Hypothalamus and appetite

Question 1

What is the limbic system? What does it coordinate?

Answer 1

Group of brain structure either side of thalamus, under cerebrum
Homeostasis, motivation and emotion

Question 2

What is included in limbic system?

Answer 2

Hypothalamus
Hippocampus
Amygdala 
Olfactory cortex 
More 
NOT forebrain

Question 3

What are the roles of the hypothalamus?

Answer 3

Hormone regulation
Arousal, sleep wake and circadian regulation
Regulation of blood volume and thirst
Regulation of temperature and appetite

Question 4

What is Circadian rhythm?

Answer 4

Release of melatonin from pineal glands in 24 hr cycle

Question 5

What controls Circadian rhythm?

Answer 5

Superchiasmatic nucleus of hypothalamus

Question 6

What influences melatonin release?

Answer 6

Light - as light increases, melatonin decreases

Melatonin = slee hormone

Question 7

Where is drinking controlled in the hypothalamus?

Answer 7

Superoptic nucleus of hypothalamus

Question 8

What is hypocretin?

Answer 8

Hormone (neuropeptide) that regulates arousal, wakefulness and appetite

Question 9

How does the effect of hypocretin (AKA orexin) differ in nocturnal/diurnal animals?

Answer 9

Nocturnal - negative effect from hypocretin

Diurnal - positive effect from hypocretin

Question 10

What is narcolepsy? What causes it?

Answer 10

Lack of hypocretin

Destruction of the cells the produce it

Question 11

Temperature increase should cause a negative feedback loop of thermogenesis to bring T back down. What happens if the body produces a positive feedback loop?

Answer 11

Hyperthermia

Hypothermia

Question 12

What does the hypothalamus do if dehydrated?

Answer 12

Hypothalamus produces ADH

Question 13

What is a neutral energy balance? What happens if this is a positive or negative balance?

Answer 13

Energy input = energy output
Positive - weight gain
Negative - weight loss

Question 14

Give examples of when an energy imbalance might be adaptive

Answer 14

Hibernation
Reproduction
Lactation

Question 15

What is the lipostat theory?

Answer 15

Hypothalamus detects signals from adipose tissue

Influences the hypothalamus to control eating behaviour and activity

Question 16

What is leptin?

Answer 16

Cytokine produced by the obese gene in fat cells

Larger fat cells - more leptin

Question 17

What does leptin act on? What does it do?

Answer 17

Neurones of hypothalamus

Decreases hunger to discourage eating (-ve feedback)

Question 18

What happens if there is a mutation/defect in the ob (obese gene)?

Answer 18

Leptin not produced - doesn’t discourage hypothalamus from eating –> obesity

Question 19

How does leptin decrease feeding behaviour?

Answer 19

Causes production of MSH in neurons (melanocyte stimulating hormone)
MSH binds to neuronal receptors and inhibits feeding behaviour

Question 20

What is the glucose theory?

Answer 20

Hypothalamus has glucose sensing neurones - detect changes in blood glucose and alter food intake

Question 21

Where is feeding regulated?

Answer 21

Hypothalamus (most parts, except superchiasmatica and super optic nuclei)
Brain stem

Question 22

What are endocannabinoids?

Answer 22

Brains natural marijuana - blocking their receptors causes food cravings