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SALIVA:
COMPOSITION:
 WATER 99.5%
 pH 6.4 – 6.9
 ORGANIC CONSTITUENTS:

ENZYMES
 Salivary Amylase
 Lingual Lipase
 Ribonuclease
 Phosphatase
 Carbonic anhydrase
 Lysozyme
 UNUSUAL
 IgA
 Blood group substances
 Kallikrein
 OTHER
 Glucose
 Urea
 Cholesterol
 Choline
 Phenols
 INORGANIC CONSTITUENTS: it is rich in potassium & bicarbonate
 Na
K
 Ca
 Mg
 Cl
 HCO3






Sulfate
Phosphate
Nitrate
Iodide
Thiocyanate
FUNCTIONS OF SALIVA
 LUBRICATION: Makes food palatable
 ANTIBACTERIAL ACTION: The mouth contains numerous bacteria, and an important function of saliva is oral hygine. The saliva contains thiocyanate, a
potent antibacterial. The lipase in the saliva will also breakdown bacteria cell walls and facilitates the passage of thiocyanate into the bacteria.
 SOLVENT ACTION: Water in saliva helps to dissolve substances in food.
 CLEANSING ACTION: Water content of saliva plus anti bacterial activity keeps mouth clean
 DIGESTIVE FUNCTION: Salivary amylase breaks poylsachharides into oligosacharides and limit dextrins
 EXCRETORY FUNCTION:
 WATER METABOLISM: It is 99.5% water & its per day secretion is 800-1500ml. Its secretion is decreased in dehydration.
 DEIODINATION:
 ESOPHAGEAL CLEARING: As bolus moves down it flushes the esophagus.
 SECRETION
The parotid secretions are mainly serous, the buccal glands mucus, and the sublingual and submandibular are a mixture of the two.
The acini secrete proteins and a fluid similar in consistency to interstitial fluid, and the ducts exchange the sodium for potassium and Bicarbonate for chlorine
leaving saliva that is rich in Potassium and bicarbonate ions.
The glands secrete between 800-1500 mls day
STIMULANTS OF SALIVA SECRETION:
Salivation is controlled via the parasympathetic system salivary nuclei in the brain stem
. Factors that induce salivation include:
Taste stimuli, especially sour taste
Higher centers especially appertite anticipation, smells and visual clues
In response to signals from the stomach and upper GI tract, particularly irritating stimuli. Salivation can also occour as a prelude to vomiting.
DEPRESSANTS OF SALIVA SECRETION:
Fight, fright and flight reactions due to sympathetic stimulation.
CLINICAL CONDITIONS:
Sjögren's syndrome is an auto immune disorder where immune cells attack the salivary and tear glands. Saliva is not secreted. This can play havoc with oral
hygiene and lead to rampant caries.
GASTRIC JUICE
 COMPOSTION:
 WATER 99%
 pH 1.3 – 2.6
 INORGANIC CONSTITUENTS:
 HCl





Na
K
Phosphate
HCO3
ORGANIC CONSTITUENTS:
 ENZYMES
o Pepsinogen
o Gastric Lipase
o
o
o
o
 OTHER
Gelatinase
Rennin
Lysozyme
Urease
o Intrinsic factor
o Trefoil peptides
 HORMONES
o Histamine
o Gastrin
o Somatostatin
DAILy SECRETION:
The adult stomach secretes about 1500 ccs in a normal day consisting of hydrochloric acid, bicarbonate rich mucous, and the digestive hormone precursor
pepsinogen. Pepsinogen is activated to its active form pepsin by the acidity of the stomach. G cells also secrete the hormone gastrin.
STIMULANTS OF GASTERIC JUICE SECRETION:
 sight, aroma, taste, thought of food
 protein rich diet entering stomach
1. INHIBITION OF GASTERIC JUICE SECRETION:
When chyme enters the deudenum
 FUNCTIONS OF GASTRIC JUICE




ROLE OF MUCINS: Protect the epithelial lining of stomach.
DIGESTIVE FUNCTION: Strong acidic environment denatures proteins
INTRINSIC FACTOR: Helps in absorption of vit B12
ROLE OF HYPOTONICITY:
PANCREATIC JUICE
COMPOSITION:
• WATER
• pH 8 – 8.3
• 1.2-1.5L/D
 INORGANIC CONSTITUENTS:
o
Cl
o
Na
o
K
o
Phosphate
o HCO3
o
Ca
o
Mg
 ORGANIC CONSTITUENTS:
 ENZYMES
o Trypsin
o Chymotrypsin
o Carboxypeptidases A & B
o Elastase
o Collagenase
o Pacreatic lipase
o Colipase
o Pancreatic amylase
o DNase RNase
o Phospholipase A2
o Cholesteryl ester hydrolase
o Alkaline phosphatase
o Lysozomal enzymes
 STIMULANTS OF PANCREATIC JUICE SECRETION:

When chyme enters duodenumdistension of intestine causes release of Cholecstokinin CCK and secretin

CCK causes release of pancreatic hormones

Secretin causes release of bicarbonate rich fluid from pancreas
BILE
•
WATER 97.4%
•
pH 7.8 – 8.6
•
SECRETION :250ML-1L/D
•
INORGANIC CONSTITUENTS:
 Cl
 Na
 K
 HCO3
 Ca palmitate

ORGANIC

bile salts

mucins

bile pigments

neutral fat

FA

phospholipids

cholesterol

IgA
FUNCTIONS OF BILE:
•
role of bile salts
•
cholesterol
•
bile pigments
•
immunoglobulins
•
Ca palmitate
•
alkaline phosphatase
•
excretory function
SUCCUS ENTERICUS:
•
WATER 98 - 99%
•
pH 8.3
•
INORGANIC CONSTITUENTS:
o Cl
o Na
o K
o HCO3

ORGANIC CONSTITUENTS:

ENZYMES
o enterokinase
o intestinal amylase
o disaccharidases
o alpha dextrinase
o peptidases
o phospholipases
o nucleotidases
o nucleosidases
FUNCTIONS OF INTESTINAL JUICE:
•
role of alkalinity
ates
•
mucus
•
immunoglobulins
•
Digestive function
Digestion
mouth
Salivar amylase
Acts on TAG to release
short & medium chain FA
stomach
No action
duedenum
CCK
Release of
pancreatic
pancreas
Pancreatic amylase
Limit dextrins form
Brush border
isomaltase
enzymes
secretin
No action
HCl
Denatures protein
CCK
Converts
polpepeptides to
oligopeptides
secretin
Ligual lipase
Pepsinogen
converted to
pepsin b HCl &
autocatalsis
No action
Release of
bicarbonate rich
fluid from
pancreas
Release of
pancreatic
enzmes
Release of
bicarbonate rich
fluid
disacharidase
Trpsinogen activated to trpsin which activates zmogen forms
of chmotrpsin, elastase, carboxpeptidase
exopeptidase
enterokinase
CCK
Release of
pancreatic
enzmes
Pancreatic lipase
secretin
Release of
bicarbonate rich
fluid
colipase
Cholesterol esterase
Phospholipase A2
lspphospholipase
FA of all chain
lengths
.Remove FA from
position 1& 3 of
TAG
Helps lipase in
attaching to lipid
aquous interface
Cholesterol plus
free FA released
from cholesterol
ester
Converts
phospholipid to
lsophospholipid
Reomes FA from
Micelles abso
& TAG, chole
phospholipid
These are pa
cids
Bile salts
Ribonucleases &
deoxribonucleases
Hdrolze dietar DNA &
RNA to oligonucletides
CCK
secretin
Release of
pancreatic
enzmes
Release of
bicarbonate rich
fluid
Pancreatic phosphodiesterases
lsophospholipid &
converts it to
glcerophosphorl
base & free FA
released
Aid in
emulsification,
micelles formed
Hdrolse
oligonucleotides
producing 3’-and
5’mononucleotides
nucleotidase