PSY 358 Lecture Notes - Lecture 7: Anterior Pituitary, Hypothalamus, Hydrogen Peroxide
9 Apr 2019
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Rhythms, Development, and Aging: hypothalamic methods
Rhythms
• Circadian (sleep) rhythms
• Ultradian: within the day
o Hormones
• Infradian rhythms
• Lunar rhythms
• Annual rhythms
o Seasons, moods
Circadian Rhythm
• 24 hours and 10 mins: rhythm if one was free running
o Free running: internal clock
• Entrained rhythm: tells you time of day (24-hour cycle)
• Zeitgeber: things that require training
o Something that entrains you
o Most common: hours of sunlight (melatonin)
o Peripheral oscillators
▪ Ghrelin production
▪ In muscles
▪ Production of urine
• With light and other zeitgebers→ 24 hours
• Can someone live on a 25-hour daily cycle?
o Yes, but difficult. Must be though about because it is changing rhythms in the body
• Cortisol is a zeitgeber
o Cortisol rises until about noon and falls throughout the day
o Peaks throughout the afternoon are opportunities for attention to be stronger; more
chances to refocus
o Naps are good for cortisol peaks during the day
• Melatonin is important for telling the type of year
• Annual rhythms are not as effective as they used to be
o Synthetic light
• Seasonal variation in what disorders/ diseases people develop
o Schizophrenia is mostly developed in winter babies
• Phrenology: study of biological processes based on the environment
o Important in studying climate change
Zeitgebers: Free-running human experiments of sleep
• Chronobiology: Study of time
o Chronotype: morning or evening people
o Original studies go back to 1904
▪ Define people by what hours of day they are most comfortable
▪ Genetic differences (in proteins called clock genes)
• Daytime zeitgebers: light
o Other types: social, eating,
Circadian Rhythms
• Superchiasmatic nucleus: contains rhythms even if it is not getting information from any brain
region. It is a pace maker
• Entrained by getting light from retinal ganglion cells
o Light is processed lastly by ganglion cells
o 2% have melonoxin: light reacting protein. Sends messages to superchiasmatic nucleus
about how much light there is
▪ Not rods or cones. Part of processing of optic track
▪ Everyone has these rhythms (even blind)
• Clock cell: found in genetically bread animal that did not have rhythm
o Animals that don’t have rhythms have a mutation in the protein
• BMAL-1
• Clock and BMAL build in nucleus→ develop PER and CRY→ come in to cytoplasm and bind in to
a single unit→ go back to nucleus and decrease its production
o Negative feedback loop
o Go up and down for 24 hours and 10 mins
o PER: period
o CRY:
o As PER and CRY go up→ gets dark
▪ Green light
o As PER and CRY go down→ gets light
▪ Blue light
Vasoactive Intestinal peptide: VIP (in hypothalamus)
-Light, serotonin, orexi
• SCN (factors release VIP through process of clock or Bmal1)→ release PER and CRY→ increase
VIP in clock cell→ message sent to pineal gland (NPY: related to melatonin. Causes activation of
NAT: synthesizes serotonin to melatonin → release melatonin
• Pineal gland has the most blood flow
• Causes activation and stimulation of neurons that release neuropeptide Y
• Pineal cell
o NPY→ melatonin
• Clock cell→ PER and CRY→ VIP→ NPY → melatonin
• Orexin: plays a role in appetite and sleep
Pinelocytes: no blood brain barrier
• NPY turns on Serotonin
• Melatonin first described in 1917 in pineal extracts
• Effect on darkening skin in frogs
