Energetics - Class Flashcards
Study for final and quiz 3
What does Energetics mean in animal physiology?
Energetics in animal physiology encompasses the study of energy flows and budgets within organisms.
Cool fact: How do anthropologists believe that humans historically hunted animals?
They believe that humans would walk or maybe slowly run after animals and track them for long periods of time, until the animal became exhausted.
So humans were endurance hunters, made to have more slow twitch muscle fibers.
What are the Sources of ATP?
- Glycolysis: This is the initial step in the breakdown of glucose and occurs in the cytoplasm of cells. It converts glucose into pyruvate, generating a small amount of ATP (net gain of 2 ATP molecules per glucose molecule) and NADH. Glycolysis does not require oxygen (anaerobic process) and is thus a quick source of ATP.
- Citric Acid Cycle (Krebs Cycle): The pyruvate produced from glycolysis is transported into the mitochondria, where it is converted into acetyl-CoA. Acetyl-CoA enters the citric acid cycle, a series of reactions that produce NADH, FADH2, and a small amount of ATP (2 ATP molecules per glucose molecule). The citric acid cycle itself is aerobic, requiring oxygen indirectly because the NADH and FADH2 produced will eventually donate electrons to the electron transport chain that requires oxygen.
- Oxidative Phosphorylation (Electron Transport Chain): This process occurs in the mitochondria’s inner membrane and is where most ATP is produced. NADH and FADH2, generated from glycolysis and the citric acid cycle, donate electrons to the electron transport chain, creating a proton gradient across the mitochondrial membrane. The flow of protons back into the mitochondrial matrix through ATP synthase drives the production of ATP from ADP and inorganic phosphate. This process is highly efficient and produces approximately 34 ATP molecules per glucose molecule, but it requires oxygen (aerobic).
(there’s also beta oxidation and amino acid oxidation)
What’s the difference between glycolysis and oxidative phosphorylation?
Glycolysis is a quick way for cells to produce ATP and does not require oxygen, making it essential for short bursts of energy and anaerobic conditions.
Oxidative phosphorylation is a more efficient way of producing ATP but requires oxygen, making it crucial for sustained, long-term energy production in aerobic conditions. It’s also part of cellular respiration, a process that includes glycolysis, the Krebs cycle, and oxidative phosphorylation.
WHat’s the gist of Glycolosis?
–>Why is glycogen preferable to glucose in this pathway?
A molecule of glucose (a six-carbon sugar) is broken down into two molecules of pyruvate (a three-carbon compound). This process occurs in the cytoplasm of cells and produces a net gain of 2 ATP molecules and 2 NADH molecules. Glycolysis does not require oxygen, making it an anaerobic pathway. It provides cells with a quick supply of energy and is the first step in both aerobic and anaerobic respiration.
–>Glycogen is what’s generated after the first step of glycolysis (Glucose-6-Phosphate), so glucose with a phosphate, which means if we start with Glygogen instead, we don’t have to use that one initial ATP for the first step!
HOw does a lack of oxygen result in the pyruvate at the end of glycolysis being turned into lactic acid?
Even though oxidative phosphorylation is more efficient in terms of generating way more ATP per glucose, how does Glycolysis still outperform it>
Because glycolysis can make the ATP FASTER, so even though it uses up more glucose to do this, it still makes more ATP over a period of time.
What are Lipases? What do they do?
Lipases are a type of enzyme that specialize in breaking down lipids (fats) into smaller molecules, typically free fatty acids and glycerol.
Energy Mobilization: Hormone-sensitive lipase (HSL) is found in adipose tissue, where it breaks down stored triglycerides into free fatty acids and glycerol. These free fatty acids can be released into the bloodstream and taken up by muscle cells. Once inside the muscle cells, the fatty acids can be oxidized in the mitochondria to generate ATP, the energy currency of the cell, which is crucial for muscle contraction and endurance activities.
Lipid Uptake: Lipoprotein lipase (LPL) is located on the vascular endothelial surface of many tissues, including muscle tissue. LPL breaks down triglycerides in lipoproteins (like VLDL and chylomicrons) circulating in the bloodstream into free fatty acids and glycerol. Muscle cells can then take up the free fatty acids and use them as an energy source. The activity of LPL is increased in response to physical activity, enhancing the muscle’s ability to use lipids as fuel during prolonged exercise.
In summary, lipases facilitate the mobilization, uptake, and utilization of fatty acids in muscle cells, playing a vital role in energy metabolism, particularly during prolonged exercise when fatty acids become a primary fuel source. This process not only supports sustained muscle activity but also contributes to overall metabolic health by regulating lipid levels in the bloodstream
True or false: When lactic acid builds up, it can lead to pH and ion imbalances.
TRUE
What limits endurance exercise?
The inability to deliver oxygen to the muscle.
What’s the difference between recovery from exhaustion for low vs high intensity exercise?
For low intensity exercise, it takes a long time to become exhausted, BUT once exhausted, the recovery time is also very slow.
For exhaustion from high intensity exercise, it happens more rapidly, but the recovery time is much faster.
Think about after you run a sprint race, you might be exhausted and fall down but then u get up again shortly after.
Metabolism vs Metabolic rate?
Metabolism is the sum of all your body’s chemical reactions, wheras Metabolic rate is the rate of conversion of energy to heat or work!
When do we use BMR (basal metabolic rate) vs SMR (Standard metabolic rate?)
BMR is generally used in the context of endotherms (animals that regulate their own body temp.)
BMR measures the energy expenditure of these animals at a resting rate.
SMR is used for exothermic animals (body temp. regulated by the environment), and it also regulates energy expenditure, but it needs to be taken at a standard temperature (hence the name) since the animal’s body temp. affects the rate of its metabolism - reptiles slow down in the cold, so they would use less energy.
Explain calorimetry.
Calorimetry is a scientific technique used to measure the amount of heat energy exchanged in a chemical or physical process.
Explain Respirometry.
Respirometry is a great way to ESTIMATE the metabolic rate of an animal.
