Anatomy & Physiology of Digestive System

1. Anatomy & Physiology
of Digestive System
Mr. Mayur Gaikar
Assistant Professor
Department of Pharmacology
College of Pharmacy (For Women), Chincholi, Nashik.

4. WHAT IS THE DIGESTIVE SYSTEM
The gastrointestinal tract (digestive tract, digestional tract,
GI tract, GIT, gut, or alimentary canal) is an organ system within
humans and other animals which takes in food, digests it and absorb
energy and nutrients, and expels the remaining waste as feces.
The major organs of the digestive system:
A. Mouth.
B. Pharynx.
C. Esophagus.
D. Stomach.
E. Small Intestine.
F. Large Intestine.
G. Rectum.

5. Accessory digestive organs:
Liver, Gallbladder, Pancreas, Salivary gland.
Functions of GI tract
•Ingestion: taking of food into the alimentary tract. i.e. eating &
drinking.
•Propulsion: mixes & moves the contents along the alimentary
tract.
•Digestion: consist of:
•Mechanical breakdown of food e.g. mastication (chewing)
•Chemical digestion of food into small molecules by enzymes.

6. • Absorption: this is the process by which digested food
substances pass through the walls of some organs of the
alimentary canal into the blood for circulation.
• Elimination: food substances that have been eaten but cannot
be digested & absorbed are excreted from the alimentary canal
as faeces by the process of defaecation.

7. A. MOUTH
The mouth is the first portion of the alimentary
canal that receives food and produces saliva.
Anteriorly – by the lips
Posteriorly – it is continuous with the oropharynx
Laterally – by the muscles of the cheeks
Superiorly – by the bony hard palate and muscular soft
palate
Inferiorly – by the muscular tongue and the soft tissues
of the floor of the mouth.

9. • The oral cavity is lined throughout with mucous membrane,
consisting of stratified squamous epithelium containing small
mucus-secreting glands.
• The palate forms the roof of the mouth & is divided into the
anterior hard palate & posterior soft palate.
• The uvula is a curved fold of muscle covered with mucous
membrane, hanging down from the middle.

10. a. TONGUE
• The tongue is a voluntary muscular organ in the mouth, that
manipulates food for mastication, and is used in the act of
swallowing.
• It is attached by its base to the hyoid bone & by a fold of its
mucous membrane covering, called the frenulum, to the floor of
the mouth
•Superior surface consists of
stratified squamous epithelium,
with numerous papillae.
•Many of these contain sensory
receptors for the sense of taste in
the taste.

12. • The human tongue is divided into two parts, an oral part at the
front and a pharyngeal part at the back.
• Blood Supply: lingual artery, external carotid artery
• Venous Drainage: lingual veins, internal jugular vein
• Nerve Supply: Hypoglossal nerve: supply voluntary muscle
• Glossopharyngeal nerve: Taste and sensation:
• Mandibular nerves: sensation, i.e. pain, temperature and tou

13. Functions
• Mastication (chewing)
• Deglutition (swallowing)
• Speech
• Taste
b. TEETH:
The human teeth function to mechanically break down items of
food by cutting and crushing them in preparation for swallowing
and digesting. Humans have four types of teeth: incisors, canines,
premolars, and molars, each with a specific function.

15. 1. Primary Teeth (temporary)
• Among deciduous (primary) teeth, ten are found in the
maxilla (upper jaw) and ten in the mandible (lower jaw), for a
total of 20.
• Start to come in (erupt) at about 6 months of age
• In the primary set of teeth,
• two types of incisors – centrals and laterals, one canine &
two types of molars – first and second.
• All primary teeth are normally later replaced with their
permanent counterparts.

16. 2. Permanent Teeth
• Among permanent teeth, 16 are found in the maxilla and 16 in
the mandible, for a total of 32. The dental formula is
2.1.2.3/2.1.2.3.
• Age 21, all 32 of the permanent teeth have usually erupted.
• The permanent teeth are the:
• Two incisor (for cutting)-central incisor, lateral incisor
• One canine (for tearing)
• Two premolar(for crushing)-first premolar, second premolar,
• Three molar (for grinding)-first molar, second molar, and third
molar.

17. The shapes of the permanent teeth

19. PARTS
Enamel:
• Enamel is the hardest and most highly mineralized substance of the body.
• It is one of the four major tissues which make up the tooth, along with
dentin, cementum, and dental pulp.
• 96% of enamel consists of mineral, with water and organic material
comprising the rest.
• The normal color of enamel varies from light yellow to grayish white.
Dentin:
• Dentin is the substance between enamel and the pulp chamber.
• The porous, yellow-hued material is made up of 70% inorganic materials,
20% organic materials, and 10% water by weight.

20. • Dentin is a mineralized connective tissue with an organic matrix of
collagenous proteins.
• Cementum
• Cementum is a specialized bone like substance covering the root of
a tooth.
• Its coloration is yellowish and it is softer than dentin and enamel.
• Dental Pulp:
• The dental pulp is the central part of the tooth filled with soft
connective tissue.
• This tissue contains blood vessels and nerves that enter the tooth
from a hole at the apex of the root.

21. Functions of Teeth
• Two incisor -for cutting
• One canine -for tearing
• Two premolar-for crushing
• Three molar-for grinding
Eruption
• Tooth eruption in humans is a process in tooth development
in which the teeth enter the mouth and become visible.
• Primary teeth erupt into the mouth from around six months
until two years of age.

22. •Blood Supply: Maxillary arteries
•Venous Drainage: Internal jugular veins
•Nerve Supply: Maxillary nerves, Mandibular nerves

23. SALIVARY GLANDS
The salivary glands in are exocrine glands that produce saliva through a
system of ducts.
• Humans have 3 paired major salivary glands:
• Parotid
• Submandibular
• Sublingual & as well hundreds of minor salivary glands.
1. Parotid glands:
• The two parotid glands are major/ largest salivary glands wrapped around the
mandibular ramus in humans.

25. • They secrete saliva to facilitate mastication and swallowing,
and amylase to begin the digestion of starches.
• Each gland has a parotid duct opening into the mouth at the
level of the second upper molar tooth.
2. Submandibular glands
• These lie one on each side of the face under the angle of the
jaw.
• The two submandibular ducts open on the floor of the mouth,
one on each side of the frenulum of the tongue

26. 3. Sublingual glands: The sublingual glands are a pair of major
salivary glands located inferior to the tongue, anterior to the
submandibular glands.
• Approximately 5% of saliva entering the oral cavity comes
from these glands.
• Small ducts that open into the floor of the mouth.
Minor salivary glands: There are 800-1000 minor salivary
glands located throughout the oral cavity within the
submucosa of the oral mucosa in the tissue of the buccal &
lingual mucosa.

27. Blood Supply: External carotid artery
Venous Drainage: Jugular veins
Composition Of Saliva
• About 1.5 litres of saliva is produced daily & it consists of:
• Water
• Mineral salts
• An enzyme: salivary amylase
• Mucus
• Lysozyme
• Immunoglobulins, Blood clotting factors

28. Function of Saliva:
• Saliva contributes to the digestion of food & to the maintenance
of oral hygiene.
• Without normal salivary function the frequency of dental caries,
gum disease and other oral problems increases significantly.
1. Lubricant of food:
• The high water content means that dry food entering the mouth is
moistened and lubricated by saliva before it can be made into a
bolus ready for swallowing.

29. 2. Chemical digestion of polysaccharides:
1. Saliva contains the enzyme amylase that begins the breakdown
of complex sugars.
2. The optimum pH for the action of salivary amylase is 6.8
3. Salivary pH ranges from 5.8 to 7.4 depending on the rate of flow;
the higher the flow rate, the higher is the pH.
4. Enzyme action continues during swallowing until terminated by
the strongly acidic pH (1.5 to 1.8) of the gastric juices, which
degrades the amylase.

30. • The digestive functions of saliva include moistening food and helping
to create a food bolus.
• This lubricative function of saliva allows the food bolus to be passed
easily from the mouth into the esophagus.
3. Role in taste:
• Saliva is very important in the sense of taste.
• It is the liquid medium in which chemicals are carried to taste
receptor cells (mostly associated with lingual papillae).
4. Non-specific defence
• Lysozyme, immunoglobulins and clotting factors present in saliva
combat invading microbes.

31. Other Function:
• Saliva maintains the pH of the mouth. Saliva is
supersaturated with various ions.

32. B. The Pharynx
• The pharynx is the part of the throat that is behind the
mouth and nasal cavity and above the esophagus and the
larynx, or the tubes going down to the stomach and the
lungs.
• The pharynx is the portion of the digestive tract that
receives the food from your mouth.
• Branching off the pharynx is the esophagus, which carries
food to the stomach,

34. Pharynx consist of three layers of tissue.
lining membrane (mucosa) is stratified squamous epithelium,
provides a lining well suited to the wear and tear of swallowing.
The middle layer consists of connective tissue which becomes
thinner towards the lower end and contains blood and lymph
vessels and nerves.
The outer layer consists of a number of involuntary muscles
that are involved in swallowing.

35. C. The Esophagus:
The esophagus or oesophagus, commonly known as
the food pipe or gullet, The esophagus is a muscular tube
connecting the throat (pharynx) with the stomach.
The esophagus runs behind the windpipe (trachea)
and heart, and in front of the spine.
Length: 25 cm
Diameter: 2 cm

37. Structure:
• The wall of the esophagus from the lumen outwards consists
of: (from inside)
a) Mucosa,
b) Submucosa (connective tissue),
c) Layers of muscle fibers between layers of fibrous tissue
d) Adventitia or serosa – outer covering (Peritoneum)

39. a) Mucosa: This consists of three layers of tissue:
• Mucous membrane formed by columnar epithelium is the
innermost layer, and has three main functions: protection,
secretion & absorption.
• Lamina propria consisting of loose connective tissue, which
supports the blood vessels that nourish the inner epithelial
layer, and varying amounts of lymphoid tissue that has a
protective function.
• Muscularis mucosa, a thin outer layer of smooth muscle that
provides involutions of the mucosa layer, e.g. gastric glands,
villi

40. Mucous membrane
In parts are subject to great wear and tear or mechanical injury,
& consists of stratified squamous epithelium with mucus-
secreting glands just below the surface.
Food is already soft, moist and where secretion of digestive
juices & absorption occur, the mucous membrane consists of
columnar epithelial cells interspersed with mucus-secreting
goblet cells.
Mucus lubricates the walls of the tract and protects them from
the damaging effects of digestive enzymes.

41. b) Submucosa:
Consists of loose areolar connective tissue containing collagen & elastic
fibres, which binds the muscle layer to the mucosa. Within it are plexuses
of blood vessels and nerves, lymph vessels and varying amounts of
lymphoid tissue.
The blood vessels are arterioles, venules and capillaries.
c) Muscle layer:
•2 layers of smooth (involuntary) muscle.
•Outer layer are arranged longitudinally inner layer encircle the wall of
the tube.
•Between these two muscle layers are blood vessels, lymph vessels &
plexus (network) of sympathetic & parasympathetic nerves, called the
myenteric plexus

42. Movement of a bolus by peristalsis.
Contraction and relaxation of these muscle layers occurs in
waves, which push the contents of the tract onwards. This type
of contraction of smooth muscle is called peristalsis

43. d) Peritoneum
Largest serous membrane of the body & closed sac, containing
a small amount of serous fluid, within the abdominal cavity.
It is richly supplied with blood and lymph vessels, and contains
many lymph nodes. It provides a physical barrier to local spread of
infection, and can isolate an infective focus such as appendicitis,
preventing involvement of other abdominal structures. It has two
layers:
parietal peritoneum, which lines the abdominal wall
visceral peritoneum, which covers the organs (viscera) within the
abdominal and pelvic cavities.

44. • It has two muscular rings or sphincters in its wall, one at
the top and one at the bottom.
• The upper and lower ends of the oesophagus are closed by
sphincters.
• The upper cricopharyngeal or upper oesphageal sphincter
prevents air passing into the oesophagus during inspiration
and the aspiration of oesophageal contents.
• The cardiac or lower oesophageal sphincter prevents the
reflux of acid gastric contents into the oesophagus.

45. FUNCTIONS
• Formation of a bolus
• Swallowing
• Food is ingested through the mouth and when swallowed
passes first into the pharynx and then into the esophagus.
• Reducing gastric reflux
• Constriction of the upper and lower esophageal sphincters
help to prevent reflux (backflow) of gastric contents and
acid into the esophagus, protecting the esophageal mucosa.

46. Blood supply
• Oesophageal arteries
• Inferior phrenic arteries
Venous drainage
• Left gastric vein

47. •The stomach is a muscular organ located on the left side of
the upper abdomen.
•The stomach receives food from the esophagus.
•As food reaches the end of the esophagus, it enters the
stomach through a muscular valve called the lower esophageal
sphincter.
D. Stomach

51. • Relations:
• Anteriorly- Left lobe of liver & anterior abdominal wall
• Posteriorly- Abdominal aorta, Pancreas, Spleen, left Kidney
• Superiorly- Diaphragm, Oesophagus & left lobe of Liver
• Inferiorly-Transverse colon & small intestine
• Left side-Diaphragm & Spleen
• Right side-Liver & Duodenum

53. • A pouch-like organ primarily designed for food storage (for 2-4
hours) , some mechanical and chemical digestion also occur .
• Contains two sphincters at both ends to regulate food movement :
• cardiac sphincter near the esophagus ,
• pyloric sphincter near the small intestine .
Divided into 3 regions :
• Fundus
• Body
• Pylorus

54. Walls of the stomach
The four layers of tissue that comprise the basic structure of the alimentary canal
are found in the stomach but with some modifications.
Muscle layer
This consists of three layers of smooth muscle fibres:
Outer layer of longitudinal fibres
Middle layer of circular fibres
Inner layer of oblique fibres.

55. Mucosa
When the stomach is empty the mucous membrane lining is
thrown into longitudinal folds or rugae, and when full the rugae
are ‘ironed out’ & the surface has a smooth.
Gastric glands are situated below the surface in the mucous
membrane and open on to it.
They consist of specialised cells that secrete gastric juice into
the stomach.

56. FUNCTIONS
•Digestion
•The stomach releases proteases (protein-digesting enzymes
such as pepsin) and hydrochloric acid, which kills or inhibits
bacteria and provides the acidic pH of 2 for the proteases to
work.
•Food is churned by the stomach through muscular contractions
of the wall called peristalsis.
•Parasympathetic stimulation increases the motility of the
stomach and secretion of gastric juice; sympathetic stimulation
has the opposite effect.

57. Absorption
some absorption of certain small molecules nevertheless does
occur in the stomach through its lining
GASTRIC JUICE
• Gastric acid, gastric juice or stomach acid, is a digestive fluid
formed in the stomach and is composed of hydrochloric acid
(HCl), potassium chloride (KCl) and sodium chloride (NaCl).
• The acid plays a key role in digestion of proteins, by activating
digestive enzymes, and making ingested proteins unravel so that
digestive enzymes break down the long chains of amino acids.

58. About 2 litres of gastric juice are secreted daily by
specialised secretory glands in the mucosa.
It consists of mucus secreted by mucous neck cells in the
glands and surface mucous cells on the stomach surface inactive
enzyme precursors: pepsinogens secreted by chief cells in the
glands.

59. Functions of gastric juice
Water liquefies the food swallowed
Hydrochloric acid -acidifies the food and stops the action of
salivary amylase.
– kills ingested microbes
– provides the acid environment needed
for effective digestion by pepsins.
Pepsinogens -activated to pepsins by hydrochloric acid.
-digestion of proteins
Intrinsic factor absorption of vitamin B12 from the ileum.
Mucus prevents mechanical injury to the stomach
wall by lubricating the contents

60. Secretion of gastric juice
Three phases of
secretion of gastric juice

61. • Gastric Secretory Cells
• Chief cells: secrete pepsinogen (an inactive enzyme).
• Parietal cells: secrete hydrochloric and (HCl) & "intrinsic
factor“ (which helps absorption of vitamin B12 in the
intestines).
• Mucous cells: secrete mucus and alkaline substances to help
neutralize HCl in the gastric juice .
• G cells: secrete a hormone called gastrin, which stimulates the
parietal cells and overall gastric.

62. E. Small Intestine
Continuous with the stomach at the pyloric sphincter.
Length 5 metres long & leads into the large intestine at the
ileocaecal valve.
Diameter: 2.5 to 3 cm
Chemical digestion of food is completed and absorption of
most nutrients takes place.

64. PARTS: The small intestine is divided into three structural parts:
(I)The duodenum (II)The jejunum (III)The ileum
The duodenum is a short structure ranging from 20 - 25 cm in
length, and shaped like a "C".
Secretions from the gall bladder & pancreas merge in a
common structure – the hepatopancreatic ampulla – and enter
the duodenum at the duodenal papilla.
The duodenal papilla is guarded by a ring of smooth
muscle, the hepatopancreatic sphincter

65. Direction of the flow of bile from the liver to the duodenum

66. The jejunum is the midsection of the small intestine,
connecting the duodenum to the ileum. It is about 2.5 m
long.
The ileum is the final section of the small intestine. It is about
3 m long, and contains villi similar to the jejunum.
Intestinal juice: About 1500 ml of intestinal juice are secreted
daily by the glands of the small intestine. It consists of:
Water, mucus, mineral salts.
The pH of intestinal juice is usually between 7.8 and 8.0.

67. FUNCTIONS
• Digestion
• The small intestine is where most chemical digestion takes
place.
• Many of the digestive enzymes that act in the small intestine
are secreted by the pancreas and liver and enter the small
intestine via the pancreatic duct.
• Digestion of proteins & carbohydrate.

68. • Absorption
• Digested food is now able to pass into the blood vessels in the
wall of the intestine through either diffusion or active
transport.
• The small intestine is the site where most of the nutrients
from ingested food are absorbed.
• Immunological
• The small intestine supports the body's immune system.
• The presence of gut flora appears to contribute positively to
the host's immune system.

69. F. The Large Intestine
• Also known as the large bowel or colon, is the last part of
the gastrointestinal tract & of the digestive system in
vertebrates.
• Water is absorbed here & the remaining waste material is
stored as feces before being removed by defecation.

71. STRUCTURE
• 1.5 metres long, 6.5 cm in diameter
• The colon divided into the
1. Caecum,
2. Colon,
3. Sigmoid colon,
4. Rectum and
5. Anal canal

72. Sections of the colon are:
• The ascending colon including the cecum and appendix
• The transverse colon including the colic flexures & transverse
mesocolon
• The descending colon
• The sigmoid colon – the s-shaped region of the large intestine

73. • The average inner diameter of sections of the colon in
centimeters
• Cecum 8.7cm
• Ascending colon 6.6cm
• Transverse colon 5.8cm
• Descending/sigmoid colon 6.3cm
• And rectum near rectal/sigmoid junction 5.7cm

74. The caecum (9 cm long)
• This is the first part of the large intestine. It is a dilated region
which has a blind end inferiorly & is continuous with the
ascending colon superiorly.
• Containing Ileocecal valve
• The ileocecal valve is a sphincter muscle valve that separates the
small intestine and the large intestine.
• Its critical function is to limit the reflux of colonic contents into
the ileum.

75. The ascending colon
• This passes upwards from the caecum to the level of the liver
where it curves acutely to the left at the hepatic flexure to
become the transverse colon.
• The unwanted waste material is moved upwards toward the
transverse colon by the action of peristalsis.
• Peristalsis is a radially symmetrical contraction & relaxation
of muscles that propagates in a wave down a tube.

76. Transverse colon
• The transverse colon is the part of the colon from the hepatic
flexure to the splenic flexure.
Descending colon
• This passes down the left side of the abdominal cavity then
curves towards the midline. After it enters the true pelvis it is
known as the sigmoid colon.
• One function of the descending colon in the digestive system is
to store feces that will be emptied into the rectum.

77. Sigmoid colon
• The sigmoid colon is the part of the large intestine after the
descending colon and before the rectum.
• The name sigmoid means S-shaped.
• The walls of the sigmoid colon are muscular & contract to
increase the pressure inside the colon, causing the stool to
move into the rectum.

78. Rectum
This is a slightly dilated section of the large intestine about
13 cm long. It leads from the sigmoid colon and terminates
in the anal canal.

79. The Anus
• The anus is the external opening of the rectum.
• Its function is to control the expulsion of feces.
• Two sphincters control the exit of feces from the body during
an act of defecation.
• Internal sphincter, consisting of smooth muscle, is under the
control of the autonomic nervous system.
• External sphincter , formed by skeletal muscle, is under
voluntary control

80. Structure
Four layers of tissue are present in (GI tract) the caecum,
colon, the rectum and the anal canal.
The arrangement of the longitudinal muscle fibres is
modified in the caecum and colon. They do not form a smooth
continuous layer of tissue but are instead collected into three
bands, called taeniae coli, situated at regular intervals round the
caecum and colon.

82. The lining membrane of the anal canal consists of
stratified squamous epithelium continuous with the mucous
membrane lining of the rectum above and which merges with
the skin beyond the external anal sphincter.
In the upper section of the anal canal the mucous
membrane is arranged in 6 to 10 vertical folds, the anal
columns. Each column contains a terminal branch of the
superior rectal artery and vein.

83. FUNCTIONS
• Absorption: Water Mineral salts, vitamins and some drugs
are also absorbed into the blood capillaries.
• Microbial activity:
Colonised by certain types of bacteria, which synthesise
vitamin K and folic acid.
They include Escherichia coli, Enterobacter aerogenes,
Streptococcus faecalis and Clostridium perfringens.These
microbes are harmless, in humans. So, become pathogenic if
transferred to another part of the body, e.g. E. coli may cause
cystitis if it gains access to the urinary bladder

84. Gases nitrogen, Hydrogen, carbon dioxide and methane are
produced by bacterial fermentation of unabsorbed nutrients,
especially carbohydrate
•Mass movement & Defaecation
•The large intestine does not exhibit peristaltic movement as in
other parts of the digestive tract.
•Only at fairly long intervals (about twice an hour) does a wave
of strong peristalsis sweep along the transverse colon forcing its
contents into the descending and sigmoid colons known as mass
movement.

85. Blood Supply
• the superior mesenteric artery (SMA)
• and inferior mesenteric artery
Venous Drainage
• the inferior mesenteric vein
• the superior mesenteric vein

86. Physiology of Digestion
• The mouth is the beginning of the digestive tract.
• Chewing breaks the food into pieces that are more easily
digested, while saliva mixes with food to begin the process of
breaking it down into a form your body can absorb and use.
• From pharynx food travels to the esophagus or swallowing
tube.
• By means of a series of contractions, called peristalsis, the
esophagus delivers food to the stomach.
• The lower esophageal sphincter keep food from passing
backwards into the esophagus.

87. • The stomach secretes acid & powerful enzymes that continue
the process of breaking down the food.
• When it leaves the stomach, food is the consistency of a liquid
or paste.
• From there the food moves to the small intestine.
• The small intestine continues the process of breaking down
food by using enzymes released by the pancreas & bile from
the liver.
• Bile is a compound that aids in the digestion of fat and
eliminates waste products from the blood.

88. • Peristalsis is also at work in this organ, moving food through
and mixing it up with digestive secretions.
• The duodenum is largely responsible for continuing the
process of breaking down food, with the jejunum and ileum
being mainly responsible for the absorption of nutrients into
the bloodstream.
• pancreas secretes enzymes into the small intestine.
• These enzymes break down protein, fat, and carbohydrates
from the food we eat.

89. • Stool, or waste left over from the digestive process, is passed
through the colon by means of peristalsis, first in a liquid state
and ultimately in solid form as the water is removed from the
stool.
• A stool is stored in the sigmoid colon until a "mass
movement" empties it into the rectum once or twice a day.

90. The Pancreas
• The pancreas is a glandular organ in the digestive system and
endocrine system of vertebrates.
• It is located in the abdominal cavity behind the stomach.
• It is an endocrine gland producing several important
hormones, including insulin, glucagon, somatostatin &
pancreatic polypeptide, all of which circulate in the blood.
• Length: 15 cm or 6 inch
• Wt: 60 grams

93. • Structure
• Anatomically, the pancreas is divided into the head of
pancreas,
• the neck of pancreas,
• the body of pancreas,
• and the tail of pancreas.
• The neck is about 2.5 cm or 1 inch long and lies between
the head and the body
• The body is the largest part of the pancreas and lies behind the
pylorus.
• The tail ends by abutting the spleen.

94. The pancreas is both an exocrine and endocrine gland.
The exocrine pancreas:
Consists of a large number of lobules made up of small acini,
the walls of which consist of secretory cells.
Each lobule is drained by a tiny duct and these unite eventually
to form the pancreatic duct, which extends the whole length of
the gland and opens into the duodenum.
Just before entering the duodenum the pancreatic duct joins the
common bile duct to form the hepatopancreatic ampulla.
The duodenal opening of the ampulla is controlled by the
hepatopancreatic sphincter (of Oddi) at the duodenal papilla.

95. The function of the exocrine pancreas is to produce pancreatic
juice containing enzymes that digest carbohydrates, proteins and
fats.
The endocrine pancreas:
Distributed throughout the gland are groups of
specialised cells called the pancreatic islets.
The islets have no ducts so the hormones diffuse directly
into the blood. The endocrine pancreas secretes the hormones
insulin and glucagon, which are principally concerned with
control of blood glucose levels.

96. Function of Pancreas:
• The pancreas is involved in blood sugar control & metabolism within the
body. Sugar control and metabolism.
• Pancreatic islets are four main types of cells which are involved in the
regulation of blood glucose levels.
Each type of cell secretes a different type of hormone:
• α alpha cells secrete glucagon (increase glucose in blood)
• β beta cells secrete insulin (decrease glucose in blood)
• δ delta cells secrete somatostatin (regulates/stops α and β cells)
• γ (gamma) cells, secrete pancreatic polypeptide.

97. Liver
largest gland in the body.
Superiorly– diaphragm
Anterior -abdominal wall
Inferiorly – stomach, bile ducts, duodenum, hepatic flexure
of the colon, right kidney and adrenal gland
Posteriorly – oesophagus, inferior vena cava, aorta, gall
bladder, vertebral column and diaphragm
Laterally – lower ribs and diaphragm.

98. Structure
• The liver is a reddish-brown wedge-shaped organ with
four lobes of unequal size & shape.
• weighs 1 to 2.3 kg
• width -15 cm.
• It is both the heaviest internal organ and the largest gland
in the human body.

100. 1
2
3
4

101. • The liver is grossly divided into two parts when viewed
from above – a right and a left lobe.
• The falciform ligament, divides the liver into a left and
right lobe.

102. The Portal fissure:
Name given to the region on the posterior surface of the
liver where various structures enter and leave the gland.
The portal vein enters, carrying blood from the stomach,
spleen, pancreas and the small and large intestines.
The hepatic artery enters, carrying arterial blood. It is a
branch from the coeliac artery, which is a branch from the
abdominal aorta.
Nerve fibres, sympathetic and parasympathetic, enter here.
The right and left hepatic ducts leave, carrying bile from
the liver to the gall bladder.
Lymph vessels leave the liver, draining some lymph to
abdominal and some to thoracic nodes.

103. Structure:
Lobes of the
liver are
made up of
tiny
functional
units, called
lobules
flow of blood and
bile in a liver
lobule

104. Lobules are hexagonal in outline & are formed by
cubical-shaped cells, the hepatocytes arranged in pairs of
columns radiating from a central vein. Between two pairs of
columns of cells are sinusoids.
Amongst the cells lining the sinusoids are hepatic
macrophages (Kupffer cells) whose function is to ingest and
destroy worn out blood cells and any foreign particles present in
the blood flowing through the liver.

105. Functions of the liver
•Carbohydrate metabolism
•Fat metabolism
•Protein metabolism: Deamination of amino acids,
Transamination, Synthesis of plasma proteins.
•Breakdown of erythrocytes and defence against microbes
•Detoxification of drugs and toxic substances
•Inactivation of hormones
•Production of heat
•Secretion of bile
•Storage

106. Composition of bile
Between 500 and 1000 ml of bile are secreted by the liver daily.
Bile consists of:
Water
Mineral salts
Mucus
Bile pigments, mainly bilirubin
Bile salts, which are derived from the primary bile acids, cholic acid
and chenodeoxycholic acid
Cholesterol.

107. Gall bladder
The gall bladder is a pear-shaped sac attached to the
posterior surface of the liver by connective tissue. It has a
fundus or expanded end, a body or main part and a neck, which
is continuous with the cystic duct.

110. • Structure
• sits in a shallow depression below the right lobe of the liver, that is
grey-blue in life.
• Length-7 to 10 cm or 2.8 to 3.9 inches
• Diameter -4 cm or 1.6 inch
• The gallbladder has a capacity of about 50 millilitres
• The gallbladder is shaped like a pear, with its tip opening into the
cystic duct.
• gallbladder is divided into three sections:
• the fundus,
• The body,
• and the neck.

111. • Functions
• The main purpose of the gallbladder is to store bile, also
called gall, needed for the digestion of fats in food.
• bile flows through small vessels into the larger hepatic ducts
and ultimately though the cystic duct into the gallbladder,
where it is stored.

112. • BLOOD SUPPLY : the cystic artery
• VENOUS DRAINAGE: the cystic veins