Diet and metabolism Flashcards
nutrition definition
scientific study of the sum of the processes concerned with growth maintenance and repair of the living body
nutrients definition
components of food which have recognisable functions in the body
essential nutrients definition n
can’t be made by the body
water
conditionally essential nutrients
when the body is unable to synthesise enough to meet normal metabolic demand
e.g. disease induced deficiency
chemical strucure of food affects what
the way nutrients are handled in the body
glycaemic index
how quickly a carbohydrate containing food causes an increase in blood glucose
what can carbohydrates be
high or low GI index
high GI index example
simple carbohydrate such as glucose solution
low GI index example
complex carbs e.g. starch
takes longer to release individual glucose molecules
factors affecting how quickly carbohydrates from food are released into the blood stream
how refined carbohydrate is: processed CHO has fibre removed so broken down more rapidly
physical structure: wheat has fine particles giving increased surface area
how carbohydrate is cooked: increased cooking increases GI of pasta, al dente has lower GI
which factors slow down digestive enzymes and speed of digestion
fibre protects starch from digestive enzymes or the speed of digestion
fat and/or acid delays gastric emptying and slows breakdown of carbohydrate and absorption of glucose
graph displaying GI breakdown time
factors affecting obesity
lack of information about what constitutes a healthy diet, including portion sizes
motivation to adhere to healthy diet
calorie rich fast food is cheap and easily available, healthy options are often expensive
takes time and planning to prepare healthy meals and life is bus y
childhood obesity as an emerging problem
overweight child often becomes obese adult
develops health issues as a consequence
malnutrition and ill health spiral
what does the body do with its nutrients
catabolism
anabolism
catabolism definition
breakdown of complex molecules to release energy
anabolism definition
use of energy to construct molecules
what is metabolism composed of
catabolism and anabolism
catabolism
anabolism
stored glucose
glycogen
glucose as energy
pyruvate
glucose conversion
ribose 5-phosphate
glucose to glycogen
stored in the muscle and liver
anabolic
glycolysis
1 molecule of glucose to 2 pyruvate
pyruvate enters citric acid cycle to provide further energy
pyruvate also able to enter other pathways
ribose-5-phosphate
nucleotide precursor via anabolic pathway
generated by pentose phosphate pathway
releases energy
phosphorylation of glucose
by glucokinase
and one molecule of ATP
forms glucose 6 phosphate which is common to all pathways of carb metabolism in liver
lactate from anaerobic metabolism
can be utilised by converting to pyruvate
then to glucose
via cori cycle
potential uses of carbohydrate metabolism in the liver
release as blood glucose for transport and used elsewhere
stored as glycogen
produced energy in citric acid cycle
conversion to something else via pyruvate and acetyl co enzyme A
conversation to something else via ribose 5 phosphate
conversion to something else via pyruvate and acetyl co enzyme A, liver metabolism
cholesterol (steroid hormones, bile, fat soluble vitamins)
free fatty acids (alternative mitochondrial energy supply)
triacylglycerol and phospholipids (fat=energy storage)
conversion to something else using ribose-5-phosphate carb metabolism liver
nucleotides for RNA/DNA/ATP
carbohydrate metabolism in the liver basic concept
catabolic hormones: glucagon and adrenaline
work to oppose
anabolic hormone: insulin
what does insulin promote in carbohydrate metabolism in the liver
glycogen synthesis
glucose metabolism
storage of fatty acids in the adipose tissue, adipogenesis
what does insulin inhibit carbohydrate metabolism in the liver
glycogen breakdown
gluconeogenesis, don’t need extra glucose in fed stated
what does glucagon/adrenaline promote carbohydrate metabolism in the liver
glycogen breakdown
gluconeogenesis, do need extra glucose if fasted/stress
GLUT2 glucose transport protein function
facilitates uptake of glucose by liver
glucose metabolism after an overnight Fast basic
anabolism off
catabolism on
mechanism of glucose metabolism after and overnight fast
gluconeogenesis promoted by high glucagon
kidney also able to contribute to gluconeogenesis
most glucose used by brain as in short supply
other tissues used alternative substrates e.g. fatty acids and ketones in presence of low insulin
glucose metabolism in the Fed state basic
anabolism on
catabolism off
mechanism of glucose metabolism in the Fed state
high insulin : glucagon
brain continues to use glucose but other tissues switch to using glucose for metabolism and storage following uptake of glucose from small intestine and release of insulin from pancreas
muscle in fed state
glucose metabolism and glycogen storage
adipose in the fed state
glucose take up and stored as fat
liver in Fed state
glycogen storage promoted and gluocneogenesis suppressed
potential uses of fat metabolism in the liver
storage in adipose tissue
energy production
ketone bodies
cholesterol
energy production fat metabolism in liver
beta oxidation to acetyl co enzyme A via citric acid cycle
conversion to something else via acetyl co enzyme A
ketone bodies fat metabolism in liver
gluconeogenesis by product
used as fuel
release of fat metabolism in liver mechanism
released as
plasma lipoproteins e.g. VLDL or HDL
free fatty acids
fat metabolism in the liver
without insulin fatty acid entry into the mitochondria and ketone body synthesis are unrestricted
beneficial as allows body to function in absence of glucose
detrimental in type 1 diabetes as leads to diabetic ketoacidosis DKA
what is cholesterol
waxy
fat like substance
travels through blood on proteins called lipoproteins
2 sources of cholesterol
It’s made by your body and used to make hormones and digest fatty foods.
It’s found in foods – Eg, egg yolks, fatty meats, and “regular” cheese.
what happens when boy has too much cholesterol
When your body has too much cholesterol, it can build up on the walls of your blood vessels. These deposits are called plaque.
As your blood vessels build up plaque deposits over time, the inside of the vessels
narrow and allows less blood to flow through to your heart and other organs.
When plaque build up totally blocks a coronary artery carrying blood to the heart, it causes a heart attack.
other than narrowing of arteries due to plaque how else may a heart attack occur
Another cause of heart attack is when a plaque deposit bursts and releases a clot in
a coronary artery.
cause of angina
Angina is caused by plaque partially blocking a coronary artery, reducing blood flow to the heart and causing chest pain.
facts about cholesterol
doesn’t dissolve well in blood
attaches itself to the fatty proteins to circulate through the body
when talking about specific cholesterol types what does that mean
different types of proteins that carry cholesterol in the bloodstream
HDL, high-density lipoprotein
tightly bound to cholesterol
won’t let it get loose to attach to arterial walls
may pick up cholesterol attached to wall
reduces deposit side
keeps cholesterol in solution
moves it safely
GOOD cholesterol
LDL, low-density lipoprotein
deposits cholesterol on walls of arteries
becomes oxidised and damages lining of arteries
allowing mineral and fat deposits
triglycerides
type of blood lipid often misunderstood as cholesterol type
fat metabolism in the fasted state
low insulin means anabolism off and catabolism on
lipolysis occurs
stored fat (TAG, triacyclglycerol) broken into 2 components
breakdown of TAG
NEFA= FFA used as energy by muscle, liver and kidneys
also to ketone bodies and some back to TAG
glycerol used by liver for TAG production, glycolysis and gluconeogenesis
fat metabolism in the Fed state
fat absorbed from the small intestine is packaged in TG rich particles (chylomicrons) transported via lymphatic
activation of lipoprotein lipase LPL in adipose tissue and muscle released NEFA or FFA, can be taken up and stored as TAG
protein metabolism basics
Proteins contain a combination of Sulphur and Nitrogen in addition to Carbon, Hydrogen and Oxygen (unlike Carbohydrate and Fat)
Proteins are large molecules, broken down to their constituent amino acids during digestion
potential uses of liver amino acids
- Synthesis of Liver / Plasma Proteins (Albumin, Globulins, Coagulation)
- Released via blood for Tissue Protein synthesis
- Conversion to something else (Nucleotides, Hormones, Porphyrins)
- Catabolism via Urea/Ornithine Cycle – generates Urea and Ammonia
Pyruvate and Acetyl CoA as intermediate steps for
a. Gluconeogenesis and Glycogen storage
b. Energy production
c. Fatty acid synthesis - Alanine from muscle converted into Pyruvate and used for energy via the Citric acid cycle or used for gluconeogenesis
