HAP-20306
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The Physiology book ends each chapter with a very concise, pointwise summary of each sub. chapter.
A - College H14. Energy metabolism and thermoregulation
3.4 phys. ATP
Cells temporarily save energy as ATP. This compound consists of ADP and phosphate, the reaction
between these two is a condensation reaction, the reaction is called phosphorylation. The energy
required for the reaction is 7 kcal.
- Substrate-level phosphorylation =
- Oxidative phosphorylation = ADP + p > ATP
This form requires mitochondria and oxygen.
When ATP is broken down energy is released. The reaction is called ATP hydrolysis.
3.5 phys. Glucose oxidation
We obtain energy by reacting oxygen with glucose.
Every mole glucose amounts to 686 kcal energy being released. > oxidation of one mole glucose is
enough energy to make 98 mole ATP. In reality only 32 mole is synthesized.
C6H12O6 + 6 O2 + 32 ADP + 32 P > 6 CO2 + 6 H2O + 32 ATP
The net energy change of this reaction is negative; thus, the reaction can proceed in forward
direction. About 33% of the 686 kcal is used.
3.6 phys. Stages of glucose oxidation
https://www.youtube.com/watch?v=00jbG_cfGuQ
crash course – ATP and Respiration
Stages of glucose oxidation >
1. Glycolysis
Splits glucose into 2x pyruvate.
2 ATP are consumed and 4 produced.
2 NAD+ are reduced to NADH for each glucose molecule.
Glucose + 2 NAD+ + 2 ADP + 2P > 2 pyruvate + 2 NAPH + 2 H+ + 2 ATP
Pyruvate will be used in the next step in glucose oxidation.
, 2. The Krebs cycle
The step that links glycolysis to the Krebs cycle is the conversion of pyruvate to acetyl CoA. One
glucose creates two acetyl CoA.
By the end two CO2 molecules have
been generated.
One ATP is generated.
3 NADH and 1 FADH2 are produced.
The final product is oxaloacetate.
(this reacts with acetyl CoA and the
cycle starts over again.)
4. Oxidative phosphorylation
Oxidative phosphorylation is derived of two steps, 1 electron transport through the mitochondrial
membrane and 2, harnessing the energy to make ATP called chemiosmotic coupling. The two
enzymes created in the Krebs cycle release their protons and electrons to the electron transport
chain.
Electrons pass through the chain and go from one acceptor to the next.
The created energy is used to transport hydrogen against the gradient of the mitochondrial
membrane. This hydrogen forms water as product.
A reduction in oxygen has the potential to stop/slow all ATP producing processes due to a depleting
supply of NAD+.
However, cells can break down LDH to produce NAD+, a byproduct of this reaction is lactate. > allows
muscles to keep working even when oxygen is low. When oxygen is again available lactate and NAD+
form LDH to prevent harmful side effects of lactate building up in cells.
Corgi cycle = lactate produced in muscle cells is transported to liver, converted to glucose and
transported back to muscle cells.
3.7 phys. Energy storage and use
Proteins and fats can be broken down to acquire energy or put together to store energy.
When glucose is abundant it is stored as glycogen = glycogenesis. Breaking down glycogen =
glycogenolysis.
The nervous system requires an uninterrupted glucose supply.
Creation of glucose can be done by the liver via gluconeogenesis. Sources can be; glycerol, lactate
and amino acids.
Adipose tissue is the primary storage for fat.
Breaking down of fat is called lipolysis. Breaking down of protein is called proteolysis.
21.1 phys. An overview of whole-body metabolism
Two critical concepts drive the control of energy. Food intake is intermittent, so the body must store
nutrients. Glucose level must always be maintained because the brain relies on it.
21.2 phys. Energy intake, utilization and storage
There are 3 possible fates for nutrients in a cell.
1. Biomolecules are broken down to release energy that’s used for the functioning of the cell
2. Biomolecules are used as substrate to create new molecules
, 3. Biomolecules are converted into energy storage molecules. (primary two: glycogen and
triglyceride.)
21.3 phys. Energy balance
The energy content of protein and carbohydrates is 4 calories per gram, fat is 9 calories per gram.
Energy output exists in two forms, heat and work. In the body 60% is heat, 40% is work.
Energy requiring processes in a cell can be mechanical (generate movement), chemical (form bonds)
and transport (move a molecule).
Amount of energy expended per minute = metabolic rate.
BMR is minimal/basal metabolic rate (energy required for performing necessary tasks). This varies
per tissue.
21.4 phys. Energy metabolism, absorptive and postabsorptive state
(anabolic reaction = construction of a molecule. Katabolic = deconstructing molecules)
Absorptive state (3/4 hours after eating) = primarily anabolic.
Skeletal muscle cells can convert glucose into glycogen. (most body cells can’t)
The liver converts glucose to glycogen and stores it. Triglycerides made from glucose are transported
to adipose tissue for storage. The liver also takes up amino acids, it can synthesize proteins but
mostly makes keto acids to then proceed to make fatty acids. Triglycerides are transported packaged
in very low-density lipoproteins, VLDLs.
Adipocytes store energy as triglycerides or fat.
The body’s ability to store fat is unlimited as opposed to glucose.
Postabsorptive state, nutrient absorption ceases in this state. It is primarily catabolic. The main
function is to maintain blood glucose levels. Glucose sparing is the process in which most tissues use
different energy sources to spare glucose to use for the nervous system. Most tissues use fatty acids
as energy.
The glucose in muscle cells derived from glycogen can only be used by that specific cell (it cannot be
moved out of the cell because it lacks the enzyme to remove a phosphate group that makes the
move impossible). The liver is the main source of plasma glucose.
Ketogenesis occurs in the liver during this state. Fatty acids are converted to ketones. These ketones
are needed by the nervous system to produce energy in times of prolonged fasting.
Adipose tissues supply fatty acids to the blood stream as energy for body cells.
, 21.5 phys. Regulation of absorptive and postabsorptive metabolism
Previous mentioned states are triggered by changes in insulin levels. Insulin promotes the synthesis
of energy storage molecules and other processes characteristic for the absorptive state.
Several factors influence insulin secretion. (like glucose levels and (para)sympathetic activity)
The liver and the nervous system are not affected
by insulin.
Glucagon counters insulins actions. They oppose each
other.
Insulin promotes absorptive state. (produced
by alpha cells in islets of Langerhans)
Glucagon promotes postabsorptive state.
(produced by beta cells)
When blood sugar decreases, insulin is inhibited
and glucagon released.
_________________________________________________________________________________
The Physiology book ends each chapter with a very concise, pointwise summary of each sub. chapter.
A - College H14. Energy metabolism and thermoregulation
3.4 phys. ATP
Cells temporarily save energy as ATP. This compound consists of ADP and phosphate, the reaction
between these two is a condensation reaction, the reaction is called phosphorylation. The energy
required for the reaction is 7 kcal.
- Substrate-level phosphorylation =
- Oxidative phosphorylation = ADP + p > ATP
This form requires mitochondria and oxygen.
When ATP is broken down energy is released. The reaction is called ATP hydrolysis.
3.5 phys. Glucose oxidation
We obtain energy by reacting oxygen with glucose.
Every mole glucose amounts to 686 kcal energy being released. > oxidation of one mole glucose is
enough energy to make 98 mole ATP. In reality only 32 mole is synthesized.
C6H12O6 + 6 O2 + 32 ADP + 32 P > 6 CO2 + 6 H2O + 32 ATP
The net energy change of this reaction is negative; thus, the reaction can proceed in forward
direction. About 33% of the 686 kcal is used.
3.6 phys. Stages of glucose oxidation
https://www.youtube.com/watch?v=00jbG_cfGuQ
crash course – ATP and Respiration
Stages of glucose oxidation >
1. Glycolysis
Splits glucose into 2x pyruvate.
2 ATP are consumed and 4 produced.
2 NAD+ are reduced to NADH for each glucose molecule.
Glucose + 2 NAD+ + 2 ADP + 2P > 2 pyruvate + 2 NAPH + 2 H+ + 2 ATP
Pyruvate will be used in the next step in glucose oxidation.
, 2. The Krebs cycle
The step that links glycolysis to the Krebs cycle is the conversion of pyruvate to acetyl CoA. One
glucose creates two acetyl CoA.
By the end two CO2 molecules have
been generated.
One ATP is generated.
3 NADH and 1 FADH2 are produced.
The final product is oxaloacetate.
(this reacts with acetyl CoA and the
cycle starts over again.)
4. Oxidative phosphorylation
Oxidative phosphorylation is derived of two steps, 1 electron transport through the mitochondrial
membrane and 2, harnessing the energy to make ATP called chemiosmotic coupling. The two
enzymes created in the Krebs cycle release their protons and electrons to the electron transport
chain.
Electrons pass through the chain and go from one acceptor to the next.
The created energy is used to transport hydrogen against the gradient of the mitochondrial
membrane. This hydrogen forms water as product.
A reduction in oxygen has the potential to stop/slow all ATP producing processes due to a depleting
supply of NAD+.
However, cells can break down LDH to produce NAD+, a byproduct of this reaction is lactate. > allows
muscles to keep working even when oxygen is low. When oxygen is again available lactate and NAD+
form LDH to prevent harmful side effects of lactate building up in cells.
Corgi cycle = lactate produced in muscle cells is transported to liver, converted to glucose and
transported back to muscle cells.
3.7 phys. Energy storage and use
Proteins and fats can be broken down to acquire energy or put together to store energy.
When glucose is abundant it is stored as glycogen = glycogenesis. Breaking down glycogen =
glycogenolysis.
The nervous system requires an uninterrupted glucose supply.
Creation of glucose can be done by the liver via gluconeogenesis. Sources can be; glycerol, lactate
and amino acids.
Adipose tissue is the primary storage for fat.
Breaking down of fat is called lipolysis. Breaking down of protein is called proteolysis.
21.1 phys. An overview of whole-body metabolism
Two critical concepts drive the control of energy. Food intake is intermittent, so the body must store
nutrients. Glucose level must always be maintained because the brain relies on it.
21.2 phys. Energy intake, utilization and storage
There are 3 possible fates for nutrients in a cell.
1. Biomolecules are broken down to release energy that’s used for the functioning of the cell
2. Biomolecules are used as substrate to create new molecules
, 3. Biomolecules are converted into energy storage molecules. (primary two: glycogen and
triglyceride.)
21.3 phys. Energy balance
The energy content of protein and carbohydrates is 4 calories per gram, fat is 9 calories per gram.
Energy output exists in two forms, heat and work. In the body 60% is heat, 40% is work.
Energy requiring processes in a cell can be mechanical (generate movement), chemical (form bonds)
and transport (move a molecule).
Amount of energy expended per minute = metabolic rate.
BMR is minimal/basal metabolic rate (energy required for performing necessary tasks). This varies
per tissue.
21.4 phys. Energy metabolism, absorptive and postabsorptive state
(anabolic reaction = construction of a molecule. Katabolic = deconstructing molecules)
Absorptive state (3/4 hours after eating) = primarily anabolic.
Skeletal muscle cells can convert glucose into glycogen. (most body cells can’t)
The liver converts glucose to glycogen and stores it. Triglycerides made from glucose are transported
to adipose tissue for storage. The liver also takes up amino acids, it can synthesize proteins but
mostly makes keto acids to then proceed to make fatty acids. Triglycerides are transported packaged
in very low-density lipoproteins, VLDLs.
Adipocytes store energy as triglycerides or fat.
The body’s ability to store fat is unlimited as opposed to glucose.
Postabsorptive state, nutrient absorption ceases in this state. It is primarily catabolic. The main
function is to maintain blood glucose levels. Glucose sparing is the process in which most tissues use
different energy sources to spare glucose to use for the nervous system. Most tissues use fatty acids
as energy.
The glucose in muscle cells derived from glycogen can only be used by that specific cell (it cannot be
moved out of the cell because it lacks the enzyme to remove a phosphate group that makes the
move impossible). The liver is the main source of plasma glucose.
Ketogenesis occurs in the liver during this state. Fatty acids are converted to ketones. These ketones
are needed by the nervous system to produce energy in times of prolonged fasting.
Adipose tissues supply fatty acids to the blood stream as energy for body cells.
, 21.5 phys. Regulation of absorptive and postabsorptive metabolism
Previous mentioned states are triggered by changes in insulin levels. Insulin promotes the synthesis
of energy storage molecules and other processes characteristic for the absorptive state.
Several factors influence insulin secretion. (like glucose levels and (para)sympathetic activity)
The liver and the nervous system are not affected
by insulin.
Glucagon counters insulins actions. They oppose each
other.
Insulin promotes absorptive state. (produced
by alpha cells in islets of Langerhans)
Glucagon promotes postabsorptive state.
(produced by beta cells)
When blood sugar decreases, insulin is inhibited
and glucagon released.
