METABOLISM
NUTRITION
Nutrient
substance in food, provides energy, forms new body compnenets, assists in bodily
processes
Nutrients Needed
Carbohydrates
Lipids
Proteins
Vitamins
Minerals
Water
Essential Nutrients
Nutrients we must obtain through our diet, body can not make them
3 fatty acids and 8 amino acids
METABOLISM
All of the chemical reactions that are necessary to maintain life
Two Phases:
Anabolism
building process, small into large, uses energy
Catabolism
breaking down process, large into small, releases energy
CARBOHYDRATE METABOLISM
Glucose Catabolism
Glycolysis - occurs in cytoplasm
C-C-C-C-C-C -----> C-C-C + C-C-C 2ATP + 2NADH
(Pyruvic Acid)
Intermediate Reaction
C-C-C ------->C-C + CoA -----> CO2 + NADH+
(Pyruvate) (Acetyl) (Coenzyme A)
Krebs Cycle - occurs within Matrix of Mitochondrion
• Complete oxidation of Glucose forming 3NADH+, 1FADH+, 2 CO2, 2ATPs
AND rebuilds Oxaloacetic Acid to keep cycle going.
Electron Transport Chain (ETC)
• Occurs along the cirstae of Mitochondrion
• Acceptor Molecules - “Cytochromes”
• O2 used as the final electron acceptor releasing 34 ATPs.
Purpose of Glucose Catabolism??
Release energy for cellular activities
Glucose Anabolism
Glycogenesis
• combining glucose molecules to build Glycogen
Glucose ----------> Glycogen
• occurs in liver and skeletal muscles
Glycogenolysis
• breaking down of glycogen to glucose
Glycogen ------------> Glucose (Glucose Catabolism)
Gluconeogenesis
• “New” sugars produced from non-carbohydrate molecules
Fats/Proteins -----------> Glucose
LIPID METABOLISM
Lipid Catabolism - of Triglycerides
Glycerol---> glyceraldehyde phosphate which enters the Kreb’s Cycle producing
18-19 ATP
3 Fatty Acid Chains - catabolized in liver through Beta Oxidation - broken into
Acetic Acid fragments, these combine with Coenzyme A forming Acetyl CoA ---
>Kreb’s Cycle
Ketones or Ketone Bodies - acetyl CoA in excess, Liver converts it to Ketones,
released into blood, causing Acidosis
Lipid Anabolism = Lipogenesis
Occurs when levels of glucose and ATP are high or when digested fats aren’t used
immediately for energy
Acetyl CoA -----> Fatty Acids
Fatty Acids combine with glycerol to form Triglycerides
PROTEIN METABOLISM
Protein Catabolism
Deamination - removal of amine (NH2) group
The NH2 is converted to NH3 at the Liver, combines with CO2 forming Urea --
>Kidneys
Transamination - the resulting group is converted to a Keto Acid (has O where
amine group was) then converted to 1 of several acids
resulting acid enters Kreb’s Cycle
Protein Anabolism = Protein Synthesis
DNA forms RNA directs placement of Amino Acids to form Protein
Control of Metabolism
Hormonal
What are the major hormones that control Metabolism?
Lagniappe
Cholesterol - not an energy source, a structural component
Bound to Lipoproteins for circulation in blood
HDL - High Density Lipoproteins, transport cholesterol from the peripheral tissues
to Liver to be broken down
LDL - Low Density Lipoproteins, transport cholesterol to peripheral tissues to be
used in membranes, hormones, etc.
Which is worse for you, High HDL or High LDL levels? Why?
Vitamins and Minerals
Vitamin - organic compounds needed in minute amounts for growth and good health
most function as co-enzymes
Two Groups
Fat Soluble
bind with lipids and are absorbed with them most are stored examples - A, D, E,
K
Water Soluble
are absorbed with water from GI tract
examples B complex and C
Minerals - inorganic substances that help regulate body processes
Include: Ca, P, Fe, Cu, I, Na, K, Cl, Mg, S
Basal Metabolic Rate
BMR
rate at which metabolic processes occur when body is at rest
Factors Affecting BMR:
Age
Gender
Hormones
Body Temperature
(See diagram in text of Regulation of Body Temperature)