Ex Phys Chapter 2 Fuel for Exercise: Bioenergetics and Muscle Metabolism

bioenergetics

conversition of substrates to energy that can then be used by that cell and other cells in the body

1 kcal (1000cal) defintion

the amount of heat energy needed ot raise 1 g of water 1 celcius from. 14.5 to 15.5

difference between anabolism and catabolism

anabolism = synthesis of molecules, catabolic = breakdown of molecules

metabolism

all of the chemical reactions in the body

substrates

fuel sources from which we make energy.

-amino acids, glycerol, triglycerol, carbs, fats, proteins

difference between glucose and glycogen

Glucose is the sugar in our bloodstream that our body uses for energy. Glycogen is a stored form of energy.

how many calories are in a gram of carbs? how many kcals can be derived from our glycogen stores?

4.1. 2500 kcal

how many kcals in a gram of fat? how many kcals can be derived from our fat stores?

9.4. 70000+ kcals

fat is stored as a _______ and needs to be broken down into ___________ and _________ which can then be used to produce ATP

triglycerides; free fatty acids and glycerol

glycerol can make some ATP (T/F)

true

rank the types of glycogen storage forms (3)

-muscle glycogen

-liver glycogen

-blood glucose

how many kcals come from protein?

4.1 kcal/g

gluconeogenesis

formation of glucose from noncarbohydrate sources

lipogensis

the process of converting protein into fatty acids

mass action effect

an abundance of one particular fuel can cause cells to rely more on that source than on alternatives

endergonic reactions

require energy to be added. endothermic. anabolic

exothermic

produce energy. exothermic, catabolic

enzymes

catalysts that regulate the speed of reactions by lowering the energy of activation thus speeding up the reaction

what are the 2 factors that effect enzymes?

temperature and pH

rate-limiting enzyme

a particularly important enzyme that is usually located in an early step in the pathway which determines enzyme activity through negative feedback

_____ are used during short, high intensity exercises whereas ____ are used for long duration exercise

carbs, fat

phosphorylation

the addition of a low energy ADP to a phosphate group. requires considerable amount of energy

phosphocreatine

found in muscle tissue; provides a rapid source of high-energy ATP for muscle contraction. donate a phosphate to ADP to form ATP

creatine kinase (CK)

separates the phosphate from PCr which can then be used to produce ATP

the combination of ATP and PCr stores can sustain the muscles energy needs for ___-_____

3-15 seconds

the breakdown of ATP yields how many kcal/mol

7.3

glycogensis

synthesis of glycogen from glucose

glycogenolysis

the breakdown of glycogen down to glucose 1-phosphate which then enters the glycolysis pathway

without the presence of oxygen pyruvic acid turns into _______

lactate

_____ requires ATP to turn into glucose-6-phosphate, whereas _____ does not

glucose, glycogen

how does lactic acid in the blood stream impair physical performance?

-by creating an acidic environment which can impair the glycolytic enzyme function

-decreases the fibers' calcium-binding capacity which impedes muscle contraction

phosphofructokinase (PFK)

rate limiting enzyme in glycolysis. sensitive to ADP and Pi stores. (ie high ADP + Pi stores = increase in PFK activity = sped up glycolysis

how many net ATPs can be produced in glycolysis if we start at glycogen? Glucose?

3 ATP, 2 ATP

where does glycolysis take place?

in the cytoplasm of the cell

where does oxidative production of ATP take place?

mitochondria

reactive oxygen species (ROS)

Toxic byproducts of oxygen metabolism.

why are mitochondria distributed non-uniformly around the outside of the cell?

the optimize high metabolic rates while minimizing risk for increasing ROS production

what does pyruvic acid turn into with the presence of oxygen?

acetyl CoA

for every 1 glucose of molecule that enters the glycolytic pathway, how many pyruvate are formed?

2

what is the rate limiting enzyme in the krebs cycle and how does it work?

isocitrate dehydrogenase and is inhibited by ATP and activity by ADP + Pi

electron transport chain

a group of mitochondrial protein complexes located in the inner mitochondrial membrane that contain a series of enzymes and iron containing proteins that serve as electron magnets that transfer electrons

where do the excess H+ go from glycolysis, the conversion of pyruvic acid to ACh, and the krebs cycle go?

they combine with the coenzymes NAD and FAD to create NADH and FADH2

how many ATPs are yielded per NADH? FADH2

2.5, 1.5

how many ATPs are produced from the complete oxidation of glucose? and from which stage does each amount come from?

33 from glycogen, 32 from glucose:

-3 from glycolytic pathways

-5 from 2 NADH from glycolytic pathways

-5 from 2 NADH from pyruvate to ACh conversion

-15 from 6 NADH from krebs cycle

-3 from 2 FADH2 from krebs cycle

-2 from substrate level-phsophorylation

how many NADH and FADH2 are produced per krebs cycle turn?

3 NADH and 1 FADH2

lipolysis

breakdown of fat (specifically triglycerides into FFA and glycerol

what are the 2 places where fat is stored in the body?

within muscle fibers and in adipose tissue cells called adipocytes

beta-oxidation

the process of converting FFA into acetyl CoA in the mitochondria by chopping 2-carbon acyl units which then become acetyl CoA which then enter the Krebs cycle

what is the common intermediate through which all substrates enter the Krebs cycle for oxidative metabolism

Acetyl CoA

if a FFA originally has 16-chain chain, beta-oxidation yields ____ molecule of acetyl CoA

8

why does the complete combustion of a FFA molecule require more oxygen compared to a glucose molecule

because an FFA molecule contains considerably more carbon molecules compared to a glucose molecule

difference between white and brown fat?

white: lipid storage and breakdown

brown: transfer energy from food directly into heat

oxidation

removing an electron

reduction

addition of an electron

describe how creatine kinase is a negative feedback system?

if ATP levels decrease, CK activity increase

if ATP levels increase, CK activity decreases

glycolysis can occur with or without oxygen (T/F)

true

how much energy does protein provide?

4.1 kcal/g

difference between lactate and lactic acid

similar structure but lactic acid has an additional H+ ion

monocarboxylate transport (MCT) proteins

facilitate the movement of lactate between cells and tissues and likely within cells

what are the outcomes of lactate that produced by glycolysis and within a muscle fiber

-glycolysis: taken up by the mitochondria within the same fiber and directly oxidized

-within a muscle fiber: transported away to an adjacent type I fiber where it can then be oxidized

using lactate as a metabolic fuel accounts for ___ -___ % of lactate removal during exercise

70-75

cori cycle

the process of transporting lactate produced in the muscle to the liver where it is reconverted to pyruvic acid and back to glucose and transported back to the working muscle

what causes runners "hitting the wall"

when around mile 20-22 glycogen stores (~2000-2200 found in the liver and muscle) run out and since the body is not as efficient at converting fat to energy, running pace slows and the runner suffers from fatigue

oxidative capacity of muscle (QO2)

the measure of the muscles maximal capacity to use oxygen which ultimately depends on tis oxidative enzyme concentration, fiber type composition, and oxygen avaialability

what are the 2 most frequently measured aerobic enzymes?

succinate dehydrogenase and citrate synthase

more type ___ fibers in the muscle, the greater the oxidative capacity in said muscle

I

oxidation of fat yields ___-___ more times ATP than glucose

3-4

every round of beta-oxidation yields how many NADH? FADH2

1 + 1

lactic acid occurs in any living cell? (T/F)

false

what factors determine oxidative capacity?

-enzyme activity

-fiber composition

-O2 availability vs O2 need