reproductive behavior Flashcards
Define sexual dimorphism
condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organ
In humans, biological sex is determined by 5 factors, what are they?
sex chromosomes
gonads
sex hormones: androgen signalling
internal reproductive anatomy
external anatomy
Identify the gonads in males and females and the gametes they produce
males:
testes → sperm
females:
ovaries → ova
Explain the male sex organ development
SRY gene → development of testes → embryonic testicular release of anti-mullerian hormone and androgen
What are the functions of anti-mullerian hormone and androgen?
anti-mullerian: stops development of mullerian system (internal female sex organs)
androgen: triggers development of male sex organ (internal and external)
Explain the female sex organ development
XX chromosome → development of ovaries → no release of hormones before puberty
Explain these genetic abnormalities and their consequences
- Turner syndrome
- Swyer syndrome
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
What happens if there is insufficient production of anti-Mullerian hormone?
insufficient defeminisation
male and female internal organs
functional external male organ
What happens if there is insufficient androgen signaling?
sterile
short vagina
external female genitalia
no internal sex organ
What happens when there is excess androgen hormone?
male: minimal effect
female: masculinisation of sex organ
Differentiate the Mullerian system, the Wolffian system and the primordial external system
Mullerian: development of internal female sex organ
Wolffian: development of internal male sex organs
Primordial: development of external male sex organ
Explain the process of puberty that starts from the hypothalamus to hormone release
hypothalamus →
kisspeptin →
GnRH →
anterior pituitary →
gonadotropic hormone: FSH and LH →
testes/ovaries →
testosterone/estradiol
How can you decrease a male’s sexual behavior?
no testosterone = no sperm production = ↓ ability to have sex
Name the differences between menstrual cycle and estrous cycle
Menstrual:
- primates + human
- menstruation cycle
- sexual activity throughout the cycle
Estrous:
- mammals other than primates
- reabsorb endometrium
- sexual activity only during estrous phase
What is the difference between organizational effects and activational effects of sex hormones?
organizational effects: during the development of the body. permanent
activational: after puberty
Describe the behaviour a birth-castrated rat (no androgen, low testosterone) would have if we inject it progesterone and estradiol in adulthood
female sexual behaviour
What is the female neural circuit for sexual behaviour?
ventromedial nucleus of hypothalamus (VMH)→
periaqueductal gray matter (PAG) →
nucleus paragigantocellularis (nPGi) →
motor neurons → mating behaviour
What are the consequences to a lesion to the VMH?
no sexual behaviour, even if injected with estradiol or progesterone
An electrical stimulation to the VMH or an injection of estradiol/progesterone increases..
sexual behaviour, even in females whose ovaries have been removed
What is the male neural circuit for sexual behaviour?
medial preoptic area (mPOA) →
periaqueductal gray matter (PAG) →
nucleus paragigantocellularis (nPGi) →
motor neurons → mating behaviour
A lesion in the medial preoptic area will result in …
no sexual behaviour
the sexually dimorphic nucleus is located in the …
medial preoptic area
What is the definition of pheromones?
chemical release by one animal that affects behaviour of another animal
What is the Lee-Boot effect?
female mice without male urine present →
slowing down / stopping of estrous cycle
What is the Whitten effect?
female mice with male urine present → synchronisation of cycles
What is Vandenbergh effect?
female mice with male urine present → earlier onset of puberty
What is the bruce effect?
unfamiliar male scent → termination of pregnancy
Which hormone is known to be the “love hormone”?
oxytocin
When are levels of oxytocin and vasopressin more elevated?
during sex, childbirth and breastfeeding
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
b
What is the main difference between pheromones and hormones?
Pheromones released by one animal affect the behaviour of another animal; hormones released by one animal affect the same animal
