1. FUNCTIONAL ANATOMY of DIGESTIVE SYSTEM
M. MANSYUR ROMI

2. THE DIGESTIVE SYSTEM
The overall function: to transfer nutrients in food from the external to the internal environment where they can be distributed to cells of the body via circulatory system
The processes that are important:
Ingestion
Digestion
Secretion
Motility / Propulsion
Absorption
Excretion

3. Quantities of material processed per day:
1200ml water
800g food
1500 ml saliva
500ml bile
2000ml gastric juice
1500ml pancr.juice
8500ml intest. abs
1500ml intest.secret
350ml colon abs
100ml water
50g solids

4. REGULATION of INGESTION
Hunger includes two sensations:
From the stomach: hunger contractions/pangs
Associated with low levels of nutrients in the blood
Alimentary regulation: concerned with immediate effects of feeding on the GIT
Nutritional regulation: concerned with the maintenance of normal stores of fat and glycogen in the body
Coordinated by: feeding & satiety centres

5. Feeding centre: in the lateral hypothalamus
Stimulation  hyperphagia
Lesions  lack of appetite & progressive inanition (loss of weight)
Satiety centre: in the ventromedial nuclei of hypothalamus
Stimulation  complete satiety (aphagia)
Lesions  voracious eating & obesity
Operates primarily by inhibiting the feeding centre

6. Appetite: a desire for specific food
Control of appetite via higher centers including:
areas in the amygdala where sensations of smell have an important role
cortical areas of limbic system

7. ORGANS of DIGESTIVE SYSTEM
I. Tractus Alimentarius
Cavum oris, Pharynx, Oesophagus, Gaster, Intestinum tenue (duodenum, jejunum, ileum), Intestinum crassum (coecum, colon ascendens, c.transversum, c.descendens, c.sigmoideum), Rectum, Anus
II. Associated Organs:
Dentes, Lingua, Gld. Saliva
Hepar, Vesica fellea, Pancreas

9. Functions of the oral cavity:
Chewing (mastication)
Taste (gustation)
Digestion
Lubrication
Swallowing
Speech
Protection from harmful ingested substances

10. Chewing Movements of the jaw (temporomandibular joint) and the tongue
Muscles involved:
M.masseter (M)
M.pterygoideus lateralis (PL)
M.pterygoideus medialis (PM)
M.temporalis (T)
Mm.suprahyoid (SH)
Mm.infrahyoid (IH)

11. Movements: Muscles: Elevation M, T, PM Depression PL, SH, IH
Protrution M, PL, PM
Retrution M, T
Side-gliding M, T(c.l), P(i.l)

12. The tongue The body: free movable portion
The base/root (radix): attached to the floor of the oral cavity and forms part of the anterior wall of the pharynx
It is divided by sulcus terminalis: ant & post
Muscles:
Intrinsic: vertical, transversal, longitudinal (s & i)
Extrinsic: originate outside, mainly on mandible and hyoid, and pass into the tongue

13. The tongue and taste Lingual glands: Papillae: The body: mainly serous
The base: mainly mucous
The tip: are mixed
Papillae:
Anterior & lateral: fungiform & foliate
The base: circumvalate
Taste buds: several thousands in tongue, palate & epiglottis

14. Nerves of the tongue
General afferent: branch of n.mandibularis (3rd. C.n. V)
Special afferent, differentiate:
Anterior :chorda tympani (c.n. VII)
Posterior: glossopharyngeal (c.n. IX)
Palate & epiglottis: vagus (c.n. X)
Efferent to intrinsic muscles: hypoglossus (c.n. XII)

15. Nerves of the tongue

16. Salivary glands The parotid: contains only serous cells
produce a watery secretion, high amylase
Stenson’s duct: vestibulum oris M2
The submandibular:
mostly serous, some mucous & mixed
produce a weak amylase, contain lysozyme
Wharton’s duct: caruncula sublingualis
The sublingual:
mainly mucous, some serous
produce a particularly thick mucous
Ducts: each gland opens beneath the tongue

17. Location of salivary glands

18. Control of secretion Autonomic nerves: Sympathetic: Parasympathetic:
Cell body in the gln.cervicale superior
Stimulate a more transient effect
Release noradrenalin -> vasoconstriction -> dry mouth when frightened
Parasympathetic:
Pregln.fibers in the branches of c.n. VII & IX
Provide a stronger & long lasting stimulus
Release: acetylcholine, subst.P, vasoactive intestinal peptide (VIP)

19. PHARYNX A muscular tube, 12 – 14 cm long
Extends from: cranial base – 6th cervical vert. and the lower border of the cricoid cartilage
Nasopharynx
Opening of eustachian tube, tonsils
Oropharynx
Behind the isthmus faucium, above the epiglottis
Triangular fossa with palatina tonsils
Laryngopharynx
Behind the choana, above the isthmus pharyngis

20. MUSCLES of the ORAL & COLLI REGIONS

21. SWALLOWING The bolus of food is passed back1 2
The bolus of food is passed back
into the oropharynx by the tongue
Respiration is reflexly inhibited
Isthmus between nasopharynx and oropharynx is closed
The larynx is carried upward and forward by the suprahyoid muscles
Opening the laryngopharynx is closed
The airway is firmly closed
(by the aryepiglottic, vestibular and vocal cords)

23. SWALLOWING 1 As the food passes into the oropharynx: 2
Epiglottis is bent back (almost to horizontal position)
Food is deflected by the epiglottis into the piriform fossae
Carried down into the laryngopharynx and esophagus
(The very sensitive mucosa of the larynx ensures that any material that does enter the airway stimulates coughing)

25. OESOPHAGUS A muscular tube about 25cm, It is constricted:
At its commencement, 15cm from incisor teeth
Where crossed by aortic arch (22.5cm from–id-)
Where crossed by left bronchus (27.5cm –id-)
As it transverse the diaphragm (40cm –id-)
The top 1/3: surrounded by skeletal muscle
The lower two-third: smooth muscle
Both muscles are under the control of vagus

26. OESOPHAGUS

27. OESOPHAGUS
The upper esophageal sphincter (UES): (hypopharyngeal sphinct/m.cricopharyngeus) thickening of circular skeletal muscle
The lower esophageal sphincter (LES): the last 1-2 cm, not anatomically distinguishable as a sphincter but the pressure is greater than in the stomach
A functional external sphincter provided by crural diaphragm, usually the right crus
Case: gastro esophageal reflux (GER)

29. VENTRICULUS / GASTER (STOMACH)
Rugae: folds present on the inner surface of the empty stomach, flatten out as fills
An additional oblique muscle layer present
The muscle layers are not evenly distributed
It is highly developed in the pylorus where it becomes a sphincter which regulates stomach emptying
The stomach is separated from the duodenal bulb by the pyloric sphincter

30. VENTRICULUS / GASTER

31. The stomach has folds called rugae and is a big muscular pouch which churns the bolus (Physical Digestion) and mixes it with gastric juice, a mixture of stomach acid, mucus and enzymes.

33. Structures opening in the 2nd part of the duodenum
The bile duct unites with the pancreatic duct forming a dilatation called the hepatopancreatic ampulla (ampulla of Vater).
The ampulla opens on an elevation called the major duodenal papilla.
The accessory pancreatic duct opens one-inch above the major duodenal papilla, forming a smaller elevation called the minor duodenal papilla.

34. Blood supply of duodenum

35. Vesels In general, the veins are equivalent to the arteries,
Vesels In general, the veins are equivalent to the arteries, ending in the portal vein. Nerves The stomach and duodenum possess both intrinsic and extrinsic nerve supplies.
The extrinsic supply is derived mainly from the vagus nerves, Vagal fibres are both afferent (sensory) and efferent. The efferent fibers are involved in the receptive relaxation of the stomach and the stimulation of gastric motility, as well as having a secretory function.
The sympathetic supply is derived mainly from the coeliac ganglia.

36. Motility of The Digestive Tract
Skeletal muscle: mouth, pharynx, upper 1/3 of esophagus, external anal sphincter
Smooth muscle: in the remaining tracts, consist of two layers:
Outer longitudinal coat
Inner circular coat
Two types:
Phasic
Tonic

37. Smooth muscle of GIT
Phasic: contract & relax in a matter of seconds, present in: main body of esophagus, gastric anthrum, small intestine
Tonic: contract in a slow & sustained (mnts – hrs), present in: lower esophageal sphincter, ileocecal sphincter, internal anal sphincter
Action potentials are triggered in a few ‘pacemaker’ cells, which most numerous in the longitudinal layer, then transmitted throughout the muscle sheet

38. Control of secretion & motility
Mechanisms: neural, hormonal & paracrin
Neural:
Intrinsic:
Myenteric (Auerbach’s) plexus between longitudinal & circular layers, control of GIT motility
Submucous (Meissner’s) plexus, control secretion & blood flow
Extrinsic: autonomic nervous system

39. Sympathetic nerves

40. Parasym pathetic nerves

42. The Human Digestive System
Jejunum
The jejunum is where the majority of absorption takes place.
It has tiny fingerlike projections called villi lining it, which increase the surface area for absorbing nutrients.

43. The Human Digestive System
Ileum
The last portion of the small intestine is the ileum, which has fewer villi and basically compacts the leftovers to pass through the caecum into the large intestine.

44. Coecum and Terminal Ileum

45. INTESTINUM CRASSUM

46. The Human Digestive System
The large intestine (or colon) is used to absorb water from the waste material leftover and to produce vitamin K and some B vitamins using the helpful bacteria that live here.

47. The Human Digestive System
All leftover waste is compacted and stored at the end of the large intestine called the rectum.
When full, the anal sphincter loosens and the waste, called feces, passes out of the body through the anus.

48. RECTUM AND ANUS

53. Duodenum Dr

54. Arteries
On the lesser curve, the left gastric artery, a branch of the coeliac axis, forms an anastomotic arcade with the right gastric artery, which arises from the common hepatic artery.
The gastroduodenal artery, which is also a branch of the hepatic artery, passes behind the first part of the duodenum. Here it divides into the superior pancreaticoduodenal artery and the right gastroepiploic artery.
The superior pancreaticoduodenal artery supplies the duodenum and pancreatic head, and forms an anastomosis with the inferior pancreaticoduodenal artery, a branch of the superior mesenteric artery.
The right gastroepiploic artery runs along the greater curvature of the stomach, eventually forming an anastomosis
with the left gastroepiploic artery, a branch of the splenic artery.
The fundus of the stomach is supplied by the vasa brevia
(or short gastric arteries), which arise near the termination of the
splenic artery

55. Primitive Gut
The primitive gut is formed during the fourth week as the head, tail and lateral folds incorporate the dorsal part of the yolk sac into the embryo.
The cranial and caudal extremities of the tract is derived from ectoderm of the stomodeum (primitive mouth) and the proctodeum (anal pit)

56. The endoderm of the primitive gut gives
The muscular and fibrous elements of the digestive tract, and visceral peritoneum are derived from the splanchnic mesoderm.
The primitive gut is divided into three parts: the foregut, the midgut and the hindgut, which are supplied respectively by three branches of the dorsal aorta: the celiac artery, the superior mesenteric artery and inferior mesenteric artery.

57. dr. Mansyur Romi, S.U
Oral cavita, Oesophagus, stomach
Block 11, Prog-int 2004

58. The foregut The derivatives of the foregut are the following:
1. the pharynx
2. the lower respiratory tract
3. the esophagus
4. the stomach
5. the duodenum
6. the liver and pancreas, and
7. the billiary apparatus

59. The midgut The derivatives of the midgut are the following:
1. the small intestines except proximal duodenum to point of entrance of the common bile duct
2. the cecum and appendix
3. the ascending colon
4. two-third proximal part of the transverse colon

60. The hindgut The derivatives of the hindgut are the following:
1. The left one-third distal part of the transverse colon
2. the descending colon
3. the sigmoid colon
4. the rectum
5. the upper portion of the anal canal and
6. part of the urogenital system

61. dr. Mansyur Romi, S.U
Oral cavita, Oesophagus, stomach
Block 11, Prog-int 2004

64. RECTUM AND ANUS