Explained about Mouth,Pharynx, oesophagus,Stomach

1. Human Anatomy and Physiology-II
Digestive system
(Mouth, Pharynx, Oesophagus and
Stomach)
Mr N.JEGAN
Associate Professor
K.M.COLLEGE OF PHARMACY.
MADURAI.

2. Parts of digestive system
Digestive system consist of following parts
1. Mouth
2. Pharynx
3. Oesophagus
4. Stomach
5. Small intestine
6. Large intestine
7. Rectum
8. Anus

4. Mouth

5. Mouth
• It is otherwise known as
oral cavity or buccal
cavity.
• It encloses
1.Teeth
2.Tongue
3.salivary glands.

6. FUNCTIONS OF MOUTH
1. Ingestion of food materials
2. Chewing the food and mixing it with saliva
3. Appreciation of taste of the food
4. Transfer of food (bolus) to the esophagus by
swallowing
5. Role in speech

7. Tongue
The tongue is a voluntary muscular structure
which occupies the floor of the mouth.
It is attached by its base to the hyoid bone and
fold of its mucous membrane covering, called the
frenulum.

8. Tongue contains:
• A root at which blood vessel and nerves pass.
There are four types of taste bud(Sense taste)
present on the upper surface.
1.Circumvallate papillae
2.Fungiform papillae
3.Filiform papillae
4. Folate papillae

9. Papillae , Taste bud and sensation of different taste

10. Functions of the tongue
1.Mastication (chewing)
2. Deglutition (swallowing)
3. Speech
4. Sense the taste
5. Mixing of Food with saliva
6. Push the food to esophagus

11. Teeth

12. Teeth
The teeth are embedded in the alveoli or
sockets of the alveolar ridges of the mandible and
the maxilla .
There are 32 permanent teeth, each half of the
upper and lower jaw contains 8 Teeth.
They are:
2 incisors
1 canine
2 premolars
3 molars

14. Structure of a tooth
The shapes of the different teeth vary, the
structure is the same and consists of:
1. The crown
It protrudes from the gum
2.The root
This part embedded in the bone
3.The neck
Slightly narrowed region where the crown
merges with the root

15. In the centre of the tooth is the pulp cavity
containing blood vessels, lymph vessels and nerves.
It surround the hard ivory-like substance called
dentine .
Outside the dentine of the crown is a thin layer
of very hard substance, the enamel.

17. Functions of teeth
• Chewing of food
1. The incisor and canine teeth are the cutting
teeth and are used for biting off pieces of food.
2. Premolar and molar teeth, with broad, flat
surfaces, are used for grinding of food.
• Speech
• Appearance

18. Salivary Gland

19. SALIVARY GLANDS
• Salivary gland are Exocrine gland.
• It secrete Saliva
• Saliva pour their secretions into the mouth.
There are three pairs of salivary gland:
1. Parotid glands
2.Submandibular glands
3. Sublingual glands.

20. 1.Parotid Gland
One on each side is present below and anteriorly
front of each ear. These are largest of the salivary
gland.
2. Submandibular Gland
It is a major pair of salivary gland located
beneath the lower jaws.
3. Sublingual Gland
It is situated inferior to the tongue, and anterior
to the submandibular glands.

22. Structure of salivary gland
• Salivary glands are formed by acini or alveoli.
• Each acinus is formed by a small group of cells
which surround a central globular cavity.
• The draining each acinus is called intercalated
duct. Many intercalated ducts join together to
form intralobular duct.
• Which unite to form the main duct of the gland

24. Saliva
Salivary gland secrete- 1000 mL to 1500 mL of saliva is
secreted per day.
Composition of Saliva

25. FUNCTIONS OF SALIVA
1.Preparation of Food for Swallowing
2. Digestive Function
Saliva has three digestive enzymes
1.Salivary amylase-It acts on cooked or boiled starch and
converts it into dextrin and maltose.
2. Maltase -Converts maltose into glucose
3. Lipase -It hydrolyzes fat into fatty acids
3. Cleansing and Protective functions
Saliva prevents bacterial growth by removing materials
4. Saliva helps in speech
5.It excrete some waste product like mercury, potassium iodide.

27. Pharynx

28. Pharynx
• The pharynx is a tube 12 to 14 cm long that extends from
the base of the skull.
• Common space used by both the respiratory and digestive
systems (Common pathway for both air and food).
• Pharynx is divided into three parts:
Nasopharynx
Oropharynx
Laryngopharynx

29. 1.Nasopharynx
It is not the part of
Digestive system
2. Oropharynx
Posterior to Oral
cavity
3. Laryngopharynx
below the oropharynx
and connected to the
esophagus

30. Digestive function of Pharynx
• It get the food from mouth
• It also involve the swallowing of food
• It carry the food to the stomach through
esophagus

31. OESOPHAGUS

32. Esophagus(Food Pipe)
• It runs from pharynx to stomach.
• It is about 25 cm long tube.
• It is a mucus muscular membrane lined tube.
• They perform peristalsis movement
(involuntary rhythmic muscle contraction).

33. Function
1.The lining of the esophagus secrete mucus.
2.Lubricating food
3.To support the movement of food.

34. Peristalsis
• It is the contraction and
relaxation of the food in the
esophagus and the food is
forced down the to the
stomach.
• This movement is
involuntary.

35. Deglutition or Swallowing
• This occurs in three stages after mastication is
complete and the bolus has been formed.
• It is initiated voluntarily but completed by a
reflex (involuntary) action.

36. Three stages of Deglutition
1.The mouth is closed and the voluntary muscles
of the tongue and cheeks push the bolus backwards
into the pharynx.
2. It stimulated by a reflex action initiated in the
walls of the oropharynx .Contraction of Pharynx
muscles propels the bolus down into the oesophagus.
3.The presence of the bolus in the pharynx
stimulates a wave of peristalsis which propels the
bolus through the oesophagus to the stomach.

37. Stomach

38. Stomach- Shape and Location
• The stomach is a J-shaped dilated
organ
• Location- situated just below the
diaphragm on the left side in the
abdominal cavity.
• Capacity- Empty stomach is 50 ml
- It is capable of expanding
up to 4 L

39. PARTS OF STOMACH
Stomach has three parts:
1. Fundus- It is a small dome shaped structure,
elevated above the level of esophageal opening.
2. Body- It extends from just below the fundus up to the
pyloric region.
3.Pylorus- Pyloric region has two parts, antrum and
pyloric canal.

40. Stomach-Sphincter and Curvature
Two sphincter-It prevent the backward flow of food.
1.Cardiac sphincter
Between esophagus and stomach.
2. Pyloric sphincter
Between stomach and Small intestine
It has two curvatures.
1.The lesser curvature is short, lies on the Right side.
2.The greater curvature –It is in left side of stomach.

42. Structure of Stomach layers
1.Outer serous layer: Formed by peritoneum
2. Muscular layer: Made up of three layers of smooth muscle
fibers
oblique muscle
circular muscle
longitudinal muscle
3.Submucus layer: Formed by areolar tissue, blood vessels,
lymph vessels and nerve
4. Inner mucus layer: Lined by mucus secreting columnar
epithelial cells. The gastric glands are situated in this layer.

44. GLANDS OF STOMACH –GASTRIC GLANDS
Glands of the stomach or gastric
glands are tubular structures made
up of different types of cells.
1. Chief cells or pepsinogen cells
2. Parietal cells or oxyntic cells
3. Mucus neck cells
4. Enterochromaffin (EC) cells
5. Enterochromaffinlike (ECL) cells
These glands open into the
stomach cavity via gastric pits.

45. Secretory function of cells in gastric
glands

46. Functions of the stomach
1.Temporary storage of food- Allow act the digestive
enzymes pepsins to act.
2. Chemical digestion — pepsins convert proteins to
Polypeptides
3. Mechanical breakdown — the three smooth
muscle layers enable the stomach to act as a churn,
gastric juice is added and the contents are liquefied to
chyme
4. Absorption of water, alcohol and some lipidsoluble
drugs
.

47. 5. non-specific defence against microbes —
provided by hydrochloric acid in gastric juice.
6. preparation of iron for absorption
7. Production of intrinsic factor needed for
absorption of vitamin B12 in the ileum

48. Thanking you