological sex is determined by 5 factors, what are they?

Answer 2

sex chromosomes
gonads
sex hormones: androgen signalling
internal reproductive anatomy
external anatomy

Question 3

Identify the gonads in males and females and the gametes they produce

Answer 3

males:
testes → sperm
females:
ovaries → ova

Question 4

Explain the male sex organ development

Answer 4

SRY gene → development of testes → embryonic testicular release of anti-mullerian hormone and androgen

Question 5

What are the functions of anti-mullerian hormone and androgen?

Answer 5

anti-mullerian: stops development of mullerian system (internal female sex organs)
androgen: triggers development of male sex organ (internal and external)

Question 6

Explain the female sex organ development

Answer 6

XX chromosome → development of ovaries → no release of hormones before puberty

Question 7

Explain these genetic abnormalities and their consequences
- Turner syndrome
- Swyer syndrome

Answer 7

Turner syndrome: only one sex chromosome (X0)
Swyer syndrome: when you’re a XY but have a bad SRY gene

Consequences:
- sterile
- female internal and external organs
- no puberty

Question 8

What happens if there is insufficient production of anti-Mullerian hormone?

Answer 8

insufficient defeminisation
male and female internal organs
functional external male organ

Question 9

What happens if there is insufficient androgen signaling?

Answer 9

sterile
short vagina
external female genitalia
no internal sex organ

Question 10

What happens when there is excess androgen hormone?

Answer 10

male: minimal effect
female: masculinisation of sex organ

Question 11

Differentiate the Mullerian system, the Wolffian system and the primordial external system

Answer 11

Mullerian: development of internal female sex organ
Wolffian: development of internal male sex organs
Primordial: development of external male sex organ

Question 12

Explain the process of puberty that starts from the hypothalamus to hormone release

Answer 12

hypothalamus →
kisspeptin →
GnRH →
anterior pituitary →
gonadotropic hormone: FSH and LH →
testes/ovaries →
testosterone/estradiol

Question 13

How can you decrease a male’s sexual behavior?

Answer 13

no testosterone = no sperm production = ↓ ability to have sex

Question 14

Name the differences between menstrual cycle and estrous cycle

Answer 14

Menstrual:
- primates + human
- menstruation cycle
- sexual activity throughout the cycle

Estrous:
- mammals other than primates
- reabsorb endometrium
- sexual activity only during estrous phase

Question 15

What is the difference between organizational effects and activational effects of sex hormones?

Answer 15

organizational effects: during the development of the body. permanent
activational: after puberty

Question 16

Describe the behaviour a birth-castrated rat (no androgen, low testosterone) would have if we inject it progesterone and estradiol in adulthood

Answer 16

female sexual behaviour

Question 17

What is the female neural circuit for sexual behaviour?

Answer 17

ventromedial nucleus of hypothalamus (VMH)→
periaqueductal gray matter (PAG) →
nucleus paragigantocellularis (nPGi) →
motor neurons → mating behaviour

Question 18

What are the consequences to a lesion to the VMH?

Answer 18

no sexual behaviour, even if injected with estradiol or progesterone

Question 19

An electrical stimulation to the VMH or an injection of estradiol/progesterone increases..

Answer 19

sexual behaviour, even in females whose ovaries have been removed

Question 20

What is the male neural circuit for sexual behaviour?

Answer 20

medial preoptic area (mPOA) →
periaqueductal gray matter (PAG) →
nucleus paragigantocellularis (nPGi) →
motor neurons → mating behaviour

Question 21

A lesion in the medial preoptic area will result in …

Answer 21

no sexual behaviour

Question 22

the sexually dimorphic nucleus is located in the …

Answer 22

medial preoptic area

Question 23

What is the definition of pheromones?

Answer 23

chemical release by one animal that affects behaviour of another animal

Question 24

What is the Lee-Boot effect?

Answer 24

female mice without male urine present →
slowing down / stopping of estrous cycle

Question 25

What is the Whitten effect?

Answer 25

female mice with male urine present → synchronisation of cycles

Question 26

What is Vandenbergh effect?

Answer 26

female mice with male urine present → earlier onset of puberty

Question 27

What is the bruce effect?

Answer 27

unfamiliar male scent → termination of pregnancy

Question 28

Which hormone is known to be the “love hormone”?

Answer 28

oxytocin

Question 29

When are levels of oxytocin and vasopressin more elevated?

Answer 29

during sex, childbirth and breastfeeding

Question 30

A patient has 3 sex chromosomes: XXY. What gonads will they have?
a. ovaries
b. testes
c. mix of both
d. gonads will stay undifferentiated

Answer 30

b

Question 31

What is the main difference between pheromones and hormones?

Answer 31

Pheromones released by one animal affect the behaviour of another animal; hormones released by one animal affect the same animal