L3 Fat and Protein Metabolism

Question 1

How do we optimize movement as a PT?

Answer 1

to have optimal movement, a person must have adequate oxygen and fuel sources supplied to their muscles

PT should recognize this as a prerequisite to optimal movement

Question 2

What are the limiting factors in any cell’s ability to produce energy?

Answer 2

1. Availability of O2 to breakdown fuel
2. Availability of appropriate fuel/energy stores

Question 3

What determines any cell’s availability of oxygen?

Answer 3

Blood supply to the cell
Amount of O2 in the blood
Oxygen uptake from lungs
Oxygen partial pressure in environment

Question 4

What energy stores are available in the body?

Answer 4

ATP (limited stores)
Creatine phosphate (muscle)
Glucose (not stored)
Glycogen (liver, muscle)
Protein (not used as energy)
Fat (limitless supply)

Question 5

Creatine Phosphate

Answer 5

Considered high energy phosphate intramuscular reservoir
4-6x greater concentration than ATP

CP –> C + P + energy, ADP + P + energy –> ATP

Question 6

What activities rely exclusively on ATP and CP?

Answer 6

Short duration, high intensity exercise
Brief bursts of max power output

Question 7

Normal fasting blood concentration

Answer 7

70-99 mg/dl

Question 8

Glycogen stores

Answer 8

1. Hepatocytes, highest concentration per cell. 90-100 g total
2. Skeletal muscle cells, lower concentration, total exceeds liver @ 325 g
3. Very small amounts in kidney

Question 9

Glycogen catabolism

Answer 9

requires several enzymes, results in glucose-6-phosphate

GSP can be broken down to pyruvate in glycolysis

ONLY liver (and some kidney) can produce free glucose from glycogen

Question 10

Glycogen anabolism

Answer 10

condensation reaction
occurs when there is enough energy in the cell, so PFK activity decreases, which slows glycolysis.

Question 11

Functions of Fat

Answer 11

adipocytes either synthesize or catabolize triglycerides

Endocrine organ

Adipocytes release adipokines that act on brain, muscle, liver

Question 12

Obesity and adipokines

Answer 12

increased leptin
decreased adiponectin
increased resistin

Question 13

Leptin

Answer 13

suppresses hunger, increases energy metabolism, improves insulin sensitivity, regulates puberty/reproduction, promotes anti-inflammatory effects in CV system

Question 14

Adiponectin

Answer 14

released from subcutaneous fat
strong anti-inflammatory effect in vasculature, sensitizes tissue to insulin

ultimately increases fatty acid oxidation and glucose uptake into skeletal muscles

Question 15

Resistin

Answer 15

stimulates inflammation and impairs vascular relaxation

Question 16

Obesity and leptin

Answer 16

very few obese people have leptin mutations
most obese people produce plenty of leptin, but fail to respond to it.
Obesity is usually due to leptin resistance

Question 17

Adipokines promote a state of _____ _______ in obesity

Answer 17

chronic inflammation

Question 18

Lipid Catabolism (Big steps)

Answer 18

Lipolysis
FFA transport
Beta oxidation

Question 19

Lipolysis

Answer 19

breakdown of triglycerides into glycerol and free fatty acids, performed by lipases.

Question 20

Lipases

Answer 20

under hormonal control
LIPOLYSIS IS THE ONLY STEP OF FAT BREAKDOWN THAT IS REGULATED

Question 21

What increases lipolysis rate?

Answer 21

epinephrine, cortisol, low level of insulin

Question 22

What decreases lipolysis rate?

Answer 22

normal or high levels of insulin

Question 23

Free fatty acid transport

Answer 23

FFA move from the blood to the cells that need energy

must be transported to the mitochondria where beta oxidation occurs

Question 24

Beta oxidation of FFA Steps

Answer 24

Catabolism of fatty acids
1. Enzymes remove 2 carbon units and their Hs from the acid end of FFA
2. Continues until entire FFA is converted into acetyl CoA, which goes to the Krebs Cycle

Question 25

Beta Oxidation general

Answer 25

1. Occurs inside the mitochondrial matrix 2. FFA are major energy source b/c oxidation yields large amounts of energy 3. due to complexity of chemical reactions, oxidation is slow

Question 26

ATP produced with 1 FFA

Answer 26

146 ATP sooo much more carbon vs glucose

Question 27

What determines the % of your body's energy needs being derived from lipid?

Answer 27

30-80% energy is derived from lipids 1. Nutritional Status 2. Intensity of exercise 3. Duration of exercise 4. Level of fitness 5. Mode of exercise 6. Carb intake before exercise 7. BMR

Question 28

Carbs as metabolic primer

Answer 28

More lipid is mobilized that can be used for energy when carb breakdown is limited happens because carb intake triggers insulin release. Low or absent insulin increases rate of lipolysis more FFA that can be used, ketones are produced

Question 29

Ketone bodies

Answer 29

liver's solution to the accumulation of Acetyl-CoA is to make ketones

Question 30

Ketogenesis

Answer 30

Synthesis of ketone bodies by the liver Insulin deficiency > Increased mobilization of FFA > Increased FFA delivery to liver > increased oxidation of FFA by liver > accelerated production by liver

Question 31

Ketosis

Answer 31

abnormally high level of ketones in blood Ketones can be used as a mechanism of energy generation, like in the brain Ketones are ACIDS

Question 32

Ketoacidosis

Answer 32

can lead to coma and death, body is no longer buffering the acids sweet-smelling breath of person in ketosis is due to acetone

Question 33

Epilepsy

Answer 33

some cases can improve on a ketogenic diet

Question 34

Lipid utilization ______ with ______ exercise INTENSITY

Answer 34

decreases increasing mostly endurance exercises are going to use lipids as energy source

Question 35

Lipid utilization _______ with ________ exercise DURATION

Answer 35

increases increasing

Question 36

Conditions that will increase lipid utilization

Answer 36

Fasted moderate intense exercise long duration of exercise fit individuals running (vs cycling) decreased carb intake before exercise

Question 37

Lipogenesis

Answer 37

Fat anabolism once fatty acids are formed, triglyceride is made by linking that fatty acid chain to glycerol occurs in the cytosol of fat and liver cells formation of FFA requires 8 ATP

Question 38

Protein Catabolism

Answer 38

Protein is not generally considered a major energy source Critical in maintaining blood glucose levels during starvation, prolonged intense exercise before protein can be used for energy, nitrogen has to be removed

Question 39

Protein and amino acid catabolism steps

Answer 39

1. Proteases break peptide bonds between AA 2. Amino acids can be catabolized to provide ATP or intermediates for fat and carb synthesis after nitrogen removal

Question 40

How does the body remove nitrogen from AAs?

Answer 40

1. Oxidative deamination 2. Transamination

Question 41

Oxidative deamination

Answer 41

amino group gives rise to ammonia and is replaced by oxygen to form a keto acid (kreb cycle intermediate) catabolic process

Question 42

Transamination

Answer 42

amino group is transferred from one amino acid to a keto acid to form another/different amino acid anabolic process

Question 43

Ammonia

Answer 43

produced with oxidative deamination gas that passes through cell membranes into the blood can be highly toxic if it accumulates Urea is produced to negate accumulation

Question 44

Urea

Answer 44

Liver MAKES urea Kidneys EXCRETE urea major nitrogenous waste product of protein catabolism and is excreted into urine 2NH3 + CO2 = urea

Question 45

How and why is urea clinically measured?

Answer 45

in a test called blood urea nitrogen. Should be between 6-25 mg/dL increased urea is toxic and can cause cognitive problems. High urea is much more common than low urea

Question 46

Reasons for increased BUN

Answer 46

high protein intake kidney dysfunction excessive protein breakdown

Question 47

Reasons for decreased BUN

Answer 47

Liver failure, causes accumulation of ammonia malnutrition

Question 48

How does the body actually make the nonessential amino acids?

Answer 48

from carbohydrates/ketoacids and other amino acids via transamination reason behind why calorimeter value is higher than the actual kcals protein provides

Question 49

Amino acids come from...

Answer 49

1. ingested proteins 2. synthesis of nonessential amino acids via transamination 3. continuous catabolism of our own body protein

Question 50

Healthy adults and nitrogen

Answer 50

Healthy individuals are in nitrogen balance, so amount of nitrogen ingested is equal to the amount of nitrogen excreted individuals that are healing from injury, surgery, illness need more protein than athletes

Question 51

Negative nitrogen balance

Answer 51

not enough protein severe injury or illness wasting

Question 52

Positive nitrogen balance

Answer 52

kids in growth spurts

Question 53

What group LACKS protein intake?

Answer 53

elderly women

Question 54

Protein intake in athletes

Answer 54

primary nutritional problem with most athletes is ingesting excessive protein and not enough carbs in trained athletes, excessive protein intake isn't helpful, but can cause renal failure. those in weight restricting sports may lack protein intake

Question 55

Gluconeogenesis

Answer 55

biosynthesis of new glucose from intermediates derived from other fuel molecules, not from glucose occurs in the liver it is ABSOLUTELY CRITICAL to maintain normal blood glucose levels

Question 56

Substrates for gluconeogenesis

Answer 56

Lactate via cori cycle Pyruvate (major input!!) Glycerol Amino Acids

Question 57

"detours" in glycolysis

Answer 57

used for liver cells to produce pyruvate or lactate when it lacks it only possible in gluconeogenic cells that have necessary enzymes (like liver cells)

Question 58

Gluconeogensis from glycerol

Answer 58

only the glycerol backbone of lipids can be used FFA canot b/c carbons are lost as CO2