Seminar on carbohydrates,proteins,and fat./endodontic courses

Carbohydrates,Proteins and Fat.
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

INTRODUCTION
• The foods on which the body lives,with
the exceptions of small quantities of
substances such as vitamins and
minerals,can be classified as
carbohydrates,fats and proteins.

CARBOHYDRATES
• The carbohydrates are widely distributed
both in animal and plant tissues.
• In plants,they are produced by
photosynthesis.
• In animal cells,carbohydrates in the form
of glucose and glycogen serve as an
important source of energy for vital
activities.

DEFINITION
• Carbohydrates may be defined as polyhydroxy
alcohols with aldehydes or ketones and their
derivatives.
CLASSIFICATION
• Carbohydrates are divided into four major
groups as follows:
1. Monosaccharides
2. Disaccharides
3. Oligosaccharides
4. polysaccharides

CLASSIFICATION OF CARBOHYDRATES
carbohydrates
Monosaccharides Disaccharides Oligosaccharides Polysaccharides

1.MONOSACCHARIDES
• These are carbohydrates which cannot be
hydrolyzed into a simpler form.
• They are often called as “simple sugars”.
• General formula:Cn(H2O)n.

Monosaccharadies are further classified as:
Carbon atoms Aldoses Ketoses
Trioses Glyceraldehyde
or Glycerose.
Dihydroxyaceto
ne.
Tetroses Erythrose. Erythrulose.
Pentoses Ribose.Xylose.
Arabinose.
Ribulose.Xylulo
se.
Hexoses Glucose.Galact
ose.Mannose.
Fructose.
Heptoses Glucoheptose.
Galactoheptose
Sedoheptulose.

2.DISACCHARIDES
• These carbohydrates produce two
molecules of the same or different
monosaccharides on hydrolysis.
• General formula:Cn(H2O)n_1.
• Examples: lactose,maltose,sucrose

3.OLIGOSACCHARIDES
• These carbohydrates produce 2-10
molecules of monosaccharides on
hydrolysis.
• Examples:maltotriose.

4.POLYSACCHARIDES
• These carbohydrates produce more than 10 molecules
of monosaccharides on hydrolysis.
• These can be further classified as
homopolysaccharides if the same monosaccharide
molecules are produced on hydrolysis or
heterosaccharides if more than one monosaccharide in
alternating repeating sequence is produced on
hydrolysis.
• Homopolysaccharides
examples:starch,glycogen.cellulose.dextrin.
• Heteropolysaccharides
examples:mucopolysaccharides.

Monosaccharides.
• Of all the monosaccharides, pentoses
and hexoses are the most important
compounds in our body.
• Important pentose is ribose,which occur
in nucleic acids.
• Physiologically important hexoses are
glucose, galactose and fructose.

Disaccharides
• The physiologically important disaccharides are
maltose,lactose and sucrose.
• Maltose:(malt sugar)
• It does not occur in the body.
• Its sources are germinating cereals and malt.
• It is the intermediary product in the breakdown
of starch by the enzyme amylase in the
alimentary canal.
• It is hydrolyzed to glucose by the enzyme
maltase and the products are absorbed.

• Lactose:(milk sugar)
• It is present in milk and formed in the
lactating mammary gland.
• It is hydrolyzed to glucose and galactose
by the enzyme lactase in the alimentary
canal and the products are absorbed.

• Sucrose:(cane sugar)
• It does not occur in the body but occurs in
cane sugar,pineapple,carrot roots,sweet
potato and honey.
• It is hydrolyzed to glucose and fructose
by the enzyme invertase(sucrase) in the
alimentary canal.

Polysaccharides
• Homopolysaccharides:
• The physiologically important
homopolysaccharides are
cellulose,glycogen,starch,dextrins.

• Cellulose:
• It is the main constituent of the supporting
tissues of plants and forms a considerable part
of our vegetable diet.
• Owing to the difference in chemical
structure,cellulose is not acted upon by
amylases present in the digestive juices.
• It is of considerable human dietetic value only
because it adds “bulk” to the intestinal
contents,thereby stimulating peristalsis and
elimination of food residues

• Glycogen:(animal starch)
• It is the reserve carbohydrate found in liver
and muscles of animals and human beings.
• The glycogen content of liver is more than that
of muscle.
• It is also found in plants which have no
chlorophyll system(eg,fungi and yeasts),but not
in green plants.

Starch:
• It is the store carbohydrate of chlorophyll
containing plants.
• It is the most important source of
carbohydrates in our food and is found in
cereals,potatoes,legumes and other
vegetables in high concentrations.

Dextrin:
• Dextrins are formed by the partial hydrolysis of
starch by an enzyme(salivary amylase),dilute
mineral acids or heat.
• Examples are:amylodextrin,erythrodextrin and
achrodextrin.
• The final product of hydrolysis of starch by an
amylase is maltose which is hydrolysed to
glucose by maltase.

Heteropolysaccharides:
• The heteropolysaccharide situated in extra
cellular matrix is called
glycosaminoglycan, such as hyaluronic
acid,chondroitin sulphate,heparin,kerato
sulphate.

Hyaluronic acid:
• It occurs in the synovial fluid,in the skin and
vitreous humour.
• The presence of enzyme hyaluronidase
increases the rate of diffusion of substances
through tissues containing hyaluronic acid.
• Hyaluronic acid in tissues acts as a cementing
substance.

Chondroitin sulphates
• They occur in the ground substance of
connective tissue and they are
components of cartilage, tendon, and skin.
• They have a marked capacity to bind
water and contribute to the resistance to
compression of connective tissue.

Heparin
• It occurs in most cells and is present in
liver, lung and the arterial wall.
• It is used in medicine as an
anticoagulant.

Keratosulphate:
• It is the component of cartilage and
cornea.

DIGESTION OF CARBOHYDRATE
Hydrolysis as the basic process of digestion:
• Almost all carbohydrates of diet are large
polysaccharides or disaccharides,which are
combinations of monosaccharides bound
together by condensation.
• This means that a hydrogen ion has been
removed from one of the monosaccharides,while
a hydroxyl ion has been removed from the next
one.

• The two monosaccharides are then combined
with each other at these sites of removal, and
the hydrogen and hydroxyl ions combine to form
water.
• When the carbohydrates are digested back into
monosaccharides, specific enzymes return the
hydrogen and hydroxyl ions to the
polysaccharides and thereby separate the
monosaccharides from each other.

• This process is called hydrolysis, is the
following (in which R”-R’ is a
disaccharide):
R”-R’+H20 R”OH+R’H
DIGESTIVE
ENZYME

DIGESTION OF CARBOHYDRATES IN
THE MOUTH AND STOMACH.
• When the food is chewed, it is mixed with
saliva, which contains the enzyme ptyalin
(an α-amylase) secreted mainly by the
parotid glands.
• This enzyme hydrolyzes starch into the
disaccharide maltose and other small
polymers of glucose that contain three to
nine glucose molecules (such as
maltotriose and α limit dextrans that are
the branch points of starch molecule).

• But the food remains in the mouth only for
a short period, and probably not more
than 5 percent of all the starches that are
eaten will have become hydrolyzed by the
time food is swallowed.
• Digestion continues in the body and
fundus of the stomach for as long as 1hr
before the food becomes mixed with the
stomach secretions.

• Then the activity of the salivary amylase is
blocked by the acid of gastric secretions
because it is non active as an enzyme
once the pH of the medium falls below
about 4.0.
• Nevertheless, on the average, before the
food becomes completely mixed with the
gastric secretions, as much as 30 to 40
percent of the starches will have been
hydrolyzed mainly to maltose.www.indiandentalacademy.com

DIGESTION OF CARBOHYDRATES IN
THE SMALL INTESTINE
Digestion by pancreatic amylase:
• Pancreatic secretions like saliva,contain a
large quantity of α-amylase that is almost
identical in its function with the α-amylase
of saliva but it is several times as
powerful.
• Therefore within 15 to 30 minutes after the
chyme empties from the stomach into the
duodenum and mixes with the pancreatic
juice,virtually all the starches are digested.

• In general, all starches are almost totally
converted into maltose and other very
small glucose polymers before they have
passed beyond the duodenum or upper
jejunum.

Hydrolysis of disaccharides and small
glucose polymers into monosaccharides by
the intestinal epithelial enzymes.
• The enterocytes lining the villi of the small
intestine contain the four enzymes
lactase,sucrase,maltase, and α-
dextrinase,which are capable splitting the
disaccharides lactose,maltose and
sucrose as well as other small glucose
polymers into their constituent
monosaccharides.

• These enzymes are located in the
membranes of the microvilli brush border
of the enterocytes, and the disaccharides
are digested as they come in contact with
these membranes.
• Lactose splits into a molecule of galactose
and a molecule of glucose.
• Sucrose splits into a molecule of fructose
and a molecule of glucose.

• Thus, the final products of carbohydrate
digestion are all monosaccharides, and
they are absorbed immediately into portal
blood.

Absorption of carbohydrates
• Essentially all food carbohydrates are
absorbed in the form of
monosaccharides;only a small fraction are
absorbed as disaccharides and almost
none as larger carbohydrate compounds.
• By far the most abundant of the absorbed
monosaccharides is glucose, usually
accounting for more than 80 percent of
carbohydrates absorbed.

Transport of glucose by sodium co-transport
mechanism
• glucose absorption occurs in a co-
transport mode with the active transport of
sodium.
• There are two stages in the transport of
the sodium through the intestinal
enterocyte.

• First is the active transport of sodium
through the basolateral membranes into
the paracellular spaces,thereby depleting
the sodium inside the cells.
• This decrease in sodium inside the cells
then causes sodium in the intestinal lumen
to diffuse through the brush border of
enterocyte to its interior by facilitated
diffusion.

• The Na+ first combines with a transport
protein, but the transport protein will not
transport the Na+ to the interior of the cell
until it also combines with some other
appropriate substance such as glucose.
• Therefore, intestinal glucose also
combines simultaneously with the same
transport protein, and then both the Na+
and glucose are transported together to
the interior of the cellwww.indiandentalacademy.com

• Additional transport of glucose occurs by
“solvent drag” through the cell junctions
into the paracellular spaces.
• This is important at high concentrations.
• When glucose is transported through the
enterocyte and finally into the paracellular
spaces,this causes greatly increased
glucose concentration in the paracellular
spaces.

• This high glucose concentration in turn
causes increased osmotic pressure in the
paracellular space, which in turn causes
water to be absorbed osmotically from the
intestinal lumen through the cell junctions
directly into the paracellular space without
going through the interior of the intestinal
enterocyte.
• This is known as “solvent drag”.

Absorption of other monosaccharides
• Galactose is absorbed by almost exactly the
same mechanism as glucose.
• Fructose is transported by facilitated diffusion
all the way through the enterocyte but not
coupled with sodium transport.
• Also,much of fructose is converted into
glucose on its way through the enterocyte and
finally transported in the form of glucose rest of
the way into paracellular spaces.

METABOLISM OF CARBOHYDRATES
• By means of circulation,the blood glucose
is distributed to various tissues of the
body.In the tissues the fate of glucose is
as follows:
• It may undergo catabolism to produce
energy. The energy is stored as ATP and
utilized for the purpose of various works
(muscular contraction,glandular secretion
etc).

• The first stage of catabolism is via the
glycolytic pathway (also called the
Embden Meyerhof Pathway, EMP);the 6
carbon atomed structure glucose is
converted into 3C structure,pyruvic acid.
• This stage yields small amount of ATP.
• This stage can occur in the absence of
oxygen.

• In the next stage of catabolism,the pyruvic
acid enters the krebs cycle (also called
the citric acid cycle) and broken down to
CO2 and H2O.This stage yields much
more greater amount of ATP and cannot
proceed without oxygen supply.

GLYCOLYTIC PATHWAY
• Site: catabolism of glucose via EMP
occurs mainly in the brain, RBC and
muscles.

GLYCOLYTIC PATHWAY
(FLOW CHART)

Metabolic fates of pyruvate:
• Under anaerobic conditions:
under anaerobic conditions, pyruvate is
reduced to lactate. This reaction is
catalyzed by lactate dehydrogenase and
requires NADH+H+.
lactate dehydrogenase
pyruvic acid lactic acid .
NADH+H+ NAD+

• Under aerobic conditions:
Under aerobic conditions,pyruvate is
transported to mitochondria where it is
oxidatively carboxylated to acetylCoA.

KREBS CYCLE
• This is also called as citric acid cycle or
tricarboxylic acid cycle.
• Site:it occurs within the mitochondria of
the cell.
• Here the pyruvic acid formed in the
glycolytic pathway enters the krebs cycle
and broken down to Co2 and H2O.
• This stage yields much greater amount of
ATP and cannot proceed without oxygen
supply.

KREBS CYCLE
(FLOW CHART)

• It is also known as pentose phosphate
pathway (ppp).
• It is alternative important mechanism for
the break down and oxidation of glucose.
• Site:liver and fat cells.
HEXOSE MONOPHOSOHATE SHUNT

HEXOSE MONOPHOSPHATE SHUNT

ROLE OF LIVER IN CARBOHYDRATE
METABOLISM
• Liver acts as a glucostat.
• When blood sugar level tends to fall liver
under the influence of certain hormones,
releases glucose into the blood and
increases gluconeogenesis.
• Conversely,in hyperglycemia liver
removes glucose from the blood by
glycogenesis.

In liver the following fundamental actions go
on:
1. Glycogenesis.
2. Glycogenolysis 3. Gluconeogenesis.

GLYCOGENESIS
• It is the process by which glycogen is
formed from glucose.

GLYCOGENOLYSIS
• It is the process by which glycogen is
broken down to simpler products.

GLUCONEOGENESIS
• It is the conversion of substance other
than carbohydrates such as proteins and
fat, into glycogen.

PROTEINS
DEFINITION:
Proteins may be defined as the high
molecular weight mixed polymers of α-
amino acids joined together with peptide
linkages.

CLASSIFICATION
1. SIMPLE PROTEINS
CLASS OF
PROTEINS
EXAMPLE
ALBUMIN SERUM
ALBUMIN
GLOBULIN SERUM
GLOBULIN
GLUTELINS GLUTENIN OF
WHEAT
PROLAMINES GLIADIN OF
WHEAT
PROTAMINES SALMINE OF
SALMON
SPERM
HISTONES GLOBIN OF
HEAMOGLBIN
SCLEROPROT
EINS
KERATIN

2.CONJUGATED
PROTEINS
CLASS OF
PROTEINS
EXAMPLE
NUCLEOPROTEI
NS
NUCLEOPROTA
MINES.
LIPOPROTEINS LIPOPROTEIN
OF EGG-YOLK.
GLYCOPROTEIN
S
MUCIN(SALIVA)
PHOSPHOPROT
EINS
CASEINOGEN
METALLOPROTE
INS
SIDEROPHILIN
CHROMOPROTE
INS
HAEMOGLOBIN
FLAVOPROTEIN
S
FLAVOPROTEIN
S OF LIVER AND
KIDNEYwww.indiandentalacademy.com

3.DERIVED PROTEINS
b.Secondary
derivatives
Class of
proteins
examples
proteoses Albumose from
albumin
peptones
peptides Glycyl-alanine.
a.Primary
derivatives
Class of
proteins
examples
proteans Fibrin of
fibrinogen
metaproteins Acid and
alkali
metaproteins
Coagulated
proteins
Cooked
proteins www.indiandentalacademy.com

DIGESTION OF PROTEINS
DIGESTION BY HYDROLYSIS:
• Proteins are formed from amino acids that
bound together by peptide linkages.
• Digestion occurs when proteolytic
enzymes break these linkages and return
the hydrogen and hydroxyl ions
respectively to the amino acids.

DIGESTION OF PROTEINS IN THE
GASTRO INTESTINAL TRACT.

ABSORPTION OF PROTEINS
• Most proteins are absorbed through the
luminal membranes of the intestinal epithelial
cells in the form of dipeptides,tripeptides, and
a few free amino acids.
• The energy for most of this transport is
supplied by a sodium co-transport mechanism
in the same way that sodium co-transport of
glucose occurs.
• A few amino acids are transported by
facilitated diffusion.

STORAGE OF AMINO ACIDS AS
PROTEINS IN CELLS
• Almost immediately after the entry into
the cells,amino acids are combined by
peptide linkages, to form cellular proteins.
• Yet many intacellular proteins can be
rapidly decomposed again into amino
acids under the influence of intracellular
lysosomal digestive enzymes, and these
amino acids in turn can be transported
back out of the cell into the blood.

RELEASE OF AMONO ACIDS FROM THE CELLS
AND REGULATION OF PLASMA AMINO ACID
CONCENTRATION.
• Whenever the plasma amino acid
concentrations fall below their normal
levels,amino acids are transported out of the
cells to replenish the supply in plasma.
• Because cellular proteins in the liver can be
synthesized rapidly from plasma amino acids
and many of these in turn can be degraded
and returned to the plasma almost equally as
rapidly,there is constant equilibrium between
the plasma proteins and amino acids.

ESSENTIAL AND NON ESSENTIAL
AMINO ACIDS
• Nonessential amino acids are those ten
which are synthesized within the cells.
• Essential amino acids are those other ten
which either cannot be synthesized in the
body or are synthesized in quantities too
small to supply the body’s needs.

CATABOLISM OF PROTEINS
• The fate of amino acids,which have
become excess is as follows.
1.Transamination.
2.Deamination.

UREA FORMATION BY LIVER
• The ammonia released during deamination is released
from the blood almost entirely by conversion into urea.

OXIDATION OF DEAMINATED AMINO
ACIDS
• Once the amino acids have been
deaminated the resulting ketoacid that has
been formed can, in most instances be used
to release energy for metabolic purposes as
follows:
i. The keto acid is changed into an appropriate
substance that can enter the citric acid
cycle;and
ii. This substance is then degradaded by this
cycle and used for energy in the same
manner as acetylCoA.

LIPIDS
• DEFINITION
lipids are heterogeneous group of
compounds related to the fatty acids either
actual or potential,insoluble in
water,soluble in organic solvents such as
ether,chloroform and benzene and
chemically are esters of fatty acids.

CLASSIFICATION OF LIPIDS
• They are classified as:
1. Simple lipids.
2. Compound lipids.
3. Derived lipids.

1. Simple lipids.
These are esters of fatty acids with
various alcohols.
A. Fats.
• They are esters of fatty acids with
glycerol.
• They are the best reserve of food
material in the human body.

B. waxes.
• They are esters of fatty acids with higher
alcohols other than glycerol.
• In the human body the commonest
waxes are esters of cholestrol.

2.Compound lipids.
These are esters of fatty acids containing
groups in addition to an alcohol and a fatty
acid.
A.Phospholipid.
• Alcohol+fatty acid+phoshphoric acid+nitrogen
containing base and other substitutes.
• They are present in large amounts in nerve
tissue,brain,liver,kidney,pancreas and heart.

B. Glycolipids.
• They contain fatty acids+amino
acids+carbohydrates.
• Further classified into:
Cerebrosides- chief constituent of myelin
sheath.
Gangliosides-present in brain.

C.lipoproteins.
• Composed of lipoprotein complex.
• It transports and delivers the lipids to
tissues.
• Maintains the structural integrity of cell.

3.Derived lipids.
These are substances derived from above
group by hydrolysis.
A.Fatty acids.
these are obtained by hydrolysis of fats.
B. Alcohols.
C. Steroids.

DIGESTION OF FAT
• Almost the entire fat portion of the diet
consists of triglycerides, which are
combinations of three fatty acid molecules
condensed with a single glycerol
molecule.
• A small amount of triglycerides is digested
in the stomach by lingual lipase that is
secreted by lingual glands in the mouth
and swallowed with the saliva.

• The first step in fat digestion is to break
the fat globules into smaller sizes so that
the water soluble digestive enzymes can
act on the globular surfaces.
• This is known as emulsification of fat.
• This occurs under the influence of bile
salts and phospholipid lecithin.

• By far the most important enzyme for the
digestion of triglycerides is pancreatic lipase in
the pancreatic juice.
• Most of the triglycerides are split by pancreatic
lipase into free fatty acids and 2-
monoglycerides.
• The cholestrol esters and phospholipids are
hydrolyzed by two other lipases in the pancreatic
secretion.

ABSORPTION OF FATS
• Both the digestive end products become
dissolved in the central lipid portion of the
bile acid micelles.
• In this form,the monoglycerides and the
fatty acids are carried to the surface of the
microvilli in the brush broder.
• Here they diffuse immediately through the
enterocyte cell membrane to the interior of
the enetrocyte.

• After entering the enterocyte, the fatty
acids and monoglycerides form new
triglycerides.
• These reconstructed triglycerides
aggregate first within the endoplasmic
reticulum and then in the golgi apparatus
into globules that contain absorbed
cholesterol, absorbed phospholipids.
• These globules are then called
chylomicrons.www.indiandentalacademy.com

• From the basolateral surfaces of the
enterocytes, the chylomicrons wend their
way into the central lacteals of the villi and
from here are propelled, along with the
lymph, by the lymphatic pump upward
through the thoracic duct into the blood.

CATBOLISM OF FATTY ACIDS.
• Of different classes of lipids, it is the
triglycerides (free fatty acids) whose main
duty is to generate energy and store it as
ATP.
• Fatty acids can be obtained from
cholesterol esters and phospholipids.
• SITE:the triglycerides are hydrolyzed in
adipose tissue(subcutaneous fat in
abdomen,thigh,buttock and so on).

• The free fatty acids are released which are
brought to different organs such as
liver,muscles and heart where they are
furthur catabolised.
• They are catabolised by a process called
‘β oxidation’, within the mitochondria.
• The end products are active acetate
molecules which reenters the krebs cycle.

NUTRITIONAL SIGNIFICANCE OF
CARBOHYDRATES, PROTEINS AND
FAT.
CARBOHYDRATE
• Daily requirements:400gms/day.
• Carbohydrate rich foods are rice, cane
sugar, potato etc.
• They are valuable for muscle muscle
activities.
• One of the major sources of energy.
• They are known as protein sparers.

• Deficiency of carbohydrates in relation to
prosthodontics:
• Lactose intolerance due to failure in
secretion of lactase enzyme which is
essential for the degradation and
absorption of lactose in milk.
• This causes reduction in calcium
absorption in small intestine which leads
to osteoporosis in elderly.

• Chondroitin sulphates of
mucopolysaccharides contribute to
resistance to compression of connective
tissues.

Proteins:
• Daily requirements:60-65 gms/day.
• Protein rich foods are:meat, fish, cows
milk, egg, dal, legumes,wheat.
• Protein is required for replenishment of the
lost tissue due to wear and tear.
• For synthesis of new enzymes
• For maintainance of concentration of
plasma proteins.

• Deficiency of proteins in relation to
posthodontics:
• In the elderly, protein depletion of body
stores is seen primarily as a decrease of
skeletal mass.these changes are
conspicuous in the small muscles of hand
and in the muscles of mastication.
• It causes xerostomia.

• In complete denture wearers, saliva plays
an important role in the retention of the
dentures.
• Oral dryness may have a negative effect
on oral comfort and masticatory function
and so may contribute to protein energy
malnutrition.

• Protein deficiency may also be one of the
factors for causing burning mouth
syndrome.

FAT
• Daily requirements:for a person
consuming
2,500kcal/day,about625kcal(70gms).
• Essential fatty required in our diet are
linoleic acid,linolenic acid and arachdonic
acid.
• People who consume these in diet do not
develop hypercholestrolemia.

• It serves as an efficient source of energy
when stored in an adipose tissue.
• It serves as an insulating material in the
subcutaneous tissues.

REFERENCES
1. Textbook of biochemistry:A.C.Deb
2. Textbook of human physiology:Guyton
3. Textbook of human physiology:Chaudary
4. Essential of complete
prosthodontics:Sheldon winkler.
5. Textbook of geriatric dentistry:
P.Holm;Pederson;H.Loe
6. Complete prosthodontics:Mosby-Wolfe
7. Prosthodontics for the elderly: dr odont

Seminar on carbohydrates,proteins,and fat./endodontic courses

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Seminar on carbohydrates,proteins,and fat./endodontic courses