BZ 300 1nd Edition Lecture 5Outline of Last Lecture HomeostasisDrive TheoryBehavior regulationDisplacement BehaviorRedirected BehaviorSelf Directed BehaviorBiological Rhythms DefinitionsProperties of Biological RhythmsTypes of Biological RhythmsEvidenceOutline of Current Lecture Chapter 4. HomeostasisCircadian Rhythms continued…ZeitgebernPacemakersSCN (Suprachiasmatic nuclei)Pineal gland Molecular basisSignificance of rhythmsPhysiological RegulationFeedingSatietyInsulin control systemFat storagePainTypes of painSharpInflammationCyclooxygenase enzymes (COX ensiymes)Opioid receptors Demonstration of pain sensation in animalsFear Time budgets Ethograms These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.LearningIntergenerational predictability Learning curve MemoryShort-term memory Longer term memory Long-lasting memoryCurrent LectureHomeostasisCircadian Rhythms continued… Zeitgebern- is the time giver. Zeitgeber allows the internal clock to be synchronized with external environment signals.Light/dark cycles are directly affiliated with the zeitgeber, may not need the entire cycle to keep the rhythm, a pulse could suffice. Why does light regulate the clock? It is Constant, predictable everyday, great indicator of where you are in terms of rhythm. The pacemakers allow an animal to free run the rhythm and maintain normal rhythms without the time giver.Ex. If you take the head off of a cockroach you lose the internal rhythm, but if you transplant theoptic lobes you can transplant the daily rhythm into the recipient. The pacemaker for cockroaches are in the optic lobes, and it takes about four weeks for the rhythm to resume normality.Ex. Sea hares- if you remove eyes optic nerves and cultivate them in the darkness they emit a steady signal that give a steady rhythm. Examples of genetic basis for rhythmsSCN (suprachiasmatic nuclei) in vertebrates there is a direct connection from the retina to the hypothalamus, known as SCN. If you cut the connection between the retina and hypothalamus, the rhythm will be lost. These SCN areas are essential for circadian rhythms in mammals.They govern sleep wake cycle, rhythms of hormones, feeding. However they do not govern every cycles, the temperature cycle remains intact if SCN is removed. Pineal gland is light sensitive. The skin is thin enough over it to receive light, making it a third eye. Produces melatonin, (cure for jet lag).If pineal gland is removed and hamsters are given melatonin it will basically mimic a short day, in terms of the rhythm. Pineal gland may be related to reproductive cycles in some way. Molecular basis: Circadian rhythms are an underlying mechanism that is the same across all organisms. Circadian rhythms are the daily build up of phosphorylated protein under positive feedback until it gets to a threshold. Then a negative feedback is signaled until the protein is degraded and then the pattern begins again. This pattern is the molecular formula and basis for circadian rhythms.Significance of rhythms. At certain times of day, an organism will be more or less successful on visual things. Rhythms regulate the time when organisms will be most successful. Ecological: rhythms have a cue for environmental variables.For terrestial isopods, the same conditions in evening that would promote activity, could inhibit activity during the day to help protect the creature. This is because terrestial isopods are crustaceans, and by inhibiting the activity during the day it reduces the risk of drying out. Predictability in rhythms are important. This can be influenced by human behavior in the sense that we have a need to find reasons/ patterns. Ability to anticipate predictable change is selected for and favored under most conditions. Hence why rhythms have evolved so readily with evolution.What favored the switch to diurnality, the evolution in primates? less competition, longer time to find them, shift in times when resources are used, partition resources. Avoid many things if you shift activity time. Good vision and a diurnal lifestyle could have favored a rhythm to a primate. The bigger you get, the more predators you escape? All of these ideas may have worked together to favor the use of night and use of day in primates. Ex. Honeybee foraging: within hives bees are active 24/7, as bees age and older bees leave the hive to forage, they leave the hive. This is a diurnal activity. Bees change rhythm with age to have a diurnal activity versus 24/7 activity.Applications, Annual rhythms, built on circadian rhythmsAnimals begin to prepare quite early for hibernation with burrows, extending hours, food, migration-Migratory birds will anticipate migratory season with help of biological clocks. There are many practical aspects to rhythms, all sorts of everyday behavior happen rhythmically. The primary importance of rhythm is that it allows a sense of intuition of behavior that is going on in the environment. Physiological Regulation: Sleep- conserves energy, deactivation, brain and memory repair. Has some very important benefits. Animals sleep cycles may be coordinated with risky times by predators. Other behaviors mitigate risk associated with sleep to increase awareness of what is going on with in environment while they sleep, i.e., birds sleeping at the end of a perch or in a herd.High levels of melatonin with the pineal gland associated with drowsiness, regulates sleep. Three interrelated mechanisms control feeding. They ultimately influence the control of food intake. Gives you a basis of how it is regulated on physiological basis not simply mentally. Satiety is the sense of fullness after eating; they do not get the sense of fullness after eating leading to overeating. Carbohydrate intake increases seratonin and reduce feeding behavior, butdoes not happen right away and can easily overshoot satiety. In insects there are stretch receptors and if those are cut, it will feed until it literally explodes because there is no feedback and regulation.Insulin control system- seen across taxa in all animals. Regulates blood sugar and is secreted in response to high blood sugar, are the hormones of glucose storage. When working, you get normal levels of blood sugar and signals when to consume sugar or not.Fat storage- essential for egg production, migration and hibration, live on fat storage. Regulationof appetite through satiety control