LIPIDS Flashcards
(140 cards)
1
Q
- a family of substances that are insoluble in water but soluble in nonpolar solvents and solvents of low polarities, such as diethyl ether.
- They are not defined by functional groups, thus they have a variety of structures and functions.
- They contain many nonpolar C—C and C—H bonds and few polar bonds resulting in their water insolubility.
- found in biological systems are either hydrophobic or amphipathic.
A
Lipid
2
Q
- a heterogeneous group of compounds that are related more by their physical than by their chemical properties.
- They are relatively insoluble in water and soluble in a non-polar solvent.
- It is greasy to touch and leaves a permanent oily stain on the paper.
- lighter than water
- poor conductors of heat and electricity and therefore serve as excellent insulators for the body, slowing the loss of heat through the skin.
A
Lipids
3
Q
Are colorless with bland odor and taste. When heated strongly, undergoes decomposition forming acrid flammable vapors and when ignited, they burn with a sooty flame.
A
Pure lipids
4
Q
a major source of energy for the body, and they also provide the hydrophobic barrier that permits the partitioning of the aqueous contents of cells and subcellular structures.
A
Lipids
5
Q
also act as precursors for other lipids and play a role in the transport of other lipids in the body. They also function as emulsifying agents in the gastrointestinal tract.
A
lipids
6
Q
Deficiencies or imbalances of lipid metabolism
A
can lead to some of the major clinical problems encountered by physicians, such as atherosclerosis and obesity.
7
Q
REACTIONS OF LIPIDS
A
HYDROLYSIS
HYDROGENATION
OXIDATION
8
Q
Fats and oils can be hydrolyzed in the presence of an acid, a base, or specific enzymes known as lipases.
A
Hydrolysis
9
Q
The hydrolysis of fats and oils in the presence of a base is used to make soap and is called
A
saponification.
10
Q
Acid, base, or specific enzymes used to hydrolyze fats and oils are called
A
lipases
11
Q
Fats and oils that are in contact with moist air at room temperature eventually undergo oxidation and hydrolysis reactions that cause them to turn rancid, acquiring a characteristic disagreeable odor
A
Oxidation
12
Q
The double bonds in fats and oils can undergo ____.
Chemically, it is essentially identical to the catalytic hydrogenation reaction described for alkenes.
A
Hydrogenation
13
Q
CATEGORIES OF LIPIDS
A
HYDROLYZABLE
NONHYDROLYZABLE
14
Q
can be converted into
smaller molecules by hydrolysis.
A
Hydrolyzable lipids
15
Q
Cannot be cleaved into
smaller molecules by aqueous hydrolysis.
A
Nonhydrolyzable lipids
16
Q
Hydrolyzable lipids are derived from ______
A
fatty acids
17
Q
carboxylic acids (RCOOH) with
long C chains of 12-20 C atoms.
have an even
number of C atoms.
A
Fatty acids
18
Q
have no double bonds
in their long hydrocarbon chains.
A
Saturated fatty acids
19
Q
have 1 or more double
bonds (generally cis) in their long hydrocarbon
chains.
A
Unsaturated fatty acids
20
Q
are essential fatty
acids; they cannot be produced by the body
and must be consumed.
A
Linoleic and linolenic acids
21
Q
called an omega-6 acid, because
of the position of the first C=C in the nonpolar chain.
A
Linoleic acid
22
Q
called an omega-3 acid, because
of the position of the first C=C in the nonpolar chain.
A
Linolenic acid
23
Q
- esters formed from a fatty acid and a
high molecular weight alcohol. - hydrophobic due to long nonpolar C chains
- They form protective coatings on bird’s feathers
and sheep’s wool and make up beeswax. - hydrolyzed with water
in the presence of acid or base to re-form the
carboxylic acid and alcohol they came from.
A
Waxes
24
Q
three esters
formed from glycerol and three molecules of
fatty acids.
A
Triacylglycerols (triglycerides)
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Triacylglycerols that have three identical fatty
acid side chains
Simple triacylglycerols
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Triacylglycerols that have two or three different
fatty acids.
Mixed triacylglycerols
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Triacylglycerols that contain only saturated
fatty acids; they make up most animal fat and are
solids at room temperature.
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Saturated triacylglycerols
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triacylglycerols that contain at least one
unsaturated fatty acid; they make up most
vegetable oils and are liquids at room temperature.
Unsaturated triacylglycerols
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triacylglycerols that have 1 C=C bond.
Monounsaturated triacylglycerols
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triacylglycerols have many C=C
bonds.
Polyunsaturated triacylglycerols
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________ the number of double bonds in the
fatty acid chain __________ the melting point of the
triacylglycerol.
19
Increasing
decreases
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- have higher melting points; they are solids
at room temperature.
- are derived from fatty acids with few double
bonds.
Fats
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- have lower melting points; they are liquids
at room temperature.
- are derived from fatty acids having a larger
number of double bonds.
Oils
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used to build cell membranes, insulate
the body, and store energy for later use.
fats
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It is recommended that no more than _____% of a
person’s caloric intake should come from lipids
20-35%
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A high intake of ________________ is
linked to heart disease
saturated triacylglycerols
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stimulate cholesterol synthesis,
which can lead to cholesterol plaques building up
inside arteries.
Saturated fats
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lower the risk of
heart disease by decreasing the level of cholesterol
in the blood.
Unsaturated triacylglycerols
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are
very helpful in lowering the risk of heart attack.
Triglycerols formed from omega-3 fatty acids
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if the double bond of the unsaturated
triacylglycerol is ____, the beneficial effect is lost.
trans
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which are primarily synthesized
instead of naturally occurring, act like saturated
fats and increase the cholesterol levels in the blood.
Trans fats
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Triacylglycerols are hydrolyzed with water in the
presence of ____,____, or _____ in the body
acid, base, or enzymes
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Humans store energy as ________ in
adipose cells below the surface of the skin, in the
breast area, and surrounding internal organs.
triacylglycerols
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To metabolize triacylglycerols for energy, the esters
are hydrolyzed by enzymes called ______
lipases
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metal salts of fatty acids prepared by
basic hydrolysis (saponification) of a triacyl-
glycerol.
polar head
ionic end
nonpolar tail
nonpolar end 27
Soaps
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dissolve grease and oil and
the polar head makes it soluble in water.
nonpolar tails
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made from lard (from hogs), tallow
(from cows or sheep), coconut oil, or palm oil
Soaps
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lipids that contain a P atom.
Phospholipids
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Two common types of phospholipids
phosphoacylglycerols and sphingomyelins.
50
- the main component
of most cell membranes.
- Structurally, they resemble a triacylglycerol, except
the third fatty acid has been replaced with
a phosphodiester bonded to an alcohol
- main types are cephalin, lecithin
Phosphoacylglycerols
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- do not contain a glycerol
backbone, they have a sphingosine backbone
instead.
-do not contain an ester; their
single fatty acid is bonded to the backbone by
an amide bond.
sphingosine
Sphingomyelins
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the coating that surrounds
nerve cells, is rich in sphingomyelins.
myelin sheath
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- surrounds the cytoplasm, the
aqueous medium inside the cell.
- acts as a barrier to stop the
passage of ions and molecules into or out of the
cell.
- selectively
permeable.
cell membrane
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the major component of cell
membranes, contain a hydrophilic polar head and
two hydrophobic nonpolar tails.
Phospholipids
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When phospholipids
are mixed with water,
they assemble in a
lipid bilayer
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are embedded
in the lipid bilayer membrane. (structure of cell membrane)
Proteins and cholesterol molecules
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embedded within the
membrane and extend outward on one side only.(structure of cell membrane)
Peripheral proteins
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extend through the entire bilayer. (structure of cell membrane)
Integral proteins
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Sometimes carbohydrates are attached to the
exterior of the cell forming __________ and ________.
glycolipids and glyco-
proteins.
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Small molecules like O2 and CO2 can ____
through the cell membrane, traveling from ____
to ________concentration.
diffuse
higher
lower
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what does larger polar molecules need to cross efficiently?
facilitated transport
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Ions like Cl− or HCO3− travel through ________
integral
protein channels
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Other ions, Na+, K+, and Ca2+, move against the
concentration gradient; this required energy input
and is called
active transport.
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a group of lipids whose carbon
skeletons contain several fused rings
Steroids
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- the most prominent steroid, is
synthesized in the liver and found in almost all
body tissues.
- It is obtained in the diet from many sources,
including meat, cheese, butter, and eggs
Cholesterol
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Elevated levels of cholesterol in the bloodstream
lead to
coronary artery disease, heart attack, etc
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insoluble in the aqueous medium
of blood.
cholesterol
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It is transported through the bloodstream by
lipoproteins, aggregates of phospholipids and
proteins.
cholesterol
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-transport
cholesterol from the liver to the tissues.
-deposit cholesterol on the walls of arteries
when they carry more than is needed to form
cell membranes.
-This forms plaque, which restricts blood flow.
- bad cholesterol
Low-density lipoproteins (LDLs)
70
- transport
cholesterol from tissues back to the liver.
- reduce the level of cholesterol in the blood-
stream by bringing excess back to the liver
- good cholesterol
High-density lipoproteins (HDLs)
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Recommended level of HDL
HDL > 40 mg/dL,
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Recommended level of LDL
LDL < 100 mg/dL
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total serum cholesterol recommended level
total serum cholesterol
< 200 mg/dL
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a molecule that is synthesized in
one part of an organism, which then elicits a
response at a different site
hormone
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Two important classes of steroid hormones
sex hormones
adrenal cortical steroids
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female sex hormones
estrogens
progestins
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male sex hormones
androgens
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The estrogens ______ and ______ control
development of secondary sex characteristics,
regulate the menstrual cycle, and are
made in the ovaries.
estradiol and estrone
79
The progestin __________ is called the
“pregnancy hormone”; it is responsible for the
preparation of the uterus for implantation of a
fertilized egg.
52
progesterone
80
are androgens
made in the testes.
They control the development of secondary sex
characteristics in males.
Testosterone and androsterone
81
-Synthetic androgen analogues that promote muscle growth.
-They have the same effect as testosterone, but
are more stable, so they are not metabolized as
quickly
-They have come to be used by athletes and body
builders, but are not permitted in competitive
sports.
Prolonged use can cause
physical and psychological problems
Anabolic
steroids
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regulates blood pressure and volume
by controlling the concentration of Na+ and K+
in body fluids.
Aldosterone
83
serve as anti-inflammatory
agents, which also regulate carbohydrate
metabolism.
Cortisone and cortisol
84
Prolonged use of these steroids can have
undesired side effects, including bone loss and
high blood pressure.
Aldosterone, Cortisone and cortisol
85
a synthetic alternative, has similar
anti-inflammatory properties.
Prednisone
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- are organic compounds required in
small quantities for normal metabolism and
must be obtained from the diet.
-water soluble or fat soluble
- They are stored in adipose cells to be used when
needed.
58
Vitamins
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four fat-soluble vitamins
A, D, E, and K
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found in fruits, vegetables, fish, liver, and
dairy products.
four fat-soluble vitamins (A, D, E, and K)
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-found in liver, fish, and dairy products,
and is made from β-carotene.
-It is needed for vision and for healthy mucous
membranes.
-deficiency causes night blindness and
dry eyes and skin.
Vitamin A
90
- can be synthesized from cholesterol.
- It can be obtained in the diet from many foods,
especially milk, and helps regulate Ca and K
metabolism.
- A deficiency causes rickets (bone
malformation).
vitamin D
91
an antioxidant, protecting unsaturated
side chains in fatty acids from unwanted
oxidation.
*Deficiency causes numerous
neurological problems, although it is rare.
vitamin E
92
regulates the synthesis of clotting
proteins (prothrombin), and deficiency of this
leads to excessive or fatal bleeding.
62
Vitamin K
93
are two types of
eicosanoids
Prostaglandins and leukotrienes
94
-very potent compounds, which
are not stored in cells, but rather synthesized in
response to external stimulus
-they are local mediators,
performing their function in the environment in
which they are synthesized.
eicosanoids
95
- carboxylic acids that contain
a five-membered ring and have a wide range of
biological activities.
- responsible for inflammation
- decrease gastric secretions,
inhibit blood platelet aggregation, stimulate
uterine contractions, and relax smooth muscles
Prostaglandins
96
relieve pain and
inflammation by blocking the synthesis of these
molecules.
Aspirin and ibuprofen
97
There are two different cylcooxygenase enzymes
responsible for prostaglandin synthesis called
COX-1 and COX-2
98
involved in the usual production of
prostaglandins.
COX-1
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responsible for additional prostaglandins
in inflammatory diseases like arthritis
COX-
100
inactivate both COX-1 and -2,
but increase risk for stomach ulcer formation.
Nonsteroidal anti-inflammatory drugs (NSAIDs)
101
characterized by chronic inflammation,
so inhaled steroids to reduce this inflammation are
commonly used.
Asthma
102
molecules that contribute to the
asthmatic response by constricting smooth
muscle of the lung.
Leukotrienes
103
act by blocking the synthesis
of leukotriene C4, which treat the disease instead
of just the inflammation symptoms.
New asthma drugs
104
Based on their reaction with water:
These are compounds that can be converted into smaller molecules by hydrolysis.
– These are compounds that are derived from fatty acids.
Examples: Fats, oils, waxes, phospholipids, lipoproteins
Hydolyzable lipids
105
Based on their reaction with water:
These are compounds that cannot be cleaved into smaller molecules by hydrolysis.
Examples: steroids, prostaglandins, vitamins, hormones
Non-hydolyzable lipids
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Based on their structure:
Esters of fatty acids with various alcohols.
Examples: triglycerides and waxes
Simple lipids
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– Lipids containing parts other than fatty acids and alcohol.
– Found in cell membranes, brain, nervous tissues, myelin sheaths of nerves, and blood platelets
Examples: phospholipids, sphingolipids, glycolipids, and lipoproteins
Complex lipids
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– These compounds are products of hydrolysis of simple and complex lipids
Examples: steroids, prostaglandins, vitamins, hormones
Derived lipids
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are carboxylic acids with long, unbranched carbon chains. Naturally occurring fatty acids have an even number of carbon atoms.
They contain a polar end and a non-polar end.
Apart from the carboxylic acid (-COOH) group, fatty acids have no functional groups, except that some do have double bonds.
Fatty acids
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Fatty acids that only contain single bonds
Saturated fatty acids
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Fatty acids that contain at least one double bond.
unsaturated fatty acids
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Unsaturated fatty acids with one double bond
monounsaturated fatty acids
113
Unsaturated fatty acids with two or more double bonds
polyunsaturated fatty acids.
114
Unsaturated fatty acids that have two hydrogen atoms on the same side of the double bond, which creates a kink in the structure.
cis Fatty acids
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Unsaturated fatty acids that have two hydrogen atoms on the opposite side of the double bond, which results in a similar structure to that of saturated fatty acid.
trans Fatty acids
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fatty acids that cannot be produced by the body
Essential fatty acids
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Simple Lipids
Triglycerides
Oils
Waxes
118
Also known as triacylglycerols
Humans store energy as triglycerides in adipose cells below the surface of the skin, in the breast area, and surrounding internal organs.
Hydrolyzed by enzymes called lipases to produce energy.
Complete metabolism of a triglycerides yields: CO2, H2O, and energy.
Triglycerides
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- A mixture of triglycerides containing a high proportion of long-chain, saturated fatty acids
- Mostly obtained from animals
- have higher melting points
- Solids at room temperature.
Fats
120
- A mixture of triglycerides containing a high proportion of long-chain, unsaturated fatty acids, or short-chain, saturated fatty acids
- are fats in the liquid state
- have lower melting points
- Liquids at room temperature.
- Mostly obtained from plants and fish
Oils
121
- They are esters of fatty acids with high molecular weight alcohols.
- Because of their long nonpolar C chains, they are very hydrophobic.
- Form protective coating on plants and fruits, and in animal
waxes
122
Complex Lipids
Phospholipids
Sphingolipids
Lipoproteins
123
- Also called phosphoglycerides or glycerophospholipids
- Long-chain fatty acids on a glycerol backbone attached to a phosphoric acid molecule containing an alcohol substituent. (usually amino alcohol)
- The essential components of cell membranes and are found in small concentrations in other parts of the cell.
Phospholipids
124
A class of lipids built from long-chained fatty acids attached to a sphingosine backbone rather than glycerol.
Sphingolipids
125
Found in the myelin sheath surrounding nerve cells
Sphingomyelin
126
Often called cerebrosides because of their abundance in brain tissue
Glycolipids
127
- are the primary means of transport of cholesterol among tissues
- Secreted by the small intestine and liver into the circulating blood
- Composed of lipids and special proteins (apolipoproteins).
Lipoproteins
128
They are formed in the mucosal cell of the intestine. They deliver triglycerides to the adipose tissue and muscle. They also deliver dietary cholesterol to the liver
Chylomicron
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They are formed in the liver for the export of triglycerides. They transport triglycerides from the liver to the muscle and adipose tissue for storage or energy
Very Low-Density Lipoproteins
130
They are primary carriers of cholesterol in the blood for delivery to the tissues.
Low-Density Lipoproteins
131
They are scavengers for cholesterol from peripheral tissues. They also return cholesterol to the liver for metabolism.
High-Density Lipoproteins
132
Derived Lipids
Steroids
Sterols
Bile Salts
Fat-Soluble Vitamins
Hormones
Ketone Bodies
Eicosanoids
133
a group of lipids whose carbon skeletons contain several fused rings
Steroids
134
-Also known as steroid alcohol
-Occur naturally in plants, animals, and fungi
-Plant sterols have cholesterol-lowering properties
Sterols
135
Precursor for vitamins and hormones
Elevated levels of cholesterol in the bloodstream lead to coronary artery disease, heart attack, etc.
Transported through the bloodstream by lipoproteins.
Cholesterol
136
- are oxidation products of cholesterol.
- are powerful detergents.
- Responsible for fat emulsification
- The secretion of bile salts and cholesterol into the bile by the liver is the only mechanism by which cholesterol is excreted.
Bile Salts
137
- Vitamins are organic compounds and vital nutrients that an organism requires in limited amounts.
- They cannot be produced by the body.
- are stored in the body for long periods of time.
- They pose a greater risk of toxicity than water-soluble vitamins.
- Vitamins A, D, E, K
Fat-Soluble Vitamins
138
- serve as an energy source for the heart, kidney, and skeletal muscles, thereby preserving the limited glucose for use by the brain.
- Produced by the liver from the breakdown of fatty acids during periods of low food intake, carbohydrate restrictive diets, starvation, prolonged intense exercise, or in untreated type 1 diabetes mellitus.
Ketone bodies
139
- metabolites of arachidonic acid.
- Responsible for inflammatory responses, on the intensity and duration of pain and fever, and on reproductive function.
- Inhibits gastric acid secretion
- Regulates blood pressure through vasodilation or constriction
- Inhibits or activates platelet aggregation and thrombosis.
a. Prostaglandins (PGs)
b. Thromboxanes (TXs)
c. Leukotrienes (LTs)
d. Lipoxins (LXs).
Eicosanoids
140
- chemical messengers that are secreted directly into the blood, which carries them to organs and tissues of the body to exert their functions.
- Cholesterol is the starting material for the synthesis of steroid hormones.
a. Adrenocorticoid hormones
b. Sex hormones
Hormones
