1. DIGESTIVE
SYSTEM
Presented by group #5
•Syeda Faheela Fateem
•Ushba Arshad
•Najam-us-Sahar
•Noor Kiran
•Dania Arif
•Kashaf Arman
•Sadia Iqbal
•Sobia Altaf
•Sabahat Zulfiqar
•Narmeen Javed
Conducted By Dr.`Qamar uz Zaman
2. 1. WHAT IS DIGESTION?
The process in the alimentary canal by which food is broken up physically,as by the action of an
enzymes, and converted into a substance suitable for a absorption and assimilation into the body.
Types of Digestion:-
There are two types of digestion:
Mechanical Digestion
Chemical Digestion
1. Mechanical Digestion:-
In this type of digestion, breakdown particles into smaller pieces so as to increase the surface
area for the action of enzyme.
FUNCTION:
It helps in tearing, riping and beating down of food.
2. Chemical Digestion:-
In this type of digestion, involves ''enzymatic reactions'' which digest the food into simpler
chemical forms.
FUNCTION:
It is used in digestive enzymes to breakdown food.
4. PHASES OF DIGESTION:-
There are 3 types of digestion phases:
Cephalic Phase
Gastric Phase
Intestinal Phase
1: Cephalic Phase:
In this type smell, sight, thought or initial taste
of food activate neural centers and prepares
mouth and stomach for food to be eaten.
2. Gastric Phase:
In this type, neural and hormonal mechanism
promote gastric secretion and motility.
3.Intestinal Phase:
In this type, it begins when food enter small
intestine and slows exit of chyme from
stomach and stimulates flow of bile and
pancreatic juice.
5. 2.Ingestion
Ingestion is the process of consuming something and taking it
into the body. Usually, the word is used to describe taking
food in through the mouth, as humans and many animals do.
It can also be used to describe the absorption of materials or
nutrients by a cell or organism. For example, a cell may ingest
nutrients by absorbing them.
In mouth saliva is present. Saliva moistens and lubricates the
food, with the aid of a slippery substance called mucin, making
swallowing easier as well as dissolving some of the food and
allowing it to be tasted.
6. Teeth
As we know that food is taken into the mouth
by the help of teeth which help Different
types of teeth are present which are
discussed below:
Incisors:
The incisors at the front of the mouth have
a sharp biting surface and are used for
cutting or shearing food into small
chewable pieces.
Canines:
The canines are situated at the 'corners' of
the dental arches. They have a sharp,
pointed biting surface. Their function is
to grip and tear food. It helps in chewing,
cutting or shearing.
Tooth Types:
7. Premolars:
The premolars, unlike the incisors and
canines, have a flat biting surface.
Their function is to tear and crush
food.
Molars:
The molars are the largest of the teeth.
They have a large flat biting surface.
The function of the molars is to
chew, crush and grind food.
8. Salivary Glands
Three Salivary glands are
present in our mouth:
1) Parotid gland: On the insides
of the cheeks.
2) Submandibular gland: at the
floor of the mouth.
3) Sublingual gland: under the
tongue.
9. 3. PROPULSION OF THE DIGESTIVE
SYSTEM
PROPULSION – (MOTILITY):
“Propulsion is the movement of food along the digestive tract”
The major means of propulsion is peristalsis, a series of alternating contractions and
relaxations of Smooth muscles that forces food to move forward”
10. PROCESS OF PROPULSION
DEGLUTITION
Act of swallowing
Facilitated by secretions of saliva
and mucus
Involves mouth, pharynx and
esophagus
3 STAGES
VOLUNTARY-bolus passed to
oropharynx
PHARYNGEAL-Involuntary passage
through esophagus to stomach
ESOPHAGEAL-Involuntary passage
through esophagus to stomach
Peristalsis pushes bolus forward.
11. PERISTALSIS IN ESOPHAGUS
A straight muscular tube
which connects the mouth
with the stomach
Food takes 4 to 8 seconds as
it passes to the stomach
Its walls contains smooth
muscles that contract in wavy
motion (peristalsis)
Peristalsis propels food and
liquid slowly down the
esophagus into the stomach
Cardiac sphincter (ring like
valve) relaxes to allow food
into the stomach
12. PERISTALSIS IN STOMACH
The stomach generates
mixing waves that
churns the food
It causes mixing of food
with the gastric
secretions and converts
the food into semi fluid
called CHYME.
When the food is mixed
thoroughly, peristaltic
wave forces the chyme
to move forward.
13. SEGMENTATION IN SMALL
INTESTINE
SEGMENTATION-
Movement of material back
and forth to foster mixing
into the small intestine.
It mixes the chyme with
rhythmic local contraction
of the intestine.
14. MOVEMENT OF LARGE INTESTINE
MASS MOVEMENT:
Movement of material
happens in large sections
that constricts at once.
Sluggish movement
Slow, powerful movements
Occurs 3 to 4 times per
day
15. DEFECATION REFLEX
Force out rectum when sphincter relaxes .
Presence of feaces in the rectum causes
defecation reflex.
Internal anal sphincter is relaxed
Defecation occurs with relaxation of the voluntary
(external) anal sphincter.
16. ABNORMAL PROPULSION OF
FOOD
“Abnormality of smooth muscle function in
gastrointestinal tract”
Change in the speed, strength or coordination of
the muscles of the esophagus, stomach, small
intestine and/or the large intestine.
It may cause dysphagia (difficulty swallowing),
heart burn, chest pain and vomiting.
17. Definition:
It is the breakdown of food into smaller particles so it can
more easily be processed by the digestive system.
Mechanical digestion is something that starts in the mouth & is the first step in the process of
digestion which starts once you ingest the food. It is less complex method which occurs in
the mouth.
Mechanical digestion process:
Mechanical digestion occurs in the following locations:
Mouth- teeth, tongue, palates
Epiglottis- food pipe
Stomach- muscular churning action of stomach
18. Mouth:
It is a simple process of breaking down of solid food materials into tiny pieces
inside the mouth.The food in the mouth is called Bolus.
It is done to make it ready for further processing with enzymes and chemicals.
The mechanical digestion starts in the mouth and help is taken from tongue, saliva
and teeth.
When the food is ingested into the mouth, the brain sends signal to the salivary
glands to secrete saliva to soften the food.
It is further divided into three parts.
Teeth, Tongue & Palates
1- Teeth:
The teeth also speed up this process by chewing the food and breaking it into
smaller food particles & this process is known as mastication.
The action of the teeth is grinding, cutting & tearing.
Incisors: These are the teeth that you use to take bites of your food.
Canines: These are your sharpest teeth and are used for ripping and tearing food
apart.
Premolars: They are used for chewing and grinding the food.
Molars: Primary molars are also used for chewing and grinding food.
19. 2- Tongue:
The tongue also plays a major role by shifting the food material all around
the mouth by helping the teeth to grind the food into smaller particles. The
swallowing is another important part in mechanical digestion as the tongue presses
against the roof of the mouth and the chewed food is pushed
towards the back part of the mouth.
3- Palates:
The soft palate located over the roof of the mouth guides in the passage
of food by not allowing it to pass through the nose cavity.
Mechanical digestion breaks down food particles to smaller particles and is an important part in the digestion process.Mechanical digestion breaks down food particles to smaller particles and is an important part in the digestion process.Mechanical digestion breaks down food particles to smaller particles and is an important part in the digestion process..
20. Epiglottis:
The epiglottis is a soft cartilage tissue that is attached at the root of the
tongue and restricts the passage of food into the windpipe and also
prevents the entry of air into the esophagus that is the food pipe.
Once the food is down into the food pipe it is further broken down into
smaller particles with the help of digestive enzymes.
Stomach:
It performs a little mechanical digestion as the muscles expand &
contracts to move the food around in the stomach.
This is an order to expose the food to move of the chemical secretions
in the stomach & thus digest it easier.
Mechanical digestion breaks down food particles to smaller particles and
is an important part in the digestion process.
21. 5-CHEMICAL DIGESTION
Definition:
It is the enzymatic hydrolysis in which chemical breakdown of food into
smaller molecules, brought about by enzymes is called chemical
digestion.
Chemical digestion process:
Chemical digestion occurs in the following locations.
1-Digestion of food in mouth :
The chemical & mechanical digestion begins in mouth.
The teeth grind the food, while the three pairs of salivary glands secrete
saliva .
Saliva contains an enzyme ptyalin which acts upon starch to break it
partly into maltose.
The masticated & partially digested food takes the form of bolus & then
pushed into esophagus.
22. 2- Digestion of food in Stomach:
Stomach is a large bag like, thick walled structure which stores food as it
passes down the esophagus.
Food is digested chemically. It walls contain gastric glands which secrete
gastric juice containing the HCl & enzymes called pepsin & rennin.
HCl kill the germs in the food & also softens the food.
Renin helps to curdle the milk.
Pepsin acts on proteins to break them into peptones.
In peristalsis the bolus convert into liquid chyme after 4 hrs of mechanical
&chemical digestion.
Chyme passes through the pyloric sphincter into the small intestine.
23. ENZYMES:
They speed up the chemical reactions without being used by
themselves. they are performing the function of digestion are called
hydrolytic enzymes & are secreted by the digestive glands.
A) LIVER:
Largest gland of the body, located in the abdomen underneath the
diaphgram.
BILE: It secretes an alkaline yellowish green juice called bile,
which is stored in sac like gall bladder attached with it.
Bile contain pigments & some salt including NaHCO3 but not
enzymes.
It breake larger molecule of fat into smaller droplets by the
process called emulsification.
B) PANCREAS:
It s look alike a leaf situated between the duodenum & the stomach.
PANCREATIC JUICE: It is colourless secretion & it is passed
through the pancreatic duct in the duodenum.
It contains NaHCO3 and many enzymes.
3- Digestion of food in Small intestine:
In small intestine remaining process of digestion is completed as
well as the absorption of nutrients from the digested food takes .
It has three parts from which the food passes:
1- Duodenum 2- Jejunum 3- Ileum
24. DUODENUM:
In Which the digestive juices from the pancreas & liver combine with
acidic chyme making it thin and watery. Both of these secretion
contain bicarbonate ions which first neutralize the chyme & turn it
alkaline.
JEJUNUM:
Middle segment of the small intestine found b/w the duodenum
and the ileum. Most of the nutrients present in food are
absorbed by before being passed on to the ileum for further
absorption.
ILEUM:
Duodenum is followed by ileum. In this digestion is completed by the
intestinal juices secreted by glands present in the wall s of the
intestine. The enzymes amino peptide & disaccharide converts
peptide into amino acids & lactose, maltose & sucrose into glucose
respectively.
ABSORPTION INTO VILLI OF ILEUM:
Glucose , fructose , amino acids, glycerol & fatty acids etc are
absorbed into the body. In villus dense network capillary and a single
lymph vessel called lacteal is present. Nutrients other than fatty acids
are taken ito blood flowing in capillaries of villi which join to form
hepatic portal vein which carries absorbed food to liver.
26. 4- Assimilation of digested food:
The incorporation of food by a cell into its component is called
Assimilation .
Depending upon the requirement of the cell, this food can be
used either to build new protoplasm or to obtain energy to perform
various activities.
5- Digestion of food in large intestine:
The undigested food pass from ileum to large intestine.
It consist of caecum, appendix, colon & rectum
The reabsorption of water occurs so the food become hard & is
termed as faeces.
Intestinal bacteria cause fermentation of undigested matter.
EGESTION: The faeces are stored in the rectum for the time begin
& then egested outside the body through anus.
27.
28. Mechanism of Absorption in the human
body is done by two main digestive
organelle, these are:
Small Intestine
Large Intestine
29. To understand how the process of absorption takes place in the Intestine, it is necessary to first understand
the structure & anatomy of the Intestine.
SMALL INTESTINE
Small intestine is the section of the digestive tract where the majority of the food or
nutrients absorption takes place.
It starts from pyloric sphincter to the ileocecal valve.
It follows a twisty path & takes up much of the space within the abdomen.
It is approximately 20feet or 5metres in length & has a small diameter as compared
to large intestine.
It is divided into 3 regions:
Duodenum
Jejunum
Ileum
DUODENUM
The first part of small intestine just
beyond the stomach is DUODENUM.
It is shortest of the 3 regions of small intestine.
Its small size doesn't means that it’s not important.
In fact it is the duodenum that receives many of the
digestive juices needed for the breakdown of food into
nutrients.
JEJUNUM
The middle section of the small intestine is JEJUNUM.
As the nutrients have broken down into smaller units in the duodenum, these small units
can now be absorbed through the wall of jejunum & dropped into the blood stream to be
carried to the cells through out the body.
Jejunum is a prominent site for nutrients absorptions.
30. ILEUM
The terminal section of the small intestine is called the ILEUM.
It is the lowest section of small intestine & is found near the groin.
Groin is the area between the abdomen and the upper thigh on either side of
the body.
It follows the jejunum & it provide additional surface area for the absorption of nutrients,
It also provide a place for the absorption of vitamin B12 & bile salts.
ABSORPTION IN SMALL INTESTINE
REGION ABSORPTION
DUODENU
M
In the duodenum bile breaks down fat particle into smaller droplets & converts it into fatty
acids. These acids are discharged into blood lymph to decrease the inflammation in the body.
Iron ions are also actively absorbed here. The basic principle of iron absorption in proportion’s
to human body need of iron, especially for the formation of HAEMOGLOBIN.
Absorption of some other important nutrients like calcium, phosphorous, copper, vitamin
A,D,E,K & many others, also takes place in the duodenum.
JEJUNUM
In the jejunum with the action of pancreatic enzymes produced by its walls, breakdown &
absorption of lipids, amino acids, monosaccharides or small peptides takes place.
Some of the vitamins like B,C etc or many nutrients magnesium, zinc, riboflavin etc absorbed in
the jejunum as well.
Thus, bulk of chemical digestion & nutrients absorption takes place in the duodenum.
ILEUM
Many bile salts & vitamins are absorbed into the blood stream through the last part of the small
intestine.
Absorption of vitamin B12, C, K, some other water soluble vitamins, bile salts & nutrients that
were not absorbed in the jejunum, also takes place in the ileum.
31. LARGE INTESTINE
The large intestine is the final section of the gastrointestinal tract that performs the vital task of absorbing water and
vitamins with converting digested food into feaces
The large intestine is about 5 feet (1.5 m) in length and 2.5 inches (6-7 cm) in diameter in the living body,
Although shorter than the small intestine in length, the large intestine is considerably thicker in diameter, thus
giving it its name LARGE.
Large intestine takes about 16 hours to finish the digestion of food.
It has 3 parts:
Colon
Cecum
Rectum
COLON
The colon is the last part of digestive system.
Recycling of various nutrients take place in colon.
It consists of the following Four regions:
ASCENDING COLON
It is the first main part of the large intestine, which passes upwards from the
caecum on the right side of the abdomen.
DESCENDING COLON
The part of the large intestine which passes downwards on the left side of the abdomen
towards the rectum.
TRANSVERSE COLON
The middle part of the large intestine, passing across the abdomen from right to left below the stomach.
SIGMOID COLON
It is the S-shaped part of large intestine, leading to the rectum.
32. CECUM
The cecum joins the ileum to the colon.
It is the receiving pouch for the waste matter.
RECTUM
It is the last section of the large intestine, terminating at the anus.
ABSORPTION IN LARGE INTESTINE
PARTS ABSORPTION
ASCENDING COLON It helps in the absorption of water & other key nutrients from the waste
materials & recycle it back into the body. Basically, here the process of
extraction starts.
DESCENDING COLON It compacts the faeces & store faecel matter until it is discharged via the
anus in defecation.
TRANSVERSE COLON It is important part of colon because in this phase the bacteria furthur
breakdown the food into smaller unit by a process called fermentation.
SIGMOID COLON
The walls of the sigmoid colon are muscular, and contract to increase the
pressure inside the colon, causing the stool to move into the rectum
CECUM
Cecum absorb fluids and salts that remain after completion of intestinal
digestion and absorption. The internal wall of the cecum is composed of a
thick mucous membrane, through which water and salts are absorbed.
RECTUM The rectum acts as a temporary storage site for faeces.
33. 7. EXCRETION
The excretory system is essential to one’s health.
Its responsibility is to remove waste from the
body. The excretory system is made up of
numerous organs that work in unison to ensure
that waste is effectively removed from your body.
Below are the details of the excretory system
organs, along with the roles they play in
detoxification
34. Primary Excretory System Organs
1.Kidney:
Kidneys are bean-shaped
organs of a reddish brown
color that are found in the
sides of the vertebral
column. Once the body
has extracted what it
needs from food and
drink, it sends the wastes
to the kidneys. The
kidneys filter the wastes,
including urea, salt and
excess water, which are
flushed out of the body as
urine
35. 2. Skin:
The skin performs its
excretory function via
the sweat glands. These
glands produce sweat
that contains salt, excess
oils, water, and other
unnecessary substances
which are then excreted
out of the body through
small pores. Sweating
also helps to cool the
body during
evaporation.
36. 3. Lungs:
The lungs are very
important excretory
organs as they expel
carbon dioxide from
the body via
exhalation. The lungs
use cells known as
alveoli to remove the
carbon dioxide from
our blood. Otherwise,
the carbon dioxide
would accumulate and
have a detrimental
effect to our body
37. Accesory Organs Of Excretory System
1. Liver:
Although considered a
secondary, or accessory
excretory system organ, the
liver plays a vital part in
keeping the body clean.
Harmful poisons and chemicals
that are either produced in the
body or consumed are broken
down and detoxified by the
liver. For example, a bi-product
of the metabolic process within
the body is ammonia and the
liver processes this into urea, a
less harmful substance which
continues to be filtered and
excreted by the kidneys as
urine.
38. 2. Gallbladder:
Although the
gallbladder does not
have a highly significant
role to play in the
excretory system, it does
have a function that
assists the overall
process. Bile, a liquid
produced by the liver to
break down waste, is
first stored in the
gallbladder. When
needed, it is discharged
into the small intestine
whose role is to break
down fats, ethanol and
other acidic wastes.
39. 3. Urinary Bladder:
The waste fluid that
is created in the liver
and collected in the
kidney is transferred
into the urinary
bladder where it is
temporarily stored
until the individual
urinates. The
urinary bladder
provides a short
term solution for
storing urine in the
body until it is
ultimately
discharged.
40. 4. Ureters:
The ureters tubes of
smooth muscle fiber
transfer liquid waste
from the kidneys into
the urinary bladder.
The urine is moved
with peristaltic
movements which
force the urine away
from the kidneys. The
ureters also have
ureterovesical valves
which ensure the
waste fluid does not
travel back into the
kidney.
41. 5. Urethra:
The urethra runs
through the penis
in males, and serves
as a carrier of
semen as well as
urine for their
ultimate discharge
out of the body. The
urethra tube is
shorter in females
and is just above
the vaginal
opening.
42. 8- GIT DISORDERS
DISEASES:
Gastro intestinal diseases refers to diseases involving the gastro intestinal tract,
namely esophagus mouth, stomach, large intestine, small intestine, accessory
organs of digestion, the liver, gall bladder, pancreas.
The GI tract is responsible for moving food & liquid into & out of the body.
1- Diarrhea:
It refers to the condition of large number of watery motion. It is usually
caused by the infection of colon or food poisoning. It may occur due to several
causes.
`ENTRITIS` caused by a virus or bacteria in the intestinal tract due to the
infection the mucosa becomes irritated. The motility of the intestinal wall
increases many folds. Sometimes `Cholera` may cause diarrhea ,causing
extreme quantities of bicarbonate ions to be secreted into the intestinal tract
along with the massive amounts of sodium ions and water, loading to the
death. Infants and young children are easily dehydrated due to diarrhea .The
physician must be consulted immediately to diagnose and treat the patients.
43. .
2- Dyspepsia:
It is commonly known as epigastric discomfort following meals. It may be due to
peptic ulcer. This is characterized by heart-burn, flatulance, by the nausea and
vomiting with or without abdominal pain. Some person have peristent dyspepsia
for which no cause can be found. Dyspepsia cause by disturbances in the motor
function of the alimentary tract.
44.
45. 4- Pepticulcer
It is the damaged area of the mucosa caused by the digestive action of
gastric juice, in the few centimeters of the duodenum.
They are classified as `GASTRIC`or DUODENTAL.
Duodental ulcer are caused by excessive secretion of acid and pepsin
by gastric glands.
CAUSES- Drugs, stress, heavy alcohol and tobacco etc.
46.
47. 9. DIGESTIVE HORMONES
HORMONES
Hormones are chemical messengers secreted into blood that modify the
Physiology of target cells
Gastrointestinal Hormones:
Gastrointestinal (GI) hormones are the hormones secreted in GI tract. These
hormones are polypeptides in nature and belong to the family of local
hormones . Major function of these hormones is to regulate the secretory
activities and motility of the GI tract.
Some Basic Principles:
With over thirty different hormones identified as being produced in the GI tract,
the gut has been describe as the largest endocrine organ in the body.
Hormones are not secreted into the lumen of the GI tract, but into the circulatory
system, which will transport them to their destination
48. The endocrine cells within the GI tract are referred to collectively as the
“enteric endocrine system” some of the best studied hormones are:
1.Gastrin
2.Cholecystokinin
3.Secretin
4.Motilin
5.Gastric inhibitory polypeptide
1. Gastrin:
Gastrin is secreted by G cells, these are
located in the antrum of the stomach.
It is secreted in response to stimuli associated
with ingestion of the meal such as distension
of stomach, product of protein and gastrin
releasing peptide, which is released by nerves
of the gastric mucosa during vagal stimulation.
The primary action of gastrin is stimulation of
gastric acid secretion.
It stimulates secretion of pancreatic
hormones
It promotes growth of gastric mucosa
It stimulates release of pancreatic hormones
It stimulates secretion of pancreatic juice
49. 2. Cholecystokinin:
CCK is secreted by I cells in the
mucosa of the duodenum & jejunum
mainly in response to the digestive
products of fat and fatty acids in the
intestinal contents.
It stimulates the acinar cells of the
pancreas to release digestive
enzymes and stimulates the secretion
of a juice rich in pancreatic digestive
enzymes.
CCK also causes the increased
production of hepatic bile and
stimulates the contraction of the gall
bladder and the relaxation of the
sphincter of oddi.
50. 3. Secretin:
secretin was the first GI hormone
discovered
It is secreted by specialized entero
endocrine cells called S cells in the
mucosa of the duodenum in response
to acidic gastric juice emptying into
the duodenum from the pylorous of
the stomach.
Secretin stimulates exocrine
pancreatic secretion.
It Inhibits secretion of gastric juice.
It Inhibits motility of stomach.
it Causes constriction of pyloric
sphincter.
51. 4. Motilin:
Motilin is secreted by Mo cells
which are present in stomach and
intestine.
It is secreted when the chyme
from stomach enters the
duodenum.
Motilin stimulates GI motility
called migrating motor complexes
which move through the stomach
and small intestine every 90 min in
a fasted person
It accelerates gastric emptying.
It increases movement of small
intestine
52. 5. Gastric Inhibitory
Polypeptide: (GIP)
It is secreted by K cells in the
duodenum and in jejunum, it is also
secreted in antrum of stomach.
This hormone is responsible for
finding that an oral glucose load is
cleared from the blood more rapidly
than an intravenous glucose load of
the same magnitude for this action it
is also referred to as glucose
dependent insulinotropic peptide.
It stimulates insulin secretion.
It inhibits gastric secretion and
motility.
55. The average human being
has over 400 different
species of bacteria in their
colon.
Proteases, Amylases and
Lipases are the enzymes
produced by our digestive
system: are also present in
laundry detergents by which
stains can be removed.
We eat about 500 kg of food
56.
57.
58. Do you know Mr. Paul Hunn?
No?
He holds a World Record for Loudest Human Burp: 107.1
Decibels.
59. When you’re stressed, the central
nervous system sometimes decreases
proper blood flow which can lead to
tummy problems, because of the
enteric nervous system which
operates the GI tract and
communicates with the central
nervous system.
Even if you were upside down while
eating, food would still be pushed
towards your stomach.
60.
61. The average male will eat about 50 tons of food during
his lifetime; the equivalent of approximately 50 cars.
62. BONUS FOR YOU!
“Chewing may keep you slim”
A Japanese study on 450 women
proved that those who ate food
that required the most chewing,
trimmed more than inch from
their bellies.
TRY FOR ATLEAST 40 CHEWS
PER BITE; IT’S NOT GOOD
FOR DIGESTION, BUT ALSO
HELPS PEOPLE EAT LESS.
