ORGANIC CHEMISTRYCarbohydrates, Proteins and Fats

All forms of energy are not equally capable of doing physiological work.

• We are not capable of using heat to do any form of physiological work…it is wasted energy.

Physiological Work

Examples of Physiological Work

•Synthesis of macromolecules such as proteins, carbohydrates and lipids

•Generation of electrical or chemical gradients

•Muscle Contraction

MAX KLIBER: THE FIRE OF LIFE

•Life is a combustion process•You are using oxygen to burn fuel (food) to create energy (and

waste heat)

OxygenOxygen

HeatHeat

MetabolismMetabolism

YOU CONSUME O2 & FOOD TO PRODUCE ENERGY

Hydrocarbon Fuel + O2 CO2 + H2O

Heat

Combustion in a Pop Bottle Demonstration

EACH “FUEL” DEMONSTRATES A RELATIONSHIP BETWEEN THE AMOUNTS OF: •O2 consumed •ATP produced •CO2 produced

Mechanisms of Energy (ATP) Production

Oxidative Phosphorylation• 5-10 seconds

Anaerobic Respiration• 1-2 minutes

Aerobic Respiration• Conditioning dependent

All 3 major categories of food can be degraded through these processes

CARBOHYDRATE CARBOHYDRATE METABOLISMMETABOLISM

Carbohydrates are present in food in various forms: Simple sugars:

Monosaccharides

Complex chemical units: Dissacharides Polysaccharides

Digestion of Carbohydrates

Carbohydrates Ingested Mechanical Digestion via chewing Broken down into monosaccharides Absorbtion in stomach, duodenum and

proximal jejunum

BLOOD GLUCOSE REGULATIONThe Liver and Pancreas

The Role of the Liver1. Simple sugars enter freely into liver2. Galactose and Fructose are enzymatically converted to

glucose3. Glucose is stored in the liver and only the liver can release

glucose into the blood stream.4. When glucose is readily available it is incorporated into

glycogen for storage via glycogenesis.5. When blood glucose drops glucose can be released from

glycogen via glycogenolysis

Pancreatic Secretions

1. Insulin: lower blood glucose level2. Glucagon: raise blood glucose level3. Epinephrine: raise blood glucose level

CARBOHYDRATES:the major source of energy (ATP)for the body

Monosaccharidea simple sugar with the formula CxH2xOx

Galactose Glucose Fructose

Disaccharide:

2 simple sugars bonded together

The formula for a disaccharide is one oxygen and two hydrogens short of the

1:2:1 ratio because a water is removed in the bonding process.

Sucrose: table sugar Lactose: milk sugar Maltose: grain sugar

Polysaccharidemore than 2 simple sugars bonded

together

Glycogen Starch

Cellulose (can not be digested)

Glucose and the Liver Simple sugars enter the liver and

enzymes convert them to glucose The liver can release its glucose stores

as necessary or absorb blood glucose. Excess blood glucose triggers release of

glycogen which absorbs excess glucose

Carbohydrate DigestionPolysaccharides

Salivary Amylase(mouth)

Pancreatic Amylase

(small intestine)

DisaccharidesLactase

Maltase & Sucrase

(small intestine)

Lactose Maltose Sucrose

Galactose Glucose Fructose

Carbohydrate Facts monosaccharides enter the capillary blood. causes blood sugar to rise triggering the pancreas to

release insulin which is needed to move sugar from blood into cells.

When this process goes fast - as with simple sugars - you're more likely to feel hungry again soon and blood sugar will rise more rapidly or spike.

When it occurs more slowly, as with a whole-grain food, you'll be satisfied longer. These types of complex carbohydrates give you energy over a longer period of time and will cause blood sugar to rise more slowly and evenly.

If you have consumed more carbohydrates than your body needs, the glucose will be turned into glycogen and stored in your muscles and liver for use in the future. When the liver and muscle tissues exceed their capacity for storing glycogen, the excess is converted into fat.

PROTEINlarge complex molecules made up of one or more chains of amino acids held together by peptide bonds

METABOLISM OF PROTEINAmino Acids

Protein Structure: Made up of a combination of about 20

naturally occurring amino acids Joined by Peptide Bonds Carboxyllic acid and an amino group

Role of the Liver: Amino Acids stored in liver, blood stream

and body tissues Amino Acids can be transferred from one

of these locations to another Amino acids are stored by deamination

so that they can be used as an energy source (ATP)

Amino Acids as a Fuel Source Amino acids are only used as a fuel

source during starvation When there is an abundance of amino

acids they are converted into glucose (gluconeogenesis) and fatty acids and glycerol (lipogenesis)

Waste Products of Protein Metabolism Deamination forms ammonia which is

toxic The liver detoxifies ammonia by

converting it into the less toxic, water soluble substance urea.

Hormones and Protein Metabolism Human growth hormone and insulin

increase the uptake of amino acids and protein synthesis in muscle tissue.

Thyroid hormones also regulate protein metabolism

Androgens from the testes and the adrenal gland stimulate protein synthesis.

PEPTIDE BONDSwhen 2 amino acids bond water is removed (dehydration synthesis) leaving a carbon and a nitrogen directly bonded to one another

Types of Protein Dietary Proteins: ingested protein Enzyme Proteins: secretions from GI

tract and other various glands Body Proteins: sloughed off and

disintegrating mucosal layer cells

Amino acids can be converted into glucose by a series of processes.

This happens primarily during starvation.

Amino Acids

Protein

Large Polypeptides

Small Polypeptides

Pepsin (stomach)

Trypsin Chymotrypsin & Carboxypeptidasesecreted by pancreas

(small intestine)

Aminopeptidases Carboxypeptidase

& Dipeptidases(small intestine)

Protein Facts The amino acids are absorbed by the blood capillaries of the

small intestines, carried through the liver, and then go into the blood of the general circulation

Various body cells take what they need to repair and reform the protein structures they need.

Skeletal muscles act as an emergency source of protein if insufficient amounts are eaten. The body can break down its own muscle tissue, and transport the amino acids gathered from that muscle destruction to the more vital organs, if necessary.

People on very low fat diets are by default, on low protein diets. This is because most of the rich sources of protein in foods are also in sources of dietary fat. These dieters lose their muscle mass because their bodies cannibalize their own muscles as a source of the proteins that they need, but are not eating.

The blood contains amino acids at all times. Fasting does not clear them, and a high protein diet does not materially increase them. The body has a constant need for protein amino acids, and it keeps a fairly uniform balance.

LIPIDSfats and fatlike compounds, characterized by their insolubility in water

METABOLISM OF FATSThe Ultimate Fuel Source

Triglycerides (stored fats): glycerol and 3 fatty acid chains

• There is a carboxylic acid group on the end of each fatty acid chain

• The longer the chain and the smaller number of double bonds, the lower the fluidity state

Fat Chemistry

Fats are the ideal substance for storing energy because per unit weight they occupy less volume and produce more ATP than carbohydrates and protein.

• 60% of the energy requirement of the heart, under basal condition, is derived from fat

Fat as an Energy Source

Glycerol can be liberated by the breakdown of triglycerides(lipolysis) in the liver and fat cells.

• Glycerol molecules can be recombined to form glucose through glycogenesis (reverse glycolysis)

• Fatty acids can also be converted into some amino acids and are then used to make proteins.

The Role of the Liver

FATS LIPID MOLECULES COMPOSED OF:

•Glycerol: 3 carbon skeleton with 3 alcohol groups

•3 fatty acids: carbon skeleton with a carboxylic acid group on one end

PHOSPHOLIPID

contains a glycerol and fatty acids like a fat molecule but the 3rd fatty acid is replaced by a phosphate group

SATURATED FATTY ACIDcontains a carbon skeleton with no double bonds

Unsaturated Fatty Acid contains a carbon skeleton with at least

one double bond

Bonding of lipids is a dehydration synthesis reaction

Glycerol liberated by the breakdown of lipids can be recombined to form glucose.

Unemulsified Fats

Bile Saltsproduced by the liver

Pancreatic Lipase (small intestine)

Monoglycerides Glycerol & Fatty Acids