Digestion Lecture 2 Flashcards

Question

Absorption in the Stomach

Answer 1

* There is only a small amount of nutrient absorption that takes place in the stomach * Some water * Ions * short chain fatty acids * certain drugs (aspirin) * alcohol

Answer 2

Plays key role in nutrient digestion and absorption * 90 percent of nutrient absorption occurs in small intestine * Most of remaining 10 percent occurs in large intestine * Average overall length = 6 m (19.7 ft) * Diameter ranges from 4 cm (1.6 in.) near stomach to 2.5 cm (1 in.) near large intestine

Answer 3

1. Duodenum * 25 cm (10 in.) in length * Segment closest to the stomach * Acts as a “mixing bowl” * Receives chyme from stomach and digestive secretions from liver, gallbladder, and pancreas * Mostly retroperitoneal * Duodenal glands produce mucous secretions * Has few circular folds and small villi * Main function is to neutralize acidic chyme

Answer 4

* Between the duodenum and ileum * ~2.5 m (8.2 ft) in length * In the peritoneal cavity * Has numerous circular folds and abundant, long villi * Majority of chemical digestion and nutrient absorption occurs in jejunum

Answer 5

* Final segment of small intestine * ~3.5 m (11.5 ft) in length * Ends at the ileocecal valve * Sphincter controlling flow from the ileum into the cecum of the large intestine * Has few circular folds (none in the distal portion) * Villi are relatively stumpy * Submucosa contains aggregated lymphoid nodules

Answer 6

* simple columnar epithelium and contains many different cells * Absorptive cells (digest and absorb) * goblet cells (produce mucus) * intestinal glands (intestinal juice) * Paneth cells (lysozyme) * enteroendocrine cells * S cells: secretes secretin * CCK cells: secretes CCK * K cells: secretes glucose-dependent insulinotropic peptide (GIP)

Answer 7

* Groups of lymphatic nodules called Peyer’s patches that are present in the ileum

Answer 8

* Duodenal (Brunner’s) glands secrete alkaline mucus that helps neutralize gastric acid in the chyme

Answer 9

Has an outer longitudinal layer and an inner circular layer

Answer 10

* Completely surrounds the small intestine except for majority of duodenum * Retroperitoneal, has adventitia

Answer 11

* Series of transverse folds along the intestinal lining * Permanent feature * compare to rugae * Roughly 800 folds in the small intestine * Mostly in the jejunum * Increase AS for absorption

Answer 12

* Small mucosal projections that increase surface area for absorption * Covered by epithelial cells * Surfaces covered with microvilli * Contains arteriole, venule, blood capillary, and lacteal

Answer 13

* Extensive capillary network in the lamina propria * Carries absorbed nutrients to the hepatic portal circulation

Answer 14

* Transports materials that cannot enter blood capillaries * Example: * Absorbed fatty acids assembled into protein–lipid packages (chylomicrons) too large to diffuse into bloodstream * Transported by lymphatic system to venous circulation

Answer 15

* Moves villi back and forth, exposing surfaces to intestinal contents * Squeezes lacteal, assisting in lymph movement

Answer 16

* Projections of apical membrane of absorptive cells * Creates a brush border with brush border enzymes

Answer 17

* Carpet of microvilli on the surface of the epithelial cells * Increases surface area for absorption * Contains enzymes that digest materials * Epithelial cells can then absorb breakdown products

Answer 18

* The pancreas has endocrine and exocrine functions * The exocrine functions of the pancreas contribute to digestion

Answer 19

* Location: retroperitoneal organ that lies posterior to the greater curvature of stomach * Three major parts: Head, body, tail

Answer 20

* Delivers exocrine secretions to the duodenum * Joins the common bile duct from the liver and gallbladder and enters duodenum as a common duct at the hepatopancreatic ampulla (ampulla of Vater) * The ampulla opens at the major duodenal papilla

Answer 21

* Branches from the pancreatic duct and empties separately into the duodenum * Occurs in 3–10 percent of the population

Answer 22

* 99% are pancreatic acini * Contain pancreatic acinar cells * Secrete pancreatic enzymes and buffers * EXOCRINE

Answer 23

* 1% are pancreatic islets * Secrete hormones (glucagon, insulin, somatostatin, and pancreatic polypeptide) * ENDOCRINE * Discussed in detail in Endocrine Section

Answer 24

* About 1200 - 1500 mL of pancreatic juice are produced each day * Combination of mostly water and ions (secreted by epithelial cells lining the duct) and exocrine secretions (enzymes and buffers) * Sodium bicarbonate: buffers acidic stomach chyme * Pancreatic juice is slightly alkaline (7.1-8.2) which stops the action of pepsin and creates proper pH for enzymes to act in the small intestine

Answer 25

* Pancreatic amylase: digests starch * Proteolytic enzymes: digests protein * Pancreatic lipase: main fat-digesting enzyme * Nucleases (Ribonuclease and deoxyribonuclease): digest RNA and DNA * Trypsinogen: digests protein

Answer 26

* Carbohydrase (breaks down certain starches) * Almost identical to salivary amylase

Answer 27

* Breaks down certain complex lipids * Main fat digesting enzyme

Answer 28

* Ribonuclease and deoxyribonuclease: Break down RNA or DNA

Answer 29

Break proteins apart into mixture of dipeptides, tripeptides, and amino acids * Secreted as inactive proenzymes * Activated in the duodenum * Active forms include trypsin, chymotrypsin, carboxypeptidase, elastase

Answer 30

* Trypsinogen is released from the pancreas and will reach the small intestine and will encounter enterokinase (a brush-border enzyme) which activates trypsin, which then acts on the other inactive enzymes to activate them

Answer 31

* Largest visceral organ * Weighs 1.5 kg (3.3 lb) * It is inferior to the diaphragm and occupies most of the right hypochondriac and part of the epigastric region of the abdominopelvic cavity * The gallbladder is a pear shaped sac that is located in a depression of the posterior surface of the liver and hangs from the anterior margin * Wrapped in tough fibrous capsule * Covered by layer of visceral peritoneum

Answer 32

1. Carbohydrate metabolism 2. Lipid metabolism 3. Protein metabolism 4. Processing of drugs and hormones 5. Excretion of bilirubin 6. Synthesis of bile salts 7. Storage 8. Phagocytosis 9. Activation of vitamin D

Answer 33

1. Left lobe 2. Right lobe 3. Caudate lobe 4. Quadrate lobe

Answer 34

* Separated from the left lobe by the falciform ligament * Round ligament is a thickening in the posterior margin of the falciform ligament * Marks the path of the fetal umbilical vein

Answer 35

* On the posterior surface of the liver

Answer 36

* Located between the left lobe and the gallbladder

Answer 37

* Temporarily stores bile produced by the liver

Answer 38

* Carries bile from the liver and gallbladder to the duodenum

Answer 39

* Make up 80% of the liver * major functional cells of liver * Wide variety of metabolic, secretory, and endocrine functions * secrete bile (excretory product and digestive secretion)

Answer 40

* Immune function

Answer 41

* ducts between hepatocytes that collect bile * exits livers as common hepatic duct

Answer 42

* highly permeable blood capillaries receiving oxygenated blood from hepatic artery and deoxygenated nutrient-rich blood from hepatic portal vein * Hepatic sinusoids will converge and deliver blood to a central vein which then drains into the inferior vena cava

Answer 43

* a bile duct * a branch of the hepatic artery * a branch of the hepatic portal vein

Answer 44

1. A branch of the hepatic portal vein * Receives blood from the hepatic portal system bringing blood from abdominal viscera 1. A branch of the hepatic artery proper 2. A bile duct

Answer 45

1. Hepatic lobule 2. Portal lobule 3. Hepatic acinus

Answer 46

* Liver contains ~100,000 liver lobules * Hexagonal shape in cross section * Surrounded by six portal triads (one at each corner of the lobule) * Each roughly 1 mm in diameter

Answer 47

* Triangle cornered by three central veins

Answer 48

* the smallest functional * contains a small portal tract at the center and central veins at the periphery * divided into zones 1, 2, and 3 * zone 1 surrounds the portal tract and zone 3 surrounds the hepatic venule * Mostly descriptive reasons * Although, zone 3 is more prone to ischemic damage than zone 1

Answer 49

1. Blood enters the liver sinusoids from branches of the hepatic portal vein and hepatic artery proper 2. Hepatocytes adjacent to the sinusoids regulate solute and nutrient levels by absorption and secretion 3. Stellate macrophages (Kupffer cells) in the sinusoidal lining engulf pathogens, cell debris, and damaged blood cells 4. Sinusoids all drain into a central vein 5. Hepatocytes secrete bile into a network of narrow channels called bile canaliculi 6. Bile canaliculi merge to form bile ductules then carry to bile ducts

Answer 50

* Hepatocytes secrete 800-1000mL of bile daily * Mostly water, bile salts, cholesterol, lecithin, bile pigments and several ions * Bilirubin is the principal bile pigment * Where does bilirubin come from? * Partially excretory product/partially digestive secretion * Bile salts play role in emulsification (the breakdown of large lipid globules into a suspension of small lipid globules) Also aid in absorption of lipids following digestion

Answer 51

* Hollow, pear-shaped organ * Located in the depression on the posterior surface of the liver’s right lobe * Divided into three regions: the fundus, the body, and the neck * Mucosa layer consists of simple columnar epithelium arranged in rugae similar to that in the stomach * Between meals, stores and concentrates bile secreted from the liver * Contraction of smooth muscle fibers eject contents of gall bladder into cystic duct

Answer 52

* Right and left hepatic ducts collect bile from the liver bile ducts * Hepatic ducts unite to form the common hepatic duct * Bile flows from the common hepatic duct into: * The common bile duct (to the duodenum) * The cystic duct (to the gallbladder for storage) * When needed, contraction of the gallbladder forces bile back along the cystic duct to the common bile duct * The common bile duct penetrates the duodenal wall and meets the pancreatic duct at the hepatopancreatic ampulla (ampulla of Vater, duodenal ampulla) * The hepatopancreatic sphincter encircles the lumens of these areas where they enter the duodenum * Prevents flow of bile into the duodenum except at mealtime

Answer 53

* Liver produces about 1 L of bile per day * Unless hepatopancreatic sphincter is open, bile flows into the gallbladder for storage * Release of CCK by the duodenum triggers: * Dilation of the hepatopancreatic sphincter * Contraction of the gallbladder * Bile is ejected into the duodenum * Bile salts break apart lipid droplets through emulsification

Digestion Lecture 2 Flashcards

(77 cards)