Macronutrients- Exam 1

Key themes

One: All cells need a constant supply of ATP

Two: Blood glucose levels must remain relatively constant

Three: Must spare body protein

Four: Metabolic flexibility

Randle cycle

The use of one macronutrient inhibits the use of another

Fatty acid oxidation inhibits

pyruvate dehydrogenase

Requirements for Survival

One: Must synthesize compounds that are not found in diet

Two: Protect from toxins and changing environments

How to meet requirements for survival

One: Fuel oxidation pathways

Two: Fuel storage and mobilization

Three: biosynthesis

Four: Detoxification and waste disposal

Mechanism for Fuel → Reduced Co enzyme

Oxidation

Mechanism for reduced coenzyme → ATP

ETC

Fuel oxidation pathways require

oxygen

In the fed state, excess fuels go to

storage

In the fasted state, fuel storage is

oxidized and becomes ATP

Adipose fuel storage

TAG

Muscle and liver fuel storage

glycogen

Energy Requirements are a cumulation of

basic functions and physical activity

ATP cycle

ATP → Energy utilization → ADP → energy production → ATP

Energy production in ATP cycle

macronutrients, O2 make ATP and release water and heat

Energy utilization in ATP cycle

uses one Pi from ATP and is used to support body functions

Ways ATP is used

Sodium potassium pumps

biosynthesis

detoxification

muscle contraction

thermogenesis

As concentration of ADP increases…

oxidation of fuels increases

Major carbohydrates

starch, sucrose, lactose, fructose, glucose

Proteins are a source of

nitrogen

There are ____ essential amino acids

9

Triglycerides are made of

a glycerol and three fatty acids

Triglycerides are a good form of fuel storage because

they have high energy with a low weight burden

Fat utilization in liver

gluconeogenesis

Storage of glycogen

liver and msucle

Glycogen storage in the muscles is used for

energy during exercise

Glycogen storage in liver is used for

maintaining blood glucose

Daily expenditure

One: Basal metabolic rate

Two: Physical activity

Three: thermic effect of food

Factors that may effeect resting metabolic rate

gender, age, body temperature, environmental temperature, thyroid status, pregnancy

Fatty acid requirements

omega 3 and omega 6 (alpha linoleic)

Protein requirements

0.8 gram per day/ kg of body weight

Positive nitrogen balance

nitrogen in is higher than nitrogen out

Stage where nitrogen balance is positive

childhood, growth, pregnancy

Stage where nitrogen balance is zero

healthy adult

Nitrogen balance

Nitrogen in and nitrogen out are equal

Stage where nitrogen balance is negative

Nutrient deficiency, catabolic stress

Negative nitrogen balance

Nitrogen in is less than nitrogen out

What occurs during the fed state

digestion and absorption

Fate of glucose in fed state

One: Ox for energy

Two: Used to synthesize other compounds

Three: Stored as glycogen or TAG

Fate of amino acids in fed state

One: Energy source

Two: Protein synthesis

Three” Synthesis of nitrogen containing compounds

Fate of fats in fed state

One: Stored as TAG

Two: Synthesize membrane lipids

Three: oxidized for energy

Carbohydrates are absorbed as

monosaccharides

Carbohydrates go directly to

the blood stream

Major enzyme for breaking down carbohydrates

pancreatic amylase

Raising insulin lowers

glucagon

Fate of glucose in the liver (fed)

One: stored as liver glycogen

Two: used in glycolysis

Three: Converted to triglycerides for energy

Glucose to the brain (fed)

Oxidized for energy

Glucose in RBC (fed)

Oxidized for energy anaerobically

Glucose in muscles (fed)

One: oxidized for energy

Two: Stored as muscle glycogen

All tissues take up glucose in the

fed state

Fate of fat in the fed state

One: Triglycerides in the SI are broken down by pancreatic lipase and absorbed and transported via chylomicrons

Two: Fatty acids go to adipose tissue where glycerol from the liver comes to make triglycerides to be stored in adipose tissue

Three: glycerol returns to liver

VLDL

Carries fats away from the liver (fats produced by the body) and cholesterol

Fate of proteins in liver (fed)

TCA cycle

Synthesize nitrogen containing compounds

Flush out in the urea cycle

Proteins are broken down to enter the

free amino acid pool

Uses of amino acids

synthesize nitrogen containing compounds and other

Ways amino acid pool is replenished

Diet

Body proteins

Goals of the fasted state

maintain ATP

maintain blood glucose

maintain metabolic flexibility `

Blood glucose peaks ___ hour after eating

One

After ___ hours, blood glucose returns to normal

two

Short term fast time

8-12 hours

Liver is critical to maintaining

blood glucose

How liver maintains blood glucose

Degrades liver glycogen

Gluconeogenesis

Ketone body synthesis maintains blood glucose by

acting as another energy source to spare glucose

Gluconeogenesis can start from what three molecules

lactate, glycerol, amino acids

Lactate common source

Red blood cells (anaerobic glycolysis)

Glycerol common source

Released from lipolysis

Amino acid common source

protein degredation in muscles

Ways adipose tissue sustain the body during a fast

oxidize fatty acids for energy, convert fatty acids to ketone bodies

In a short term fast, ketone bodies are used primarily by

skeletal muscle

In a long term fast, ketone bodies are used primarily by the

brain

Lipolysis triggers

stress hormones from exercise and glucagon

Triglycerides use

Glycerol goes to liver for gluconeogenesis

Fatty acids go to the liver for ketone body synthesis

Fatty acids go to other tissues for energy oxidation

Long term fast changes

Muscles: Decrease KB use and increase FA use

Liver: Increases KB production

An increase to KB in the blood decreases the overall need for

glucose

in a long term fast, almost all KB are going to the

brain

In a long term fast, almost all gluconeogenesis is supported by ___________ from the _____________ tissue

glycerol; adipose

In a short term fast, nitrogen excretion is

high

In a long term fast, nitrogen excretion is

low

In a long term fast, protein degredation

decreases

In a long term fast, gluconeogenesis occurence

decreases

In a long term fast, ketone body production

increases

Enzyme activity

Hormone → Signal transduction → activity of enzyme

Enzymes act as

catalysts

Regulation of an enzyme pathway depends on the ability to

flux through the pathway

Three mechanisms for regulating enzymes

One: Substrate/ product concentration

Two: Regulation by changing the conformation of the active site

Three: Change enzyme concentration

Products ___________ their enzymes

inhibit

Velocity of an enzyme is dependent on the

concentration of substrate

Maximum velocity

maximum rate of a reaction

Km

half of the maximum velocity

Concentrations of substrate below the Km are more sensitive to

concentration changes

Isoenzymes

enzymes that have the same substrates and products but have different affinities for the substrate and thus different Km values

High Km means the affinity is

low

Low Km means the affinity is

high

Allosteric

a molecule bonds to an enzyme somewhere other than the active site, acitivating or inactivating the enzyme

in the presece of an activator, the concentration of the substrate to meet the Km is

lower

Activators _________ the affinity for an enzyme

increase

Inhibitors ___________ the affinity for an enzyme

decrease

Advantages of allosteric activation

don’t occupy active site

don’t need to look like substrate/ product

Acts quickly

Phosphorylation of an enzyme occurs by

protein kinase A

Phosphorylation can either ____________ or _________________ an enzyme