metabolism—how do we obtain energy from foods? susan algert, ph.d., r.d
TRANSCRIPT
![Page 1: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/1.jpg)
Metabolism—How do we obtain energy from foods?
Susan Algert, Ph.D., R.D.
![Page 2: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/2.jpg)
Metabolism
• Human body releases energy from chemical bonds in nutrients the body uses for fuel.
• As bonds break they release energy
• During metabolism, energy, water and carbon dioxide are released
![Page 3: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/3.jpg)
Energy yielding nutrients
• From carbohydrates—glucose
• From lipids (trigylcerides)—glycerol and fatty acids
• From proteins—amino acids
![Page 4: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/4.jpg)
The Cell
• Cells are work centers of metabolism
• Cells have similar structures
• Two basic parts—nucleus and cytoplasm
• Mitochondria are power generators that contain energy generating pathways
![Page 5: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/5.jpg)
Breaking down glucose for energy--aerobic
• 6-C glucose split in half making two 3-Carbon compounds
• Glycolysis means glucose splitting• -Carbon compounds become 2
pyruvates• Pyruvates will break down further to
form ATP and heat
![Page 6: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/6.jpg)
Glucose retrieval via the Cori cycle--anaerobic
• When less oxygen is available, pyruvate is converted to lactic acid
• Liver can convert lactic acid to glucose in a recycling process
• Pathway is muscle glycogen to glucose to pyruvate to lactic acid ( in liver) to glucose to glycogen
![Page 7: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/7.jpg)
Pyruvate to Acetyl Co-A
• Irreversible step
• Aerobic
• Acetyl Co A to Carbon Dioxide via the TCA cycle
Electron Transport Chain
• Acetyl Co-A to fat
![Page 8: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/8.jpg)
Pyruvate is pivotal
• ATP levels are low—metabolic pathways flow toward the production of ATP
• Depending on O-2; ATP routes pyruvate to acetyl Co-A or lactate
• ATP is abundant; pyruvate converted to oxaloacetate or amino acid alanine; oxaloacetate converted to glucose and then glycogen
![Page 9: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/9.jpg)
Acetyl Co-A at the crossroads
• Breakdown pathways for glucose, fatty acids and some amino acids converge at acetyl-CoA.
• Acetyl Co-A cannot return to pyruvate, but enters energy making pathways
• Acetyl Co-A can also make ketone bodies and fatty acids
![Page 10: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/10.jpg)
Glycerol and fatty acids
• Glycerol to pyruvate
• Fatty acids to Acetyl Co-A
Beta oxidation
• Glucose not retrievable from fatty acids
• Breakdown of acetyl-Co-A
• Fat burns in flame of carbohydrate
![Page 11: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/11.jpg)
When a person draws on stores
• Fat used to fuel brain
• Acetyl Co-A fragments from fatty acids combine to produce ketone bodies
• Ketone bodies can provide some fuel for brain cells
• When ketone bodies contain an acid group they are called keto acids (COOH)
![Page 12: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/12.jpg)
Energy Compounds
• ATP used to power cellular functions
• NADH and FADH-2 carry energy for synthesis of ATP
• NADPH delivers energy for biosynthesis
![Page 13: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/13.jpg)
Amino Acid Catabolism
• Amino acids are deaminated and enter TCA cycle
• Amino acids used to make pyruvate can make glucose
• Amino acids that make Acetyl Co-A provide energy or body fat but not glucose
![Page 14: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/14.jpg)
Energy retrievable from amino acids-
• Glucogenic amino acids- a.a. broken down into pyruvate or intermediate of the TCA cycle; gluconeogenesis
• Ketogenic amino acids—an a.a.a broken down into acetyl CoA which can be converted into ketone bodies
![Page 15: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/15.jpg)
Transamination
• Transfer of amino group from one amino acid to a keto acid, producing a new non essential amino acid and a keto acid
![Page 16: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/16.jpg)
Electron Transport Chain
• Series of proteins that serve as electron carriers
• Mounted in sequence on membrane inside mitochondria
• Carriers receive electrons, it passes electrons and gives up energy until end when any usable energy has captured body’s ATP molecules
![Page 17: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/17.jpg)
TCA and ETC
• Body’s most efficient means of capturing the energy from nutrients and transferring it into the bonds of ATP
• Last step of ETC low energy electrons with H atoms combine with O2 from the lungs to make H2O
![Page 18: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/18.jpg)
Which fuels can make glucose
• Parts of protein and fat that can make pyruvate can provide glucose; parts that make acetyl Co A cannot, but provide fat
• Glucose is needed to fuel CNS and red blood cells
• If there is not enough glucose the body will break down protein
![Page 19: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/19.jpg)
Making glucose on low Carb diets
• Fat delivers mostly acetyl, so that you need to break down protein tissue to make glucose
• High protein diets make your body convert protein to glucose and convert ammonia to urea in the liver
• Urea is excreted via the kidneys• Water is needed to excrete urea
![Page 20: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/20.jpg)
Energy yielding nutrients-fat provides most kcals per gram
• Nearly all bonds in a fatty acid are between carbons and hydrogens
• Oxygen can be added to all of them (making CO2 and H2O)
• Energy in bonds is released as they are oxidized
• Glucose has less potential for oxidation as oxygen is already bonded to each C
![Page 21: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/21.jpg)
Feasting
• Surplus protein—Deaminate and convert to acetyl Co-A and fat
• Surplus carbohydrate--Glycogen
• Surplus fat--Lipogenesis
![Page 22: Metabolism—How do we obtain energy from foods? Susan Algert, Ph.D., R.D](https://reader030.vdocuments.us/reader030/viewer/2022032606/56649e885503460f94b8d5ca/html5/thumbnails/22.jpg)