NS 1150 Prelim 2(Credits to KCK)

First Law of Thermodynamics

Energy can change forms but is neither created nor destoryed

Glycolysis

Breaking down of glucose into (2) pyruvate

Catabolic

B-Oxidation

Breakdown of fatty acids into acetyl-CoA

Catabolic

Lipolysis

Breakdown of triglycerides to fatty acids and glycerol

Catabolic

Proteolysis

Breakdown of protein to amino acids

Catabolic

Gluconeogensis

Glucose synthesis from noncarbohydrate sources

Anabolic

Glycogenesis

Formation of glycogen

Anabolic

Lipogenesis

Synthesis of fatty acids and triglycerides

Anabolic

How are metabolic pathways used to be able to do work: moving muscles, synthesize, & transport

Catabolic reactions(favorable) are coupled with anabolic reactions(unfavorable standalone)

Catabolic Pathway or Catabolism

Breaking down compounds(Thermodynamically Favorable)

Anabolic Pathway

Needs energy, putting together macromolecules(Thermodynamiccaly Unfavorable)

ATP

Adenosine Triphosphate or the high energy compound released during breakdown

2 ways that Acetyl CoA proceed

• Synthesis of fats for storage (lipogenesis, anabolic pathway)

• Oxidative phosphorylation (generates ATP)

Stores of energy(macronutrient - simple form - stored form - primary store site)

CHO - glucose - glycogen - liver > muscle

Lipids/Fat - free fatty acid - triglycerides - adipose tissue>muscle>serum

Proteins - amino acids -(CANNOT BE STORED) - Muscle

• Under very extreme metabolic condition (starvation) will muscle be broken down

Oxidative Phosphorylation

Primary Source of ATP at rest & steady state exercise lating >3min

• Primarily uses Carbs & Fat as substrates

• Occurs when O₂ supply is sufficient

• Takes place in Mitochondria

Mitochondrion Regions

Inner compartment(contains the matrix) - site of pyruvate to acetyl CoA, fatty acid oxidation, and TCA cycle

Inner membrane - site of the electron transport chain reaction

Subsystem of Oxidative Phosphorylation

Aerobic glycolysis (CHO-Glucose-Pyruvate-Acetyl CoA)

Aerobic lipolysis (Fatty Acid - Acetyl CoA)

Oxidation of CHO: Aerobic glycolysis

Glycolysis (glucose to pyrivate) - occurs in cytosol

Tricarboxylic Acid (TCA) Cycle - mitochondria

Electron Transport chain (ETC) - mitochondria

What macronutrients can make acetyl-CoA

All macronutrients can be used

Glucose - Pyruvate - Acetyl CoA

Fatty Acids - Acetyl CoA

Amino acids - Pyruvate - Acetyl CoA

What are the high energy electron carriers produced in TCA cycle

NADH and FADH2 are coenzymes that supply electrons to the oxidative phosphorylation system

What is the Oxidative System(ETC) comprised of

A series of electron carriers mounted in the mitochondrial intermembrane space(IMS)

Complexes I through IV & protein complex F1F0 ATP Synthase(Complex V)

Function of Oxidative System(ETC)

• Coenzymes NADH and FADH2 supply electrons, which are carried through protein complexes (and the redox centers inside them) to pump H+ across the membrane to outer, therby powering ATP synthase (spinner!)

• Oxygen accepts the electrons and combines w/hydrogen to form H₂O

Net ATP 36-38 per glucose

Oxidation of Fat: Aerobic lipolysis

Fatty acid is activated with CoA group to form Fatty acyl-CoA entering the innermembrane space and reacts with carnitine yielding acyl carnitine that enters the matrix and B-oxidation removes 2 carbon units to generate NADH and FADH2 and acetyl-CoA

*B-Oxidationn process repeats until entire chain is broken down

What is Stored Triglyceride(TG) broken down into

1 glycerol molecule and 3 fatty acids

What are the 3 type of energy expenditure

Basal(resting) metabolic rate - energy needed to perform normal body functions (respiration, circulation, digestion)

Thermogenesis - the energy cost of food processing (ingestion, digestion, absorption, transport, & storage)

Physical Activity - Body movement determining activity induced

Factors influencing Basal Metabolic Rate(BMR)

Genetics - determine how body utilizes

Age - BMR decreases with age

Sex - Male have higher BMR than females of equal size and weight

Growth - BMR higher during periods of growth

Body weight - BMR increases as weight body increase

Body Composition - More muscle higher BMR than more adpipose tissue

Energy Restriction - Fasting

How is heat measured

Calorimetry - The science that studies the change in energy of a system by measuring heat exchange

Calorimeter - An instrument to measure the transfer of heat

What are calories

1 cal is the unit of E required to increase the temperature of 1 g of water by 1 C

1000 cal = 1kcal = 1 dietary calorie(USA)

1kcal = 4148 Joules

Bomb calorimeter

Determine the energy content of nutrients(boom)

Carbohydrates = 4.3kcal = 4kcal

Protein = 5.65 kcal = 4 kcal

Fat = 9.45 kcal = 9 kcal

Alcohol = 7.0 kcal = 7 kcal

Calorimetry rooms

Measures body heat production, not practical or accurate

Indirect Calorimetry

Measures respiratory gas exchange —> O2 consumed and CO2 produced per min

• estimates energy expenditure

Respiratory Exchange Ratio (RER)

RER = Co2Made / O2 Used

Measurement of how many CHO or fat we are using for energy

Classification of Carbohydrates (Simple vs Complex)

Simple Sugars = Monosaccharides & Disaccharides

Complex Carbohydrates = Oligosaccharides & Polysaccharides

What are monosaccharides 

Single unit sugar that differ in arragement of atoms (glucose serve as an essential energy source)

i.e Glucose, Fructose, and Galactose 

What are Disaccharides

Pairs of monosaccharides

Put together by condensation & apart by Hydrolysis

• Glucose + Glucose = Maltose

• Glucose + Fructose = Sucrose

• Glucose + Galactose = Lactose

What are oligosaccharides

Made of 3-10 monosaccharides

Human lack the enzyme to digest some dietary oligosaccharides, pass into large intestine where gut bacteria break them down

i.e Stachyose & Raffinose

What are polysaccharides

Chains of monosaccharide

Made almost exclusively by glucose 

i.e Glycogen, Starch, Fiber, Amylopectin, & Amylose

Exmples of CHO

Sugar, Starches, & Fiber

Where can CHO be found

All plants food, & milk

Not in animal-source food or fats

Monosaccharides Sources

Glucose = consumed as a component of disaccharides & polysaccharides (dextrose)

Galactose = milk

Fructose = naturally in fruits & honey (soft drinks, ready to eat cereal, high frcutose corn syrup)

Where can Disaccharides food source be found

Sucrose = Fruits, vegetables, and gains(table sugar)

Lactose = Milk

Maltose = Barley

What is lactose intolerance

inability to digest lactose due to deficiency in lactase

25% of US adults are lactose intolerant

Where is Complex CHOs food source found in

Starch = Plant product like grains(wheat, rice), root crops, tubers(yams & potatos), and legums(beans & peas)

Glycogen(storage of glucose for animals) = limited extend in meats

• Not a significant contributor of CHO

Fiber(dietary fiber/non-starch polysaccharides) = structural component of platns(stems, cell wall) & indigestable by humans

Branch vs Linear Polysacchrides

Branch is more easily digested than linear

Whole Grains vs Refined Grains

Whole grain = Endosperm(starchy potion w/some protein), Brain(fiber filled w/vitamin B), Bran(Vitamin B & E, phytochemicals)

Refined Grain = Only Endosperm(no nutrient left)

Difference between whole grain stamps

100% Stamp = All of the grain is whole grain (min = 16gram of whole grain per serving)

50% Stamp = At least 50% of grain is whole (min = 8gram of whole grain per serving)

Basic Stamp = Significant whole grain primarily of refined grain (min = 8g of whole grain per serving)

What is High Fructose Corn Syrup (HFCS)

Made from corn

Enzyme convert starch into individual glucose molecules

Additional enzyme convert some of the glucose into fructose 

• Most HFCS is 55% furctose & 45% glucose 

• Sucrose is 50% furctose & 50% glucose 

What are the affect of HFCS consumption

Fructose is converted to glucose, glycogen, or fatty acid and stored in the liver

Excessive fructose lead to metabolic dyfunction associated steatotic liver disease(MASLD) previously known as non-alcohol fatty liver disease(NAFLD)

• Increase TG

• Increase LDL-C

• Increase Visceral Fat

Which part of the GI Tract is CHO halted

Stomach

Enzyme involved in Digestion of Carbohydrates

Mouth = Salivary amylase 

Pancreas = Pancreatic amylase

Small Intestine = Maltase, Sucrase, & Lactase

Absorption of CHO

Only monosaccharides can be absorbed by enterocytes, then enter bloodstream and sent to liver via hepatic portal vein

What happens in the liver for CHO absorption

Fructose and Galactose are converted to glucose and glycogen

What are the 3 metabolic fate of glucose

Cellular Respiration - ATP production (FUEL)

Stored as Glycogen - Glycogenesis

Converted to Fatty Acid & Stored as Adipose Tissue - Lipogenesis

• Excessive fructose consumption increases lipogenesis

Body Functions of Glucose

Brain/Central Nervous System - Primary source of energy for brian and CNS

Muscle - Muscle glycogen is the primary energy source for the body(exercise)

Red Blood Cells - Glucose is the primary source of RBC (90% catabolized anaerobically)

Functions of Carbohydrates

Energy Reserves

• Glucose levels high = Liver uses glucose to make glycogen

• Glycogen stores are key in maintaining steady levels of glucose

Prevents protein catabolism in body

• Decrease gluconeogenesis

  • (amino acid/lactate/glycerol —>glucose)

• Spares muscle tissue

Functions of Starch & FIber

Slows breakdown of starch into glucose

• Soluble fiber traps nutrients & delays GI tract transit, promoting slower glucose absorption

Enhance Health of LI

• Block absorption of unwanted constituents

• Increase stool weight, ease passage, reduce transit time

• Promote Healthy gut bacteria

RDA intake for CHO

130g/day for adults & children(minimum glucose used by brain)

• Higher during pregnancy & lactation

• No UL for total CHO intake

• Added Sugar no more than 25% of total kcal or <10% of total kcal

Acceptable Macronutrient Distribution Range(AMDR) for CHO

DRI for CHO 45-65% of daily E intake

Daily Value for a 2000kcal: 900 to 1300kcal = 225g - 325g of CHO

DRI recommendation for fiber

No established RDA or UL

Adequate Intake:

• 21-25g/day for women

• 30-38g/day for men

What are the 3 health effects of excess sugar

Dental cavities

Nutrient Deficiencies

Obesity

Dental Cavities

Naturally occuring & added sugar contribute to tooth decay

• Bacteria ferment sugar from food

• Drinks(w/sugar & low pH) erode tooth enamel

Nutrient Deficiencies

Added sugar contribute to nutrient deficiencies by displacing nutrient(donut for breakfast)

Faactors of Obesity

Biological Factor

• Genetic & Metabolic

Social/Environmental

• Cultural, Behavioral, Socioeconomic

What role does genetics play

Causative role in only a few cases of obesity

What are the Genetics of Obesity

Syndromic Form(affects broader)

• Chromosomal rearrangements(large scale change in gene)

• Pleiotropic(one gene affect multiple organ)

Non-Syndromic Form

• Polygenetic(multiple gene)

• Monogentic(one gene)

What is Monogenic Obesity

related to mutation in genes that are vital for the regulation of appetite and satiety

• POMC,NPY,LEP,LEPR,MC3R

Energy Balance

Related to obesity and overweight by calories consumed and calories expended

• increase energy dense food (high fat & sugar)

• increase in physical inactivity (work,transportation,urban)

What chronic noncommunicable diseases(4) does obesity contribute to

Cardiovascular diseases, Chronic Respiratory Disease, Diabetes, & Cancer

What is Glucose Homeostasis

Hormonal and Neural mechanism that the body uitlizes to maintain blood glucose levels at relatively steady level

What does the uptake of plasma glucose into cells require

GLUT or Glucose Transportors

What are the different types of GLUT

14 GLUT isoforms throughout the body

• GLUT1

  • blood, blood brain barrier, heart(lesser extent)

• GLUT2

  • Liver, Pancreas, SI

• GLUT 3

  • Brain, Neurons, Sperm

• GLUT 4(most abundant receptor)

  • Skeletal Muscle, Adipose Tissue, Heart

How is glucose uptake different in enterocytes

Mainly driven by sodium dependent active transport mechanism of SGLT1(Sodium linked Glucose Transportor)

Pancreas(15 cm in length) function in glucose homeostasis

Produce key hormones 

• B-Cells release Insulin (high sugar level released)

• A-Cells release Glucagon (low sugar level released)

Liver function in glucose homeostasis

Stores and release energy

• glycogen(stored sugar)

Acinar cells

exocrine; pancreatic jucie 95% of cells

Islet of Langerhans

Hormone producing cells(endocrine); 2-5% of cells

• Beta Cells - insulin

• Alpha Cells - Glucagon

Insulin & GLUT 4 Relationship

Insulin serves as signal for rapid transfer of GLUT 4 into cell membraneof muscle & adipose cells, increasing transport of glucose

Are all tissues insulin dependent

No

• Brain is always permeable to glucsoe (GLUT 1 & GLUT 3)

• Skeletal muscle are insulin dependent at rest but not during exercise

Glucose Homeostasis: After a Meal

Blood Glucose increase, stimulate release of insulin allowing insulin dependent glucose transporters to take up glucose into cells; promotes formation of glycogen in liver & conversion of excess glucose into fat .

Glucose Homeostasis: In between meals

Low blood glucose stimulate release of glucagon allowing breakdown of glycogen in the liver and released into blood

• Epinephrine(hormone from fight/flight) also raises blood glucose

What happens if regulation of glucose fails

Hypoglycemia (low sugar) <70mg/dL

Hyperglycemia (high sugar)

What is Diabetes Mellitus (DM)

Group of metabolic disease characterized by elevated level of glucose blood (hyperglycemia)

• T1DM - 5% diabetes cases(childhood,gene, lack of insulin)

  • no known way to prevent

• T2DM - 90-95% diabetes cases(middle-age, insulin resistance)

  • preventable

Risk Factors of T2DM

Family History

• history of gestational diabetes

Sedentary lifestyle

• exercise <3x per week

Overweight or obese

• vascular disease history

What causes T1DM

Autoimmune disease - destruction of pancreatic B-cells, failure to produce insulin

What causes T2DM

Chronic elevated level of blood glucose increasing insulin but receptors are not responsive

Chronic complication of DM

• Cell produce sugar alcohols - toxicity & distention(bloating)

• Cell produce glycoproteins - loss of protein function

• loss of circulation & nerve function

• infection - poor circulation

What are the loss of circulation & nerve function in DM complication

Disease of large blood vessels(Macrovascular)

• Diabetic cardiomypopathy

Disease of small blood vessels(Microvascular)

• diabetic retinopathy

• diabetic nephropathy

Disease of the nerves

• diabetic neuropathy(affect legs before hand)

How is diabetes diagnosed

Hemoglobin A1C(HbA1C) - represents average blood sugar levels over past 3-4 months (life span of RBC)

Glucose tolerance test(GTT) - measure blood sugar before and after a drink containing glucose

What is the most lipid in the human body and food

Fatty acids

What are fatty acids(FA) comprised of

Carbon, Hydrogen, & Oxygen atoms

What are the 2 carbon backbone of fatty acids

Alpha end - with a carboxylic group (COOH)

Omega end - with a metyhyl group (CH3)

Chain Length of Fatty Acids(affects chemical & physical function)

Short Chain FA

• 2-5 carbon, predominant

Medium Chain FA

• 6-12 carbons

Large Chain FA

• >12 carbons

Type of saturation of Fatty Acids

Saturated (Solid at RT)

• Maximum possible number of H atom bound to e/carbon 

Unsaturated (liquid at RT)

• Mono-unsaturated(MUFAs) - one double bond

• Poly-unsaturated(PUFAs) - many double bonds

Unsaturated FA classification

Cis Unsaturated FA

• H atoms are positioned on the same side of the double bond

• Bending of FA, liquid at RT

• Contain Omega 3 & Omega 6 FA

Trans Unsaturated FA

• H atoms are positioned on opposite sites of double bond

• No bending of FA, Solid at RT

• Associated with Increased CDV

Systematic naming of Unsaturated FA

Alpha naming system

• Position of the double bond relative to alpha carbon

Omega naming system

• Position of the double bond relative to omega carbon

• Does not identify whether the double bond is cis or trans

Food source of where lipids are found

Fats, Milk, Starch, animal Source

What are the 3 complex fatty acid molecules

Triglycerides

Phospholipids

Sterols

What are triglycerides(TG) or Triacylglycerol(TAG)

Primary dietary lipid & major source of energy

Composed of 1 glycerol + 3 FA bounded by ester linkages

What are Phopholipids(PL)

Found Naturally in most foods

Composed of 1 glycerol + 2 FA bounded by ester linkages

PL have a phophate containing polar head group

Amphipathic(Hydrophilic & Hydrophobic)

What are Sterols & Sterol esters

Lipids w/multi-ring structure

Composed of 1 chloestrol + 1 FA bonded by ester linkage

Can be synthesized endogenously

Needed to synthesize bile acid & steriod hormone(membrane fludiy)