CIS Biochem Review Flashcards
liver fn. during metabolism
- Maintain blood glucose
- Synthesize ketones from Acetyl-CoA when we switch to lipolysis
- Synthesize fatty acids, convert to triglycerides and release as VLDLs
Requirements:
- Absorptive state: glucose and amino acids for energy
- Post-absorptive state: lactate, glycerol and amino acids for gluconeogenesis
adipose
fn. during metabolism
Functions:
- Take up fatty acids and convert to triglycerides for long-term storage
- Release fatty acids into circulation
Requirements:
- Glucose to produce glycerol phosphate for the esterification of fatty acids
- Switch to fatty acids during post-absorptive
resting skeletal mm. fn. during metabolism
Functions:
Release amino acids into the blood
Requirements:
- Absorptive state: glucose for oxidation and glycogen stores, amino acids for protein synthesis
- Post-absorptive: Fatty acids and ketones for energy
active skeletal mm. energy needs?
Fast-twitch
- Anaerobic glycolysis from glycogen
Slow-twitch
- Oxidative metabolism of glycogen
- After several hours, switch to lipolysis
absorptive state
- occurs after a meal
- blood glucose level increases
- insulin is released:
- In liver and mm: stimulates glycogen synthesis to be increased, after glycogen stores are filled, glucose is converted to fatty acids
- protein synthesis increases in muscle
- adipose: triglycerides synthesis increases
- brain/blood cells: insensitive to insulin
Post-absorptive state
- during fasting/12 hours/ overnight
Glucagon is released
- Liver: glycogenolysis occurs, glucose released into blood, AA’s and FA’s taken in for gluconeogensis
- Epinerphrine released:
1. Muscle: AA’s released into blood
2. Adipose: FA’s released into blood
muscle contraction activates TCA cycle
- increases in Ca2+
- increase in ADP
- decrease in NADH/NAD + ratio
anaerobic mm. contraction
= High-Intensity Exercise
The need for ATP exceeds the mitochondria’s capacity for oxidative phosphorylation, thus focus on anaerobic glycolysis (glucose –> 2 pyruvate –> lactate using lactate dehydrogenase)
Lactate production
- Increased NADH/NAD+ ratio directs pyruvate into lactate
H+ production
- At intracellular pH, lactic acid dissociates to lactate and H+
- Decreases pH and causes pain and fatigue
aerobic mm. metabolism
Low-Intensity Exercise
Rate of ATP utilization is lower
- Fibers can generate ATP from oxidative phosphorylation
Increase CO2
- Complete oxidation of glucose to CO2
exercise and TCA cycle
- exercise increases ATP utilization
- increases TCA cycle: generates NADH and FADH2, which are driving force for ETC
- results in increased ETC, and generation of NAD and FAD+ (driving force for TCA cycle)
- if ETC wasn’t working, would build up NADH, which would inhibit TCA cycle
messengers of exercise feedback: 1-ATP/ADP ratio 2-NADH/NAD+ 3-Ca2+ 4-Citrate
- myosin ATPase generates ADP:
* * Increase in ADP stimulates:
- Isocitrate deyhydrogenase (rate limiting step in TCA)
- results in ETC forming NAD+ and FAD - ETC utilizes NADH:
- decrease in NADH stimulates isocitrate dehydrogenase along with malate dehydrogenase
NOTE: if not getting enough O2, results in halting of ETC - build up of NADH - results in lessening of TCA cycle
- increased Ca2+:
- stimulates isocitrate dehydrogenase
- alpha-ketoglutarate dehydrogenase - When NADH/NAD+ ratio increases:
- citrate inhibits Acetyl CoA entering the TCA (exerts negative feedback on the system)
- NAD+ is allowed to increase
Increase in ADP stimulates:
Isocitrate deyhydrogenase
ETC to form NAD+ and FAD
Decrease in NADH stimulates:
Isocitrate dehydrogenase
Malate dehydrogenase
Increase in Ca2+ stimulates
Isocitrate dehydrogenase
Alpha-ketoglutarate dehydrogenase
When NADH/NAD+ ratio increases
Citrate inhibits Acetyl CoA entering the TCA cycle
NAD+ is allowed to increase
isocitrate dehydrogenase
stimulated by ADP and Ca2+, and decreased NADH
inhibited by rising NADH
