Zoology 101: Animal Biology Last Lecture Outline Lecture 25 1. Conduction of action potentials2. SynapsesCurrent lecture 1. Brain and the effect of Sleep2. Movie notes Brain and the effect of sleep• Brain stem: critical for function ◦ midbrain: pons, medulla oblengota ◦ Evolutionary conserved; same across species due to similar heart beat, breathing, digestion and sleep functions • Reticular formation controls arousal and sleep by filtering sensory information◦ input from touch, pain temperature, and nerves from ears • Sleep is essential- active process◦ Maintenance, repair, resortation▪ genes important for neuron maintenance are expressed in sleep in birds and rodents (Model organisms)◦ Learning and memory consolidation ▪ helps memories stick, strongest for procedural tasks • Sleep leaves animals vulnerable ◦ aquatic animals must sleep and breathe◦ all animals must avoid predation ◦ unihemisphere sleep: half of brain awake while other half is asleep ▪ recorded by EEG ▪ Low frequency: characterize sleep ▪ high frequency: wakefulness • Impacts blood sugar levels ◦ pancreas affect metabolism: regulating fuel levels ◦ alpha cells: glucagon (peptide hormone)- increases glucose levels ◦ Beta cells: insulin (peptide hormone)- lowers blood glucose leves ◦ Negative feedback: counteracts initial change, primary mechanism of homeostasis ◦ Positive feedback amplifies change ◦ low blood glucose levels → alpha release glucagon and sent to liver, liver breaks it down into glucose and sends it out ◦ High blood glucose → beta release insulin, cells take in more glucose, blood glucose goes down or liver takes it in and stores it ◦ In sleep deprivation, body response to high glucose levels resemble insulin resistance,precursor to diabetes • Diabetes ◦ Body doesn't produce or properly use insulin → high blood sugar ▪ type one: beta cells destroyed by immune system; no insulin made , injection ▪ Type two: need abnormally high levels of insulin, Beta cells can't meet demand, receptors down regulated, linked to obesity• treatment: well balanced diet and exercise • Appetite ◦ leptin is an appetite suppressing hormone produced by fat cells (adipose), more adipose → more leptin in bloodstream ◦ weight loss: decreased adipose, leptin, and energy expenditure while having increased appetite and intake ◦ Weight gain: increased adipose, leptin and energy expenditure, while decreased appetite and food intake ◦ leptin insensitive animals become obese ◦ Lack of sleep leads to decreased leptin levels ◦ Ghrelin: appetite stimulating hormone released by stomach cells ◦ Food deprivation leads to increased ghrelin in bloodstream ▪ Increases our desire for high calorie foods ▪ Combination of increased ghrelin and decreased leptin lead to over eating which leads to obesity Movie notes• Sleep is critical • Rats died after being awake for 24 hours for 5 days • Evolution adapted to sleep• People did 40% worse on memorizing words after no sleep • Sleep enhances memory • 20-30% enhancement after a night of sleep • We don't need to to stay awake to get more done (misconception) • 4 hours a night : cumulative impairment to think quickly, attention and memory at 1st night, each night gets worse, comprehension affected • In driving, we only need 2 seconds to drift off the completely out of a lane → microsleeps happen when we are awake • Famous accidents are associated with sleep deprivation • unconscious of how we are impaired; we have “adapted” ourselves to the lack of sleep • Sleep deprivation causes mood swings • Affects parts of the brain; when showed bad pictures, after a good nights sleep, the amygdala had a normal response. After limited sleep, the amygdala had a very strong response • Psychiatric disorders show similar to sleep deprivation • Prediabetic state after 6 nights of 4 hrs of sleep ◦ Hunger increased ◦ sex drive
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