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Flashcards in GI - Structure & Function Deck (82):
1

What's the major function of the GI tract?

Mechanical & Chemical Breakdown

2

This is a hollow tube that extends from the mouth to the anus.

GI Tract

3

The walls of the GI tract have several layers, what are they?

1) Mucosa
2) Muscularis mucosae
3) Submucosa
4) Tunica muscularis (Circular & Longitudinal muscle)
5) Serosa

4

Except for swallowing and defecation, which are controlled voluntarily, the functions of the GI are controlled by _________ & _________ autonomic nerves...collectively called the ________ plexus and intestinal __________.

-Intrinsic & Extrinsic
-Enteric
-Hormones

5

Digestion begins with the mouth with chewing & salivation. What's the digestive component of saliva?

Alpha-amylase
-Initiates carb digestion

6

The esophagus is a muscular tube (tunica muscularis) that transports food from the mouth to stomach. What are the two muscle types w/in the esophagus?

-Upper = striated
-Lower = smooth muscle

7

What term describes how the food is propelled through the GI tract by the tunica muscularis?

Peristalsis

8

Swallowing is controlled by the swallowing center in the reticular formation of the brain. What are the two phases of swallowing?

1) Voluntary - Oropharyngeal
2) Involuntary - Esophageal

9

What has to open to admit swallowed food into the stomach and then closes to prevent regurge?

Lower esophageal sphincter

10

The stomach is a baglike structure that ________ digestive juices, ______ and ______ food, and _______ partially digested food (chyme) into the duodenum.

-Secretes
-Mixes & Stores
-Propels/Moves

11

What are the smooth muscles of the stomach?

-Outer longitudinal
-Middle circular
-Internal oblique

12

What nerve stimulates gastric (stomach) secretion and motility?

Vagus

13

What hormones stimulate & delay gastric emptying?

-Stimulate = Gastrin & Motilin
-Delay = Secretin & Cholecystokinin

14

Gastric glands in the funds and body of the stomach secrete this, which is needed for Vit. B12 absorption, and hydrochloric acid, which dissolves food fibers, kills microorganisms, and activates the enzyme pepsin.

Intrinsic Factor

15

What cells in the stomach secrete pepsinogen & what's pepsinogen converted to in the acid environment created by hydrochloric acid?

-Chief cells
-Pepsin

16

What stimulates acid secretion?

1) Vagus nerve
2) Gastrin
3) Histamine

17

What inhibits acid secretion?

1) Sympathetic stimulation
2) Cholecystokinin

18

What NT stimulates pepsin secretion?

Acetylcholine

19

What is the function of mucus in the stomach?

Protection of the stomach wall from acid and digestive enzymes

20

What are the three phases of acid secretion by the stomach?

1) Cephalic phase (anticipation & swallowing)
2) Gastric phase (Food in stomach)
3) Intestinal phase (Chyme in intestines)

21

What 3 segments make of the small intestines?

1) Duodenum
2) Jejunum
3) Ileum
-5m total length

22

What occurs in the small intestines?

Digestion and absorption of all major nutrients & most ingested water occurs in SI

23

The peritoneum is a double layer of membranous tissue that contains what two layers?

1) Visceral (covers ab. organs)
2) Parietal (along ab. wall)

24

What is the primary blood supply to the SI provided by?

Superior Mesenteric Artery

25

The duodenum receives chyme from the stomach through what valve?

Pyloric valve

26

The presence of chyme in the duodenum stimulates this to occur from liver, gallbladder, & pancreas?

-Liver & GB = Bile
-Pancreas = Digestive enzymes and alkaline secretions

27

Bile and enzymes flow into the duodenum through an opening guarded by what sphincter?

Sphincter of Oddi

28

Bile, produced in the ______ is necessary for fat _________ & _________.

-Liver
-Digestion & Absorption

29

Biles alkalinity helps neutralize ______, thereby creating a pH that enables the _________ enzymes to digest proteins, carbs, & sugars.

-Chyme
-Pancreatic

30

What are enzymes secreted by the small intestines that act in SI to digest Cabs, Pros, & Fats?

1) Maltase
2) Sucrose
3) Lactase

31

What are the Pancreatic enzymes that act in the SI for digestion of macronutrients?

1) Proteases
2) Amylase
3) Lipase

32

Besides SI & Pancreatic enzymes, what other substance is needed to aid in digestion w/in the SI of Macronutrients?

Bile salts

33

Digested substances are absorbed across the _________ wall and then transported to the _______ through the _______ vein, where they are metabolized further.

-Intestinal
-Liver
-Portal

34

What valve connects the small and large intestines and prevents reflux into the small intestine?

Ileocecal valve

35

What are the small, finger-like projections that extend from the SI mucosa and increase its absorptive surface area?

Villi

36

Sugars, AA's, and Fats are absorbed primarily by the ______ & ______; bile salts and Vit. B12 are absorbed by the _______.

-Duodenum & Jejunum
-Ileum

37

Bile salts emulsify and _______ fats and incorporate them into water-soluble ________ that transport them through the unstirred layer to the _______ border of the intestinal mucosa.

-Hydrolyze
-Micelles
-Brush

38

The fat content of the micelles readily diffuses through the epithelium into _______ in the villi. From there fats flow into __________ and into the systemic circulation, which delivers them to the ______.

-Lacteals (Lymphatic ducts)
-Lymphatics
-Liver

39

Minerals and water-soluble vitamins are absorbed by _____ & _____ transport throughout the SI.

-Passive & Active

40

What are the jobs of the longitudinal & circular muscles of the intestines?

-Longitudinal = propels chyme along
-Circular = mix chyme & promote digestion

41

This is a reflex that inhibits gastric motility when the ileum is distended?

Ileogastric reflex

42

This reflex inhibits intestinal motility when one's intestinal segment is over distended?

Intestinointestinal reflex

43

This reflex increases intestinal motility when gastric motility increases?

Gastroileal Reflex

44

What does the large intestine consist of? (parts)

1) Cecum
2) appendix
3) Colon: Ascending, Transverse, Descending & Sigmoid
4) Rectum
5) Anal Canal

45

These are three bands of longitudinal muscle that extend the length of the colon?

Teniae Coli

46

These are pouches of colon that are formed with alternating contraction and relaxation of the circular muscles?

Haustra

47

The mucosa of the _______ intestine contains mucus-secreting cells and mucosal folds, but no _____.

-Large
-Villi

48

What are two functions of the large intestine?

1) Massage of the Fecal mass
2) Absorbs water & electrolytes

49

Distention of the ileum with chyme causes the _________ reflex, or the mass __________ of feces to the rectum.

-Gastrocolic
-Propulsion

50

When is defecation stimulated?

-When the rectum is distended with feces

51

For defecation to occur after stimulation, what has to happen with sphincters?

Internal relaxes & External also has to voluntarily relax

52

Where are the largest number of intestinal bacteria located?

Colon
-Anaerobes consist of Bacteroides, Clostridia, Coliforms, & Lactobacilli

53

The intestinal tract is ______ at birth and becomes totally colonized within __ to __ weeks.

-Sterile
-3-4 weeks

54

What are three ways that endogenous infections of the GI tract occur?

1) Excessive proliferation
2) Perforation of intestine
3) Contamination from neighboring structures

55

What is the functions of the liver?

1) Digestive
2) Metabolic
3) Hematologic
4) Vascular
5) Immunologic

56

What are the ligaments that support the liver?

1) Falciform
2) Round
3) Coronary

57

What are the functional cells of the liver?

Plates of hepatocytes

58

What artery supplies blood to the liver?

Hepatic artery

59

What vein receives from the inferior and superior mesenteric veins?

Portal vein

60

What are the small channels that hepatocytes secrete bile into & these channels drain bile into the common bile duct and then to the duodenum?

Bile Canaliculi

61

What are the capillaries located b/w the plates of the hepatocytes?

Sinusoids

62

What is the name of the cells that are part of the mononuclear phagocyte system, line the sinusoids and destroy microorganisms in sinusoidal blood?

Kupffer cells

63

The primary bile acids are synthesized from __________ by the hepatocytes. The primary acids are then conjugated to form _____ _____. The secondary bile acids are the product of bile salt ___________ by bacteria in the intestinal lumen.

-Cholesterol
-Bile Salts
-Deconjugation

64

Most bile salts and acids are recycled. What's the absorption of bile salts and acids from the terminal ileum and their return to the liver known as?

Enterohepatic circulation of bile

65

What is a pigment liberated by the lysis of aged red blood cells in the liver and spleen?

Bilirubin

66

Fat absorbed by intestinal lacteals is primarily ___________, which are hydrolyzed to _______ and _____ ______ _____.

-Triglycerides
-Glycerol
-Free Fatty Acid

67

What is the saclike organ located in the inferior surface of the liver that stores bile b/w meals and ejects it when chyme enters the duodenum?

Gallbladder

68

Stimulated by ___________, the gallbladder contracts and forces bile through the _____ duct and into the _____ bile duct.

-Cholecystokinin
-Cystic
-Common

69

This is a gland located behind the stomach that has endocrine and exocrine functions?

Pancreas

70

What are the endocrine pancreas hormones?

Glucagon & Insulin

71

What is the exocrine pancreas alkaline solution and enzymes that are secreted and digest proteins, carbs, & fats?

1) Trypsin
2) Chymotrypsin
3) Carboxypeptidase
4) a-amylase
5) Lipase

72

What stimulates the pancreas to secrete alkaline fluid and enzymes?

Alkaline fluid = Secretin
Enzymes = Cholecystokinin & Ach

73

Pancreatic secretions originate in _____ and ducts of the pancreas and empty into the duodenum through the ______ bile duct or an accessory duct that opens directly into the duodenum.

-Acini
-Common

74

What are the most commonly used tests to evaluate structure in addition to direct observation by endoscopy?

Radiographs & Scans

75

______ & ______ analysis and ______ studies provide important info about digestion, absorption and secretion.

-Gastric
-Stool
-Blood

76

What are commonly used to used to Dx alterations in liver function?

Plasma chemistry levels and imaging procedures

77

What are the enzymes of particular importance when assessing plasma chemistry levels?

LDH, AST, & ALT

78

What does plasma bilirubin levels reflect?

Alterations in bilirubin & bile metabolism

79

What liver issues may manifest in prolonged prothrombin times?

Hepatitis & Chronic Liver Disease

80

What is indicative of obstructive disease of the gallbladder?

Elevated serum bilirubin
Elevated Urine urobilinogen
Increased Fat stool

81

What's the most significant indicators of pancreatic dysfunction?

Serum amylase & Stool fat
-Both will be increased

82

Aging reduces gastric motility and secretions, particularly of __________ ______. These changes slow gastric ________ & ________.

-Hydrochloric Acid
-Digestion
-Emptying