Chapter 7 Nutrition and Metabolism

Nutrients Nutrients: Those molecules and minerals required by the body from the outside world besides O 2 and H 2 O –Minerals: Ca ++, Fe ++, Na +, Cl - Mg ++, K +, I - etc. –Vitamins –Amino acids: protein –Fats –Sugar: carbohydrates

Metabolism >How the body uses nutrients  The balance between making (anabolism) and breaking down (catabolism) molecules  Energy metabolism

Our cells live in a world of sea water Oxygenated salt water

Minerals Elements that the body picks up and uses for a variety of purposes associated with electrical charge

Electrical Potentials Na +, K +, Cl - most common Requires the constant input of energy to maintain

Calcium Eg: CaCl 2 Water Ca Cl - Balanced in circulation, must be “just right” Stored in the bone An intracellular activator Only selectively allowed inside cells

Iron Fe ++, Fe +++ : very good at moving electron around The body store all it can get in the liver Why your blood is the color of rust

Phosphorus Necessary in circulation, not to much, not to little Some uses –Condensed energy (ATP) A ~P~P~P –DNA A ~P~ T ~P~ G ~P~ C ~P ………. –Turning proteins “on” and “off” Protein (inactive) Protein ~P (active) –Along with Ca the structure of bone

Other Minerals Iodine (I - ): thyroid hormone Zinc (Zn ++ ): Insulin Magnesium (Mg ++ ) Copper (Cu ++ ) Etc Also Drugs: Lithium (Li + ) Bromine (Br - )

Mineral Flow Water soluble

Vitamins Natural Drugs Regulate and facilitate reactions Organic Molecules Two Classes –Water soluble –Fat soluble

Water Soluble B complex : a group of vitamins involved in energy reactions C: A vitamin involved in maintaining tissue integrity Digestion in and kidney out like minerals

Fat Soluble A: Stored in the liver, enters the body through digestion, Important for vision, integrity of the outside barriers, To much is toxic A, D, K, E Not soluble in the water of the blood so the liver must make special proteins to carry them around the body

Fat Soluble cont. D: Stored in the liver. Both enters the body through digestion and made by the skin in response to skin. To much is toxic K: Both enters through digestion and is made by bacteria living in the large intestine. Necessary for blood clotting E: Enters through digestion. Antioxidant

Drug Problems Birth control pills and alcohol increase liver metabolism and decrease absorption of B complex vitamins. Diuretics cause loss of water soluble vitamins Antibiotics can kill the bacteria in the large intestine that make vitamin K

Storage Into storage in times of feast and out of storage in times of famine Feast and famine occur every day…Breakfast Most cells store some sugar for their own use The brain does not store The liver stores sugar for the brain The musculature stores amino acids for the body Fat stores fat for the body

Feast and Famine

Carbohydrates/Sugar The most valuable source of energy because it is the only substrate which can provide some energy with out O 2 …Oxygen debt Only fuel for the brain Full use yield CO 2 and H 2 O Another use is structure and signaling, glycoproteins

Why glucose (sugar) is so important

The liver feeds the brain when you don’t eat for awhile

Proteins/Amino Acids Amino acids can be used for energy C, H, O, N (S) The N is in the form of NH 3 (ammonia) which is toxic The NH 3 is detoxified by the liver (urea) and removed by the kidney Musculature is major amino acid storage

When needed, the proteins that provide muscle strength can be broken down and the amino acid carbon sent to the liver and kidney to synthesize sugar Musculature: amino acid storage

Fat The largest source of stored energy How long you live when subjected to starvation depends on how much fat you have Light weight and insulation Requires O 2 to get any energy Tonic (red) muscles use a lot of fat

Hormones Insulin Glucagon Glucocorticoids Adrenalin Control the storage and removal from storage of sugar, amino acids, and fat

Insulin: The Feast Hormone A protein made by the beta islet cells of the pancreas The signal for release is excess sugar and amino acids in circulation after you eat Almost all cells have receptors for insulin Insulin receptors are proteins in the surface membrane of the cell

Insulin cont. When insulin binds to the insulin receptor on a cell, sugar and amino acid channels are opened and the cell takes these nutrients up The single exception is nerve cells, they can take up nutrients anytime they want All other cells need permission (insulin) to take up nutrients

Glucagon The first stage famine hormone A protein made and released by the alpha islet cells of the pancreas The signal is not enough sugar in circulation Only liver cells have glucagon receptors in their surface membrane Directs liver cells to breakdown glycogen into sugar and release the sugar into circulation

Glucocorticoids The second stage famine hormone The liver can only store enough sugar to feed your brain for hours Depleted sugar in the liver is replaced by making more sugar out of amino acid carbon from the musculature

Glucocorticoids cont. Steroid hormones made by the adrenal gland The signal is adrenocorticotrophic hormone (ACTH) from the pituitary gland The brain directs the pituitary to release ACTH The signal for the brain are many diverse including stress and infection also daily pattern

Glucocorticoids cont. Made from progesterone which is made from cholesterol Shift the muscle into net degradation of proteins Directs the liver to make proteins necessary for sugar and urea synthesis Suppresses the immune system Causes muscle and other tissues to be insulin resistant Mobilizes fat to feed other tissues

Gluconeogenesis

Flow of Substrates

Adrenalin Emergency energy Sympathetic nervous system by way of nerves directs the adrenal gland to release Almost all cells have adrenalin receptors on their surface Acute stress response

Adrenalin cont Does many things related to energy –Directs liver to breakdown glycogen and release sugar –Directs muscle to breakdown glycogen for its own use –Directs fat to release fat –Changes blood flow to direct the delivery to brain, heart, skeletal muscle

Many Drugs influence metabolism Coffee, tea All speeds: nicotine, cocain, Alcohol Etc.