nutrition 1 Flashcards
what is a nutrient
a substrate found in food that performs one or more specific functions in the body
macronutrients are..
-carbohydrates
-fat
-protein
-water
>1g/day
micronutrients are…
-vitamins
-minerals
-trace elements
<1 g/day
what are the functions of nutrients?
- provision of energy
- regulation of metabolism
- promotion of growth and development
what are essential nutrients?
cannot be synthesised by the body so must be obtained through diet
what are non essential nutrients?
can be synthesised by the body and can also be essential for the body but no need to obtain from diet
what are conditionally essential diets?
essential at certain times/conditions
what are dietary reference values?
estimates of the nutrient requirements for groups or populations
Estimated Average Requirement (EAR)
average requirement for energy or a nutrient - approximately 50% of a group of people will require less and 50% will require more
Reference Nutrient Intake (RNI)
amount of nutrient that is enough to ensure the needs of nearly all the group (97.5) are being met
Lower Reference Nutrient Intake (LRNI)
the amount of a nutrient that is enough for only the small number of people who have low requirements 2.5 %
Safe Intake
amount judged to be a level or range of intake at which there is no risk of deficiency or toxicity risk
what is the protein requirement and intake?
EAR- 0.6 g/kg/day
RNI - 0.75 g/kg/day
what happens in the mouth?
mechanical breakdown
mixing
starch and lipid degradation
what happens in the stomach?
- storage
- mixing
- sterilization
- protein hydrolysis
- lipid digestion
- emulsification
what happens in the small intestine?
- enzyme hydrolysis
- exit fatty acids, amino acids, water,monosaccharides, micronutrients
what happens in the large intestine?
- fermentation dehydration
- exit short chain fatty acids, water minerals, gas production
what are the functions of carbohydrates?
- energy
- central nervous system
- fibre : health and benefits
- physical activity
carbohydrates are made up of:
glucose
fructose
galactose
glucose + glucose = maltose
glucose + fructose= sucrose
glucose + galactose= lactose
How is glucose and galactose transported form the intestinal lumen to the blood?
By SGLT1 and GLUT 2
How is fructose transported from the luminal membrane to the blood?
By GLUT 5 and GLUT 2
Approximately how much glucose is transported to the muscle ?
5 mmol/l
What are the functions of lipids ?
- fuel source
- protection of vital organs
- cell membrane constituents
- precursors of bile, hormones, and steriods
- fatsoluble vitamin intake
- palatability
where are triglycerols found ?
in plasma incorporated into the core of a lipoprotein
How are lipids absorbed?
through free fatty acids
TG are recycled in liver and stored or oxidised in adipose
exciting stuff basically
what are the functions of proteins?
- provide structure to all cells in the human body
- enzymes that increase the rate of metabolic reactions
- central role in the metabolism of many organs and tissues
- precursor for synthesis of body proteins
- precursor and regulators of the synthesis of neurotransmitters, hormones, DNA and RNA
essential amino acids
- histidine
- leucine
- isoleucine
- lysine
- methionine
- phenylalanine
- threonine
- tryptophan
- valine
ingested amino acids can
contribute to protein turnover
where is water found ?
2/3 in cells
1/3 extracellular
60% of the body
intake normally 2 l/day
functions of water
- nutrient transport
- protection
- temperature regulation
- biochemical reactions
- medium for reactions
where does 95% of the absorption take place ?
duodenum and jejunum of small intestine
