Energy Balance I - Macronutrients Flashcards
Nutrition:
total of the processes of ingestion, digestion, absorption, and metabolism of food and the subsequent assimilation of nutrient materials into the tissues
Nutrient:
a substance found in food that performs one or more specific functions in the body
The food we eat is part of our _____ and contains ____.
- nutrition
- nutrients
Food provides nutrients that have one or more _____ or _____ functions in the body.
- physiological
- biochemical
Nutrients are usually divided into 6 different categories:
- carbohydrates
- fats
- proteins
- vitamins
- minerals
- water
Nutrients for which the daily intake is more than a few grams are referred to as _____.
macronutrients
4 macronutrients:
- carbohydrate
- fat
- protein
- water
3 micronutrients:
- vitamins
- minerals
- trace elements
Nutrients that are needed in only small amounts (less than 1 g/day) are referred to as _____.
micronutrients
Most nutrients are ______.
micronutrients
3 functions of nutrients:
- promotion for growth and development
- provision of energy
- regulation of metabolism
Growth and development function of nutrients is mainly performed by _____.
protein
____, ____ _____, and ____ consist largely of proteins, and proteins are required for any ____ ____ or ____.
- muscle
- soft tissues
- organs
- tissue growth
- repair
_____ and _____ are important building blocks for the skeleton.
- calcium
- phosphorus
Provision of energy function of nutrients is mainly performed by ____ and ______.
- carbohydrate
- fat
Although protein can also function as fuel, its contribution to EE is usually _____.
limited
Nutrients used for the regulation of metabolism:
- vitamins
- minerals
- protein
Enzymes:
proteins that play an important role as catalysts that allow metabolic reactions to proceed at far higher rates than they would spontaneously
The interaction between _____, _____, and _____ in the regulation of metabolism can be complex.
- vitamins
- minerals
- proteins
Ex. of an enzyme:
- phosphorylase: breaks down carb stores in liver and muscles
- hemoglobin: found in erythrocytes (RBC)
Describe the hemoglobin molecule. Complex of….
- protein (polypeptide chains)
- non protein groups (porphyrin rings) that hold iron (to which oxygen molecules can be bound)
Macronutrients are molecules that provide _____.
energy
The general formula of a carbohydrate is:
CH2O
A carbohydrate can be one or a combination of many of these _____ units.
CH2O
4 types of carbohydrates:
- monosaccharides
- disaccharides
- polysaccharides
- fibre
Saccharides =
sugars
Examples of mono and disaccharides:
- sugar
- fruit juices
- fruits
- sweetened cereals and baked goods
- jam
- candy
- chocolate
Examples of polysaccharides:
- starches
- cereal
- potatoes
- pasta
- rice
- bread
Examples of fiber:
- whole grain cereals
- oats
- fruits
- vegetables
Glycogen is a ______. It is stored in _____ and _____.
- polysaccharide
- liver (80-100 g)
- skeletal muscles (300-900 g)
Glycogen is the storage form of _____ in animals, including humans.
carbohydrate
Dietary fibre comprises the _____ parts of plants that ____ broken down and absorbed in the _____ ____ _____.
- edible
- are not
- human gastrointestinal tract
Fibre = ____ plant _____.
structural plant polysaccharides
The human small intestine has no ____ to break down these _____ (fibre) and thus they ______ be digested.
- enzyms
- polysaccharides
- cannot
Dietary fibre is often divided into:
- soluble fibre
- insoluble fibre
Insoluble fibre:
possesses water attracting properties that help increase bulk, soften stool, and shorten transit time through the intestinal tract
Soluble fibre:
undergoes metabolic processing through fermentation and yields end products that have broad, significant health effects
Examples of insoluble fibre:
- whole grain foods
- bran
- nuts
- seeds
- vegetables (green beans, cauliflower, zucchini, celery)
- skins of some fruits (tomatoes)
Examples of soluble fibre:
- legumes
- oats
- rye
- barley
- some fruits and fruit juices (prune, plums, berries)
- vegetables (broccoli, carrots)
- root vegetables (potatoes, onions)
6 metabolic pathways of carbohydrate metabolism:
- glycogenesis
- glycogenolysis
- glycolysis
- gluconeogenesis
- tricarboxylic acid cycle
- pentose phosphate pathway
Glycogenesis:
synthesis of glucose
Glycogenolysis:
breakdown of glycogen
Glycolysis:
oxidation of glucose
Gluconeogenesis:
production of glucose from non-carb intermediates
Tricarboxylic acid cycle:
- Krebs cycle
- oxidation of pyruvate and acetyl CoA to CO2 and H2O
Pentose phosphate pathway:
production of pentose phosphates and nicotinamide adenine dinucleotide phosphate (NADPH)
*See chart
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Fat or lipids are compounds that are _____ in ______ solvents such as _____, _____, and ______.
- soluble
- organic
- acetone
- ether
- chloroform
Oil is ____ at room temperature.
liquid
Fat is ____ at room temperature.
solid
Lipids are molecules built of:
- carbon
- hydrogen
- oxygen
Lipids have little ____ relative to ____ and ____.
- O
- C and H
Typical structure of fatty acid is:
16 C, 32 H, and 2 O
Simple lipids type:
- neutral fats
- waxes
Examples of simple liquids:
- neutral fats: triacylglycerol
- waxes: beeswax
Compound lipids type:
- phospholipids
- glycolipids
- lipoproteins
Examples of compound lipids:
- phospholipids: lecithins
- glycolipids: cerebrosides
- lipoproteins: chlomicrons
Derived lipids type:
- fatty acids
- steroids
- hydrocarbons
Examples of derived lipids:
- fatty acids: palmitic acid
- steroids: cholesterol
- hydrocarbons: terpenes
Triacylglycerols =
- triglycerides
- the most abundant dietary lipids consumed humans
Triglycerides are composed of ….
1 glycerol backbone esterified with 3 fatty acids
Triglycerides differ in their ____ _____ composition.
fatty acid
Lipids in the human body include…
- fatty acids
- triacylglycerols
- lipoproteins
- phospholipids
Fatty acids differ in their chain length (number of carbons):
- short chain fatty acids (SCFAs): < or equal to C6
- MCFAs: C8 or C10
- LCFAs: > or equal to C12
Fatty acids differ in the number and location of double bonds:
- saturated fatty acids (SFAs): no double bonds
- monounsaturated fatty acids (MUFAs): 1 double bond
- polyunsaturated fatty acids (PUFAs): > or equal to 2 double bonds (n-3 and n-6)
Trans fatty acids:
unsaturated fatty acids that contain at least one double bond in the trans configuration (opposite sides)
Naturally occurring trans fatty acids:
produced in the gut of some animals and foods made from these animals (eg. milk and meat products)
Artificial trans fatty acids:
created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid
Fatty acids containing a trans double bond have….
- decrease mobility
- reduced fluidity
- hardening of fat
Why are trans fatty acids/fats so popular?
- easy to use
- inexpensive to produce
- last a long time
- give foods a desirable taste and texture
Consumption of trans fats increases the risk of coronary heart disease by….
raising levels of bad LDL cholesterol and lowering levels of good HDL cholesterol
Cholesterol:
lipid found in the cell membranes of all animal tissues
Cholesterol is transported in the ____ _____.
blood plasma
Cholesterol is considered a sterol, meaning it is a combination of ….
- steroid
- alcohol
Cholesterol is required to ….
build and maintain cell membranes
Cholesterol regulates ____ _____ over a wide range of ______.
- membrane fluidity
- temperatures
Cholesterol is important to maintain ______.
homeostasis
Functions of cholesterol:
- aids in the manufacture of bile
- is important for the metabolism of fat soluble vitamins
- is the major precursor for the synthesis of vitamin D and various steroid hormones
Bile:
- stored in the gallbladder
- helps digest fats
Lipids are an important ____ ____, especially during prolonged exercise.
energy source
Large amounts of ____ can be stored in the body.
fat
Fat is stored mainly in _____ _____ _____ from which it is mobilized and transported to the organ that uses it.
subcutaneous adipose tissue
Skeletal muscle contains a directly accessible store of fat called….
intramuscular triacylglycerol
Lipids have many important functions:
- fuel most cells, important fuels for the contracting muscle
- protects vital organs
- intake of fat soluble vitamins A,D,E and K and carotenoids depends on daily fat intake
- provide the transport medium in the body
- makes food more tasty and attractive
How does fat protect vital organs?
a layer of adipose tissue covers these organs to protect them against trauma
Only some of the lipid forms can be used as a fuel. Oxidizable lipid fuels include:
- fatty acids
- intramuscular triacylglycerols
- circulating plasma triacylglycerols
The regulation of fatty acid oxidation is closely linked to ______ _____.
carbohydrate status
When CHO levels are low, to obtain energy from fat…..
- triglycerides must first be broken down by hydrolysis into glycerol and fatty acids
- process is called lipolysis
Lipolysis happens in the _____.
cytoplasm
In the mitochondrion, the resulting fatty acids are oxidized by _______ into ____ ____, which is used by the _____ cycle.
- beta-oxidation
- acetyl CoA
- Krebs
Fatty acids –> (beta oxidation) ____ ____ –> (Krebs cycle) ____
- acetyl CoA
- energy
The _____ that is released from triglycerides after lipolysis directly enters ____ ____.
- glycerol
- glycolysis pathway
If excessive acetyl CoA is created from the oxidation of fatty acids and the _____ _____ is overloaded and cannot handle it, the acetyl CoA is diverted to create _____ _____.
- Krebs cycle
- ketone bodies
3 ketone bodies:
- beta-hydroxybutyrate
- acetoacetate
- acetone
When glucose levels are plentiful, the excess acetyl CoA generated by glycolysis can be converted into ____ and subsequently _____. This process, called ______ creates _____ from the acetyl CoA.
- fatty acids
- triglycerides
- lipogenesis
- lipids
Lipogenesis takes place where?
in the cytoplasm of adipocytes and hepatocytes
Each amino acid consists of a _____ atom bound to 4 chemical groups:
- carbon
- a hydrogen atom
- an amino group, which contains nitrogen
- a carboxylic acid group
- a side chain, which varies in length and structure (different side chains give different properties to the amino acid)
Of the ____ amino acids normally found in dietary protein, humans can synthesize ____.
- 20
- 11
The amino acids that can be synthesized =
nonessential AA
The AA that cannot be synthesized and must be derived from the diet =
essential AA
AA have central roles in the _____ of many organs and tissues.
metabolism
AA –> precursors for the synthesis of ____ ____ + precursors and regulators of the synthesis of important _____ _____ and compounds with a ____ ____ ____.
- body proteins
- metabolic mediators
- regulatory biological activity
Ex. of AA:
- neurotransmitters
- hormones
- DNA
- RNA
Proteins provide _____ to all cells in the human body
structure
Proteins are a integral part of the …
- cell membrane
- cytoplasm
- organelles
Many proteins are ____ that increase the rate of metabolic reactions.
enzymes
____, _____, and _____ are composed largely of proteins.
- muscle
- skin
- hair
____ and _____ are composed of minerals embedded in a protein framework.
- bones
- teeth
When a diet is deficient in protein, structures break down, resulting in:
- reduced muscle mass
- loss of skin elasticity
- thinning hair
Muscle is mostly _____. _____ is a good source of protein.
- muscle
- meat
Most common sources of protein:
- meat
- fish
_____ could be at risk for marginal protein intake, and often compensate by eating more _____ and ____.
- vegetarians
- grains
- legumes
Grains and legumes do not contain all essential AA:
- grains: lack lysine
- legumes: lack methionine
- exception: well processed soybean protein
____ of a protein relates to the degree to which that protein contributes to daily requirements.
quality
Most recent method to measure the protein quality of food:
protein digestibility corrected AA score (PDCAAS)
PDCAAS evaluates protein quality based on the ____ requirements of humans.
AA
PDCAAS: Protein quality rankings are determined by comparing the ____ ____ ____ of a specific food protein against a ____ ____ ____ ____. Maximum score = _____.
- amino acid profile
- standard amino acid profile
- 1.0
Score of 1.0 in PDCAAS means…
after digestion of the protein, it provides, per unit of protein, 100% or more of the indispensable AA required
_____ and ____ of protein are important.
- amount
- quality
High quality protein:
contains all the essential AAs (9)
Incomplete or low quality protein:
protein that is deficient in one or more AA (unable to support human life and growth)
____ protein is generally of higher quality than ____ protein. Why?
- animal
- plant
- all essential AA are present
- in larger quantities and in proper proportions
An appropriate selection of _____ _____ sources can provide an adequate supply of ____, but consumption of ____ _____ is more likely to ensure a balanced intake.
- plant protein
- AA
- animal protein
Protein from different sources that balances the AA intake is called…..
complimentary protein
By combining plant foods such as ____ and ____, it is possible to obtain a balanced intake of AA.
- rice
- beans
Ingested AA are transported into the ____ for dispersal to the ____ and _____ throughout the body to be used to create new proteins.
- bloodstream
- liver
- cells
If AA exist in excess, the body has no capacity or mechanism for storage; thus they are converted into ____ or ____, or they are _____.
- glucose
- ketones
- decomposed
AA decomposition results in _____ an ____ waste.
- hydrocarbons
- nitrogenous
The _____ waste that is liberated in AA decomposition is converted to ____ in the ____ cycle and eliminated in the ____.
- nitrogen
- urea
- urea
- urine
AA can also be used as a source of _____ especially in times of starvation.
energy
Processing of AA results in the creation of metabolic intermediates, including:
- pyruvate
- acetyl CoA
- acetoacyl CoA
- oxaloacetate
- -a- ketoglutarate
AA can serve as a source of energy production through the ____ ____.
Krebs cycle
