hormones and behaviour

Question 1

what causes hunger

Answer 1

leptin ( not hungry) and ghrelin (hungry)

Question 2

where is leptin released from

Answer 2

-specialised fat-storage cells
-the more fat storage cells the more leptin released into blood
-leptin sends signals to hypothalamus for less hunger

Question 3

when is ghrelin released

Answer 3

-if leptin levels are low
-released from stomach for more hunger

Question 4

behavioural endocrinology

Answer 4

-hormones play a big role in development of structure e.g. glands
-hormones can have activation effects e.g. altering neural networks
-hormones underpin timing of reproduction when conditions are most favourable

Question 5

what do internal clocks do

Answer 5

regulate behaviour, all animals have them

Question 6

types of internal clocks

Answer 6

1) very short: locomotion e.g. heartbeat
2) circadian: 24h, resting or foraging
3) circa lunar: 1 month, menstrual cycle
4)circannual: 1 year, migration, reproduction

Question 7

what are clocks essential for

Answer 7

-navigation using sun or stars
-timing of migration
-foraging
-breeding

Question 8

what are the two hypotheses for rhythms

Answer 8

1) environment-independent timing mechanisms
-predicts that animals will continue to have the same rhythms irrespective of the environment
2) environment-dependent timing mechanisms
-predicts individual rhythms can be reset by changes in the environment

Question 9

environment- independent control test

Answer 9

-take away all possible external stimuli (light temp) and keep animals in isolation and in a constant environment
-results: individuals have various forms of rhythms

Question 10

evidence of circannual rhythm in golden-mantled ground squirrel

Answer 10

-used 5 individuals for this experiment
-gave us a good insight on how circannual rhythms work
-constant light and temperature was used
-golden-mantled ground squirrel have a year long circannual rhythm

Question 11

environment-dependent control example

Answer 11

-jetlag resolves itself as internal clock resets itself to new conditions

Question 12

invasive experiments showing how internal clocks work

Answer 12

-x optic nerve- ability to maintain rhythm but inability to change it to new environment (take away info from their eyes)
-x optic lobe- rhythm breaks down (lobe is disconnected and this is key to how the rhythm is maintained)
-no melatonin produced

Question 13

how is the production of melatonin inhibited in humans

Answer 13

sunlight to eye which sends signal to the optic nerve which is received by the optic lobe. signal then sent to pineal gland which inhibits melatonin
-process the same in all animals

Question 14

naked mole rats

Answer 14

-not dependent on anything above ground
-their normal day just consists of foraging
-they have no regular rhythm
-live in colonies underground for their whole life
-feed on roots
-similar to honey bees as they have a queen who does all the reproducing

Question 15

what’s endocrine action

Answer 15

hormones secrete into the blood

Question 16

whats paracrine action

Answer 16

hormones diffuse across cells

Question 17

why is migration an example of importance of clocks and hormones: fat deposition

Answer 17

feed a lot and all food turns into fat for winter periods when they migrate

Question 18

why is hibernation an example of importance of clocks and hormones: fat deposition

Answer 18

animals can stop themselves up with food for autumn months so they can survive hibernation- this is a behavioural change as more food is being eaten

Question 19

importance of clocks and hormones: reproduction

Answer 19

-prolactin can influence individuals by making them more parental
-without progesterone the body can’t maintain pregnancy as the progesterone levels drop before giving birth to tell body that the body doesn’t want to be pregnant anymore

Question 20

importance of clocks and hormones: infanticide

Answer 20

-crocodiles: birth offspring and they stop eating as they don’t want to eat its offspring- this is due to prolactin
-mouses: male mouses are aggressive to mice pups but turn parental after sex but after 7 weeks turns back aggressive as it kills any pups that aren’t his- due to female insemination of someone else

Question 21

motivation to mate controlled by hormones

Answer 21

-in mammals and birds
-in female Rhesus monkeys motivation to mate is greatest at point in her esters cycle when the hormone oestrogen peaks
-mating isn’t a physiological balance like hunger
-hormonal drives are always present- need to be switched off

Question 22

sex peptides in drosphillia

Answer 22

-after copulation, egg laying rate increases and sexual receptivity of females declines
-advantageous for female to mate with more than one male
-males might not be the father hence why they don’t mate as much
-sex peptides cause behavioural changes which are transferred with sperm during insemination- detected by sensory neurones in uterus

Question 23

effects of copulation in green anole- anolis carolinensis

Answer 23

-red chin is their way of showing courtship behaviour
-mechanical stimulation of females genital tract during copulation stimulates production of prostaglandin (becomes abundant in females blood streams)