Biology 212 Anatomy & Physiology I Dr. Thompson Nutrition

Body requires, among many other things: a) Water = b) c) d) e) It must also be able to

Two types of metabolism: Catabolism = e.g. proteins amino acids starch glucose glucose CO 2 + H energy fatty acid CO2 + H20 + energy Occurs: digestive system, inside cells Anabolism = e.g. glucose glycogen fatty acids + glycerol triglycerides amino acids proteins Occurs: inside cells

Body requires, among many other things: a) Water = solvent for all body fluids b) Electrolytes (ions, minerals) for osmotic balance electrical signals c) Vitamins = cofactors for enzyme-catalyzed reactions d) Structural molecules to replace damaged ones e) Fuel molecules to produce energy

Human body consumes 2,000 – 5,000 kilocalories per day and must replace this through fuel molecules in the diet 1 kilocalorie (Kcal) = 1,000 calories 1 calorie = measurement of energy Specifically = amount of heat necessary to increase the temperature of one gram of water by one degree centigrade

Human body consumes 2,000 – 5,000 kilocalories per day and must replace this through fuel molecules in the diet 1 kilocalorie (Kcal) = 1,000 calories 1 calorie = measurement of energy Specifically = amount of heat necessary to increase the temperature of one gram of water by one degree centigrade Just to put things in perspective: 5,000 kcal = amount of energy needed to heat 50 kg (~110 pounds) of water from freezing to boiling

kcal/hour Activity per kg body wt Running – 9 minute mile 5.3 Cross-country skiing 4.4 Jogging 4.2 Racquetball 3.9 Basketball 3.8 Swimming 3.5 Tennis mph 2.7 Hiking 2.5 Walking 2.2 Housecleaning 1.6

Primary sources of fuel molecules in diet: Also possible:

Regardless of type of Complete catabolism results in fuel molecule used:

Most commonly used fuel molecule = glucose First stage One molecule of glucose (C 6 H ) produces 2 molecules pyruvic acid (C 3 H 6 O 2 ) 2 molecules ATP Oxygen not required

Most commonly used fuel molecule = glucose If oxygen IS NOT available,

Most commonly used fuel molecule = glucose If oxygen IS available,

Tricarboxylic acid cycle: Each pyruvic acid molecule gives off one carbon atom, then combines with 3 molecules of oxygen (O 2 ) to produce 3 molecules CO 2 3 molecules H 2 O 18 molecules ATP

Thus: If no oxygen available: If oxygen available:

Carbohydrates such as starch are readily available in diet & Can easily be broken down to form glucose, which is easily absorbed from intestine into blood so

(Excess glucose must be removed from blood and stored) 1.

(Excess glucose must be removed from blood and stored) 2.

Similarly: If enough glucose not available in diet, Other molecules, primarily products of fat catabolism & amino acid catabolism can be converted to glucose molecules through gluconeogenesis and also stored as glycogen; primarily in liver

Glucose not only fuel molecule many cells can use Recall:

Most cases: catabolism of molecules produces no toxic products Occasionally: toxic products can result must be converted to non-toxic molecules and removed For example: 1) 2) 3)

Body requires, among many other things: a) Water = solvent for all body fluids b) Electrolytes (ions, minerals) for osmotic balance electrical signals c) Vitamins = cofactors for enzyme-catalyzed reactions d) Structural molecules to replace damaged ones e) Fuel molecules to produce energy It must also be able to safely get rid of waste products which might be toxic

Recall : Two types of metabolism: Catabolism = breaking larger molecules into smaller ones e.g. proteins amino acids starch glucose glucose CO 2 + H energy fatty acid CO2 + H20 + energy Occurs: digestive system, inside cells Anabolism = building smaller molecules into larger ones e.g. glucose glycogen fatty acids + glycerol triglycerides amino acids proteins Occurs: inside cells

Many macromolecules constantly need replacement through anabolism from smaller molecules, for example: Amino acids Enzymes, Contractile proteins Membrane proteins Monosaccharides Glycoproteins Receptors Fatty acids + glycerol Glycolipids Phospholipids Nucleotides Nucleic acids

Many of these smaller molecules (monomers) recycled from catabolism of larger molecules (polymers) Others must be obtained through diet

Amino acids which can’t be formed from = other amino acids Fatty acids which can’t be formed from = other fatty acids All monosaccharides can be formed from so other monosaccharides Nucleotides can be formed from other so nucleotides & other molecules

Recall: Body requires, among many other things: a) Water = solvent for all body fluids b) Electrolytes (ions, minerals) for osmotic balance electrical signals c) Vitamins = cofactors for enzyme-catalyzed reactions d) Structural molecules to replace damaged ones e) Fuel molecules to produce energy

In addition to fuel molecules and structural molecules, human body constantly losing other molecules such as Water Electrolytes such as Na +, K +, Ca ++, Mg ++, Cl -, PO 4 - Vitamins These must also be replaced through the diet

Metabolism in summary: 1. Fuel molecules, structural molecules, & other molecules must be obtained through diet 2. Within cells: Fuel molecules catabolized to produce ATP Molecules can be interconverted Large structural molecules formed Ions used for many purposes etc. 3. Old molecules broken down Waste products removed