WEEK 1: Nutrient uptake and metabolism Flashcards
what are conditionally-essential nutrients?
factors that cannot be synthesized fast enough to support growth or maintenance
what are non-essential nutrients?
factors that can be produced by the body/do not have defined issues resulting from deficiency. We don’t have a biological drive to consume these.
where is the major site of digestion?
small intestine. It requires enzymes from the pancreas
why is mechanical digestion important?
it releases nutrients and breaking down matrix structure of food to digest
what specialist proteins do hydrophilic nutrients require to cross cell membranes to be absorbed? What is this process called?
Monosaccharides
Amino acids
Ions
Co-transport
how does the epithelium support the co-transport of proteins?
produces sodium ions at a relatively high conc. The cellular conc of sodium ions remains low so the process can continue.
are lipids hydrophobic or hydrophilic?
hydrophobic
what is the function of the thoracic duct?
it transports lymph back into the circulatory system
hydrophilic factors go straight to the bloodstream. Where do lipid factors go?
lymphatic system
what is the hepatic portal system?
The hepatic portal system is the venous system that returns blood from the digestive tract and spleen to the liver
where does the hepatic portal system lead to?
the liver
which part of the blood stream do hydrophilic factors go?
hepatic portal system
what is a chylomicron?
a large lipoprotein structure
what is catabolism?
Catabolism is the breakdown of absorbed substances to their constituent parts which cause the release of free energy and production of ATP and NADH.
what is anabolism?
the synthesis of complex molecules, tissues and stores within the body. Requires input of energy to occur.
name one organ important in nutrient storage?
liver
what is a functional pool?
where nutrients are put to use, eg iron in rbcs
what is a storage pool?
where nutrients are stored
give an example where functional and storage pools over lap.
Calcium is stored in the bones and also utilised there
what stages occur when a nutrient is deficient.
low storage levels –> low tissue levels –> poor biochemical function
at what stage do deficiency symptoms appear?
poor biochemical function
what 1 vitamin can the body synthesize itself?
vitamin D
what is a vitamin?
Organic compounds that are required in small amounts for the normal functioning of the body and maintenance of metabolic integrity. They mostly cannot be synthesized by the body.
what foods are a source of vitamin C?
Green vegetables, citrus fruits, potatoes, berries
what are some roles of vitamin C? (4)
Collagen formation
Formation of adrenaline/noradrenaline
Absorption of iron
Antioxidant defence
what are some water soluble vitamins?
- vitamin C
- vitamin B group, this includes:
B1
B2
Niacin
Biotin
Pantothenic acid
B6
Folic acid
B12
where are fat soluble vitamins stored?
in the liver, along side water soluble B12
how are fat-soluble vitamins absorbed?
via co-transport alongside dietary fats/lipids
what are the fat-soluble vitamins?
Vitamin A (retinol, retinal, retinoic acid)
Vitamin D (ergosterol, cholcalciferol)
Vitamin E (tocopherol, tocotrienol)
Vitamin K (phylloquinone, menaquinone)
what are some roles of vitamin A? (4)
Vision pigment
Epithelial differentiation
Reproduction
Possible antioxidant roles
what are some roles of vitamin D? (2)
Bone maintenance/calcium homeostasis
Proposed roles in immune/inflammatory response
what is the role of vitamin E?
Membrane-bound protection against oxidative stress
what are some roles of vitamin K? (3)
Blood-clotting
Post-translation protein modification
Bone development and health
what percentage of vitamins are absorbed in the small intestine?
40 - 90 %
what do fat-soluble vitamins require to be absorbed?
dietary fats
what are minerals?
elements needed by the body in small amounts for health and maintenance.
what amount of major/macro minerals are needed?
diet in amounts greater than 100 mg per day or are present in the body in amounts greater than 0.01% of body weight
what amount of trace minerals are needed?
diet in amounts less than 100 mg per day or are present in the body in amounts less than 0.01% of body weight.
is iron a trace mineral or macro mineral?
trace mineral
where is iron stored?
in the liver and enterocytes bound to ferritin
what can happen if there is excess or an unbound iron state?
toxicity - can induce free radical formation
what percentage of dietary Fe is absorbed?
~10%
which is more readily to be absorbed? Fe3+ or Fe2+?
Fe2+ or haem Fe
what is transferrin?
a protein that transports iron in circulation
what processes does iodine deficiency affect?
thyroid hormones
which thyroid hormones in particular are affected by iodine deficiency?
T3 and T4
what does the exocrine pancreas digest?
macronutrients
what does the endocrine pancreas do?
helps utilise absorbed macronutrients via insulin and glucagon
when there are no energy sources for the body (starvation), what is used as a source?
protein in the body starts being utilised
insulin drives the synthesis of?…
triglycerides
how is fructose (sugar) absorbed by the intestine?
converted into phosphorylated compounds that enter the glycolytic pathway
how is galactose (sugar) absorbed by the intestine?
converted into phosphorylated glucose
