DIGESTIVE SYSTEM
BY ACHMAD AMINUDDIN
FUNCTIONS
INGESTION:
taking food into the mouth.
SECRETIO:
release of water,acid, buffer, and enzymes i
nto the lumen of the GI tract.
MIXING AND PROPULSION:
churning and propulsion of food through the
GI tract.
CONTINUATION
DIGESTIO:
mechanical and chemical breakdown of food
ABSORPTION:
passage of digested products from the GI tr
act into the blood and lymph.
DEFECATION:
the elimination of feces from the GI tract.
ORAL REGION
INCLUDES :
– THE ORAL CAVITY
– TEETH
– GINGIVAE
– TONGUE
– PALATE
– THE REGION OF THE PALATINE
– TONSILS
ORAL CAVITY
CONSIST OF
– THE ORAL VESTIBULE
– THE ORAL CAVITY PROPER
IS WHERE FOOD IS INGESTED AND PRE
PARED FOR DIGESTION
THE TEETH AND SALIVA FASILITATE TH
E FORMATION OF A MANAGEABLE FOO
D BOLUS
THE ORAL VESTIBULE
IS THE SLIT LIKE SPACE BETWEEN THE
LIPS AND CHEEKS SUPERFICIALLY.
COMMUNICATES WITH THE EXTERIOR T
HROUGH THE ORAL FISSURE ( ORIFI CE
OF MOUTH )
THE SIZE OF THIS OPENING IS CONTRO
LED BY THE ORBICULARIS ORIS M.
THE ORAL CAVITY PROPER
BOUNDARIES
– LATERAL AND ANTERIOR
THE MAXILLARY AND MANDIBULAR ALVEOLAR ARCHES H
OUSING THE TEETH.
– POSTERIOR
THE TERMIAL GROOVE OF THE TONGUE.
PALATOGLOSSAL ARCHES.
– THE ROOF
THE PALATE.
– POSTERIORLY COMMUNICATES WITH
THE OROPHARYNX.
ORAL VESTIBULE
CONTAIN
ORBICULARIS M.
SUPERIOR AND INFERIOR LABIAL M.
VESSELS AND NERVES.
ARE COVERED BY
SKIN.
MUCOUS MEMBRANE
PHILTRUM.
THE VERMILLION BORDER.
THE GINGIVAE
COMPOSED OF FIBROUS TISSUE COVE
RED WITH MUCOUS MEMBRANE.
FIRMLY ATTACH TO THE ALVEOLAR PR
OCESSES OF THE JAWS AND THE NECK
S OF THE TEETH.
TEETH
SET IN THE ALVEOLI OF THE UPPER AND LOWER JA
WS.
CHILDREN HAVE 20 DECIDUOUS ( PRI MARY ) TEETH.
THE FIRST TOOTH USUALLY ERUPS AT 6 TO 8 MONT
H OF AGE AND THE LAST TOOTH BY 20 TO 24 MONTH
OF AGE.
THE PERMANENT TEETH NORMALLY 16 INEACH JAW,
3 MOLARS, 2 PREMOLARS,1 CA NINE AND 2 INCISORS
, USUALLY IS COMPLE TE BY THE MIDTEENS EXCEPT
FOR THE 3rd MOLAR, WICH USUAL LY ERUP DURING T
HE LATE TEENS OR EARLY TWETIES
TEETH
CONSIST OF,
– THE CROWN
PROJECTS FROM THE GINGIVA
– THE NECK
THE PART OF THE TOOTH BETWEEN THE CROW
N AND ROOT.
– THE ROOT
IS FIXED IN THE ALVEOLUS BY A FIBROUS PERI
ODONTAL MEMBRANE.
COMPOSITION OF THE TOOTH
DENTIN is covered by
ENAMEL over the crown
CEMENT over the root
PULP CAVITY, contain
– CONNECTIVE TISSUE.
– BLOOD VESSELS.
– NERVES.
ROOT CANAL transmits the nerves and vessels to
and from the pulp cavity
SALIVA
SALIVARY AMYLASE
source ; salivary glands.
substrates : starches ( polysacharides ).
products : maltose ( disaccharide ).
maltotriose ( trisaccharide ).
a-dextrins.
LINGUAL LIPASE
source : lingual glands in the tongue.
substrates : triglycerides ( fats and oils ) and
other lipids.
products : fatty acids and diglycerides.
PALATE
THE HARD PALATE
– SEPARATES THE AMTERIOR PART OF THE
ORAL CAVITY FROM THE NASAL CAVITY.
THE SOFT PALATE
– SEPARATES THE POSTERIOR PART OF THE
ORAL CAVITY FROM THE NASOPHARYNX S
UPERIOR
THE PALATINE TONSIL
LIES IN A TONSILAR SINUS ( FOSSA ), B
OUNDED BY,
– PALATO GLOSSAL ARCH.
– PALATOPHARYNGEAL ARCH.
– TONGUE.
PHARYNX
EXTENDS FROM THE CRANIAL BASE TO
THE INFERIOR BORDER OF THE CRICOI
D CARTILAGE ANTERIORLY AND THE IN
FERIOR BORDER OF THE C6 VERTEBRA
POSTERIORLY.
INTERIOR OF THE PHARYNX
- NASOPHARYNX.
- OROPHARYNX.
- LARYNGOPHARYNX
ESOPHAGUS
A MUSCULAR TUBE THAT EXTENDS FROM TH
E PHARYNX TO THE STOMACH
DESCENDS THROUGH THE POSTERIOR MEDI
ASTINUM, ESOPHAGEAL HIATUS IN THE DIAP
HRAGM JUST JUST TO THE LEFT OF MEDIAN
PLANE AT THE LEVEL OF VT 10 , ENTER THE
STOMACH THROGH CARDIAL ORIFICE TO THE
LEFT OF MID LINE AT THE LEVEL OF THE 7 T
H LEFT COSTAL CARTILAGE AND VT 11
ESOPHAGUS
Pharyngoesophageal junction – cardia.
Striated muscle ( voluntary ) – upper third.
Smooth muscle ( involuntary – lower third.
Mixture -- in between.
Cervical eophagus
- upper third.
- begin posterior to and at the level of the
inferior border of the cricoid cartilage / C6
vertebra.
- Pharyngoesophageal junction is the superior
esophageal shincter is produced by the cricopharyngeal
part of the inferior constrictor muscle.
- lie between the trachea and the cervical vertebral column.
- the recurrent laryngeal n.lie in the tracheoesophageal groove.
ESOPHAGUS
The esophagus descends in to the posterior media
stinum from the superior mediastinum passing pos
terior and to the right of the arch of the aorta.
Passes through the esophageal hiatus in the diaph
ragm at the level of the T10 vertebra anterior to th
e aorta.
Three constrictions
- the arch of the aorta.
- the left main bronchus.
- the diaphragm.
NERVES OF THECERVICAL ESOP
HAGUS
Somatic motor and sensorik – upper half.
Parasympathetic, sympathetic
and visceral sensory -- lower half.
The cervical esiphagus receives
- somatic fibers via branches from the
recurrent laryngeal nerve.
- vasomotor fibers from the cervical
sympathetic trunk.
VESSELS OF THE CERVICAL E
SOPHAGUS
Branches of the inferior thyroid arteries.
Tributaries of the inferior thyroid veins.
Paratracheal lymp nodes.
Inferior deep cervical lymph nodes.
DEGLUTITION
THE MOVEMENT OF FOOD FROM THE MOUTH
INTO THE STOMACH.
FACILITATED BY THE SECRETION OF SALIVA
AND MUCUS AND INVOLVES THE MOUTH,PHA
RYNX AND ESOPHAGU
THREE STAGES;
- the voluntary stage, the bolus is passed in
to the oropharynx.
- the pharyngeal stages.
- the esophageal stage.
STAGE I : VOLUNTARY
THE BOLUS IS COMPRESSED AGAINST
THE PALATE AND PUSHED FROM THE M
OUTH IN TO THE OROPHARYNX, MAINL
Y BY MOVEMENTS OF THE MUSCLES O
F THE TONGUE AND SOFT PALATE
Fig 8.39 A , B
STAGE 2 INVOLUNTAY AND RAPI
D
THE SOFT PALATE IS ELEVATED, SEALI
NG OFF THE NASOPHARYNX FROM THE
OROPHARYNX AND LARYNGOPHARYNX.
THE PHARYNX WIDENS AND SHORTENS
TO RECEIVE THE BOLUS OF FOOD AS T
HE SUPRAHYOID MUSCELS AND LONGI
TUDINAL PHARYNGEAL MUSCLES CONT
RACT, ELEVATING THE LARYNX
STAGE 3 ; INVOLUNTARY
SEQUENTIAL CONTRACTION OF ALL TH
REE CONSTRICTOR MUSCLES FORCES
THE FOOD BOLUS INFERIORLY IN TO TH
E ESOPHAGUS
STOMACH
A FOOD BLENDER.
RESERVOIR.
CHIEF FUNCTION , ENZYMATIC DIGESTI
ON, GASTRIC JUICE CONVERTS A MASS
OF FOOD IN TO A LIQUID MIXTURE – CH
YME – THAT PASSES IN TO DUODENUM.
STOMACH
HAS 4 PARTS AND 2 CURVATURES,
– CARDIA.
– FUNDUS.
– BODY.
– PYLORIC PART.
– LESSER CURVATURE.
– GREATER CURVATURE.
FUNCTIONS OF THE STOMACH
MIXES SALIVA, FOOD AND GASTRIC JUICE TO
FORM CHYME.
SERVES AS RESERVOIR FOR FOOD BEFORE
RELEASE INTO SMALL INTESTINE.
SECRETE GASTRIC JUICE, WHICH CONTAIN H
Cl ( kills bacteria and denatures protein ), PEPSIN
( begins the digestion of proteins ), INTRINSIC FA
CTOR ( aids absorption of vit. B12 ), AND GASTRI
C LIPASE ( aids digestion of triglycerides ).
SECRETES GASTRIN INTO BLOOD.
VISCERAL REFERED PAIN
SMALL INTESTINE
EXTENDS FROM THE PYLORUS TO THE
ILEOCECAL JUNCTION.
THE PRIMARY SITE OF ABSORPTION OF
NUTRIEN FROM INGESTED MATERIAL.
CONSIST OF DUODENUM, JEJUNUM AN
D ILEUM.
DUODENUM
SUPERIOR PART.
DESCENDING PART.
HORIZONTAL PART.
ASCENDING PART.
JEJUNUM AND ILIEUM
6 – 7 METERS.
JEJUNUM , two – fifth.
ILEUM , three – fifth.
THE MESENTERY
– ATTACHES THE JEJUNUM AND ILEUM TO THE POS
TERIOR ABDOMINAL WALL.
– THE ROOT OF THE MESENTERY, EXTENDS FROM T
HE DUODENOJEJUNAL JUNCTION ON THE LEFT DI
DE OF V.L. 2 TO THE ILEOCOLIC JUNCTION AT THE
RIGHT SACROILIAC JOINT ( 15 CM LONG ).
LARGE INTESTINE
CONSIST OF
– CECUM.
– COLON
ASCENDING.
TRANSVERSE.
DESCENDING.
SIGMOID.
– RECTUM.
– ANAL CANAL.
COLON CAN BE DISTINGUISE
D FROM SMALL INTESTINE,
TENIA COLI (excep appendix and rectum ).
HAUSTRA.
OMENTAL APPENDICES.
CALIBER.
CECUM
THE FIRST PART OF THE LARGE INT
ESTINE.
INTRA PERITONEALLY.
HAS NO MESENTERY.
THE ILEUM ENTER THE CECUM ,
– ILEOCECAL ORIFICE.
– ILEO CECAL VALVE.
APPENDIX
EXTENDS FROM THE POSTEROMEDIAL
ASPECT OF THE CECUM, INFERIOR TO
THE ILEOCECAL JUNCTION/
HAS THE MESOAPPENDIX.
USUALLY RETROCECAL.
ITS BASE MOST OFTENLIES DEEP TO M
c. BURNEY POINT.
THE ASCENDING COLON
FROM THE CECUM TO THE RIGHT COLI
C FLEXURE.
RETROPERITONEAL ( 25 0/0 has a short
mesentery ).
THE TRANSVERSE COLON
THE LARGEST AND MOST MOBILE.
FROM THE RIGHT FLEXURE TO THE L
EFT COLIC FLEXURE.
DESCENDING COLON
RETRO PERITONEALLY.
FROM THE LEFT COLIC FLEXURE IN TO
THE LEFT ILIAC FOSSA.
IN THE ILIAC FOSSA HAS A SHORT MES
ENTERY ( 33 0/0 ).
THE SIGMOID COLON
S SHAPED LOOP.
FROM THE ILIAC FOSSA TO THE THIRD
SACRAL.
HAS ASIGMOID MESOCOLON.
THE ROOT OF THE SIGMOID COLON HA
S AN INVERTED V SHAPED ATTACHME
NT.
RECTUM AND ANAL CANAL
THE FIXED TERMINAL PART OF THE
LARGE INTESTINE.
CONTINUOUS INFERIORLY WITH TH
E ANAL CANAL.
RECTUM
fig 3.33 429
RECTUM
The rectosigmoid junction lies anterior to the S3 ve
rtebra. At this point , the taenia of the sigmoid colo
n spread out to form a continuous outer longitudin
al layer of smooth muscle, and the fatty omental a
ppendices are discontinued.
The sacral flexure of the rectum
The rectum ends anteroinferior to the tip of the coc
cyx, immediately before the anorectal flexure of th
e anal canal, that occur as the gut perforates the p
elvic diaphragm
fig 241 272
RECTUM
The roughly 80° the anorectal flexure is an i
mportant mechanism for fecal continence, b
eing maintained during the resting stage by t
he tonus of the puborectalis muscle and by i
ts contraction during peristaltic contraction if
defecation is not to occur.
The ampula of the rectum receives and hold
s an accumulating fecal mass until it is expel
led during defcation
fig 3.8 372
RECTUM
Peritonium covers the anterior and lateral su
rface of the superior third of the rectum, only
the anterior surface of the middle third, and
no surface of the inferior third because it is s
ubperitoneal.
Rectovesical pouch.
Rectouterine pouch.
Pararectal fosae
fig 3.34 430
ARTERIL SUPPLY OF THE RECTU
M
The superior rectal artery, the continuation of the i
nferior meenteric aretry, supply the proximal part o
f the rectum.
The right and left middle rectal arteies, arising fro
m the inferior vesical arteries, supply the middle a
nd inferior parts of the rectum
The inferior rectal arteries, arising from the pudend
al arteries, supply hte anorectal junction and anal
canal.
Anastomosis betwen these arteries provide potenti
al colateral circulation
VENOUS DRAINAGE
The superior , middle and inferior rectal veins.
The superior rectal vein drains into the portal veno
us system.
The middle and inferior rectal veins drains into sys
temic system
The rectal venous plexus
- the internal rectal venous plexus.
- the externsl rectal venous plexus
LYMPHATIC DRAINAGE
From the superior half of the rectum pass to
the pararectal l.n , and then to the inferior m
esenteric l.n , -- lumbar l.n.
From the inferior half of the rectum drains dir
ectly to sacral l.n.
From distal ampulla , drains into the internal
iliac l.n.
FIG 3,35 431
INNERVATION OF THE RECTUM
The sympathetic supply is from the lumbar spinal c
ord, conveyed via lumbar splanchnic nerves and t
he hypogastric / pelvic plexuses and through the p
eriarterial plexus of the inferior mesenteric and sup
erior rectal arteri
The parasympathetic supply is from the S2 – S4 s
pinal cord level, passing via the pelvic splanchnic
nerves and the left and right inferior hypogastric pl
exuses to the rectal plexus.
All visceral afferent fibers follow the parasympathe
tic fibers retrogradely to the S2 – S4 spinal sensor
y ganglia.
INNERVATION OF THE RECTUM
fig 3.36 432
ANAL CANAL
Anal canal extends from the superior aspec
t of the pelvic giaphragm to the anus.
Surrounded by internal and axternal anal sp
hincters, descends posteroinferiorly betwee
n the anococcygeal ligament and the perine
al body
FIG 3.42 B
FIG 3.43
THE INTERNAL ANALSPHINCTER
IAS, is an involuntary sphincters surroundin
g the superior two third of the anal canal
It contraction ( tonus ) is stimulated and mai
ntained by sympathetic fibers from the super
ior rectal ( periarterial ) and hypogastric plex
uses ; its contraction is inhibited by parasym
pathetic fiber stimulatin
THE EXTERNAL ANAL SPHINCTE
R
EAS , is a large voluntary sphincter that forms a br
oad band on each side of the inferior two thirds of t
he anal canal
EAS , is attached anteriorly to the perineal body a
nd posteriorly to the to the coccyx via the anococc
ygeal ligament; it blends superiorly with the pubore
ctalis muscle.
EAS , is supplied mainly by S4 through the inferior
rectal nerve, although its deep part also receives fi
bers from the nerve to the levator ani
ANAL CANAL
Extends from the superior aspect of the pelv
ic diaphragm to the anus
Surroumded by internal and external anal sp
hincter,descends posteroinferiorly between t
he anococcygeal ligamentum and the perine
al body.
Anal column
- contain the terminal branches of the
superior rectal artery and vein
fig 3.45
ARTERIAL SUPPLY OF THE ANAL
CANAL
The superior rectal arteriy supplies the anal
canal superior to the pectinate line.
The two inferir rectal arteries supply the infer
ior part of the anal canal as well as the surro
unding muscles and perianal skin.
The middle rectal arteries assist with the blo
od supply to the anal canal by forming anast
omses with the superior and inferior rectal ar
teries.
VENOUS DRAINAGE OF THE ANA
L CANAL
Superior to the pectinate line, the internal rectal pl
exus drains chiefly into the superior rectal vein ( tri
butary of the IMV ).
Inferior to the pectinate line, thr internal rectal plex
us drains into the inferior rectal vein ( tributary of t
he caval venous system ) around the margin of the
external anal sphincter .
The middle rectal veins ( tributary of the internal ili
ac veins ) mainly drain the muscularis externa of t
he ampula and form anastomoses with hte superio
r and inferior rectal veins
LYMPHATIC GRAINAGE OF THE A
NAL CANAL
Superior to the pectinata line, the lymphatic
vessels drain deeply into the internal iliac ly
mph nodes ---- the common iliac and lumbar
lymph nodes.
Inferior to the pectinata line , the lymphatic v
essels drain superficially into the superficial i
nguinal lymph nodes
INNERVATION OF THE ANAL CAN
AL
Seuperior to the pectinate line is visceral inn
ervation from the inferior hypogastric plexus,
involving sympathetic, parasympathetic, and
visceral afferent fibers Sympathetic fibers m
aintain the tonus of the internal sphincter
Parasympathetic fibers inhibit the tonus of th
e internal sphincter and evoke peristaltic con
traction for defecation.
INNERVATION OF THE ANAL CAN
AL
All visceral afferent travel with the parasymp
athetic fibers to spinal sensory ganglia S2 –
S4.
The nerve supply of the anal canal Inferior t
o the pectinate line, is somatic innervation d
erived from the inferior anal ( rectal ) nerves,
branches of the pudendal nerve.
Somatic efferent fibers stimulate contraction
of the voluntary external anal sphincter.
