Digestion and Absorption Lipids Vitamins Minerals Flashcards
1
Q
major dietary lipids are
A
triglycerides
2
Q
what lipids are products of digestion and are absorbable
A
Fatty acids
monoglycerides
cholesterol
3
Q
what is the solution to absorbing lipids
A
transform fats into water-soluble molecules
4
Q
how many gm of lipid ingested per day in western diet
A
100gm
5
Q
what is kcal/gm in lipid
A
9
6
Q
what is kcal/gam in CHO
A
4
7
Q
digestion of lipids beings where
A
stomach
8
Q
what enzymes in stomach begin digestion of lipids
A
lingual and gastric lipases
9
Q
where is digestion of lipids completed
A
SI
10
Q
what enzymes in SI complete digestion of lipids
A
pancreatic lipase, cholesterol ester hydrolase, and phospholipase A2
11
Q
what does stomach do for lipid digestion
A
slows down how much chyme is going into duodenum so you don’t overhwlem what is going on in duodenum
12
Q
what hormone slows down gastric emptying?
A
CCK
13
Q
how do Lingual and gastric lipases initiate lipid digestion?
A
hydrolyzing approximately 10% of ingested triglycerides to monoglyceride and free fatty acids.
14
Q
main purpose of bile released from GB
A
amphipathic . in the core is where breakdown will happen
15
Q
bile acids are
A
lipid soluble
16
Q
bile acids are conjugatted to
A
bile salts
17
Q
Emulsification produces
A
small droplets of lipid dispersed in the aqueous solution of the intestinal lumen, creating a large surface area for the action of pancreatic enzymes.
18
Q
emulsification allows what to work
A
pancreatic enzymes to work to break down lipid
19
Q
pancreatic enzymes to break down lipids:
A
Pancreatic lipase, cholesterol ester hydrolase, phospholipase A2 and colipase
20
Q
colipase has to be acted upon by what enzyme
A
trypsin
21
Q
pancreatic lipase activity is optimum at what pH
A
8
22
Q
what does ph need to be for stable emulsification
A
more than 6
23
Q
LCFA need what to get absorbed
A
micelle
24
Q
short and medium chain fatty acids do not need what to be absorbed
A
micelle
25
pancreatic lipase is secreted in response to
CCK
26
what does pancreatic lipase do
hydrolyzes triglyceride molecules to one molecule of monoglyceride and two molecules of fatty acid.
27
pancreatic lipase is inactived by
bile salts
28
how does body overcome the inactivation of pancreatic lipase by bile salts
colipase
29
how is colipase secreted into intestine
inactive form: procolipase
30
colipaes is activated by
trypsin
31
what does colipase do for pancreatic lipase
displaces bile salts at the lipid-water interface and binds to pancreatic lipase. With the inhibitory bile salts displaced, pancreatic lipase can proceed with its digestive functions.
32
what does cholesterol ester hydrolase do
hydrolyzes cholesterol ester to free cholesterol and fatty acids. It also hydrolyzes ester linkages of triglycerides, yielding glycerol.
33
how is cholesterol ester hydrolase secreted
as active enzyme
34
how is Phospholipase A secreted
proenzyme
35
Phospholipase A is activated by
trypsin
36
what does Phospholipase A do
hydrolyzes phospholipids to lysolecithin and fatty acids.
37
fat soluble vitamins use what mechanisms to be absorbed
same as fats. micelle formation to allow for it to be absorbed
38
what are final products of lipid digestion
monoglycerides, fatty acids, cholesterol, lysolecithin, and glycerol
39
monoglycerides, fatty acids, cholesterol, lysolecithin, and glycerol are all _____ Except:
hydrophobic except glycerol
40
surface of chylomicron is mainly
phoshpolipids
41
defiiency in apoliportein b what happens
can't make chylomicron
42
if you can't make chylomicrons what happens
cannot absorb large lipids, fatty stool
43
what promotes release of bile from gall bladder
CCK
44
fats in gut stimulate release of what
CCK
45
interfering with any step in lipid digestion will do what
cause fatty stool (steatorrhea)
46
problem with pancreatic function what happens to enzyme secretion
compromised
| so will bicarb secretion
47
gastrinoma is?
in pancreas and secretes gastrin (pancreas doesn't usually secrete gastrin)
48
what happens with gastrinoma
gastrin acts on parietal cells and massive acid secretion
| goes to duodenum and pancreas can't neutralize so then enzymes inactivated
49
gastrinoma will have impact on lipid digestion and
CHO and protein digestion
50
if you take away ileum
bile salts back to liver compormised and impacts lipid digested
51
bacterial overgrowth will do what
deconjugate bile salts → if they are bile acids they are lipiphilic, will be absorbed early in SI and will not be useful in lipid digestion and absorption b/c they won't make micelle
52
decrease absorptive surface like tropical sprue what happens
number of epithelial cells reduced
| reducing microvillar surface area
53
tropical sprue same symptoms as
celiac disease
54
differnece b/w tropical sprue and celiac
celiac: gluten
| tropical sprue: usually ppl in tropical enviornment and think it has something to do with bacteria
55
failure to synthesize apoproteins results in
significantly have defect of chylomicron to through basolateral membrane
56
vitamins are either
fat or water soluble
57
if vitamins are water soluble need what to get across cell membrane
protein mediated
58
if fat soluble vitamin need what to get across cell membrane
same as fat - chylomicron
59
what are the fat soluble vitamins
```
A
D
E
K
(KEAD)
```
60
what are the water soluble vitamins
B1, B2, B6, B12, C, biotin, folic acid, nicotinic acid, pantothenic acid
61
```
B1=thiamine
C=ascorbic acid
biotin
nicotinic acid = niacin pantothenic acid
use what transport mechanism
```
secondary transport driven by sodium
62
what mechamis is always on basolateral membrane
facilitated diffusion
63
B6 and B2 what is mechanism on apical membrane
facilitated diffusion
64
minerals are mostly absorbed where
duodenum
65
calcium roles in body
```
Bone and tooth formation
Cofactor for enzymes and proteins
Blood clotting
Muscle contraction
Nerve transmission
Intracellular signaling for hormone action
```
66
```
Bone and tooth formation
Cofactor for enzymes and proteins
Blood clotting
Muscle contraction
Nerve transmission
Intracellular signaling for hormone action
what is needed for all these
```
calcium
67
calcium absorption usually where
duodenum
68
parathyroid hormone activates 25 hydroxy vitamin D3 to
1,25 dihydroxy vitain D3
69
TRPV-6 is what channel
calcium
70
what stimulates TRPV-6 to open
vitamin D3
71
what stimulates calbindin
vitamin D3
72
what does calbindiin do
binds calcium
73
what activates calcium ATPase on basolaterla membrane
Vitamin D3
74
iron roles in body
Hemoglobin: oxygen transport and storage
(67% of body stores are in RBCs)
Energy metabolism (cytochromes are heme-proteins)
Oxidant production (immune system) and detoxification
DNA synthesis requires iron-bound proteins
75
iron primarily absorbed in
duodenum & upper jejunum
76
DMT-1 is what kind of transport
secondary active transport
| uses hydrogen as driveer solute
77
what is driver solute for DMT-1
hydrogen
78
what is ferrous iron
Fe2+
79
bile acid and salts primarily where
ileum
80
once inside intestinal epithelial cells what happens to products of lipid digestion
reesterified
81
what happens when the lipids are reesterified
they form original ingested lipids: triglycerides, cholesterol ester, and phospholipids.
82
how are reesterfieid lipids packaged in the cell
in chylomicron
83
what is at center of chylomicron
triglycerides & cholesterol
84
what is on outside of chylomicron
phospholipids & apoproteins
85
what is the majority of outside of chymoicron covered with
phospholipid
86
what synthesize apoproteins
intestinal epithelial cells
87
if body doesn't synthesize Apo B what condition results
abetalipoproteinemia
88
what is abetalipoproteinemia
a person is unable to absorb chylomicrons and, therefore, is also unable to absorb dietary lipids
89
chylomicrons are too large to enter
vascular capillaries
90
chylomicron enters what capillary
lymphatic capillary
91
draw out process of fat absorption
pg 15
92
how much of excreted bile is reabsorbed
90-95%
93
what system is used to recycle bile
enterohepatic circulation
94
where are most bile salts absorbed in intestines
terminal ileum
95
what system is used to absorb, aka what mechanism of transport is used to reabsorb bile in ileum
secondary active cotransport with Na+
96
what does it mean that some bile salts are deconjugated in intestine
they are converted back to bile acids
97
what needs to happen to bile salts in liver
they need to be conjugated again
98
what happens to bile salt that enters the colon
converted to secondary bile salts
99
what are the secondary bile salts
deoxycholic acid & lithocholic acid
100
what happens to lithocholic acid
isn't reabsorbed ,most excreted in stool
101
what happens regarding lipid absorption if there is pancreatic insufficiency
can't secrete adequate amounts of enzymes needed for lipid digestion, so triglycerides will not be able to be absorbed and will be pooped out
102
how does Zollinger-Ellison syndrome relate to lipid absorption
if there is tumor in pancreas, and it excretes too much gastring, then pH will be much too low in duodenum and the enzymes needed to degrade lipids will not be able to function
103
what happens regarding lipid absorption if ileum is removed
bile salts are not reabsorbed, liver cannot keep up with demand so there is deficiency of bile salts and if there are not enough bile salts can't form enough micelles needed for absorption
104
what does bacterial overgrowth do to bile salts
reduces effectiveness
105
how does bacterial overgrowth reduce effectiveness of bile salts
deconjugates them - removes glycine & taurine
106
bile salts in non-ionizable form, what happens to them
they are readily absorbed by diffusion
107
explain what happens regarding lipid absorption with bacterial overgrowth
bile acids are in non-ionizable form b/c the bacteria deconjuagetes them. this means the bile salts are absorbed by diffusion before they have a chance to do their job on the lipids
108
how are fat soluble vitamins absorbed
Incorporated into micelles – transported to apical membrane – diffuse across membrane into cell – incorporated into chylomicrons – extruded into lymph – general circulation
109
B1, B12, C, biotin, folic acid, nicotinic acid, and pantothenic acid - how are they absorbed
Na+ dependent cotransporter
110
absorption of vitamin B12 requires
intrinsic factor
111
what binds vitamin B12 in the mouth and stomach
R proteins (haptocorrin)
112
what bind vitamin B12 from duodenum to ileum
intrinsic factor
113
once in ileum what binds vitamin B12
transcobalamin II
114
transcobalamin II allows vitamin B12 to be
absorbed
115
what is a gastrectomy
partial or full removal of stomach
116
what happens regarding gastrectomy and vitamin B12
loss of IF may result in vitamin B12 deficiency→ pernicious anemia
117
what cells secrete IF
parietal cells
118
where are parietal cells located
stomach
119
what is pernicious anemia
body can't absorb enough vitamin B12 to make healthy RBC
120
for pts who have had gatrectomy what is done to ensur they don't develop pernicious anemia
vitamin B12 injections
121
where are calcium and iron absorbed
early in SI
122
what form is iron in when it is in early part of SI
reduced: Fe2+
123
what is mechanism for calcium absorption
Vitamin D dependent Ca2+ binding protein
124
what is mechanism for iron absorption
binds to apoferritin in intestinal cell & transferrin in blood
125
what reduces calcium absorption
anions
126
why do anions reduce calcium absorption
they bind to calcium
127
what are example ions that would reduce calcium absorption
phosphate; oxalate, phytate
128
calcium absorption is regulated by
circulating levels of plasma calcium
129
what is active form of vitamin D
vitamin D3
130
vitamin D3 is also known as
1,25-dihyroxyvitamin D3
131
if plasma calcium levels are lowered, what happens
stimulates release of parathyroid hormone → conversion to active vitamin D
132
what are the calcium channels
TRPV-6
133
what is function of Calbindin
keeps intracellular free calcium low, to allow gradient for calcium to enter cell
134
if there is vitamin d deficiency what happens to children
rickets. they don't have adeuqate calcium absorption
135
if there is vitamin d deficiency what happens to adults
osteomalacia. they don't have adequate calcium absorption
136
dietary iron is released in large amounts after digestion of
proteins
137
draw out calcium absorption
pg 33
138
draw out iron absorption
pg 36
139
what kind of iron is soluble at pH 7
ferrous: Fe2+
140
what is ferric iron
Fe3+
141
what is ferrous iron
Fe2+
142
what form of iron is absorbed across apical epithelial cells
Fe2+
143
what carrier protein allows for absorption of iron
divalent metal transporter
144
review summary slide
pg 37
145
where are the majority of CHOs absorbed
duodenum
146
where are the majority of proteins absorbed
duodenum
147
where are the majority of lipids absorbed
duodenum
148
what is cobalamin
vitamin B12
149
where is Vitamin B12 absorbed
ileum
150
where is calcium, iron, folate absorbed
duodenum
151
where is calcium absorbed besides duodenum
jejunum & ileum
152
where are majority of bile acids absorbed
ileum
