Fuel Metabolism and Nutrition: Basic Principles

Question 1

Total energy produced by carbohydrates per gram

kcal/g

Answer 1

4 kcal/g

Question 2

long-, medium- and short-chain transport

Answer 2

CMs transport the long-chain TG to the tissues. Med- and Short- chain fats are transported directly to the liver through the portal system without packaging into lipoprotein particles.

Question 3

Two major precursors of polyunsaturated compounds such as prostaglandins and eicosanoids

Hint: essential fatty acids

Answer 3

linoleic acid

a-linolenic acid

Question 4

comps tht get ox by . muscles during fasting

Answer 4

fatty acids released from adipose tsu and . KBs produced by the liver

* during exercise muscles use their own source of fuel (glycogen that was already stored) in addition to f.a. and kb

Question 5

Total energy produced by 1g of fat (kcal/g)

Answer 5

9 kcal/g

Question 6

Essential amino acids

Answer 6

valine, leucine, isoleucine

histidine, lysine

phenylalanine, tryptophan

methionine and threonine

Question 7

Two major metabolic rxns carried out by the liver during the fasting state (with time frame)

Answer 7

Glycogenolysis- 2 to 3 hrs post meal

* the body runs out of glycogen within 30 hours

Gluconeogenesis- abt 4-6 hours of fasting

After 30 hr, gluconeogenesis is the major contributor to maintain blood sugar level

Question 8

The main aa released from the muscles during the fasting state

Answer 8

alanine and glutamine

tissues such as gut and kidney metabolize the glu

Question 9

Blood level of KB during starvation

Answer 9

inc.

Blood KB inc. because muscles don’t use KB ( used by brain as the source of energy) –> less req. gluconeogenesis –> less aa required –> muscle degradation stops

Question 10

site of storage for glucose as glycogen- What’s unique about each?

Answer 10

Muscle- Oxidization and fuel

Liver-maintaining blood glucose

* excess glucose converts to TAG in the liver and gets packaged into VLDL.

Question 11

Basic principle of fed state

Answer 11

fed state ~ right after meal

Ingested fuel will be used for immediate energy needs. Excess ingested fuel will be stored: TAG, Glycogen

Insulin promotes storage

Question 12

resenthesize the digestive products of TAG

Answer 12

intestinal epithelial cells

Question 13

digestive products of dietary fat

Answer 13

dietary fat( TAG- triacylglycerol)

digests into

fatty acids

and

2-monoacylglycerol

Question 14

name two major ketone bodies prod. by the liver from acetyl-CoA during the fasting state

Answer 14

acetoacetate and B-hydroxybutarate.

Question 15

Chylomicrons enter the blood via

Answer 15

lymph

Question 16

Conseq. of Kwashiorkor

Answer 16

1. dec. protein syn. (inc serum level of albumin)
2. impacts regeneration of intestinal epithelial cells
3. compensated by malabsorption
4. hepatomegaly and distended abdomen ( lack of albumin in blood, inc. osm pressure diff. –> water accumulation .

Question 17

tissues such as gut and kidney metabolize this aa- released from the muscles during the fasting state

Answer 17

glu

Question 18

The fate of dietary fat and cholestrol

Answer 18

The same fate

dietary fat (TAG) digests into fatty acids and 2-MAG and resenthesized into TAG by intestianal epithelial cells, then packaged into chylomicrons and enter the blood stream via lymph.

Question 19

The fatty acids of VLDL are stored in this tissue

Answer 19

adipose tissue

Question 20

fatty acids of chylomicrons are stored in

Answer 20

adipose triglycerides

Question 21

The role of adipose tissue during fasting

Answer 21

As glucagon inc. fat mobilizes and degrades into compnts.

F.A.s and glycerol re converted to glucose or ketone bodies by the liver

F.A.s are also used by the muscles to b ox 2 Co2 and H2O

Question 22

Basic principles of starvation

Answer 22

starvation~ prolonged fasting

changes in the usage of fuel storage that allows survival for prolonged period of time.

Question 23

Negative nitrogen balance

Answer 23

When the rate of excretion>ingestion

Question 24

Total energy produced by 1g of protein (kcal/g)

Answer 24

4 kcal/g

Question 25

Kowashiorkor

Answer 25

results from a diet **adequate in calories**, **but low** in protein

Question 26

Positive N balance

Answer 26

When ingestion \> excretion ( Synthesis is dominant)

Question 27

Outline the fate of TAG as the main source of dietary fat

Answer 27

1- emulsification (bile salts) 2- digestion (pancreatic lipase) into f.a. and 2-monoglyceride 3- packed (micelles) 4- absorbtion (into intestinal epithelial cells) 5- resynthesis into TAG 6- packed into chylomicrons 7- enter lymph 8- enter blood circulation

Question 28

Basic principles of the _fasting state_

Answer 28

fasting state ~ in between meals and over-night usage of stored fuel until the next meal Glucagon promotes release of energy from the storage

Question 29

Marasmus

Answer 29

results from a diet **dificient/low** in **both** cal. and protein

Question 30

during this state muscles dec. use of KB and ox. fa as primary source of energy

Answer 30

starvation- prolonged fasting (3-4days)

Question 31

sucrose and lactose digestion

Answer 31

by sucrase and lactase - enzymes that are part of the complexes of brush border enzymes (epithelial cells) sucrose --\> glucose + fructose lactose --\> glucose + galactose

Question 32

3 major steps for the production of ketone bodies by the liver

Answer 32

1- inc. glucagon, TAG break-down in adipose, f.a & glycerol are released into the blood 2- B-ox and f.a conversion to acetyl-CoA (liver) 3- acetyl-coA used by the liver to syn. ketone bodies: acetoacetate and B-hydroxybutarate

Question 33

The monosaccharides that are absorbed by the body (spc. BB enzyme complexes of epithelium)

Answer 33

main: glucose to some extend: fructose and galactose

Question 34

name several major indicators of starvation state:

Answer 34

Inc. blood KB Dec. in liver gluconeogenesis Muscle protein is spared Less urea is produced

Question 35

FAE's (fatty acid esters) of glycerol

Answer 35

glycerides (mono, di and tri)- When the alcohol is glycerol.

Question 36

Total energy produced by 1 g of alcohol (Kcal/g)

Answer 36

7 kcal/g

Question 37

DEE Daily energy expenditure

Answer 37

energy required for: 1- BMR- basic metabolic rate and 2- Energy required for physical activity.

Question 38

how is muscle degradation is spared during prolonged fasting (3-4 days of starvation)

Answer 38

Brain shifts from using glu to KB. and muscles dec. using KB. As a result: Blood KB inc. because muscles don't use KB ( used by brain as the source of energy) --\> less req. gluconeogenesis --\> less aa required --\> muscle degradation stops

Question 39

location for CM and VLDL formation

Answer 39

CMS are made only in intestinal epithelium cells, whereas VLDLs are **also** synth. in liver. At the cellular level, CMs are made in the ER and later processed in the golgi- the process of glycosylation of apolipoproteins takes place in golgi.

Question 40

Fate of glucose upon digestion

Answer 40

1- majority of carbohydrates get digested to glucose 2- glucose gets oxidized into body fuel 3- Excess glucose gets strored as glycogen in the **liver and muscle** **4- In t**he **liver,** gets converted to TAG and transported into the circulation by **VLDL**.

Question 41

CM (Chylomicron) components

Answer 41

TGs, fat sol. Vits, and cholestrol coated with a layer of: apolipoprotein (A and B), cholestrol ester, and phospholipids.

Question 42

hyperlipidemia

Answer 42

elevated blood lipid levels normal is \<150 mg/dL

Question 43

Energy production (general concept)

Answer 43

when fuels are oxidized to CO₂ and H₂O.

Question 44

sources of carbon for gluconeogenesis

Answer 44

lactate- produced by RBC's and exercising muscles glycerol- TG breakdown in adipose tsu A.A.- mainly alanine from muscle breakdown propionate (minor source) from oxidation of odd chain fatty acid

Question 45

a direct way to measure protein synthesis

Answer 45

through the measurment of serum albumin levels. \_ diets that are adequate in cal but low in protein leads to reduced serum albumin level

Question 46

The liver's function during fasting

Answer 46

produce glucose- maintiain blood sugar level ketone bodies prod.- to be released into the blood and serve as evergy source

Question 47

Answer 47

The conversion of acetoacetate to B-hyderoxybutarate

Question 48

The fate of aa's spc. glu and ala, upon muscle degradation during fasting state

Answer 48

tsus metabolize the glu- gut and kidney aa's also travel to the liver where Cs are conv'd to 1- glucose 2- KB 3- N containing comps

Question 50

the main product of f.a. oxidation that serves as a minor C contributor for gluconeogenesis (carried out by liver during the fasting state)

Answer 50

propionate

Question 51

name 4 enzymatic activities of brush border enzyme complexes

Answer 51

maltase isomaltase sucrase lactase

Question 52

The enzymes that complete the digestion of starch (main dietary carb) to glucose

Answer 52

enzymes of the complexes with **maltase** and **isomaltase** activities located on the **brush border** of epithelial cells of small intestine. Starch is the main form of carbohydrate storage in plants. The initial digestion is carried out by: _Salivary a-amylase (mouth)_ _Pancreatic a-amylase (intestine)_