Digestive System 2 (Chemical Digestion) Flashcards
(76 cards)
1
Q
chemical digestion
A
catabolic activates to break polymers into monomers
2
Q
hydrolysis
A
how we break polymers apart
every bond broken requires one H2O molecule to break it
3
Q
most important monosaccharide
A
glucose
4
Q
start starch digestion in _____; complete starch digestion in ____
A
mouth; small intestine
5
Q
what do we use monosaccharides for
A
energy or as building blocks
6
Q
oligosaccharides are about __ subunits long
A
8
7
Q
carb-digesting enzymes, in order (roughly) of appearance
A
salivary amylase pancreatic amylase dextrine glucoamylase maltase, sucrase, lactase
8
Q
salivary amylase
A
produced in salivary glands
works on starch in mouth
denatured in stomach
9
Q
pancreatic amylase
A
produced in pancreas
works on starch in small intestine
10
Q
dextrinase
A
produced in brush border
works on oligosaccharides in small intestine
11
Q
glucoamylase
A
produced in brush border
works on oligosaccharides in small intestine
12
Q
maltase
A
produced in brush border
works on maltose in small intestine
13
Q
sucrase
A
produced in brush border
works on sucrose in small intestine
14
Q
lactase
A
produced in brush border
works on lactose in small intestine
15
Q
t/f each disaccharide has a specific enzyme to break it into subunits
A
true
16
Q
dietary proteins
A
from foods we’re eating
17
Q
intrinsic proteins
A
from breaking down things in body
enzymes and mucosal cells
forms of protein we cannot digest
18
Q
protein digesting enzymes (in rough order)
A
pepsin rennin trypsin chymotrypsin carboxypeptidase aminopeptidase dipeptidase
19
Q
where does protein digestion start?
A
stomach
20
Q
how are protein enzymes released?
A
in inactive form
21
Q
pepsin
A
protein-digesting enzyme produced in chief cells
22
Q
rennin
A
protein-digesting enzyme produced in babies
helps babies break down milk proteins (casein/whey)
why people develop dairy intolerances
23
Q
trypsin
A
protein-digesting enzyme produced in pancreas
24
Q
chymotrypsin
A
protein-digesting enzyme produced in pancreas
25
carboxypeptidase
protein-digesting enzyme produced in pancreas and brush border
26
aminopeptidase
protein-digesting enzyme produced in brush border
27
dipeptidase
protein-digesting enzyme produced in brush border
breaks down dipeptides
gives body free amino acids to absorb
28
function of carboxypeptidase and aminopeptidase
take amino acid chain and each split off last amino acid from opposite ends
29
lipid digestion starts in ___ and finishes in ______
small intestine; small intestine
30
lipase
enzymes that break down lipids
produced in pancreas, in active form
functions in small intestine
31
why aren't lipases super effective enzymes?
fat globules are so big
| we need bile to emulsify fats and increase surface area
32
products of lipid digestion
fatty acids and glycerol
33
nucleic acid-digesting enzymes
pancreatic nuclease
nucleosidase
phosphatase
34
pancreatic nuclease
nucleic acid-digesting enzyme produced in pancreas
35
nucleosidase
nucleic acid-digesting enzyme produced in brush border
36
phosphatase
nucleic acid-digesting enzyme produced in brush border (last)
37
product of pancreatic nuclease becomes substrate for ___________
nucleosides and phosphatase
38
absorption of water-soluble substances
active transport into villi capillaries and delivery to liver
cannot cross plasma membrane or pass across villi to get into villi capillaries
requires energy; uses endocytosis
goes to bloodstream directly
39
absorption of fat-soluble substances
simple diffusion into villi lacteals and delivery to blood by lymph
aided by micelles
goes to lymph then to bloodstream
40
where does absorption occur?
in jejunum!
41
what kind of absorption occurs in ileum
absorption of bile salts
42
nutrients definition
a substance used by the body to produce energy, promote growth, provide maintenance, or stimulate repair
43
nutrients
```
water
carb
lipids
proteins
vitamins
minerals
```
44
60% of food we eat is ____
water
45
dietary carbohydrates
get mostly from plants
| glucose is most important carb
46
dietary lipids
we consume mostly neutral fats like triglycerides
can come from animal or plant sources
animal- saturated fat
plant- unsaturated/polyunsaturated fat
47
dietary proteins
both animal and plant sources
animal- complete
plant- incomplete
essential amino acids we need from diet, cannot get some from plants
48
vitamins
not used as building blocks or for energy
function as coenzymes
needed so we can get nutritional value out of major nutrients
2 types: fat-soluble or water-soluble
49
what happens if there is an excess of fat-soluble vitamins
bioaccumulation and toxicity
50
what happens if there is an excess of water-soluble vitamins
just eliminate them
51
minerals
not used for fuel or energy; can be used for building blocks
most important minerals: calcium and phosphate (make bone salts)
52
metabolism
biochemical process of conversion
| big to little or little to big
53
anabolism
building things up
| linking smaller things together to make bigger ones
54
catabolism
breaking bigger things down into subunits
55
general process of metabolism
chemical digestion and transport of products to cells
anabolism of lipids, proteins, glycogen OR catabolism of pyruvic acid and acetyl CoA
cellular respiration in mitochondria
56
anabolism and catabolism are forms of _____ reactions
redox
57
reduction
add oxygen or remove hydrogen
| loses energy
58
oxidation
add hydrogen
| gains energy
59
redox enzymes
dehydrogenases
oxidases
coenzymes
60
dehydrogenase
catalyze oxidation
| removal of H, liberates energy
61
oxidase
catalyzes transfer of oxygen
62
coenzymes
hydrogen acceptors
| NAD and FADH are important coenzymes
63
substrate-level phosphorylation
ATP synthesis within cytoplasm of cell
cell cytoplasm undergoes direct phosphorylation
direct transfer of phosphate to ADP to make ATP
if oxygen present, products of substrate-level go into oxidative phosphorylation next
64
carbohydrate metabolism
1. glucose uptake: glucose enters cells (from bloodstream) by facilitated diffusion
2. glucose immediately phosphorylated to glucose-6-phosphate
- --irreversible step of adding P to glucose; this maintains glucose gradient that promotes intake of glucose
3. glycolysis continues and results in formation of 2 pyruvic acid, 2 NADH, and net gain 2 ATP4
4. if oxygen present, oxidative phosphorylation occurs
4. if no oxygen present, pyruvate turns into lactic acid
65
what happens at the end of carbohydrate metabolism is no oxygen is present?
pyruvate is turned into lactic acid
accumulation of lactic acid changes pH --> denatures enzymes of carbohydrate metabolism
this limits amount of energy that can be produced
66
oxidative phosphorylation
1. pyruvic acid converted into acetyl coA in mitochondria
- --- generates CO2 and NADH
2. acetyl coA enters Krebs cycle
- --- generates 2 CO2 and 2 NADH and 1 ATP and 1 FADH2
3. reduced Krebs cycle coenzymes enter electron transport chain
4. hydrogens used to phosphorylate ADP
- --- generates H2O and 34 ATP
67
products of oxidative phosphorylation
CO2, H2O, NADH, ATP, FADH2
68
what happens if we have excess glucose?
high ATP levels stop glycolysis --> don't produce any more ATP
glucose converted to glycogen (glycogenesis)
glycogen stored in skeletal muscle until energy needed
drop in blood glucose stimulates glycogenolysis to release stored glycogen to glucose to body
69
gluconeogenesis
insufficient glucose availability prompts conversion of glycerol and amino acids to carb-type molecules
occurs in liver
70
how much more energy can we get from fat than from carbs
10x
71
order of nutrient preference for energy
carbohydrate
lipid
protein
72
lipid metabolism
1. absorbed lipids broken down by plasma enzymes into glycerol and fatty acids
2. glycerol converted into glyceraldehyde phosphate
- --- glyceraldehyde phosphate converted to pyruvic acid in glycolysis, then enters Krebs
3. fatty acids broken into acetic acid in mitochondria
- --- acetic acid fuses with coA to form acetyl coA, then enters Krebs
73
what happens if we have excess lipids?
high ATP and glucose levels trigger conversion of glycerol and fatty acids into triglycerides for storage
^ storage in adipose tissue
(lipolysis reverses this process)
74
lipolysis
breakdown of triglycerides into glycerol and fatty acids
75
protein metabolism
1. amino acids deaminated (remove amine)
| 2. deaminated molecules converted to pyruvic acid or to Kreb's cycle intermediates
76
what happens if we have excess proteins?
high ATP levels cause pyruvic acid formed through deamination to be converted to glucose
----opposite of glycolysis; then glucose goes through glycogenesis to be stored
hormones control protein synthesis on ribosomes
some proteins get converted to proteins in body
