Digestive System Lecture Notes

Flashcards about the digestive system and its functions.

What are the two main parts of the digestive system?

Gastrointestinal tract (GI tract, or alimentary canal) and the accessory digestive organs

What does the gastrointestinal tract include?

Oral cavity, pharynx, oesophagus, stomach, small intestine (duodenum, jejunum, ileum) & large intestine (caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anal canal)

What are the accessory digestive organs?

Teeth, tongue, salivary glands, liver, gallbladder and pancreas

Which primary germ layer are digestive organs derived from?

Endoderm, with some contribution from mesoderm

Which gastrointestinal organs are part of the foregut?

Stomach, first part of duodenum (part of small intestine)

Which accessory digestive organs are part of the foregut?

Liver, gallbladder, pancreas

Which gastrointestinal organs are part of the midgut?

Most of duodenum, jejunum, ileum, caecum, ascending colon, proximal 2/3’s of transverse colon

Which gastrointestinal organs are part of the hindgut?

Distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, superior part of anal canal

What are the two layers of serous membranes?

Outer parietal layer and an inner visceral layer

What is the parietal peritoneum?

Outer layer lining the walls of the abdominopelvic cavity

What is the visceral peritonium?

Inner layer lining the surface of the organs within the abdominopelvic cavity

What two spaces can the peritoneal cavity be divided into?

Greater sac and the lesser sac

What are the mesenteries of the digestive system?

Mesentery proper, greater omentum, lesser omentum, and mesocolon

What is the lesser omentum?

Peritoneal fold that extends from the lesser curvature of the stomach and connects the stomach & the duodenum to the liver

What is the mesocolon?

Mesentery of the large intestine

What is the mesentery proper?

Peritoneal fold suspending most of the small intestine from the posterior abdominal wall

What are intraperitoneal organs?

Organs completely surrounded by visceral peritoneum

What are retroperitoneal organs?

Organs covered by the parietal peritoneum on their anterior surfaces

What are the intraperitoneal digestive organs?

Stomach, first part of duodenum, jejunum, ileum, caecum, transverse colon, sigmoid colon, liver (except for a small area), gallbladder, tail of the pancreas

What are the retroperitoneal digestive organs?

Oesophagus, most of duodenum, most of pancreas, ascending colon, descending colon, rectum

What are the six main functions of the digestive system?

Ingestion, motility, secretion, digestion, absorption & elimination of wastes

What is ingestion?

Introduction of solids & liquids into oral cavity

What is a bolus?

Soft mass of ingested material that has been chewed & mixed w/ salvia in oral cavity

What is motility?

Movement of ingested material through GI tract

What is peristalsis?

Wave-like muscular contractions that propel ingested material along the GI tract

What is mixing?

Churning movements that dispense ingested material & combine it with digestive secretions

What is secretion?

Process of producing & releasing substances such as mucous, acid, bile & digestive enzymes into the lumen of the GI tract

What is digestion?

Breaking down material into smaller, usable components

What is mechanical digestion?

Physical breakdown through chewing in oral cavity & mixing in stomach & small intestine

What is chemical digestion?

Breaking down by digestive enzymes into smaller molecules

What is absorption?

Passage of nutrients, vitamins, electrolytes & water into blood & lymphatic vessels within wall of GIT

What is elimination of wastes?

Removal of all indigestible material & waste products secreted by digestive organs through process of defecation