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Lecture 7

PSYO 2470 Lecture 7: motivation

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Dalhousie University
PSYO 2470
Stamp Jennifer

Lecture 11: Motivation Things that motivate us - Situational dependent - Depends on the person - Lots of people seem to want the same things though o Lots of similar motivations ▪ Ex. Money - Basic motivations o Hunger o Homeostasis ▪ Maintaining internal environment with a narrow physiological range • Body temp o Hypothalamus ▪ Role in homeostasis ▪ Instinct centre • Tells us what to do when we don’t have time to think about it • Unconscious decisions o Three components of neuronal response in hypothalamus to changes in homeostasis ▪ Humoral response • Usually release of hormones from pituitary gland – release of chemicals into blood ▪ Visceromotor response • Neurons of the autonomic nervous system o Conditions that push us towards sympathetic or parasympathetic ▪ Somatic motor response • Guides voluntary behaviour • Seeking out goals of our motivations Dietary energy sources - Lipids o Fats - Amino acids o Get from proteins - Glucose o From carbohydrates - We use energy continuously but eat intermittendtly o Need to have storage mechanisms for energy o Energy balance ▪ Two basic processes: • • Anabolism o Building – building muscle o Intestines are full – energy is absorbed from intestines – lots of nutrients absorption ▪ Directed to various areas • Glycogen stored in the liver – used for glucose o Neurons can only use glucose for energy, no other energy source o All other cells can use multiple types of energy source • Triglycerides – stored as fat • Catabolism o Breaking down o Intestines are empty – body has to rely on what has been stored ▪ Triglycerides converted into fatty acids and ketones ▪ Glycogen broken down to glucose • Switching between catabolism and anabolism depending on energetic needs o Energy balance and body fat ▪ Normal – intake is equal to expenditure ▪ Obesity – intake is greater than expenditure ▪ Starvation – intake is less then expenditure ▪ Set value • Set value for energy requirements o Give an animal a period of starvation, and a period of forced excess feeding ▪ ▪ Once returned to a normal feeding schedule, weight goes back to what appears to be a set value • Set point of energy storage – should be able to find physiological processes that lead to set point ▪ Set point – optimal level of energy storage • Hunger stems from an energy deficit – being away from the set point o Glucostatic theories ▪ Optimal levels of sugar o Lipostatic theories ▪ Have a set point for fat – fat stores, fat in blood – that is optimal • If there is a deficit, we need to eat a meal to bring back to set point • Set point systems need: o A set point mechanism ▪ Need a way for body to know what the set point is o Detector mechanisms ▪ Processes that an detect changes o Effector mechanisms ▪ Need a way to deal with being in a deficiency ▪ Set point theories don’t always work well due to history • Ancestors didn’t have access to food like we do ▪ Lipostatic hypothesis • Ob/ob mice o Gene knock-out – lack gene that codes for protein called leptin o Doesn’t have a copy of the ob gene ▪ Mutant mice gain a lot of weight – thought ob gene had to do with feeling full/satiety • Parabiosis experiment • Fusing animals together – animals share a blood stream o Fuse together an ob/ob mouse with normal mice ▪ Ob/ob mice saw decrease obesity • Leptin o Protein that regulates body mass
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