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Flashcards in Gastrointestinal physiology Deck (87)
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1
Q

Where does the lacteal system transport fat to?

A

thoracic duct

2
Q

What stimulates gastrin release? (1) What inhibits it? (1)

A

stomach distension. Stomach acid in the duodenum inhibits gastrin release

3
Q

What are the macrophage-like cells in the liver called?

A

kupffer cells

4
Q

Optimal pH for protein degredation by pepsin is ___?

A

pH 1.0-3.0

5
Q

How are amino acids absorbed? (2)

A

secondary active transport linked to Na and receptor-mediated endocytosis.

6
Q

What are the substrate and products of pancreatic lipase?

A

lipase digest tiglycerides to two free fatty acids and one 2-monoglyceride.

7
Q

Normal life span of red blood cells?

A

120 days

8
Q

T/F: Parasympathetic activity stimulates salivary secretion while sympathetic activity does not.

A

false-both parasympathetic and sympathetic activity stimulate salivary secretion

9
Q

Pancreatic ducts secrete ___ and ___ when stimulated by ___?

A

mucus and alkaline fluid when stimulated by secretin

10
Q

What is the function of the lacteals in the gastrointestinal system?

A

lymphatic drainage that carries fat away from the GI.

11
Q

Conjugated or unconjugated version of bilirubin is water soluble?

A

conjugated version

12
Q

GI secretory products: What is hypersecreted in Zollinger-Ellison syndrome?

A

gastrin

13
Q

T/F- Blood and bile flow in the same direction?

A

false-blood flows toward the central vein while bile flows in the opposite direction

14
Q

GI secretory products: What stimulates the release of secretin?

A

fatty acids and acid in the duodenum

15
Q

Why is only a small amount of enterokinase required to convert trypsinogen into trypsin?

A

trypsin is atuocatalytic, meaning that a molecule of trypsin can convert more trypsinogen into trypsin.

16
Q

What are secondary bile acids? (2) How are they produced, and where?

A

formed by donjugation of bile salts by enteric bacteria-deoxycholic acid (from cholic acid) and lithocolic acid (from chenodeoxycholic acid). Lithocholic acid is helpatotoxic and is excreted.

17
Q

What are three functions of H+ in stomach secretions?

A

kills bacteria, breaks down food and activates pepsinogen

18
Q

What are the main stimuli for the release of CCK? (2)

A

fat and amino acids entering duodenum

19
Q

How do parietal cells move H+ into the lumen of the stomach?

A

H+ ions are exchanged by the proton pump for K+ ions (active antitransport)

20
Q

Where are the muccous cells of the stomach? What do they secrete? (2) Which paracrine hormone stimulates them?

A

located in the superficial part if the gastric glands (gastric pits). secrete mucus and HCO3. Secretion is stimulated by PGE2

21
Q

How are carbohydrates absorbed, generally? Which monosacharide is independently absorbed?

A

glucose and galactose via active secondary Na cotransporter. fructose is absorbed independently.

22
Q

Stomach secretions: Mucus functions to:

A
  1. protect the stomach surface form H+

2. lubricant

23
Q

What does bicarbonate in the salivary solution do?

A

neutralizes bacterial acids and maintains dental health

24
Q

Does the apical or basolateral surface o hepatocytes face the bile canliculi?

A

apical

25
Q

Proenzyme of trypsin is?

A

trypsinogen

26
Q

What are the main effects of GIP? (2)

A

inhibits stomach motility and secretion

27
Q

Name four pancreatic enzymes for protein digestion?

A

trypsin, chymotrypsin, elastase, and carboxypeptidases (secreted as proenzymes)

28
Q

What product of heme metabolism is taken up by hepatocytes?

A

bilirubin

29
Q

Sinusoids drain to the ___ vein?

A

central vein

30
Q

What is the main effect of secretin?

A

stimulates HCO3 secretion by pancreas to neutralize acid entering duodenum

31
Q

Describe the substrates and enzyme that produce H+ in the parietal cells

A

CO2 is extracted from the blood and combined wit water into H2CO3 by carbonic anhydrase.

32
Q

GI secretory products: Name 3 compounds that stimulate gastric acid secretion

A

histamine, Ach, gastrin

33
Q

Name three pancreatic enzymes for fat digestion?

A

lipase, hospholipase A, colipase

34
Q

Name the two large nerve plexuses in digestive tract. What is their function?

A

submucosal (Meissners)-controls secretions

Myenteric (auerbachs)-controls motility

35
Q

What are the effects of gastrin? (3)

A

stimulates acid secretion by parietal cells, increases motility and secretions.

36
Q

G cells are located in which 2 places?

A

antrum of the stomach and duodenum

37
Q

Glucose absorption occurs across the membrane through which mechanism?

A

sodium-glucose cotransporter

38
Q

Name three types of endocrine secreting cells of the pancreas, and the main endocrines secreted.

A

islets of langerhan-alpha cells produce glucagon, beta cells–insulin and PP cells produce pancreatic polypeptide

39
Q

What are the main effects of CCK? (4)

A

Inhibits gastric emptying, stimulates pancreatic enzyme secretion, stimulates contraction of the gallbladder and relaxation of sphincter of Oddi.

40
Q

What compound begins starch digestion?

A

alpha-amylase

41
Q

Renal excretion of this form of bilirubin

A

urobilirubin (4mg/day)

42
Q

Which enzyme cleaves trypsinogen?

A

enterokinase

43
Q

Enzyme for starch digestion that is secreted in the active form from the pancreas is?

A

alpha-amylase

44
Q

Bilirubin is conjugated in which organ?

A

liver

45
Q

What are the three main components of gastric juices secreted by the stomach?

A

mucus, pepsin and hydrochloric acid

46
Q

Where in the GI system are the cells that secrete CCK?

A

cells lining the duodenum

47
Q

GI secretory products: Name 2 compounds that inhibit gastric acid secretion

A

somatostatin, GIP, prostaglandin

48
Q

What are the substrate and products of cholesterol esterase?

A

hydrolizes cholesterol esters to yield cholesterol and free fatty acids

49
Q

List three important electrical characteristics of GI smooth muscle.

A

stretch stimulates contraction, electrical synctium with gap junctions, pacemaker activity

50
Q

Name the two primary bile acids. where are they produced?

A

cholic acid and chenodeoxycolic acid. Synthesized in the liver form cholesterol.

51
Q

Which enzyme, present in saliva, begins the digestion of carbohydrates?

A

alpha-amylase

52
Q

Chief cells secrete?

A

pepsinogen

53
Q

Bacterial conversion of which form of bilirubin occurs in the colon?

A

urobilinogen

54
Q

Secretory acini of the pancreas secrete zymogens when stimulated by ___ and ____?

A

acetylcholine and CCK

55
Q

GI secretory products: Autoimmune destruction of ___ leads to chronic gastritis and/or pernicious anemia

A

parietal cells

56
Q

Where in the GI tract is GIP made?

A

duodenum

57
Q

Name two important factors that stimulate gastric motility.

A

distension of the stomach and ACh

58
Q

Name the three glands involved in salivary secretion?

A

parotid, submandibular and sublingual

59
Q

Name four important factors that inhibit gastric motility.

A

acid in the duodenum (via secretin), fat in the duodenum (via CCK), hyperosmolarity in duodenum, distension of duodenum

60
Q

What is the term that refers to food and any mixture of enzymes in the stomach?

A

chyme

61
Q

G cells secrete_____.

A

gastrin

62
Q

Which cells produce secretin? Where are these cells located?

A

S cells of the duodenum

63
Q

Recommendations and monitoring for pancreatic insufficiency should include?

A

limit fat intake and monitor for signs of fat-soluble vitamin deficiency

64
Q

Which compounds in saliva lubricate food?

A

mucins (glycoproteins)

65
Q

Free bilirubin is complexed with ____ in circulation?

A

albumin

66
Q

Which cells secrete intrinsic factor?

A

parietal cells

67
Q

What is added to bile acids to create bile salts? (2)

A

bile acids (cholic and dexycholic) are conjugated with glycine and taurine which mix with cations to form salts.

68
Q

Describe the two types of contractions that occur in the intestines.

A

segmentation contractions (mixing), peristaltic movements (propulsive).

69
Q

Name the main components of bile. (4)

A

conjugated bile acids (cholic and chenodeoxycholic), billirubin, lecithin and cholesterol.

70
Q

Name three substances that stimulate parietal cells to secrete acid.

A

acetylcholine, histamine and gastrin

71
Q

Name the cofactor required by pancreatic lipase to displace bile from the surface of micelles.

A

colipase

72
Q

What cells secrete exocrine products in the pancreas?

A

acinar cells

73
Q

Where are parietal cells located? What do they secrete? (2)

A

located in the middle part of the gastric glands. Secrete HCl and intrinsic factor.

74
Q

What is the main stimulus for secretin release?

A

acid entering the duodenum

75
Q

Which form of bilirubin occurs in enterohepatic circulation from colon to liver?

A

urobilinogen

76
Q

Where are chief cells located? What do they secrete? (1)

A

located in the deep part of the gastric glands. Secrete pepsinogen which is converted to pepsin by acid medium. Pepsin begins digestion of proteins to peptides.

77
Q

Which form of bilirubin excreted in feces?

A

stercobilin

78
Q

GI secretory products: T/F: gastrin stimulates gastric motility

A

true

79
Q

Conjugated bilirubin is also called?

A

direct bilirubin

80
Q

What are the main stimuli for GIP release? (3)

A

fat, carbs and amino acids

81
Q

How are lipids absorbed?

A

micelles diffuse to the brush border and digested lipids (2-monoglycerides, fatty acids, cholesterol and ADEK vitamins) diffuse into enterocytes. Triglycerides are resynthesized and packaged as chlomicrons with apo B48. Leave the intestine via lymphatics to thoracic duct.

82
Q

Intrinsic factor is needed to absorb which vitamin?

A

B12

83
Q

Which condition results form elevated bilirubin levels?

A

jaundice

84
Q

Bile acids are reabsorbed only in the _____.

A

distal ileum

85
Q

What type of bond does pancreatic amylase break? What are the products?

A

hydrolyzes a-1,4-glucoside bonds forming a-limit dextrins, maltotriose and a maltose

86
Q

What makes up the portal triad?

A

bile ductule, branch of portal vein, branch of hepatic artery

87
Q

Which cells produce gastrin? Where are they located?

A

G cells of the stomach anthrum, duodenum