Block 1 082912 Metabolic Fuels

Front 1

What are the four common metabolic fuels?

Back 1

Carbohydrates, proteins, fats, alcohol

Front 2

Describe how dietary carbohydrates are processed and absorbed?

Back 2

carbohydrates are broken down by enzymes to monosaccharides and absorbed into the PBL. Hi levels of glucose in PBL stimulates insulin production (inhibits glucagon production). Insulin promotes the uptake of glucose for glycolysis or storage as glycogen

Front 3

What is the calorie value of carbohydrates?

Back 3

4 Calories per gram

Front 4

Describe the fates of glucose in the liver after a meal

Back 4

1. makes NADPH (used in other pathways and for regenerateing reduced glutathione) and ribose 5-phosphate (to synthesize nucleotides)
2.excess triacylglycerol and cholesterol are transported out of the LV as vLDL which are taken up by other tissues
3. conversion to glycogen
4. first utilized to meet the energy needs of LV (glycolysis)

Front 5

How does the brain get energy when the body is in a fed state?

Back 5

Uses glucose because it can pass through the PBL-brain barrier. Brain requires 150g of glucose a day (only 2% of body weight but uses 20% oxygen and 25% glucose)

Front 6

How does the brain get energy during fasting?

Back 6

Can use ketone bodies which can pass through PBL-brain barrier

Front 7

How do red PBL cells get energy?

Back 7

only through glucose. ATP generation is anaerobic because do not have mitochondria.

Front 8

How do muscles get energy?

Back 8

Uses fatty acids as a major fuel. Glucose uptake is insulin dependent. Excercising uses both pbl glucose and endogenous glycogen(restored after meals and the synthesis of it is regulated by insulin)

Front 9

What two organs can convert glucose to glycogen?

Back 9

Liver and skeletal muscles

Front 10

What is the Caloric value of protein?

Back 10

4 Calories per gram

Front 11

What % of proteins is nitrogen?

Back 11

16%

Front 12

What happens to excess amino acids?

Back 12

Non can be stored. All is converted into energy and nitrogen is excreted as urea. The carbon skeletons are converted to metabolic intermediates to synthesize glucose, ketone bodies, fatty acids. Or oxidized by the citric acid cycle

Front 13

How are dietary proteins converted into amino acids in the small intestines?

Back 13

Proteins are digested in the stomach by pepsin and even more in the small intestines by pancreatic proteases to form AA and oligopeptides. Oligopeptides are broken down by aminopeptidases on the plasma membrane of the intestinal mucosal cells which are then released into the PBL

Front 14

Describe the fates of dietary amino acids.

Back 14

In liver, used to synthesize proteins.
2.Serum proteins (albumin)
3. Liver proteins like enzymes
4. Heme - goes into mitochonrial cytochromes and ER enzymes
In other tissues...
5. petide hormones (insulin glucagon growth hormones)
6. neurotransmitters (GABA)
7. purine and pyrimidine bases

Front 15

Specify 2 diseases associated with insufficient protein intake.

Back 15

Kwashiorkor-edema
Marasmus-emaciated

Front 16

What are the 7 metabolic intermediates to which excess amino acids are converted to?

Back 16

Pyruvate, acetyl CoA, acetocetyl CoA, oxaloacetate, fumarate, succinyl coA alpha-keto-glutarate

Front 17

What is the protein requirement for an adult?

Back 17

56g/day with a biological value of protein of 70

Front 18

Describe how dietary fats are processed in the small intestine.

Back 18

Fats (triacylglycerols triglycerides) emulsified by bile salts and then broken down into FA and monoacylgylcerols by pancreatic lipases

Front 19

Explain why more energy can be stored as fat than as glycogen.

Back 19

Glycogen has more oxygen than fats which are more reduced and less hydrated.

Front 20

What is the Caloric value of fats?

Back 20

9 Calories per g

Front 21

How are fats process and What happens to the absorbed free fatty acids in the intestines?

Back 21

Fats (triacylglycerols and triglycerides) are emulsified by sile salts and pancreatic lipases to form free FAs. Fatty acids and monoacylglycerols reassemble into triacylglycerols and assemble with protein to form lipoprotein chylomicrons which are released into the PBL through lymph

Front 22

What happens to excessive triacylglycerols?

Back 22

Stored in adipose tissues

Front 23

Describe ethanol metabolism.

Back 23

Ethanol-->alchol dehydrogenase-->acetaldyde-->acetaldehyde dehydrogenase-->acetate

Front 24

What are the 3 fuel stores in the body?

Back 24

1. Glycogen (1%)
2. adipose (85%)
muscle proteins (14.5%)

Front 25

How much glycogen does the LV hold?

Back 25

200 g

Front 26

What promotes glycogen synthesis during the fed state?

Back 26

insulin

Front 27

What breaks down glycogen?

Back 27

glucagon

Front 28

How long does glycogen storage lasts?

Back 28

18-20 hrs

Front 29

How much protein can be degraded before body functions are impaired?

Back 29

8% thats why it's not a real energy store

Front 30

Describe how the body gets fuel during fasting.

Back 30

PBL glucose level initally drops but then is maintained at a lowered level by gluconeogensis from non carboydrate sources like fatty acids and briefly muscle proteins. FAs are converted into ketone bodies by the LV

Front 31

What is ketogenic and give examples?

Back 31

amino acids that are used to make ketone bodies or fatty acids. Ex) acetyl CoA, acetoacetyl CoA

Front 32

What is glucogenic and give examples?

Back 32

Amino acids that are used to make glucose. Ex) Pyruvate, oxaloacetate, fumarate, succinyl CoA, alpha-ketoglutarate

Front 33

Describe the relationship between urea excretion and food consumption.

Back 33

When glucose is consumed urea excretion is low, however by 12 hours of fasting a spike of urea excretion occurs because proteins are being broken down for energy use. But since proteins cannot be used too much for energy, after 3 days of fasting urea excretion levels drop because fatty acids are being broken down into ketone bodies instead