Metabolism Chapter 14 The Main Function of Metabolism Metabolism = living cells use nutrients in many chemical reactions that provide energy for vital processes and activity. Homeostasis = a healthy and relatively constant internal environment. To maintain homeostasis, the body regulates its systems to avoid dangerous lacks or excesses. Ex. You breathe to take in oxygen and expel carbon dioxide Normal metabolism helps make homeostasis possible (allow body to maintain or regain an “even keel” The Metabolic Process Chemical balance – just like a car who needs hydrogen and carbon to run our body needs the right balance of nutrients and other substances in our body Oxygen – (like “burning of gasoline that make a engine run) many metabolic processes require oxygen to take place (breathing) Temperature – (a car wont start it it’s temp. is too low) an organism’s body temperature must be within a certain range Removal of waste products – (exhaust system to rid water vapor and carbon monoxide) the waste products of metabolism are water and carbon dioxide, these are carried in the blood to the lungs where you exhale them Energy for Metabolism During metabolism, energy is both used and produced Energy originates from the sun, plants trap energy, humans eat plant they gain nutrients which provide energy for metabolism Of the 6 essential nutrients, protein, carbohydrates and fats supply energy for metabolism Glycogen = the form of carbohydrates stored in the muscles Remaining carbohydrates are converted to fat Protein is use for body mass, excess amounts are converted to fat Catabolism & Anabolism Metabolism is 2 separate process Catabolism = breaking down complex molecules into simpler ones during chemical reactions Anabolism = the combining of molecules during chemical processes in order to build the materials of living tissue Nutrients are broken down into simple material which can enter the cell, which then releases energy Molecules broken down by catabolism are reconstructed into body cells ex. Protein in peanut butter becomes protein in your muscles through anabolic reactions Cytoplasm = colloidal substance consisting of organic and inorganic substances, including proteins and water found in a living cell. This is the main component of both animal and plant cells. • Catabolism breaks down food to make cytoplasm which the body uses for maintenance during anabolic process Catabolism and Anabolism Catabolic Reaction (glycogen breaks down, which releases energy) Glycogen Glucose Anabolic Reaction (glycogen is created, which takes energy) Glucose Glucose Glycogen The ATP Cycle Adenosine Triphosphate = Certain molecules serve as energy warehouse • ATP molecules combine the compound adenosine with 3 phosphate groups, forming a chain A-P-P-P Energy is carried in the bonds between phosphate groups • When a cell needs energy the bond between the two phosphate groups is broken and the third group transfers to another molecule. • With only 2 phosphate groups remaining ATP becomes ADP which will latter turn back to ATP trough using energy to link with another phosphate group reforming ATP Storing Energy – Energy is stored when a third phosphate group bonds to ADP, forming ATP ENERGY P A P P A P P P Using Energy – When a cell needs energy, a phosphate bond in ATP breaks, release energy and produces ADP and separate phosphate group ENERGY A P P P A P P P Chemical Balance during Metabolism The cells in the body are mostly cytoplasm walled in by: Membranes = thin layers of tissue (these are semipermeable) Semipermeable = they allow varying amounts of specific substances to pass through them • The open door policy can lead to a chemical imbalance Osmosis = the movement of fluid through a semipermeable cell membrane to create an equal concentration of solution on both sides Metabolic rate = how fast the chemical processes for metabolism takes place Body Temperature We have mechanisms to keep our body temperature fairly stable • Ex. In a cold room, you shiver to increase body heat In cold-blooded creatures, (lizards) – body temperature is more dependent on environmental temperature. Lizard metabolic rate rises as it lies in the sun – thus the metabolic rate varies more in a given day than a healthy human’s rate Body Size Small animals like a rabbit have more surface area so they lose body heat more quickly, thus their metabolic rate is much higher. • In one minute a mouse breathes 150 times, elephant 6 times and a human 16 times. • In 2005 61% of the US population is considered overweight (I am sure it’s higher now) Physical Development & Age, Body Composition & Energy Supply Scientists believe that cell function rapidly in young individuals for development. Thus, metabolic rate is high, as an adult their metabolism drops to a lower, “maintenance” level Lean tissue (muscle) takes more calories to maintain than other types. Ex. Males who tend to have a greater portion of lean mass generate a higher metabolic rate. When your body sense less food availability, the body stretches the food supply by burning at a slower rate (survival mechanism) Basal Metabolism Basal Metabolism = energy used by a body at rest to maintain automatic, lifesupporting processes. • Regulating heartbeat, breathing and body temperature and a few examples. Basal Metabolic Rate = (BMR) measure of heat given off per time unit Voluntary Activities Voluntary Activities = Conscious and deliberate actions • Sedentary Activity – (reading) burns 80-100 calories per hour • Light Activity - (walking) burns 100-170 calories per hour • Moderate Activity - (brisk walk) burn 170-250 calories per hour • Vigorous Activity – (waxing your car) burns 250-350 calories per hour • Strenuous Activity - (swimming or bicycling) burns 350 + calories per hour TURN TO PAGE 212 – ANSWER QUESTIONS 1 & 2 Weight-Loss Diets To lose weight you shouldn’t starve your body – that can back fire!!! Crash Diet (BAD) • After exhausting its blood sugar and glycogen supplies for energy, the body breaks down its fat and protein deposits. (reduces muscle mass, which is eliminated in our urine and waste) • Ketones start accumulating, upsetting blood chemistry and vital cell functions – condition is acidosis • Hair loss, weakened immune system, to sudden death • Best way to eat is 5-6 small meals a day, which will help your metabolic rate and energy levels. Questions 1. 2. 3. 4. 5. 6. How is metabolism related to homeostasis? Describe an environment in which metabolism can occur. How do humans get energy? How are carbohydrates metabolized? How are anabolism and catabolism related? How is energy transferred from nutrients to the body’s cells? Questions Continued 7. 8. 9. 10. 11. 12. 13. How does a body maintain its supply of ATP? Why is osmosis necessary for metabolism? Why is your metabolic rate different from an alligator’s? How does your metabolic rate compare to small animals? Do you use energy while sleeping? – Explain. How will your body respond if you start skipping meals? How can you prevent lactic acid buildup? Why do these techniques work?