Digestion Flashcards
1
Q
digestive system
A
used to break nutrients down into forms that can be used by the body for cell metabolism
2
Q
where does the energy lie for the cells
A
within the bonds
3
Q
what are the digestive processes? (7)
A
- ingestion
- propulsion
- mechanical digestion
- chemical digestion
- secretion
- absorption
- excretion
4
Q
propulsion (2)
A
- voluntary swallowing
- alternating of smooth muscle contraction and relaxation
5
Q
peristaisis
A
involuntary smooth muscle contraction
6
Q
mechanical digestion
A
chewing and mixing food
7
Q
segmentation
A
rhythmic local contractions of the intestine
8
Q
chemical digestion
A
food broken down to monomers
9
Q
secretion
A
release of water, acids, enzymes, and salt
10
Q
absorption
A
end products from GI tract into blood or lymph
11
Q
excretion
A
elimination of indigestible substances
12
Q
what are the 2 main groups of the digestive system?
A
- alimentary canal//GI tract
- accessory organs
13
Q
What occurs in the mouth? (4)
A
- analysis of material before swallowing
- mastication
- lubrication
- limited digestion by saliva
14
Q
in the mouth there is limited ______ regulation
A
chemical
15
Q
saliva contains (7)
A
- salivary amylase
- salivary lipase
- 97% water
- lysozyme
- IgA antibodies
- mucin
- growth factors
16
Q
salivary amylase
A
breaks down polysaccharides into smaller fragments
17
Q
salivary lipase (2)
A
- breaks down triglycerides
- only works at low pH (acidic) [stomach, not the mouth]
18
Q
lysozyme
A
destroys bacteria
19
Q
mucin
A
forms thick mucus when water is added
20
Q
secretion of saliva is controlled by ____
A
autonomic nervous system (both sympathetic and parasympathetic)
21
Q
the salivatory nuclei of the ___ ___ sends action potentials down the ____ and ____ nerves to stimulate salivation
A
medulla oblongata; facial and glossopharyngeal
22
Q
is there absorption in the oral cavity?
A
very little in the mouth, some lipid soluble substances
23
Q
oral phase of saliva release? what does it result in? (2)
A
- chemoreceptors (stimulated by acidic substances)
- pressure receptors
-activation of the parasympathetic nervous system->saliva released
24
Q
cephalic phase of saliva release? what does it result in?
A
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
