Functions of Digestive system physiology.pdf

Digestive System

1. Functions of Digestive system
The digestive system is
the system of the body
that mechanically and
chemically breaks down
food.

2. •The GI tract is a
•continuous tube
•running from the
•mouth to the anus
•It measures about
•30 ft in length.
•The GI tract digests and absorbs food.

3. •It includes --
Mouth
pharynx
esophagus
stomach
small intestine
large intestine

4. •Accessory digestive organs -----
•break down foodstuff in the GI tract; the organs
involved are
•teeth,
•tongue,
•gallbladder,
•salivary glands,
•liver
•pancreas.

6. ▪Ingestion of food
▪Digestion of food
▪Secretion of various digestive juices
▪Absorption of water , salts, vitamins ,
and end products of digestion .
▪Excretion
▪Movements
▪Regulation of blood sugar.
▪Maintains water balance.

7. Salivary glands
•There are three pairs
of Salivary glands.

10. •There are three pairs of Salivary
glands.
•1)Parotid–Serous type
•Opens by Stensen’sduct.
▪Secretions are
▪thin
▪watery .
▪Contain enzymes.

11. 2)Sub
mandibular/Submaxillary-
Mixed type
Opens by Wharton’s duct.

12. •3)Sublingual---Mucus type
•Opens by Ducts of Rhivinus.
•Secretions are --thick
viscid
Contain much mucus

13. Saliva
•Total amount 1200 to 1500 cc.
•Consistency—Slightly cloudy.
•Reaction –Neutral or slightly acidic
•Sp gr.—1.002 to 1.008.

14. •Composition—Water—99.5%
Solids---.5%
•Inorganic salts –Nacl,Kcl, Ca. phosphate
etc.
•Organic
•Ptyaline(Salivary amylase),Maltase, Mucin.

15. Functions of Saliva
•Mechanical functions
•Keeps mouth moist
•Helps speech
•Helps in the process of mastication of
food stuff and formation of food
bolus .
•Acts as a Luricant.Helpsdeglutition.

16. •Dilutes hot and irritant substances .
•Prevents injury to mouth.
•Washes food debris and prevents
bacteria to grow.
•Helps in sensation of taste
•Helps to maintain water balance.

17. •Digestive functions
•Ptyalinesplits starch Maltose
•Maltase Maltose Glucose

18. Helps “Water Balance”
•Body water Saliva
•Thirst is felt Subject drinks water.
•Balance restored.

19. Act of deglutition (Act of swallowing)
Swallowing is a complex act
•It is initiated voluntarily
•And completed
•involuntarily.
•1) Buccalstage
•2) Pharyngeal stage
•3) Esophageal stage

23. Buccalstage
•Voluntary stage.
•Stimulus-----Food bolus stimulates nerve
endings at the back of the tongue and throat.
•Effect---------Tongue is drawn upwards and
back wards against hard palate .
•Food bolus is projected in to pharynx
•Respiration is inhibited.

24. Pharyngeal stage
•Involuntary stage
•Stimulus-----Food bolus stimulates
nerve endings in mucosal lining of
pharynx.

25. •Effect—Pharyngeal wall contracts
grips & squeezes food bolus in to
esophagus
•Soft palate is raised to prevent food
entering nose.
•Laryngeal wall is raised to safeguard
bronchial passages.
•Tongue is drawn stilfurther back.

26. Esophageal stage
•Involuntary
•Stimulus ---Food bolus stimulates nerve
endings in the wall of esophagus.
•Effect---
•Peristaltic waves of contraction squeeze bolus
towards cardiac sphincter.
Cardiac sphincter relaxes & allows bolus to
pass into stomach.

27. •------
•---
•---
•--
•-
•-

28. Teeth
4 INCISORS
2 CANINES
4 PREMOLARS
6 MOLARS
16 TEETH IN EACH
JAW

31. Structure of Tooth

32. Tongue
•Epithelium
• --Taste buds
• --Papillae
•Muscles –Voluntary
•Glands

33. Histology of Tongue

38. •----
•--
•--