Chapter 39

Question 1

Small intestine

Answer 1

Main digestive organ
From pyloric sphincter  ileocecal valve
6-8 m long; 2.5 cm in diameter
3 divisions
Duodenum
Jejunum
Ileum
Smooth muscle fibers in wall  peristalsis
Lined with mucus membrane that is highly adapted for secretion

Question 2

Small intestine lining

Answer 2

Adapted for secretion & nutrient absorption
Arranged into multiple circular folds called plicae
Plicae covered with villi
Villi contain blood capillaries and lymph lacteals for nutrient absorption
Mucus-secreting cells, enteroendocrine cells, and tuft cells are on microvilli
Villi covered by microvilli (‘brush border’)
Villi and microvilli increase the surface area of the small intestine hundreds of times

Question 3

Intestinal crypts

Answer 3

located in ‘valleys’ between villi; contain stem cells (rapid mitosis) from which the intestinal cell types are produced and then migrate upward to cover the villi, where they eventually slough off. Stem cells are protected by Paneth cells which produce enzymes and other substances to control the growth of bad bacteria.

Question 4

Large intestine

Answer 4

Last part of GI tract
1.5 – 1.8 m long, 6 cm in diameter
Smooth muscle fibres in wall contract for churning & peristalsis for ultimate evacuation of bowel
Lined with mucus membrane
Absorption of water, salts, vitamins
No villi = less surface area/not well suited for absorption compared to small intestine

Question 5

Cecum

Answer 5

Pouch like first section

At the level of the ileocecal valve

Question 6

Colon

Answer 6

Acsending decending trans sigmoid

Question 7

Rectum

Answer 7

Last 17-20 cm

Holding tank before exit

Question 8

Anus

Answer 8

Opening to exterior
Inner anal sphincter (invol muscle)
Outer anal sphincter (vol muscle)

Question 9

Vermiform appendix

Answer 9

“Vermiform” = worm shaped

Blind tube off cecum

Lymphatic tissue

Reservoir/breeding ground for beneficial gut bacteria

Appendicitis

Question 10

Peritoneum

Answer 10

Large, continuous sheets of serous membrane lining the abdominal cavity and covering abdominal organs.
Parietal layer 
Visceral layer 
Peritoneal space
fluid moistens and ↓ friction
Terms:
Intraperitoneal
Extraperitoneal
Retorperitoneal

Question 11

Mesentery

Answer 11

Fan-like extension of parietal peritoneum
Attaches most of small intestine to lumbar area of posterior abdominal wall. Keeps small intestine ‘in place’
Fans out from 15-20 cm from posterior border to 6 meters!

Question 12

Greater omentum

Answer 12

‘lace apron’ (due to spotty deposits of fat)
Pouch like extension of the visceral peritoneum (from the greater curvature of the stomach/1st part of duodenum)
Hangs down from lower edge of stomach and transverse colon over intestines

Question 13

Lesser omentum

Answer 13

From liver to lesser curvature of stomach/ 1st part of duodenum

Question 14

Liver

Answer 14

Largest gland in body
Under the diaphragm; fills upper right section of abdominal cavity and extends into left side
Left (1/6) and right (5/6) lobes, separated by the falciform ligament
Right lobe: right lobe proper, caudate lobe, quadrate lobe

Anatomical units are called hepatic lobules, and each one has a small branch of the hepatic vein running through its centre (See Figures in Textbook)

Hepatocytes (liver cells) are arranged around each central vein (aka intralobular vein)
On the outside ‘corner’ of each lobule there is a structure called a ‘portal triad’ which consists of the following three structure:
Interlobular artery (which is a branch of the hepatic artery)
Interlobular portal vein (which is a brand of the hepatic portal vein)
Interlobular bile duct
The structure of the lobules and the organization of the blood vessels and other structures running through the lobules allows the liver to carry out its many functions (e.g. filtering/detoxifying blood, storage or metabolism of nutrients, production/transport of bile)

Question 15

Bile ducts in liver

Answer 15

Small bile ducts form right and left hepatic ducts
Right and left hepatic ducts immediately join to form one hepatic duct
Hepatic duct merges with the cystic duct to form the common bile duct, which opens into the duodenum

Question 16

Liver functions

Answer 16

Detoxification by liver cells—ingested toxic substances and toxic substances formed in the intestines may be changed to nontoxic substances
Bile secretion by liver—bile salts are formed in the liver from cholesterol and are the most essential part of bile; liver cells secrete approximately 1 pint of bile per day
Liver metabolism—carries out numerous important steps in metabolizing proteins, fats, and carbohydrates
Storage of substances such as iron and some vitamins
Production of important plasma proteins

Question 17

Gallbladder

Answer 17

Pear-shaped; 7-10 cm long; 3 cm wide
Lies on undersurface of liver
Wall made of serous, muscular, & mucus layers
Rugae in mucosal lining allow GB to expand and store 30 to 50 ml of bile

Question 18

Gallbladder function

Answer 18

Stores bile
Concentrates bile (5x-10x)
Squirts concentrated bile into the duodenum
If bile becomes too concentrated  gallstones
Jaundice results when bile flow to the duodenum is blocked bile is absorbed into blood instead of being eliminated via fecesexcess bile pigments (yellow in colour) get deposited into body tissues

Question 19

Pancreas

Answer 19

Runs behind stomach from duodenum to spleen
Inside ‘C’ of duodenum
12-15 cm long
Main duct empties into duodenum

Question 20

Pancreas endocrine portion

Answer 20

embedded between exocrine units
called pancreatic islets
constitute only 2% of the total mass of the pancreas
made up of alpha cells and beta cells
pass secretions into capillaries

Question 21

Exocrine portion (majority) of panc

Answer 21

compound acinar arrangement (cluster of cells that resembles a many-lobed “berry“)
tiny ducts unite to form the main pancreatic duct, which empties into the duodenum

Question 22

Panc functions

Answer 22

Acinar units secrete digestive enzymes:
Lipases
Proteases
Amylases
Beta cells secrete insulin
Alpha cells secrete glucagon