9. HETERODONT
• Teeth are different types or dissimilar
Incisors
Canine
Premolars
Molars
•HSE Zoology blog •9
10. DIPHYODONT
• Teeth appear twice in
the whole life
• Milk teeth
• Permanent teeth
•HSE Zoology blog •10
11. The kind and number of teeth are explained in the
form of formula is called dental formula.
• Adult 32
permanent teeth
• Incisors 2/2
• Canine 1/1
• Premolars 2/2
• Molars 3/3
• Child 20 milk
teeth
• Incisors 2/2
• Canine 1/1
• Premolars 0/0
• Molars 2/2
DENTAL FORMULA
•HSE Zoology blog •11
12. WISDOM TEETH
• Third molar appears
after the age of 20 years
and hence is called
wisdom teeth.
•HSE Zoology blog •12
13. STRUCTURE OF TOOTH
Crown
Neck
Root
Odontoblast
Found in the dental
pulp secrete dentine
•HSE Zoology blog •13
14. TONGUE
• Freely movable
muscular organ
attached to the floor of
the buccal cavity by
frenulum.
•HSE Zoology blog •14
15. TONGUE
• The upper surface of
the tongue has small
projections called
papillae, some of
which bear taste
buds.
•HSE Zoology blog •15
16. PHARYNX
• Common passage for
digestive and
respiratory system.
• Opening of oesophagus
• Opening of larynx -
Glottis
•HSE Zoology blog •16
17. GLOTTIS
• Glottis is guarded by a
flap of tissue called
epiglottis.
• When food materials
pass through the
pharynx the epiglottis
closes the glottis.
•HSE Zoology blog •17
18. OESOPHAGUS
• Narrow muscular tube
• 30 cm long
• Leads to stomach
• Pass through the
diaphragm (a muscular
partition that separates
thorax from abdomen).
•HSE Zoology blog •18
19. OESOPHAGEAL SPHINCTER
(GASTRO OESOPHAGIAL SPHINCTER)
• Posterior region of the
oesophagus there is a
ring of muscle called
oesophagial sphincter.
• It controls the opening
of the oesophagus into
the stomach.
•HSE Zoology blog •19
20. PERISTALSIS
• The movement of food
materials in the
esophagus is effected
by the wave like
contraction and
relaxation of
longitudinal and circular
muscles of the
esophagus is known as
peristalsis.
•HSE Zoology blog •20
21. STOMACH
• Large muscular ‘J’
shaped sac.
• Lying just below the
diaphragm in the
abdominal cavity.
• Three major parts
– Cardiac
– Fundic
– Pyloric
•HSE Zoology blog •21
22. PYLORIC SPHINCTER
• The opening of the
stomach into the
duodenum is guarded
by pyloric sphincter.
• Controls the flow of
food to the intestine.
•HSE Zoology blog •22
23. SMALL INTESTINE
• Long, highly coiled,
narrow tube
• Seven metres long
• 2.5 cm diametre
• Divided in to
duodenum, jejunum &
ileum.
•HSE Zoology blog •23
24. DUODENUM
• First part of SI
• ‘U’ shaped
• Area of digestion
• Receives common
opening of the bile
and pancreatic duct.
•HSE Zoology blog •24
26. ILEUM
• Highly coiled
• Opens into the large
intestine
• Area of absorption
•HSE Zoology blog •26
27. LARGE INTESTINE
• 1.5 metres long
• Differentiated into
Caecum , Colon &
Rectum
•HSE Zoology blog •27
28. CAECUM
• Small blind sac (at the
junction of SI &LI)
• Plays no role in Nutrient
absorption.
• It hosts some symbiotic
microorganisms.
• Caecum bears a finger like
out growth of unknown
function known as
Vermiform Appendix.
•HSE Zoology blog •28
30. RECTUM
• Temporary storage of
faeces
• Rectum opens out by
Anus.
•HSE Zoology blog •30
31. HISTOLOGY OF HUMAN GUT
( Outer most )
forms a fibrous coat
Loose connective tissue layer
with blood & lymph vessels
(Inner most)-made of
secretary & absorptive cells
Smooth muscle
•HSE Zoology blog •31
32. RUGAE
• Mucosal layer forms
irregular fold in the
stomach called rugae.
•HSE Zoology blog •32
33. VILLI
• (Sing:- Villus)
• Mucosal layer forms
small finger like
folding in the small
intestine called Villi
• A villus is about 0.5 to
1 mm long
Villus
•HSE Zoology blog •33
38. MICROVILLI
• Each villus has
numerous electron
microscopic
evaginations called
microvilli.
• Both villi & micro villi
increases the surface
area for digestion and
absorption of food
•HSE Zoology blog •38
40. DIGESTIVE ENZYMES
• Hydrolyses
Group of enzymes
released from the cells
digestive system play a
major role in the extra
cellular digestion in
human
• Carbohydrase (
amylase ) carbohydrate
digesting
E.g.: ptyalin, maltose etc
• Proteases (protein
digesting)
Eg: amino peptidase,
dipeptidase
. Lipase (lipid digesting)
•HSE Zoology blog •40
41. SALIVARY GLANDS
• Secrete saliva
• Found in buccal cavity
• Three pairs of salivary
glands
1.Parotid glands
(largest)
2.Sub lingual glands
3.Sub maxillary
(Sub mandibular)
•HSE Zoology blog •41
42. SALIVA
• Derived from blood plasma
• Secrete 1.5 liters of saliva
per day
• Slightly alkaline
• Contain water & electrolyte
(Na+, K+, Cl-, HCO3
-)
• Mucin, ptyalin, lyzozyme &
inorganic salts
• Ptyalin digest starch in to
maltose
•HSE Zoology blog •42
43. LIVER
• Largest gland in the
human body
• Weighs about 1.5 kg in
adult man
• Bi lobed
• Secrete bile
•HSE Zoology blog •43
44. • Each lobe is separated
into numerous tiny
hepatic lobules, which are
the functional units.
• A lobule is formed of
numerous hepatic cells –
bile is secreted by hepatic
cells
• Each lobule is covered by
a thin connective tissue
sheath called Glisson’s
capsule
Glisson’s
capsule
LIVER
•HSE Zoology blog •44
46. GALL BLADDER
• Bile is stored and
Concentrated in a thin
muscular sac called
gall bladder.
• Capacity- 40 – 60 ml
• Absent in whale,
horses, rats etc.
•HSE Zoology blog •46
47. BILE
• Golden yellow or greenish fluid
• Alkaline nature
• Bile pigments (product of dead RBC) (biliverdin & bilirubin)
• Bile salts,
• cholesterol,
• phospholipids
• Bile salts play a very important role in the emulsification of fat
•HSE Zoology blog •47
48. GALL BLADDER
• The duct of gall
bladder (cystic duct)
along with hepatic
duct from the liver
forms a common bile
duct.
•HSE Zoology blog •48
49. GALL BLADDER
• The bile duct and
pancreatic duct opens
together into the
duodenum as common
hepato - pancreatic
duct, which is guarded
by a sphincter called
sphincter of Oddi.
Hepato - Pancreatic duct
•HSE Zoology blog •49
50. PANCREAS
• Located between stomach
& duodenum
• Second largest glands
• Heterocrine gland (both
exocrine &endocrine)
• Pancreatic duct opens into
the duodenum along with
bile duct
• Secrete pancreatic juice.
•HSE Zoology blog •50
52. GASTRIC GLANDS
• Found on the wall of
stomach
• Formed of three kinds of
cells
1. Mucous cells
2. Chief cells or
Zymogen cells
3. Oxyntic cells
or Parital cells
•HSE Zoology blog •52
55. GASTRIC SECRETIONS
Name of Cell Function
Mucous cells (Goblet cells) Secrete mucous
Oxyntic cells or Parital cells
Secretion of HCl and intrensic
factor (factor essential for the
absorption of vitamin B12)
Chief cells or Zymogen cells
Secretion of enzymes such as
pepsin , rennin, lipase etc.
•HSE Zoology blog •55
56. HCl
• Inactivate the secretion of
salivary amylase.
• Kills micro organism
• Lowers the pH of the
stomach (1.5 to 2.5)
• Activate proenzyme
pepsinogen to active pepsin.
•HSE Zoology blog •56
57. INTESTINAL GLANDS
• Simple tubular glands found throughout SI
• Two types
Crypts of Lieberkuhn
Glands of Brunner
•HSE Zoology blog •57
58. CRYPTS OF LIEBERKUHN
• Goblet cells – Mucous secreting
• Paneth cells – Enzyme secreting
Many surface area of gastro intestinal tract are
lined by evaginations of the epithelium in to sub
mucosa similar to pits. These pits of the
intestine are called Crypts of Lieberkuhn
Paneth cells
Goblet cells
villus
crypt
•HSE Zoology blog •58
59. GLANDS OF BRUNNER ( DUODENAL GLANDS)
• Confined to the sub
mucosa of the
duodenum and
secrete mucus only
•HSE Zoology blog •59
61. DIGESTION
• The teeth and tongue with
the help of saliva masticate
and mix up the food into
bolus.
• The bolus is conveyed to
pharynx and then to
oesophagus by swallowing or
deglutition.
•HSE Zoology blog •61
62. DIGESTION
• The stomach stores the food 4-5 hrs. The food
mixes thoroughly with acidic gastric juice to
form paste.- Chyme
•HSE Zoology blog •62
chyme
63. Buccal cavity
Salivary amylase
• Starch
Starch Maltose
Maltose
CARBOHYDRATE
DIGESTION
Stomach
No carbohydrate
digestion
Small Intestine
Starch Maltose
Maltose 2 Glucose
Lactose Glucose +
Galactose
Sucrose Glucose +
Fructose
P. amylase
Maltase
Lactase
Sucrase
•HSE Zoology blog •63
64. Buccal cavity
No protein digestion
Stomach
HCl
Pepsinogen Pepsin
Protein
Pepsin Peptones +
Proteoses
Peptones = larger peptides
Proteoses = smaller peptides
Small intestine
Trypsinogen Enterokinase Trypsin
Chymotrypsinogen Chymotrypsin
Procarboxy
peptidase
Carboxy
peptidase
Proteins
Peptones
Proteoses
Dipeptides
Trypsin / Chymotrypsin
Carboxy peptidase
Dipeptidase
Dipeptides Amino acids
PROTEIN DIGESTION
•HSE Zoology blog •64
65. Buccal cavity
No protein digestion
Stomach
Gastric lipase hydrolyses
only a small amount of
fat Small intestine
Fat Bile Fat droplets
Emulsification
Fat
Pancreatic lipase
Diglyceride
Monoglycerides
Fatty acids & Glycerol
FAT DIGESTION
•HSE Zoology blog •65
66. NUCLEIC ACID DIGESTION
Small Intestine
Nucleic acids Nucleotides Nucleosides Sugar + Bases
•HSE Zoology blog •66
67. END PRODUCTS OF DIGESTION
Carbohydrates
Glucose
Fructose
Galactose
Proteins
Amino acids
Fats
Fatty acids
glycerol
•HSE Zoology blog •67
68. • Complete digestion of
food take place in the
duodenum. The fully
digested food is semi
fluid in nature and is
known as Chyle
DIGESTION
•HSE Zoology blog •68
69. ABSORPTION OF DIGESTED PRODUCTS
• Absorption is the process by
which the end products of
digestion pass through the
intestinal mucosa
( transported through the
intestinal mucosa) into the
blood or lymph
• The end products of digestion
are absorbed in the jejunum
and ileum regions of small
intestine.
•HSE Zoology blog •69
70. ABSORPTION
Absorption is carried out by
– Passive transport
– Facilitated transport
– Active transport
•HSE Zoology blog •70
71. PASSIVE TRANSPORT
• Small amounts of monosaccharide like glucose, amino acids,
and some of electrolytes like chloride ions are generally
absorbed by simple diffusion.
•HSE Zoology blog •71
73. FACILITATED TRANSPORT
• Fructose and some
amino acids are
absorbed with the help
of carrier ions like
sodium. This
mechanism is called
facilitated transport.
•HSE Zoology blog •73
74. ACTIVE TRANSPORT
• Requires energy
• Various nutrients like
amino acids,
monosaccharide like
glucose, electrolytes like
Na+ are reabsorbed into
the blood by active
transport.
•HSE Zoology blog •74
76. ABSORPTION OF FAT
• Fatty acids and glycerol insoluble in water so they cannot be
absorbed directly from the lumen of the intestine.
• With the help of bile salts & phospholipids the fatty acids and
glycerol are converted into small spherical water soluble droplets
called micelles.
•HSE Zoology blog •76
77. ABSORPTION OF FAT
Micelles are reformed into very small protein coated fat
globules called chylomicrons. Which are transported in to
the lymph vessels (lactales)in the villi.
•HSE Zoology blog •77
79. LARGE INTESTINE
Functions
Absorption of water,
minerals and certain
drugs.
Secretion of mucus which
helps in adhering waste.
• No significant digestive
activity occurs in the
large intestine.
•HSE Zoology blog •79
80. LARGE INTESTINE
• The undigested and
unabsorbed substances
(faeces) enters into the
caecum of the large
intestine through the
ileo caecal valve, which
prevents the back flow
of faecal matter.
•HSE Zoology blog •80
81. EGESTION
• The egestion of faeces
to the outside through
the anal opening
(defaecation) is a
voluntary process and is
carried out by a mass
peristaltic movement.
•HSE Zoology blog •81
82. THE SUMMARY OF ABSORPTION IN DIFFERENT PARTS OF
DIGESTIVE SYSTEM
Oral cavity Stomach Small Intestine Large
Intestine
Certain drugs
coming in
contact with the
mucosa of the
mouth and
lower side of the
tongue are
absorbed into
the blood
capillaries lining
them.
Water, simple
sugars, alcohol
Glucose Fructose
Fatty acids
Glycerol
Amino acids
Water , some
minerals,
drugs
•HSE Zoology blog •82
83. DISORDERS OF DIGESTIVE SYSTEM
• Infections of the
digestive system
are caused by
bacteria, virus,
parasites like tape
worm, thread
worm, round
worm, hook
worm, pinworm
etc.
Bacteria
Tape worm
Virus
Pinworm
•HSE Zoology blog •83
Thread worm
84. VOMITING
• It is the ejection of stomach
content through the mouth.
•HSE Zoology blog •84
85. DIARRHOEA
• The abnormal
frequency of bowel
movement and
increased liquidity of
faecal discharge is
known as diarrhoea.
• It reduces the
absorption of food.
•HSE Zoology blog •85
86. JAUNDICE
• The liver is affected, skin, eyes turn
yellow due to the deposition of bile
pigments.
•HSE Zoology blog •86
87. CONSTIPATION
• The faeces are retained
with in the rectum as
the bowel movement
occur irregularly.
•HSE Zoology blog •87
88. INDIGESTION
• The food is not properly
digested leading to the
feeling of fullness.
• The cause of indigestion
are inadequate enzyme
secretion, anxiety, food
poisoning, overeating
and spicy food.
•HSE Zoology blog •88
