Digestive System Flashcards Preview

Physiology Lecture Exam > Digestive System > Flashcards

Flashcards in Digestive System Deck (50):
1

Function of Digestive System

the organ system that processes food, extracts nutrients from it, and eliminates the residue

2

Five stages of digestive

Ingestion, Digestion, Absorption, Compaction and Defecation

3

Ingestion

selective intake of food

4

Digestion

mechanical and chemical breakdown of food into a form usable by the body

5

Absorption

uptake of nutrient molecules into the epithelial cells of the digestive tract and then into the blood and lymph

6

Compaction

absorbing water and consolidating the indigestible residue into feces

7

Defecation

elimination of feces

8

Mouth

is the beginning of the digestive tract;

9

esophagus

receives food from your mouth when you swallow. the esophagus delivers food to your stomach.

10

stomach

-food storage organ
-mechanically breaks up food particles, liquefies the food, and begins chemical digestion of protein and fat
- chyme:
-most digestion occurs after the chyme passes on to the small intestine
-stomach to small intestine

11

small intestine

Made up of three segments — the duodenum, jejunum, and ileum — the small intestine breaks down food using enzymes released by the pancreas and bile from the liver. Peristalsis also is at work in this organ, moving food through and mixing it with digestive secretions from the pancreas and liver. The duodenum is largely responsible for the continuous breaking-down process, with the jejunum and ileum mainly responsible for absorption of nutrients into the bloodstream.

12

pancreas

The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar.

13

Liver

The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat. In addition, the liver is the body’s chemical "factory." It takes the raw materials absorbed by the intestine and makes all the various chemicals the body needs to function. The liver also detoxifies potentially harmful chemicals. It breaks down and secretes many drugs.

14

Gallbladder

The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats.

15

Colon (Large Intestine)

The large intestine is a highly specialized organ that is responsible for processing waste so that emptying the bowels is easy and convenient.

16

Rectum

It is the rectum's job to receive stool from the colon, to let the person know that there is stool to be evacuated, and to hold the stool until evacuation happens.

17

Anus

The lining of the upper anus is specialized to detect rectal contents. It lets you know whether the contents are liquid, gas, or solid.

18

Saliva + Food in a ball

Bolus

19

Protease enzyme is secreted by?

Stomach, Pancrease, and small intestine

20

Function of protease

Proteins are long chains of amino acids, and protease enzymes break them into peptides (smaller chains of amino acids molecules) and eventually into individual amino acids, which are small and easily absorbed in the small intestine.
proteins-------> amino acids

21

Carbohydrase Enzyme is secreted by?

Salivary glands, pancreas, and small intestine

22

Function of Carbohydrase enzyme

STARCH ----(amylase)---> MALTOSE -----(maltase)----> GLUCOSE

23

Chyme

soupy or pasty mixture of semi-digested food in the stomach

24

Lipase Enzyme is secreted by?

Pancreas and small intestine

25

Function of Lipase

Lipase is secreted by the pancreas and the walls of the small intestine. It digests complex fat (or lipid) molecules into simple, soluble fatty acid and glycerol molecules.

Lipids ----(lipase)-----> fatty acids + glycerol

26

Contractions of small intestine serve three functions:

1. to mix chyme with intestinal juice, bile, and pancreatic juice to neutralize acid
2 .to churn chyme and bring it in contact with the mucosa for contact digestion and nutrient absorption
3. to move residue toward large intestine

27

Segmentation

- the movement in which stationary ring-like constrictions appear in several places along the intestine
-they relax and new constrictions form elsewhere
-most common kind of intestinal contraction
-Doesn’t move food forward, just mixes it in place

28

Peristalsis

-gradual movement of contents towards colon
-peristaltic wave begins in the duodenum,
-milk chyme toward colon over a period of two hours
-ileocecal valve usually closed
-as cecum fills with residue, pressure pinches the valve shut
-prevents reflux of cecal contents into the ileum

29

haustral contractions

-occurs every 30 mins.
Haustral churning is contraction of the colon resulting in mixing & more importantly dividing the contents into smaller pieces in the haustra.

30

Regulation of the digestive tracts are:

neural control, hormonal, and paracrine mechanisms

31

Name the two types of reflexes of neural control and define them.

1. Short reflexes –stimulates peristaltic contractions of swallowing
2. Long reflexes - parasympathetic stimulation of digestive motility and secretion

32

hormones

chemical messengers secreted into bloodstream, and stimulate distant parts of the digestive tract
-gastrin and secretin

33

paracrine secretions

chemical messengers that diffuse through the tissue fluids to stimulate nearby target cells

34

What are the two functions of pancreas? (glands)

Endocrine and Exocrine

35

Endocrine

secretes insulin and glucagons

36

Exocrine

-secretes pancreatic juice into small intestine which breaks down all categories of foodstuff
-acini (clusters of secretory cells) contain zymogen granules with digestive enzymes

37

Pancreatic Juice

alkaline mixture of water, enzymes, zymogens, sodium bicarbonate, and other electrolytes

38

Zymogen

inactive enzymes in the pancreas

39

What are the 3 inactive enzymes in the pancreatic zymogens?

1. trypsinogen
2. chymotrypsinogen
3. procarboxypeptidase

40

Trypsinogen

secreted into intestinal lumen
converted to trypsin by enterokinase- an enzyme secreted by mucosa of small intestine
trypsinogen -----> trypsin

41

Chymotrypsinogen

converted to chymotrypsin by trypsin

42

procarboxypeptidase

converted to carboxypeptidase by trypsin

43

pancreatic amylase

digests starch

44

pancreatic lipase

digets fat

45

ribonuclease and deoxyribonuclease (pancreas)

digests RNA and DNA respectively.

46

Three stimuli are responsible for the release of pancreatic juice and bile

1. acetylcholine
2. cholecystokinin (CCK)
3. secretin

47

Acetylcholine

-from vagus and enteric nerves
-stimulates acini to secrete their enzymes during the cephalic phase of gastric control even before food is swallowed

48

cholecystokinin (CCK)

-secreted by mucosa of duodenum in response to arrival of fats in small intestine
-stimulate pancreatic acini to secrete enzymes
-strongly stimulates gall bladder
-induces contractions of the gallbladder and relaxation of hepatopancreatic sphincter causing discharge of bile into the duodenum

49

secretin (pancreas)

-released from duodenum in response to acidic chyme arriving from the stomach
-stimulates ducts of both liver and pancreas to secrete more sodium bicarbonate
-raising pH to level pancreatic and intestinal digestive enzymes require

50

transporters in small intestine

taken up by sodium-glucose transport proteins (SGLT)
glucose is transported out the base of absorptive cell into ECF by facilitated diffusion
sugar entering ECF increases its osmolarity
draws water osmotically from the lumen of the intestine, through now leaky tight junctions between epithelial cells
water carries more glucose and other nutrients with it by solvent drag
Glucose, and any remaining fructose are transported out of the base of the cell by facilitated diffusion
-Na gets kicked out with Na+ and K+ pump