Intro To Metabolism

Question 1

Fasted refers to

Answer 1

Overnight fast

Question 2

Big picture of metabolism

Answer 2

Chemical energy contained in macronutrients needs to be converted into energy cell can use to do work

Question 3

Primary organ of metabolic regulation

How?

Answer 3

Liver

Maintains blood glucose and amino acid homeostasis

Question 4

Liver insulin transporter’s Km

Answer 4

High Km –> can always bring in glucose especially after a meal

Question 5

Transporters function like

Answer 5

Enzymes

Question 6

Metabolism involves (3)

Answer 6

1. Homeostasis
2. Redistribution of chemical energy between compounds
3. Integration of metabolic pathways

Question 7

Homeostasis

2 types?

Answer 7

Maintaining a constant internal environment
- changes do occur but mechanisms are in place that compensate for those changes to bring back to “normal”

Metabolic homeostasis and pH homeostasis

Question 8

How are metabolic and pH homeostasis connected?

Answer 8

Metabolism releases weak organic acids and CO2

Need to maintain constant level of blood glucose

Question 9

Fuel availability

Answer 9

stored energy in form of glycogen or fat

Question 10

Metabolic homeostasis is the balance between

Answer 10

Fuel availability and what tissues need

Question 11

Metabolic homeostasis is determined by (3)

Answer 11

• nutrient levels
• hormone signals
• nerve signals

Question 12

What region of hypothalamus controls feeding?

Answer 12

ARC region

Question 13

Orexigenic neurons

Answer 13

Promote feeding behavior

Question 14

Anorexigenic neurons

Answer 14

Inhibit feeding behavior

Question 15

When you take in nutrients, ______ levels rise and 2 things occur:

Answer 15

Insulin levels rise

1. Metabolize some energy to maintain body function
2. The excess calories are stored for breakdown during times of fasting

Question 16

Importance of maintain blood glucose

Answer 16

Brain needs ~75% of daily need for glucose

Question 17

Fiber

Answer 17

Restricts how rapidly glucose levels (thus insulin levels) rise in the blood

Question 18

What happens to blood glucose, insulin, and glucagon levels after a meal?

Answer 18

• Blood glucose levels rise
• Insulin levels follow blood glucose and rise too
• Glucagon levels stay relatively constant

Question 19

Insulin

Made by?
Responds to?
Corresponds to?

Answer 19

Insulin = FED STATE

• Made by beta cells of pancreas
• Responds to elevated blood glucose

Question 20

Type 1 vs. Type 2 diabetic

Answer 20

Type 1: beta cells have been destroyed therefore do not produce insulin

Type 2: produce insulin, but no response because signal transduction cascade is affected

Question 21

Insulin = “______ hormone”

Why?

Answer 21

Anabolic hormone

Promotes synthesis of macromolecules

Question 22

Insulin stimulates

Answer 22

Glucose transport into skeletal muscle and adipose tissue

Question 23

Once glucose is in skeletal muscle –>

Answer 23

• Metabolized for energy

- Stored as glycogen

Question 24

Once glucose is in adipose tissue –>

Answer 24

Converted to fatty acids which are then esterified to glycerol backbone to yield triglycerides

Question 25

In liver, glucose is

Answer 25

Made into glycogen and energy Any excess can go into fatty acids

Question 26

Glucagon Made by? Responds to? Corresponds to?

Answer 26

Glucagon = FASTED STATE - Made by alpha cells of pancreas - Signals that current supply of glucose is low for the cell's needs

Question 27

Glucagon = "______ hormone" Why?

Answer 27

Catabolic It promotes the breakdown of stored fuels (glycogen and fat) to provide energy when it is not coming from the diet

Question 28

Glucagon signal transduction is the same as

Answer 28

Epinephrine

Question 29

Glucagon has no effect on ________ because ________

Answer 29

Skeletal muscle because no receptors

Question 30

_______ and _________ respond to glucagon

Answer 30

Liver and fatty acids

Question 31

In response to glucagon, in liver ____

Answer 31

Glycogen is broken down to glucose --> exits liver and enter blood

Question 32

In response to glucagon, in adipocytes ______

Answer 32

Triglycerides broken down to fatty acids --> exit liver and enter blood to provide alternative source of energy

Question 33

2 major fuel stores

Answer 33

1. Glycogen - limited | 2. Triglycerides/fatty acids- longer period of time; more nrg when oxidized

Question 34

High insulin : glucagon ratio =

Answer 34

FED

Question 35

What happens when high insulin: glucagon ratio?

Answer 35

Brain senses blood glucose is high --> CNS sends signal to pancreas to release insulin --> stimulates transport of glucose into skeleton muscle and adipose tissue --> synthesis of glycogen or fatty acids which are eventually converted into triglycerides

Question 36

Low insulin: glucagon ratio =

Answer 36

FAST

Question 37

What happens when low insulin:glucagon ratio?

Answer 37

Brain senses blood glucose is low --> CNS sends signal to pancreas to release glucagon --> promotes breakdown of liver glycogen and release of glucose into blood (Gluconeogenesis in liver)

Question 38

Glycogen breakdown can be stimulated by

Answer 38

Glucagon or epinephrine

Question 39

In fasted state, most of the glucose generated is _________. Why?

Answer 39

Is selectively saved for the brain and RBC because brain and RBC cannot oxidize fatty acids for energy NOT metabolized for energy

Question 40

Catabolism =

Answer 40

Breakdown Oxidative, exergonic Paired to making ATP which is consumed in anabolic reactions

Question 41

Anabolism =

Answer 41

Reductive, endergonic Synthesis requiring reducing equivalents Coupled to splitting ATP

Question 42

What makes ATP an efficient energy currency?

Answer 42

"High phosphoryl transfer potential"

Question 43

Why is ATP hydrolysis favorable? (3)

Answer 43

1. It reduces the electrostatic repulsion of the 3 negative charged phosphate groups 2. The inorganic phosphate has resonance stabilization, therefore entropy is increased 3. Stabilization due to hydration with H2O molecules

Question 44

Energy is ATP is contained in

Answer 44

The 3 phosphate bonds

Question 45

Other molecules with high phosphoryl transfer potential (3)

Answer 45

1. Phosphoenolpyruvate - glycolytic intermediate 2. Creatine phosphate 3. 1,3- Biphosphoglycerate (1,3-BPG) - glycolytic intermediate

Question 46

high phosphoryl transfer potential requirements (3)

Answer 46

1. Have a phosphate 2. Can transfer the phosphate to another molecule with lower energy 3. Usually a lot of energy released when phosphate is transferred

Question 47

ATP levels are maintained in equilibrium by

Answer 47

Adenylate cyclase 2 ADP ATP + AMP

Question 48

If ATP levels decrease:

Answer 48

ADP levels increase by ~50% AMP levels increase by several hundred fold

Question 49

_____ is signal for low energy state

Answer 49

AMP

Question 50

Small drop in ATP concentration is magnified by

Answer 50

Changes in AMP and ADP

Question 51

How are ATP-generating and ATP-utilizing (biosynthesis) pathways related?

Answer 51

They function inversely based on ATP availability

Question 52

Energy charge: 0 = 1 = Cellular range =

Answer 52

``` 0 = no ATP, all AMP 1 = all ATP, no AMP ``` Cellular range = 0.8-0.95 - Always trying to get back here (point of intersection)

Question 53

If have all ATP, rate of ATP generation is ______. If have no ATP, rate of ATP utilizing is ______.

Answer 53

Low Low (b/c no availability)

Question 54

If decrease ATP --> energy charge ______ and _________

Answer 54

Energy charge drops and rate of ATP generation increase

Question 55

If have ATP, _______

Answer 55

Rate of biosynthesis increases