(I) How much heat is needed to melt 26.50 kg of silver thatis initially at 25 C?
Week 11 zoo notes Body equipped to handle traditional, paleo diet Human diet is evolving How are we evolving as a species in this rapidly changing environment Then: Meat, roots, fruit, other, low on vitamin D and calcium, burn calories to hunt and gather, lean periods of little or no food Now: pesticides, growth hormones, antibiotics, high fats, processed, potential toxins, farmed More accessible sugars diabetes and obesity Foods may stress our pancreas = sugar everywhere, insulin production can’t keep up High blood glucose pancreas detects insulin released by beta cells in pancreas fat cells take in glucose from blood achieve normal blood glucose levels Also, glucagon released by alpha cells in pancreas liver releases glucose into blood Blood glucose homeostasis via negative feedback loop Glucose insulin rollercoaster: insulin and glucose rise together, insulin doesn’t go back down until glucose level goes down Too much sugar intake: pancreas has to produce excess amount of insulin and glucagon, becomes tired and stressed, develop type II diabetes (can be reversed) Apply prior knowledge: Organic molecules o Carbohydrates o Fats o Proteins Cell membrane permeability o Lipophilic = hydrophobic = lipid soluble o Lipophobic = hydrophilic = water soluble Hormones and hormone receptors are proteins o Dna RNA Protein 3 forms of stored energy: cellulose, starch, gylcogen Polysaccharides are essentially stored energy Receptors relay information: Transport proteins, enzymes, etc Hormones: slow, lasting, communication Electrical signals: relatively rapid, target single or neighboring cells, target cell determined by contact points Chemical signals: relatively long lasting, can target cells all over the body, targets determined by presence/absence of receptors Both: communicate and respond to info about the environment Pineal gland, thyroid gland, adrenal glands, pancreas Endocrine glands secrete hormones Hormones travel in the bloodstream Alter the metabolism of one or more target cells Hormones interact with target cells, no effect if cell doesn’t have a receptor Genes code for hormones and hormone receptors Repeated exposure to unusually high levels of hormones can lead to desensitizationTarget cells become less responsive (type II diabetes, reversible) (adult onset type I diabetes, nonreversible) (not related to desensitization: type I diabetes, genetic, nonreversible) Hormones are water or lipid soluble: Water soluble hormones: Hormone circulates the bloodstream, hormone binds to receptor protein, second messenger molecule activated and initiates a cell response, usually by activating an enzyme, cells activity changes One hormone can have multiple effects, multiple second messenger molecules, multiple enzymes present in cell Lipid soluble hormones: (steroid hormones) can pass straight through membrane, straight into nucleus where receptor is located, when bound by a hormone, it activates transcription of a gene, leads to production of new proteins (slower response) Part 2: Digestion Ingestion: first encounter of food mouth (teeth and tongue) Types of teeth: incisors, canines, premolars, molars Epiglottis when swallowing, a “trap door” closes that prevents food from entering trachea rather than esophagus When ingesting: food is carried down esophagus with smooth muscle contractions In the stomach Churning: mechanical digestion Enzymes and chemicals chemical digestion Pepsin protein digesting enzyme Other enzymes Hydrochloric acid Mucus Salts Water Digestion and absorption: Villi and microvilli increase surface area of small intestine Blood vessels along small intestine will absorb nutrients and deliver to body Voluntary and involuntary movements Can have some voluntary control over mouth, esophagus, and anus Liver produces bile, which emulsifies fat and breaks down (bile is not a digestive enzyme it’s an acid) Gallbladder storage unit for bile Pancreas produce and release enzymes and bicarbonate Stomach, small intestine produce digestive enzymes Salivary glands in the mouth, begin the chemical breakdown of food Nucleic Acids nitrogenous bases, sugars, phosphates Evolution: intracellular vs extracellular digestion Metabolic rates and size/weight affecting total energy needs Toxins and digestion: Apple seeds contain cyanide, brazil nut is most radioactive food, alcohol is toxic, etc. Liver= hero. Function is to break down toxins into substances the body can handle. Blood flow is directed so that it goes through the liver first, gets detoxified, then is carried out to body. Things the liver cant break down: snake venom, spider venom, etc. these are immune responses Trophic Exchange: Energy “lost” as it increases up the foodweb Biomagnification increases the amount of toxins as it goes up the food chain DDT decreased size of eagle eggs, estrogenated male alligators, so they were reproducing less and population decreased significantly Mercury, methyl mercury neurotoxin, entire planet is polluted with elevated mercury levels some from volcanoes, mostly from power plants and other human sources Mercury methylation biomagnifies up food web, decreases reproductive success, alters behavior in animals,