Module 16 Flashcards
Define metabolism
The chemical changes that occur within a cell to either manufacture energy, store energy, or build new cell structures
List the two types of metabolism
Anabolism and Catabolism
Define anabolism
The creation of large molecules from small ones with the use of energy (ATP)
Define catabolism
The breakdown of large molecules into small ones resulting in the release of energy (ATP)
List the three main energy sources and their building blocks
Triglycerides (3 fatty acid chains with one glycerol)
Proteins (amino acids)
Carbohydrates (monosaccharides)
Describe where and how glucose is stored
Inside muscle and liver cells as glycogen
Describe where and how fats are stored
In adipose tissue as triglycerides
Describe where and how amino acids are stored
Inside muscle cells as structural or functional proteins
Describe how much glucose contributes to body energy requirements and its reserve
Contributes 1% of total energy required, reserves last roughly a day
Describe how much fatty acid contributes to body energy requirements and its reserve
77% of total energy requirements, reserve can last up to 2 months
Describe how much amino acid contributes to body energy requirements and its reserve
22% of total energy requirement, death will occur before reserves are depleted
List the 3 chemical reactions/metabolic pathways that produce ATP
Glycolysis
Citric acid cycle
Oxidative phosphorylation
Briefly describe glycolysis (where it occurs, O2 requirement, ATP produced)
Occurs in the cytoplasm
Anaerobic (doesn’t require O2)
Produces 2 ATP per 1 glucose
Briefly describe the CAC (where it occurs, O2 requirement, ATP produced)
Occurs in the mitochondria
Aerobic (requires O2)
Produces 2 ATP per 1 glucose
Briefly describe oxidative phosphorylation (where it occurs, O2 requirement, ATP produced)
Closely linked to CAC in mitochondria
Aerobic (requires O2)
Produces 34 ATP per 1 glucose
Describe where glucose can enter the metabolic pathway
Enters glycolysis at the beginning of the reaction
Describe where amino acids can enter the metabolic pathway
Converted to pyruvate can enter glycolysis
Converted to acetyl CoA can enter the CAC
Describe where fats can enter the metabolic pathway
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
Describe why glucose is the most important fuel source
Only fuel source that the brain can use
Describe the process of glycolysis
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
Describe the 2 paths pyruvate can take
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
Describe how lactic acid is formed (under what conditions)
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
Describe the consequences of lactic acid build-up
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
Describe the CAC
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
Describe when the fed state happens
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
Describe then the fasted state happens
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
Describe the fed state’s processes
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
Describe the fasted state’s processes
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
List the hormones responsible for regulating metabolism
Insulin and glucagon
Describe regulation of metabolism by insulin
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
List the results of insulin release in metabolism
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
Describe regulation of metabolism by glucagon
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
List the results of glucagon release in metabolism
Increased glucogenolysis Increased gluconeogenesis Increased lipolysis Increased blood glucose levels Increased levels of fatty acids in blood
List other hormones that regulate metabolism
T3 and T4
Epinephrine
Cortisol
Describe how T3 and T4 affect metabolism
Increase breakdown and release of energy stores (released with glucagon)
Describe how epinephrine affects metabolism
Activated by SYN, increases levels of glucagon and decrease levels of insulin, causing release of stored fuel
Describe how cortisol affects metabolism
Secreted from adrenal glands, causes release of fuel stores during periods of stress (aids glucagon)
