LECTURE NOTES ON ANATOMY OF DIGESTIVE SYSTEM

PHARMACY PROGRAMNOVEMBER 2012

REV. PROF. A.S. AYETTEY

OBJECTIVESBE ABLE TO RECOGNIZE DIFFERENT PARTS OF

THE DIGESTIVE SYSTEM (mouth, esophagus, stomach, duodenum, jejenum, ileum, large bowel, anal canal)

BE ABLE TO RECOGNIZE THE FUNCTIONAL DESIGN OF THE DIGESTIVE SYSTEM

BE ABLE TO RECOGNIZE THE FUNCTIONAL ROLE OF DIFFERENT PARTS OF THE DIGESTIVE SYSTEM

BE ABLE TO WORK OUT CLINICAL PROBLEMS IN THE DIGESTIVE SYSTEM BASED ON YOUR KNOWLEDGE OF ITS FUNCTIONS

PARTS OF THE DIGESTIVE SYSTEMTHE ORAL (buccal) CAVITY

TEETH (mastication, defensive) TONGUE (aid in swallowing by rolling food, taste, sensory function-

hot and cold receptors) PALATE (also has taste fibres, and aids in rolling food) SALIVARY GLANDS

THE ORO-PHARYNX (immediately behind the oral cavity)THE ESOPHAGUS (10 INCHES; 25CM)THE STOMACH (digestion of proteins)DUODENUM – 10 INCHES; 25 CM

LIVER GALL BLADDER PANCREAS

JEJENUM 8 FEET; 2.5 METERS [absorption takes place mainly in the jejenum]

ILEUM – 12 FEET; 3.6 METERSLARGE BOWEL – 5 FEET; 1.5 METERS [absorption of water and

electrolytes and concentrate the waste into solid mass]

THE ROLE OF THE ORAL CAVITY 1TEETH

MASTICATIONTO SOFTEN FOODSPEECH

TONGUETASTEGENERAL SENSATIONDEGLUTITION - swallowingSPEECH

PALATETASTEDEGLUTITION

ROLE OF ORAL CAVITY 2SALIVARY GLANDS

PAROTID GLANDSSUBMANDIBULAR GLANDSSUBLINGUAL GLANDS

FUNCTIONS OF SALIVARY GLANDSLUBRICATION/MOISTEN FOOD SECRETION OF SALIVARY AMYLASE (STARCH

TO GLUCOSE)SECRETION OF LYSOSYMES - ANTIBACTERIALRELEASE OF ANTIBODIES – IMMUNOGLOBULIN

A TO PROTECT THE MUCOSA

FUNCTIONS OF THE STOMACHRECEPTACLE FOR FOOD AND FLUIDS

CAPACITY 2-4 LITRESPROTEIN DIGESTION

PEPSINOGEN TO PEPSIN (pH 1-2)ABSORPTION OF WATER AND ELECTROLYTESABSORPTION OF LIPID SOLUBLE SUBSTANCES

ALCOHOLSOME DRUGS SUCH AS ASPIRINCAFFEINE

PRODUCTION OF INTRINSIC FACTOR ROLE IN ABSORPTION OF VITAMIN B12

PROPULSION OF FOOD INTO DUODENUM

GASTRIC SECRETIONSGASTRIC JUICE AND CONTENTS

HYDROCHLORIC ACID (PARIETAL CELLS) ACTIVATES PEPSINOGEN SECRETION INACTIVATES INGESTED BACTERIA

MUCUS (LUBRICATION AND PROTECTION)PEPSINOGEN (ENZYME)

PEPSIN (INITIATION OF PROTEIN DIGESTION)GASTRIN (HORMONE)

STIMULATES SECRETION OF ACID INCREASES GASTRIC MOTILITY

INTRINSIC FACTOR (GLYCO-PROTEIN) FOR ABSORPTION OF VITAMIN B12 IN THE ILEUM (without

intrinsic factor there cannot be vit. B12 absorption)

FUNCTIONS OF THE DUODENUMRECEIVES FOOD-chyme (rich in lipids, starch,

amino acids) FROM STOMACHREGULATES FOOD ENTRY FROM STOMACHSECRETES HORMONESCOMPLETES PROCESSES OF DIGESTION OF

PROTEINS AND CARBOHYDRATESBEGINS THE PROCESS OF ABSORPTIONIRON ABSORPTION OCCURS PRIMARILY

HERE

DUODENAL GLAND SECRETIONSBRUNNERS GLANDS

MUCUS RICH ALKALINE SECRETION DEACTIVATES PEPSINOGEN PROTECTS DUODENUM FROM GASTRIC SECRETIONS

HORMONES SECRETIN

STIMULATES BICARBONATE SECRETION FROM THE LIVER AND PANCREAS TO REGULATE pH

TRIGGERS INSULIN SECRETION TO REGULATE GLUCOSE CHOLECYSTOKININ

PEPTIDE HORMONE RESPONSIBLE FOR DIGESTION OF FAT CONTRIBUTES TO DIGESTION OF PROTEINS

UROGASTRONE INHIBITS SECRETION OF ACID AND PEPSINOGEN

FUNCTIONS OF THE PANCREASEXOCRINE FUNCTIONS

PRODUCING DIGESTIVE JUICES THAT CONTAIN ALKALINE FLUID (BICARBONATES) CHYMOTRYPSIN (BREAKDOWN OF PROTEINS AND

POLYPEPTIDES) LIPASE (HYDROLYSIS OF LIPIDS) AMYLASE (DIGESTION OF STARCH ends in the duodenum).

ENDOCRINE FUNCTIONS – HORMONE PRODUCTIONINSULIN (LOWERS BLOOD GLUCOSE LEVEL)GLUCAGON (INCREASES BLOOD SUGAR LEVEL)SOMATOSTATIN (INHIBITS RELEASE OF GROWTH

HORMONE AND THYROID STIMULATING HORMONE)

FUNCTIONS OF THE LIVERPLASMA PROTEINS – ALBUMIN, GLOBULIN,

FIBRINOGEN(blood clotting)GLUCOSE METABOLISM(can mobilise glucose when level is

low)DEAMINATION (removal of amine group) OF AMINO ACIDS –

TO FORM UREA(to be excreted in the kidneys)CONVERSION OF AMMONIA TO UREA

FORMATION OF BLOOD CLOTTING FACTORS – I(FIBRINOGEN) II (PROTHROMBIN), IV, V, VI, VII

PROTEIN AND LIPID SYNTHESIS/CHOLESTEROL (abt 25%)STORAGE OF GLUCOSE, IRON AND VITAMINS A,D,E,K AND

B12BREAKDOWN OF HAEMOGLOBIN TO IRON AND BILEDETOXIFICATION/METABOLISM OF DRUGS

THE GALL BLADDERATTACHED TO THE LIVERRECEIVES BILE SECRETED BY THE LIVERSTORES BILECONCENTRATES BILESECRETES BILE FOR FAT DIGESTION

THROUGH THE COMMON BILE DUCTINTO THE DUODENUM

ASSOCIATED WITH CLINICAL PROBLEMS GALL STONESGALL BLADDER INFECTIONSCANCER OF THE GALL BLADDER

FUNCTIONS OF THE JEJUNUM AND ILEUMFUNCTIONS OF JEJENUM

ABSORPTION OF PRODUCTS OF DIGESTION GLUCOSE AMINO ACIDS FATTY ACIDS

ABSORPTION OF WATER SOLUBLE VITAMINS – THE B SERIES & VITAMIN C (EXCEPT B12)

ABSORPTION OF REMAINING IRON ABSORPTION OF SODIUM

FUNCTIONS OF THE ILEUM ABSORPTION OF B12 (AIDED BY INTRINSIC FACTOR) FAT SOLUBLE VITAMINS – A;D;K & E BILE SALTS ABSORPTION WATER IMMUNOLOGIC FUNCTIONS (PEYERS PATCHES) – bacteria that

must have escaped the GIT are destroyed by lymphocytes present in the Peyers patches in the ileum especially at the ileo-caecal junction.

FUNCTIONS OF THE LARGE BOWELSTORAGE OF WASTE MATTERABSORPTION OF WATERABSORPTION OF ELECTROLYTES FORMATION OF FAECESABSORPTION OF SOME VITAMINS SUCH

AS VIT KPROPULSION OF WASTE MATERIAL TO

THE ANUSDEFAECATION