digestive system

Question 1

tissue layers of the digestive tract

Answer 1

inner to outer:
lumen –> mucosa –> submucosa –> muscalris externa (inner –> outer) –> serosa

Question 2

specific functions of the digestive system

Answer 2

• ingestion, the intake of food
• digestion, the mechanical and chemical breakdown of food into a usable form
• absorption, the uptake of nutrients into blood and lymph
• compaction, the absorption of water and consolidation of wastes into feces
• defecation, the elimination of feces

Question 3

primary purposes of digestion

Answer 3

• first to break food into forms that can be used by cells
• second, to absorb nutrients so that they can be distributed to tissues

Question 4

duodenum

Answer 4

• first 25cm of the small intestine
• has internal pleats called circular folds (plicae circulares) that cause the chyme to flow more slowly and also increase the surface area for contact between the chyme and mucosa
• bile and pancreatic ducts open into the duodenum at a wrinkle called the major duodenal papilla that marks the boundary between the foregut and midgut

Question 5

appendix

Answer 5

• hangs off of the cecum (pouch in the lower right abdominal quadrant) of the large intestine and is a vestigial organ
• known as the blind tube

Question 6

stomach

Answer 6

• located in the left abdominal cavity just inferior to the diaphragm
• function: stores food, mechanically breaks it down, and chemically digests it
• it produces a mixture of semidigested food called chyme that passes to the small intestine.

Question 7

ileum

Answer 7

• part after the jejunum
• has a thinner wall, less muscular, less vascular
• contains lymphatic nodules (Peyer patches – permanent patches)
• small intestine joins the large intestine at the ileocecal junction; the ileocecal valve is a sphincter that regulates the passage of material to the large intestine

Question 8

major structural difference between small intestine and the large intestine

Answer 8

large intestine is much shorter than the small intestine and does not contain many villi for nutrient absorption

Question 9

names and numbers of the adult and deciduous teeth

Answer 9

• incisors: chisels
• canines: puncture
• premolars and molars: crush and grind
• 20 deciduous vs 32 permanent teeth

Question 10

digestive enzymes in saliva

Answer 10

• amylase: catalyzes the hydrolysis of starch into sugars
• lipase: breaks down dietary fats
• mucus: lubricant to make swallowing easier
• lysozyme: breaks down bacterial cell walls
• immunoglobulin A: antibodies to fight off infections
• electrolytes: acts as a buffer and maintains the slightly acidic pH of saliva

Question 11

hepatic lobules

Answer 11

• small cylinders with central vein, radiating plates with hepatocytes
• each hepatic lobule has a central vein and sheets of cuboidal cells called hepatocytes that radiate out from it

Question 12

hepatic sinisoids

Answer 12

• leaky capillaries
• blood-filled spaces between the plates that are lined with loosely spaced endothelial cells
• this arrangement puts hepatocytes in direct contact with plasma from which they can absorb nutrients such as glucose and amino acids for either metabolism or storage. In turn, hepatocytes secrete albumin, lipoproteins, glucose, and other products that can move directly to the blood

Question 13

hepatic macrophages

Answer 13

• kupffer cells
• remove bacteria and debris from the blood
• located in the liver

Question 14

relationships between a renal pyramid, minor calyx, major calyx, renal pelvis, and ureter

Answer 14

• renal pyramids are within the renal medulla, each with a renal papilla
• one minor calyx per renal pyramid. Collects urine.
• two or more minor calyces merge to form a major calyx
• major calyces merge to form renal pelvis within sinus
• ureter is a continuation of the pelvis that drains urine to the urinary bladder