DIGESTIVE SYSTEM
CONTENTS:
1.Digestive
system
DIGESTIVE SYSTEM
It is a physiological process in which the complex fluid
substances are converted into simple form suitable for absorption and their
subsequent utilization in our body.
The organs which are associated with the process of digestion
constitute digestive system. The different organ of digestive system are:
- · Mouth
- · Tongue
- · Oropharynx
- · Esophagus
- · Stomach
- · Small intestine
- · Large intestine
- · Colon
- · Rectum
- Anal canal
The additional organ of digestive system are teeth,
Liver, Pancreases, Gall-bladder, Salivary glands, other digestive glands.
#Why digestive is necessary:
- 1. To convert complex food substance into simple form suitable for absorption and utilization.
- 2. Production of energy required for cell survivor vital cellular activities and metabolic function.
- 3. Growth and development of the body.
- 4. Repairing the damage tissue.
- 5. Reproductive function and lactation.
- 6. Storage of food for use in emergency condition.
Physiological function of digestive system:
- 1. Intake of food
- 2. Digestion of food substances
- 3. Secretion of various digestive juice.
- 4. Absorption of vitamins, minerals, and water.
- 5. Absorption of digestive and product of carbohydrate, protein, and fat.
- 6. Maintenance of water balance.
- 7. Maintenance of acid base balance.
- 8. Maintenance of electrolyte balance.
- 9. Regulation of pH balance.
- 10 Regulation of blood sugar.
- 11. Helps in the RBC production.
- 12. Removal of Bacteria, Toxin.
Local
Hormones
Local Hormones are chemically secreted by different
digestive glands and show their physiological function on local or neighboring
glands or tissue in our body.
Some local hormones with their sight of secretion and
function are describe bellow:
- 1. Gastrin: Secreted by Stomach, small intestine.
- 2. Secretion: Secreted by pancreas.
- 3. Cholecystokinin: Secreted by gall bladder.
- 4. Pancreozymin: Secreted by pancreas.
- 5. Villikinin: Secreted by small intestine.
- 6. Interocrinin: Secreted by small intestine.
- 7. Enterogastrone: Secreted by stomach inhabit gastric secretion.
Digestive
Glands
The important digestive glands are:
- · Salivary glands.
- · Gastric glands.
- · Pancreas glands.
- · Intestinal glands.
- · Gall bladder secretion.
Salivary Glands
There are three pair of Salivary glands. They are
1.Parotid glands(1-pair): Secretes ptyalin and serous
types of secretion.
2.Sublingual glans(1-pair): Secretes mucous and serous
types of secretion.
3.Submaxilury glands(1-pair): Secretes mucous and
serous types of secretion.
Saliva
It is a viscous colorless fluid which is secreted by
three pairs of salivary glands. Small amount of saliva is also secreted by some
buccal glands of mouth cavity
.
#Characteristics
of Saliva:
1.Total
amount: 800-1500ml/day
2.Reaction:
Slightly acidic.
3.pH:
6-7
4.Gravity:
1.002-1.012
#Composition of Silva:
1.Liquid
substance: Water(99.5%)
2.Solid
substance: (0.5%)
#The solid substances are
1.Inorganic:
Na+, K+, Ca+, Cl-, CO2,
O2, KHCO3, CaCO3 etc
2.Organic:
Mucin, Cholesterol, Amino acid, Enzymes, Ptyalin etc.
#Physiological
function of Saliva:
1.Keeps
mouth moist and helps in speech.
2.Helps
in swallowing of food.
3.Acts
as lubricant.
4.Prevents
bacterial growth in mouth.
5.Helps
in teste of foods.
6.Ptyalin
helps in the digestion of carbohydrates.
8.Helps
in the excretion of toxin, heavy metal, bacteria.
9.Maintanence
of water, acid-base balance, electrolyte balance.
10.helps
in buffering activity.
Pancreatic Juice
Pancreas consists of two types
1.Exoglands
part.
2.Endoglands
part.
Exoglands part consists of acinar cells 98% of
pancreas contains Acinar cells. They produce digestive juice or pancreatic
juice.
Endoglands part is also called ISLET of Langerhans.
Only 2% of pancreas belongs to ISLET of Langerhans. Endoglands part consist of
3 types of cells.
1.α-cell
2.β-cell
3.δ-cell
α-cell:
α-cells
are the largest cells of ISLET of Langerhams.25% ocells are α-cell and Secrets
glucagon.
β-cell:
β-cells
are the smallest cells.60% of cells are β-cell and secretes Insuline.
δ-cell:
δ-cells
are intermediate in size.10% are δ-cell and secretes somatostatin.
#Characteristics:
1.Amount:
800-1500ml/day
2.Consistancy:
colorless, odorless, less viscous.
3.Reaction:
strongly alkaline.
4.pH:8-8.5
5.Specific
gravity: 1.010=1.030
#Physiological
function of Pancreatic juice:
1.Hepls
in the digestion of carbohydrate, protein, and fats.
2.Digestion
of nucleoprotein.
3.Maintanence
of H2O balance.
4.Maintanence
of acid-base balance.
5.Maintanence
of electrolyte balance.
#Composition of pancreatic juice:
1.Inorganic substance:
Water (98.5%)
2.Solid substance: (1.5%)
Solid substance consists of
a)Organic compound
b)Inorganic compound
Gastric Juice
Anatomy
of gastric glands:
There are 3 types of gastric glands present in the
stomach
1.Cardiac-Secretes
mucus.
2.Pyloric-Secretes
mucus and gastrin.
3.Glands
of body and fundus of stomach.
It
consists of 4 types of cell:
a) Peptic cell/chief
cell: This cell secrets large quantities pepsinogen and renin.
b) Oxytic /Parential
cell: This cell secretes gastric HCL and intensive factor.
c)Mucus cell: Secretes
mucus and pepsinogen.
d)Enterochromeffin cell: This
cells secretes gastrin and serotonin.
#Characteristics
of Gastric Juice:
1.Total
quantity: 500-600 ml/mea/1500ml/day
2.Reaction:
Strongly acidic.
3.PH:
1-1.004
4.Consistency:
It is cloudy and sticky due to presence of mucin.
5.Specific
gravity: 1.002-1.004
Composition
of Gastric Juice:
1.Water:
99.5%
2.Solid
substance: 0.5%
#Physiological
function of Gastric Juice:
1.Digestive
force: Gastric juice helps in the digestion of proteins and small amount of
fat.
2.Excretory
function: Gastric juice helps in the
removal of toxins, heavy metals, certain drugs etc from our body.
3.It
contains HCL, which helps in the killing of bacteria.
4.Lubricating
activity.
5.Maintanence
of H2O balance.
6.Maintanence
of acid-base balance.
7.Maintanence of electrolyte balance.Intestinal Juice
It is secreted by intestinal gland, namely Brummer’s
and Crypts of Lieberkühn.
#Characteristics
of Intestinal Juice:
1.Total amount: 2
liter/day.
2.Reaction: Alkaline.
3.pH: 7.5-5.4
4.Specific Gravity: 1.50
#Composition
of Intestinal Juice:
1.Water: 98.5%
2.Solid substance: 1.5%
#Solid
substances are
a. Inorganic substance:
Na+, K+, Ca+, Cl-, HCO3-
b. Organic substance:
1.Proteolytic enzymes
2.Carbohydrate splitting
enzymes
3.Fat splitting enzymes
4.Mucin and intensive
factor.
#Physiological
function of Intestinal Juice:
1.Intestinal juice helps
in the final digestion of carbohydrate, protein, and fat.
2.Protective function: Due
to presence of mucin and bicarbonate, it helps in the protection of duodenum from
the action of gastric HCL.
3.Maintanence of H2O
balance.
4.Maintanence of
acid-base balance.
5.Maintanence of
electrolyte balance.
6.Intensive factor: helps
in the absorption of vitamin B12 and thus helps in the formation of
RBC.
Bile and Bile Secretion
#
Characteristics:
1.total amount:
500-1000ml/day.
2.Color: Yellowish green.
3.Taste: Strongly bitter
taste.
4.Reaction: Alkaline.
5. pH: Liver bile
(7.6-7.8)
Gall
bladder bile (6.8-7.8)
Physiological
function of bile:
1.Digestive function:
Bile helps in the digestion of fats.
2.It is also helps in the
absorption of fat from GIT.
3.Laxative function.
4.Excretory function:
helps in the excretion of heavy metals, toxins, drugs, bacteria from our body.
The salts which are present in the human bile are bile
salts.
The bile salts are:
Na-glycocholate.
Na-Torocholate.
K-glcocholate.
K-Tourocholate.
The acidic substance which are present in human bile
are known as bile acids.
Bile acids are:
Glycocholic acid.
Taurocholic acid.
Cholic acid.
Deoxy cholic acid.
Lethucholic acid.
Enolic acid.
No comments