Hypothalamus II

Question 1

Symptoms of jet lag

Answer 1

constipation
mental disturbance
Hunger
Tiredness

Question 2

Name the genes/proteins involved in the cellular clock

Answer 2

Clock (stimulates genes)
BMAL1 (stimulates genes)
PERIOD (inhibits genes)
CRY (negative element)

Question 3

What is the suprachiasmatic nucleus? (SCN)

Answer 3

Paired nuclei that is at the base of the hypothalamus and is the mater clock. Has connections with the paraventricular nucleus.
Receives input from the retinohypothalamic tract and projects to: PVN, ARC (regulates feeding) and LHR (regulate behaviour)

Question 4

Describe the retinohypothalamic pathway

Answer 4

Intrinsic retinoganglion cells become excited via light (meladopsin), sends axons to the SCN, SCn projects to PVN, ARC and LHR which regulates body clock

Question 5

What happens when the SCN is lesioned?

Answer 5

Comes completely arrhythmic

Question 6

Why is the melatonin pathway important?

Answer 6

Melatonin release mediates sleep induction which is regulated by the circadian system and light. Maintains control of 24hr blood glucose levels by modulating the circadian rhythm of glucose stimulated insulin secretion

Question 7

What is the melatonin rhythm pathway?

Answer 7

Retina - SCN - Paraventricular n. - intermediolateral column of the spinal cord - superior cervical ganglion - pineal gland

Light period: light - activates GABAergic SCN - inhibits PVN and thus no melatonin

Dark period: GABA neurons are silent as they have not been activated by light. PVN neurons become activated due to disinhibition and melatonin synthesis and release begins