Chapter 9 : Reproductive behaviour
1. What is a hormone?
Hormone is a chemical that is transported by the blood to a distant site, where it exerts its effects.
Critical for the sexual differentiation of the body and the brain and adult regulation of sexual
2. What controls the release of the hormones involved in reproduction?
The hypothalamus, pituitary gland & gonad.
The hypothalamus produces chemicals that affect the pituitary gland which would in turn affect
the gonad (ovary/testes). Those would in turn release hormones that affect the whole body.
3. Know the pituitary and its hormones.
Posterior pituitary - Adirect connection to the hypothalamus
Anterior pituitary - Connect to the hypothalamus by the hypothalamic-pituitary-portal blood
vessels (HPP). The portal blood vessels then pass from one capillary bag to another without
passing the heart (e.g. liver)
Posterior pituitary Anterior pituitary
Route: 1. The hypothalamus nucleus would reach 1. The hypothalamus nucleus would
threshold and there would have action produce an action potential
2. Chemicals are then release into
2. The action potential would flow to the the blood vessels at the pituitary
axon in the pituitary stalk stalk
3. At the terminal button (neuroendocrine 3. The chemicals would then reach
neuron) would release oxytocin the anterior of the pituitary gland
4. The oxytocin would then enter the general 4. Any cell with the receptor of that
circulation chemical would respond to it
Hormones: Oxytocin 1. ACTH (Adrenocorticotropic
- Important for delivery (in general)
a. Secretion of the adrenal
a. Uterine Contractions
i. Cause menstruation
2. TSH (Thyroid stimulating
b. Milk release (breast milk) a. Controls secretion of the
thyroid i. `Milk ejection reflex 3. Prolactin
ii. Suckling => Stimuli is a. Mammary gland
detected by the b. Important for milk
1. Some of its stimuli stimulates the
2. There would be action potential and
oxytocin is released from the posterior 5. *FSH (follicle-stimulating
pituitary gland to the general circulation
hormones) & LH (luteinizing
3. It would find oxyocin receptors at the
mammary gland Gonadal secretion
4. The gland that makes milk(mammary
gland) would contract, releasing milk
5. Milk would then come out of the nipple
a. Mostly sensory stimuli stimulates
the oxytocin neurons
(Thoughts are able to do so too)
b. Found in uterine muscle & the
a. Constricts blood vessels
b. ADH decreases urine volume
4. Understand the sexual differentiation of the brain and body.
a. Testis / ovaries
2. Internal plumbing
a. Upper third of the vagina, uteries, etc (female)
3. External gentiles
**If what happen to step 3 does not affect step 1 or 2 To become a normal female (a default path)
1) Gonad becomes an ovary (release no hormones until puberty)
2) The müllerian duct develop naturally by itself when nothing happens
3) The wolffian duct dies automatically
To become a normal male:
1. Gonad have to become a testis
a. Signal from SRY (sex determining region Y) protein
2. The wolffian ducts have to stay alive
3. The müllerian duct dies
2 hormnones are made after testis is developed:
i. Keep the wolffian duct alive
2) MIS (mullerian inhibiting substance)/AMH (anti-mullerian hormones)/MIF (mullerian inhibiting
ii. Kills the mullerian ducts
1. Developed long after the internal plumbing develops
2. Sensitive to hormones even after birth
3. Understand the sexual differentiation of the brain and body. 5) What is the relationship between hormones and reproductive behavior in the male rat?
a. The female rat? Men? Women?
Rats involve in sexual behaviour solely to reproduce. If reproduction cannot take place, the rats would not
display sexual behaviour.
Humans are involved in sexual behaviour both to reproduce or for pleasure.
1. What do you think would happen if we took a female, ovariectomized her, and gave her T? Would
she show sexual behaviour?
a. Show robust male sexual behaviour
2. What do you think would happen if we took a male, castrate him, and gave him Estrogen +
Progestrone(both E then P are needed to produce female sexual behaviour but slow to effect)? Would
he show sexual behaviour?
a. Show male typical behaviour
b. Don’t show female sexual behaviour
i. Still speculating the reason