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Human Anatomy & Physiology 2 > Digestion > Flashcards

Flashcards in Digestion Deck (116):
1

digestive system

used to break nutrients down into forms that can be used by the body for cell metabolism

2

where does the energy lie for the cells

within the bonds

3

what are the digestive processes? (7)

1.ingestion
2.propulsion
3.mechanical digestion
4.chemical digestion
5.secretion
6.absorption
7.excretion

4

propulsion (2)

-voluntary swallowing
-alternating of smooth muscle contraction and relaxation

5

peristaisis

involuntary smooth muscle contraction

6

mechanical digestion

chewing and mixing food

7

segmentation

rhythmic local contractions of the intestine

8

chemical digestion

food broken down to monomers

9

secretion

release of water, acids, enzymes, and salt

10

absorption

end products from GI tract into blood or lymph

11

excretion

elimination of indigestible substances

12

what are the 2 main groups of the digestive system?

-alimentary canal//GI tract
-accessory organs

13

What occurs in the mouth? (4)

1.analysis of material before swallowing
2.mastication
3.lubrication
4.limited digestion by saliva

14

in the mouth there is limited ______ regulation

chemical

15

saliva contains (7)

-salivary amylase
-salivary lipase
-97% water
-lysozyme
-IgA antibodies
-mucin
-growth factors

16

salivary amylase

breaks down polysaccharides into smaller fragments

17

salivary lipase (2)

-breaks down triglycerides
-only works at low pH (acidic) [stomach, not the mouth]

18

lysozyme

destroys bacteria

19

mucin

forms thick mucus when water is added

20

secretion of saliva is controlled by ____

autonomic nervous system (both sympathetic and parasympathetic)

21

the salivatory nuclei of the ___ ___ sends action potentials down the ____ and ____ nerves to stimulate salivation

medulla oblongata; facial and glossopharyngeal

22

is there absorption in the oral cavity?

very little in the mouth, some lipid soluble substances

23

oral phase of saliva release? what does it result in? (2)

-chemoreceptors (stimulated by acidic substances)
-pressure receptors

-activation of the parasympathetic nervous system->saliva released

24

cephalic phase of saliva release? what does it result in?

thought, sight, smell of food

-activation of the parasympathetic nervous system->saliva released

25

what happens during sympathetic stimulation during saliva release? (2)

-a smaller production of viscous saliva with little enzyme content
-due to constriction of blood vessels feeding the glands

26

what are the functions of the stomach? (5)

-primarily a food storage
-mechanically breaks up food particles
-liquefies the food to produce chyme
-limited digestion of protein and lipids
-helps sterilize food

27

what type of tissue lines the stomach?

simple columnar epithelium that is a secretory sheet

28

the epithelium of the stomach is organized into?
what are they lined with?
at the base?

-gastric pits which are shallow depressions
-mucous epithelium (release mucin)
-gastric glands

29

what are the cells of the gastric glands? (4)

-G cell
-chief cells
-parietal cells
-mucous cells

30

mucous neck cells of gastric glands (2)

-produces mucin
-located at the top of the gland

31

parietal cells of gastric glands (2)

-produce intrinsic factors that binds to B12-> absorbed by small intestine
-produce HCl

32

pernicious anemia

caused by a drop in B12 production which is need to produce red blood cells

33

what is the purpose of HCl? (5)

-kill microbes
-denature proteins
-break down plant walls
-activate pepsin
-converts ferric(fe3) to ferrous (fe2)

34

how is acid (HCl) produced in the stomach? (4)

1. carbon dioxide diffuses into cell from the blood
2. carbonic anhydrase produces H and HCO3
3. H/K ATPase pump out H in exchange for K
4. Cl shift into cell as HCO3 goes into the blood

35

chief cells of gastric glands (2)

-produce pepsinogen
-produce rennin and gastric lipase in infants

36

pepsinogen (2)

inactive
is converted to pepsin by HCl

37

pepsin

digests proteins to shorter peptide chains

38

g cells of gastric gland

produce gastrin

39

what does gastrin stimulate?

the secretion of parietal (acid) and chief (pepsin) cells

40

somatostatin (3)

-produced by D cells
-weekly inhibits gastrin release
-released when stomach is very acidic

41

regenerative cells (2)

-at the base of the gland
-undergoes mitosis

42

gastric secretion contains (4)

mucous, acid, enzymes, and hormones

43

the regulation of gastric secretion is controlled by what?

nervous and hormonal mechanisms

44

what are the 3 phases of gastric secretion?

-cephalic
-gastric
-intestinal

45

cephalic phase of gastric secretion (4)

- directed by ANS
-occurs before food enters the stomach
-triggered by sight, smell, or thought of food
-PNS nerve fibers travel down vagus nerve

46

gastric phase of gastric secretion (2)

-occurs once food reaches the stomach
-important stimulus is distention, peptides and low acidity

47

distention=

stretch

48

when stimulated these make:
parietal cells->
chief cells->
G cells->

HCl (parietal)
pepsinogen (chief)
gastrin (G cells)

49

how are gastric effects similar to positive feedback loop?

gastrin stimulates HCl from parietal cells, which causes more gastrin to be released

50

how are gastric effects similar to negative feedback loop?

when gastrin is released in which the pH drops below 2 somatostatin is released

51

intestinal phase of gastric secretion (2)

-starts when chyme enters the small intestine
-main function is to control the entrance of acidic chyme into duodenum

52

what hormones are involved in the intestinal phase of gastric secretion? (4)

-gastrin
-secretin
-cholecytokinin (CCK)
-gastric inhibitory polypeptide (GIP)

53

secretin

-released from the small intestine if pH of chyme is less than 3
-inhibits gastric secretion

54

CCK and GIP (2)

-released from small intestine in the presence of fatty acids and lipids
-inhibit gastric secretion

55

small intestine

site of digestion and almost all absorption

56

3 regions of the small intestine

-duodenum
-jejunum
-ileum

57

gastric emptying is primarily accomplished via?

opening and closing of pyloric sphincter

58

what stimulates opening of the pyloric sphincter? (2)

-stretch of the stomach
-gastrin released

59

what stimulates closing of the pyloric sphincter? (3)

-stretch of the small intestine
-chemical receptors for acid, amino acids, and lipids
-secretion of CCK, GIP, and secretin

60

duodenum (2)

-smallest region of the small intestine
-received pancreatic juice, bile, and stomach contents

61

common bile duct

common entry point from gall bladder and pancreas

62

pyloric sphincter

attaches the stomach to the intestine

63

jejunum vs illeum

jejunum : more digestion than absorption
illeum: more absorption than digestion

64

what features are added to increase surface area of the small intestine? (2)

-plica circulate
-villi

65

plica circulate (2)

-deep folds of the inner surface
-shape causes chyme to spiral

66

villi

fingerlike projections of the mucosal surface of the intestine

67

microvilli=____where are they located?

-brush borders
-on villi and become progresssively smaller in more distal regions of the small intestine

68

cells of the villi? what are they called?

simple columnar cells; absorptive cells

69

goblet cells

secrete mucus

70

what are the cells found in the intestinal crypts (glands)? (4)

-absorptive cells
-goblet cells
-enteroendocrine cells
-paneth cells

71

paneth cells

secrete lysozymes

72

what are the cells of the submucosal layer of the small intestine? (3)

-duodenal glands
-peyers patch
-MALT

73

peyers patch

dense lymphoid nodules

74

the pancreas has 2 ducts that it can use to empty into the duodenum, what are they?

-accessory (smaller)
-pancreatic duct which fuses with gallbladder to form common bile duct (larger)

75

pancreas has an endocrine portion known as ______, and a exocrine portion that is organized into _____.

islets of langerhan; acini (small clusters of glandular epithelial cells)

76

islets of langerhan:
beta cells release _____
alpha cells release ______

insulin; glucagon

77

composition of the pancreatic juice (3)

-mostly water
-electrolytes (sodium bicarbonate)
-alkaline

78

what are the 4 enzymes in pancreatic juice?

-proteases
-pancreatic amylase
-pancreatic lipase
-nucleases

79

proteases

break peptide bonds

80

trypsinogen is activated by ______, a brush border enzyme. it is then converted to _______.

enterokinase; trypsin

81

pancreatic amylase

starch enzyme

82

pancreatic lipase (2)

-lipid enzyme
-cleaves 2 fas leaving 1 fas and a monoglyceride

83

nucleases

RNA and DNA enzyme

84

pancreatic secretion is primarily under _____ control. What 2 hormones are released to release pancreatic enzymes and juices?

hormonal;secretin and CCK

85

one of the functions of the liver is to?

synthesize and secrete bile

86

Bile (4)

-produced by the liver
-is a yellow-green alkaline solution
-role in digestion is as fat emulsifer
-stored in the gallbladder

87

what is the composition of bile? (5)

-bile salts
-phospholipids
-bile pigments
-cholesterol
-electrolytes

88

bile salts (5)

-cholesterol derivatives
-contain polar and nonpolar ends
-act as detergents for lipids
-emulsify fats
-recycled by enterohepatic circulation

89

bile pigments (2)

-most is bilirubin (waste product of heme)
-give feces its brown color (break down of urobilinogen)

90

what are the 4 regions of the large intestine?

-cecum
-appendix
-colon
-rectum

91

what are the functions of the large intestine? (3)

-chemical digestion
-absorption of lots of water
-elimination of feces

92

indigestible carbs produce _____

flatus (farts)

93

what are some examples of chemical digestion by bacteria observed in the large intestine? (3)

-fermentation of indigestible carbs
-cellulose digested to glucose
-synthesis of B vitamins

94

the enzymatic breakdown of polymers into monomers is achieved by ____

hydrolysis

95

starch (2)

-carb
-a glucose polymer

96

glycogen (2)

-not much in diet
-animal starch

97

monosaccharides (3). What is the significance of this monomers when it comes to digestion?

-glucose
-galactose
-fructose

-they can quickly be absorbed

98

disaccharides (3)

-sucrose
-lactose
-maltose

99

sucrose

glucose +fructose

100

lactose

glucose + galactose

101

maltose

glucose+ glucose

102

pancreatic amylase (2)

-takes about 10 minutes to work in SI
-produce maltose and 3 to 9 glucose chains

103

dextrinase and glucoamylase

-works on small glucose polymers
-yields maltose and glucose

104

galatose converts to _______ immediately once it enters the small intestine

glucose

105

glucose and galatose are transported ______ by _____ dependent transporters. While fructose is transported by ____ . All monosaccharides are transported paracellularly via _______

transcellular; glu//gal-sodium
facilitated diffusion; solvent drag

106

STOMACH: During protein digestion, pepsinogen->pepsin. It attacks bonds involving ____ and _____.

tyrosine and phenylalanine

107

carboxypeptidase (CPA) is what type of enzyme (2)

-brush border
-pancreatic enzyme

108

SMALL INTESTINE: Trypsin and chymotrypsin

reduce the sizes of the polypeptide by attacking internal bonds

109

CPA removes the _____end of the amino acid, while aminopeptidase/dipeptidase removes the ____ end of the amino acid.

carboxyl group; amine group
-both work best in neutral pH

110

infants absorb proteins via _____

pinocytosis

111

protein digestion occurs in the ?
lipid digestion occurs in the ?

stomach and small intestine
ALL in small intestine

112

micelle made up of (4)

fatty acids + monoglycerides + phospholipid (from bile) + bile salts

113

once inside the cell, the fatty acids and monoglycerides are resynthesized into _______. These then combine with cholesterol and ______ to make up ______.

triglycerides; phospholipid; lipoprotein

114

chylomicron

lipoprotein formed in the cell

115

where do most chylomicrons go?

lacteals or left overs are taken to the liver

116

when chylomicrons go the liver they are converted into______

low density lipoproteins (LDLs)-> adipose tissue