Hormonal Behaviour Flashcards
What hormones are involved with hunger?
Leptin and ghrelin
How are the hormones leptin and ghrelin involved with controlling hunger?
Leptin is released from specialised fat-storage cells. If there are more fat-storage cells, more leptin is released into the blood. The more leptin signals to hypothalamus makes us less hungry
If leptin levels in the blood are low, hypothalamus causes the stomach to release ghrelin. More ghrelin = more hunger
What internal and external clocks essential for?
Using sun and starts to navigate
To time migration, foraging and breeding
What are the two hypotheses for rhythms?
1) Environmental-independant timing mechanisms
2) Environmental-dependent timing mechanisms
What experiment was conducted to test the environmental-independent hypothesis?
Held 5 squirrels for 3.5 years and had them in constant light, temp and had constant available food and water
Still maintained a hibernation pattern
So hibernation/rhythms are mot dependent of the environment in this case
How is melatonin inhibited?
Eye detects sunlight
Signal is sent to the optic nerve
Signal is received by the optic lobe
Signal is sent to the pineal gland
This inhibits melatonin
Do naked mole rats have a circadian rhythm?
No
Have random patterns of being asleep and awake that changes everyday
What are hormones derived from?
Amines e.g. dopamine
Peptides e.g. vasopressin
Protein e.g. insulin
Lipid e.g. sex hormones
Endocrine vs paracrine action? Give general hormone examples e.g. lipid-based hormones
Endocrine = hormones are secreted into blood
Paracrine = hormones diffuse across cells
Protein based hormones are endocrine
Lipid based hormones can be either
What do trophic hormones do? Name some examples
Cause or prevent the release of other hormones
GnRH, FSH, CRH cause the release of others
Dopamine inhibits the release of others
What does decreased progesterone cause?
Increased prolactin
What hormones control the motivation to mate?
Testosterone, oestrogen and progesterone
What happens to females after copulation in Drosophila? Why?
Egg laying rate increases
Sexual receptivity of the female decreases
Due to sex peptide which is transferred with sperm during insemination
How do female anoles become sexually receptive?
They are courted by a male
This causes ovaries to develop and mature
Ovaries produce oestrogen
Oestrogen primes female brain to become sexually receptive
Why do female anoles become unreceptive to male courtship straight after mating?
Mechanical stimulation of a female’s genital tract during copulation stimulates prostaglandin production
