Almost all information given during the lectures of food and metabolism in 2021, all in one document. Including pictures from the slides for more clarification
FOOD AND METABOLISM
At the end of the course the student is able to:
• Describe the different basic components of food
• Describe the uptake mechanisms and transport routes of these nutrients
• Explain the relation between metabolism and health
• Explain how food can influence metabolism and plays a role in the pathogenesis of different
chronic diseases
• Evaluate food composition on the possible consequences on health
• Summarize scientific literature and write a review in the field metabolism, nutrition and health
LECTURE 1. ENERGY METABOLISM
Chapter 15,16,17 & 18
Metabolism is the sum of catabolic and anabolic
reactions in a cell. There are quite a few reactions in a
cell, they all have to collaborate, and it is a highly
integrated system.
ATP is the universal currency of free energy. The
hydrolysis of ATP to ADP result in about 30
kJ/mole. The regeneration of ATP is done by the
oxidation of fuel molecules.
Starting to sprint, the ATP will decline fast. In
muscles creatine phosphate is used to create
more phosphate. The Creatine phosphate will
even create more kJ per mole. However, when
the creatine phosphate is depleted you need different sources like aerobic and anaerobic metabolism.
Stages of catabolism:
1. Large molecules to smaller molecules: no ATP production
2. Smaller molecules to acetyl coA: little ATP production
3. Citric acid cycle: ATP production
Glycolysis is the main pathway by which glucose is converted into
acetyl CoA which than can go into the citric acid cycle. By the
,glycolysis you get ATP production. This can lead to muscle fiber
contractions. After glycolysis you will end up with pyruvate, this can
either be turned into lactate or it can go into the mitochondria and
generate ATP out of it.
If you look at glycolysis, the first steps will cost ATP, stage 2 of glycolysis
generates ATP.
If it ends here, you would have a problem, because the NAD+ is limited,
so it should be regenerated which can take place in 3 ways, but our
body mainly uses 2.
If there is low consumption of ATP the production will be
blocked. During exercise the flux trough glycolysis is increased.
Not only your muscle uses a lot of glucose, rapid growing cells also do
this. Rapid growing cells can be for example tumor cells. Radio labeled
dioxyglucose is visualized with a PET scan, this way tumor can be found.
Hypoxia alters gene
expression and increase flux
through glycolysis. High
lactate production leads to
inhibition of local immune
system. Anaerobic exercise
training enhances muscle
strength.
Summary >>>>>
,To continue the oxidation of pyruvate, it has to
enter the mitochondria. The first step is to go
from pyruvate to acetyl coA. This is done by
pyruvate dehydrogenase and is an irreversible
reaction. This process is highly regulated by
the energy status of the cell. When there is a
high energy charge there is a low flux. When
the energy charge is low there will be an
increase in the flux.
Slide 27 en 28!
The net yield of glucose oxidation is 30 ATP, 4 NADH
and 2 FADH2.
Uncoupling proteins decrease the proton gradient
resulting in decreased ATP synthesis.
Uncoupling proteins decrease the proton gradient
which results in decreased ATP synthesis. The UCP
leaks away protons. This is done in brown adipose
tissue. And the fatty acids in the adipose tissue can
activate the UCP1.
This leakage of protons and the disruption of the connection of glucose and ATP synthesis results in
heat formation. This heat formation is important in for example hibernating animals. Babies also use
this, because they lose a lot of cold because of their large surface area, this brown fat keeps them
warm.
Long time people thought when you age, the brown adipose
tissue decreases, this is true. But it never fully goes away,
the brown fat can be activated by cooling.
When you get older you have less brown fat but this can still
be activated, the brown fat uses a lot of energy
People that are used to cold temperatures usually have higher amounts of brown fat, people with
obesity usually have a lower amount of brown fat, but a higher amount of white fat.
, Summary: >>>>>>
LECTURE 2. CARBOHYDRATE METABOLISM
Chapter 16.3, 16.4 and 21
Our brain uses 120 gram glucose per day which are approximately 30 sugar cubes. The transport of
the glucose to the brain is via the blood. The blood glucose is tightly regulated between 4 and 6 mM
which is about 4 grams in adults. Part of this glucose originates from the carbohydrates from your food
which are digested and absorbed into the blood. Excess glucose can be stored as glycogen in the liver
or as fat in the adipocytes.
If you are not eating your brain and other cells still need energy. The stored glycogen in the liver is
used as a source for this energy. Breakdown of this glycogen is called glycogenolysis, which is for short-
term fasting. For long term fasting or increased energy demand gluconeogenesis is used for the
production of glucose out of amino acids and glycerol.
Cells in your body can switch between glucose and fatty acid
oxidation ^^^^. So, the nutrition status determines the glucose
use and glucose source. >>>
Failure of the regulation of blood glucose leads to the group of
metabolic diseases characterized by high blood sugar; diabetes
mellitus. Elevated levels of blood glucose (hyperglycemia) lead
to spillage of glucose into the urine. The diagnosis:
• Fasting glucose > 6.9 mM
• Random glucose > 11.1 mM
• Oral glucose tolerance test > 11.1 mM at 2 hr
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