D I G E S T I V E

Question 1

define digestion

Answer 1

a series of catabolic steps in which enzymes participate in breakdown of nutrients;

physical (mechanical) & chemical

Question 2

what are the 4 functions of the digestive system?

Answer 2

1. ingestion (taking food in)
2. propulsion (moving food by peristalsis)
3. mechanical breakdown (segmenting food to increase surface area)
4. digestion (enzymatic breakdown)
5. absorption (into blood or lymph)
6. defection (removes indigestible substances from the body)

Question 3

peristalsis

Answer 3

alternate contraction of circular (squeeze) and longitudinal (shorten) muscles to move food

Question 4

what is the function of place circulars?

Answer 4

deep circular folds of the mucosa and submucosa. permanent transverse folds. structural modifications of small intestines wall that increase reabsorption and surface area

Question 5

what digestive system structure causes dehydration and compaction of indigestible material?

Answer 5

large intestine

Question 6

list the layers of the wall of the digestive tract from lumen to outermost

Answer 6

1. mucosa
2. submucosa
3. muscularis externa
4. serosa
5. adventitia

Question 7

what are the functions of the stomach?

Answer 7

1. holds ingested food
2. protein digestion (by enzyme pepsin from chief cells)
3. degrades food physically and chemically
4. delivers chyme to small intestines
5. secretes intrinsic factor for B12 absorption
6. only absorbs alcohol and NSAIDs
7. parietal cells secrete HCl and intrinsic factor

Question 8

describe the phases of gastric secretion

Answer 8

1. cephalic: preps stomach to receive (mucous, enzymes, acids, gastrin)
2. gastric: arrival of food in stomach - neural, local, and hormonal responses cause mucous, pepsinogen, acid release, mixing waves, and begin protein digestion with pepsin
3. intestinal: controls rate of gastric emptying of chyme into duodenum - inhibits pepsinogen and acids and reduces motility

Question 9

LDL

Answer 9

low density lipoproteins

form in liver, released in blood to deliver cholesterol to peripheral tissues

Question 10

HDL

Answer 10

high density lipoproteins

in blood, recycle excess cholesterol from peripheral tissues to liver for storage or to secrete in bile

Question 11

CCK

Answer 11

cholecystokinin

secreted due to fatty chyme; enzyme rich pancreatic juice from from acinar cells; gall bladder contraction; hepatopancreatic sphincter to relax

Question 12

secretin

Answer 12

HCO3- rich pancreatic juice by duct cells, minor stimulus for bile release