unit 12 gastrointestinal system

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UNIT 12GASTROINTESTINAL SYSTEM

HILARIO CRUZADA NOVENO JR., MAN, MSN, RNLecturer

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MouthPharynx

EsophagusStomach

Small intestineLarge intestine

Anus

Organs of the Alimentary Canal

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LAYERS OF ALIMENTARY CANAL ORGANS

• All are part of the autonomic nervous system• Three separate networks of nerve fibers– Submucosal nerve plexus– Myenteric nerve plexus– Subserous plexus

ANATOMY

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Figure 16.4

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ESOPHAGUS

• Runs from pharynx to stomach through the diaphragm

• Conducts food by peristalsis (slow rhythmic squeezing)

• Passageway for food only (respiratory system branches off after the pharynx)

ANATOMY

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STOMACH ANATOMY• Located on the left side of the abdominal cavity• Food enters at the cardioesophageal sphincter• Regions of the stomach

– Cardiac region – near the heart– Fundus– Body– Phylorus – funnel-shaped terminal end

• Food empties into the small intestine at the pyloric sphincter• Rugae – internal folds of the mucosa• External regions

– Lesser curvature– Greater curvature

ANATOMY

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STOMACH ANATOMY

• Layers of peritoneum attached to the stomach – Lesser omentum – attaches the liver to the lesser

curvature– Greater omentum – attaches the greater curvature

to the posterior body wall– Contains fat to insulate, cushion, and protect

abdominal organs

• Gastric pits formed by folded mucosa• Glands and specialized cells are in the gastric

gland regionANATOMY

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STOMACH FUNCTIONS

• Acts as a storage tank for food• Site of food breakdown• Chemical breakdown of protein begins• Delivers chyme (processed food) to the small

intestine

ANATOMY

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SPECIALIZED MUCOSA OF THE STOMACH

• Simple columnar epithelium– Mucous neck cells – produce a sticky alkaline

mucus– Gastric glands – secrete gastric juice– Chief cells – produce protein-digesting enzymes

(pepsinogens)– Parietal cells – produce hydrochloric acid– Endocrine cells – produce gastrin

ANATOMY

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SMALL INTESTINE• The body’s major digestive organ• Site of nutrient absorption into the blood• Muscular tube extending form the pyloric

sphincter to the ileocecal valve• Suspended from the posterior abdominal wall

by the mesentery

ANATOMY

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SUBDIVISIONS OF THE SMALL INTESTINE

• Duodenum– Attached to the stomach– Curves around the head of the pancreas

• Jejunum– Attaches anteriorly to the duodenum

• Ileum– Extends from jejunum to large intestine

ANATOMY

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Fingerlike structures formed by the mucosa

Give the small intestine more surface area

Villi of the Small Intestine

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Small projections of the plasma membraneFound on absorptive cells

Microvilli of the Small Intestine

Absorptive cellsBlood capillariesLacteals (specialized lymphatic capillaries)

Structures Involved in Absorption of Nutrients

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UNIT 12GASTROINTESTINAL SYSTEM

HILARIO CRUZADA NOVENO JR., MAN, MSN, RNLecturer

Thank You!