Module 16

Question 1

Define metabolism

Answer 1

The chemical changes that occur within a cell to either manufacture energy, store energy, or build new cell structures

Question 2

List the two types of metabolism

Answer 2

Anabolism and Catabolism

Question 3

Define anabolism

Answer 3

The creation of large molecules from small ones with the use of energy (ATP)

Question 4

Define catabolism

Answer 4

The breakdown of large molecules into small ones resulting in the release of energy (ATP)

Question 5

List the three main energy sources and their building blocks

Answer 5

Triglycerides (3 fatty acid chains with one glycerol)
Proteins (amino acids)
Carbohydrates (monosaccharides)

Question 6

Describe where and how glucose is stored

Answer 6

Inside muscle and liver cells as glycogen

Question 7

Describe where and how fats are stored

Answer 7

In adipose tissue as triglycerides

Question 8

Describe where and how amino acids are stored

Answer 8

Inside muscle cells as structural or functional proteins

Question 9

Describe how much glucose contributes to body energy requirements and its reserve

Answer 9

Contributes 1% of total energy required, reserves last roughly a day

Question 10

Describe how much fatty acid contributes to body energy requirements and its reserve

Answer 10

77% of total energy requirements, reserve can last up to 2 months

Question 11

Describe how much amino acid contributes to body energy requirements and its reserve

Answer 11

22% of total energy requirement, death will occur before reserves are depleted

Question 12

List the 3 chemical reactions/metabolic pathways that produce ATP

Answer 12

Glycolysis
Citric acid cycle
Oxidative phosphorylation

Question 13

Briefly describe glycolysis (where it occurs, O2 requirement, ATP produced)

Answer 13

Occurs in the cytoplasm
Anaerobic (doesn’t require O2)
Produces 2 ATP per 1 glucose

Question 14

Briefly describe the CAC (where it occurs, O2 requirement, ATP produced)

Answer 14

Occurs in the mitochondria
Aerobic (requires O2)
Produces 2 ATP per 1 glucose

Question 15

Briefly describe oxidative phosphorylation (where it occurs, O2 requirement, ATP produced)

Answer 15

Closely linked to CAC in mitochondria
Aerobic (requires O2)
Produces 34 ATP per 1 glucose

Question 16

Describe where glucose can enter the metabolic pathway

Answer 16

Enters glycolysis at the beginning of the reaction

Question 17

Describe where amino acids can enter the metabolic pathway

Answer 17

Converted to pyruvate can enter glycolysis

Converted to acetyl CoA can enter the CAC

Question 18

Describe where fats can enter the metabolic pathway

Answer 18

Broken down into glycerol and free fatty acids
Glycerol can enter glycolysis
Fatty acids can be converted to acetyl CoA and can enter the CAC

Question 19

Describe why glucose is the most important fuel source

Answer 19

Only fuel source that the brain can use

Question 20

Describe the process of glycolysis

Answer 20

Glucose enters cell, immediately converted to G-6-P, which enters glycolysis or converted to glycogen
G-6-P enters glycolysis and produces 2 ATP and pyruvate

Question 21

Describe the 2 paths pyruvate can take

Answer 21

Can enter CAC and produce lots of ATP through CAC and oxidative phosphorylation
Can enter short reaction to produce some ATP and lactate
Depends on whether enough O2 is available for the CAC and oxidative phosphorylation

Question 22

Describe how lactic acid is formed (under what conditions)

Answer 22

Strenuous exercise, not enough O2 to support CAC, so pyruvate enters short reaction
Can cause accumulation of lactic acid, slowing down glycolysis, causing burning sensation in muscles

Question 23

Describe the consequences of lactic acid build-up

Answer 23

Glycolysis slows
Burning sensation in muscles
Blood vessels dilate (metabolic theory)
pH decreases, more O2 unloads from hemoglobin
Increased blood flow to increase O2 delivery to area
Reactions are reversible, so converts back to pyruvate to enter CAC

Question 24

Describe the CAC

Answer 24

Pyruvate from glycolysis or amino acid is converted to acetyl CoA
CAC in conjunction with oxidative phosphorylation produce 36 ATP from 1 glucose
By-products are CO2 (diffuses into blood to leave body at lungs) and H2O

Question 25

Describe when the fed state happens

Answer 25

After a meal Absorptive state High levels of nutrients in the blood Body's goal is to store all this new fuel for later use

Question 26

Describe then the fasted state happens

Answer 26

Post-absorptive state Between meals, in morning before breakfast When nutrient levels in blood are very low Body's goal is to maintain blood glucose by utilizing stored nutrients

Question 27

Describe the fed state's processes

Answer 27

Glucose is stored in liver as glycogen, excess are converted to fatty acids by the liver Fatty acids are released into circulation, taken up by adipose tissue and stored as triglycerides Amino acids are taken up by cells for protein synthesis, excess are converted to fatty acids

Question 28

Describe the fasted state's processes

Answer 28

Need to maintain blood glucose levels, especially for brain function Liver will produce and release glucose into blood from glycogen stores Liver can produce glucose from glycerol, amino acids, pyruvate, and lactate by gluconeogenesis Muscle cells cannot produce glucose from glycogen, but produce pyruvate or lactate, release these into blood, which go to liver

Question 29

List the hormones responsible for regulating metabolism

Answer 29

Insulin and glucagon

Question 30

Describe regulation of metabolism by insulin

Answer 30

Hormone of the fed state Secreted when blood glucose levels are high Affects most cells except brain and RBCs, targets liver, muscles, and adipose tissue Primary effect is promoting storage of nutrients and inhibiting their release

Question 31

List the results of insulin release in metabolism

Answer 31

``` Increased glucose reuptake and utilization by cells Increased glycogen formation Increased triglyceride formation Increased protein synthesis Decreased blood glucose levels Decreased fatty acid levels in the blood Decreased amino acid levels in the blood ```

Question 32

Describe regulation of metabolism by glucagon

Answer 32

Hormone of the fasted state Secreted when blood glucose levels drop below normal circulating levels Stimulates cells to release fuel stores into blood Target sites are liver and adipose tissue

Question 33

List the results of glucagon release in metabolism

Answer 33

``` Increased glucogenolysis Increased gluconeogenesis Increased lipolysis Increased blood glucose levels Increased levels of fatty acids in blood ```

Question 34

List other hormones that regulate metabolism

Answer 34

T3 and T4 Epinephrine Cortisol

Question 35

Describe how T3 and T4 affect metabolism

Answer 35

Increase breakdown and release of energy stores (released with glucagon)

Question 36

Describe how epinephrine affects metabolism

Answer 36

Activated by SYN, increases levels of glucagon and decrease levels of insulin, causing release of stored fuel

Question 37

Describe how cortisol affects metabolism

Answer 37

Secreted from adrenal glands, causes release of fuel stores during periods of stress (aids glucagon)