Exam 2 Flashcards
(172 cards)
1
Q
Alimentary organs
A
mouth esophagus stomach small intestine large intestine anus
2
Q
accessory organs
A
tongue teeth salivary glands liver pancreas gastric glands intestinal glands
3
Q
factors promoting digestion
A
mechanical
secretory
chemical
microbial- bacteria and protozoa
4
Q
mechanical
A
mastication, deglutition, regurgitation, gastric motility, intestinal motility, defecation
5
Q
secretory
A
saliva, gastric secretions, mucus secretions, digestive glands
6
Q
chemical
A
enzymes, HCl
7
Q
microbial- bacteria and protozoa
A
especially true for ruminants; large intestine
8
Q
wall of intestinal tract has four layers
A
- mucosa
- submucosa
- muscularis
- serosa
9
Q
mucosa
A
inner lining
10
Q
submucosa
A
connective tissue, blood vessels, lacteal (lymph), nerves
11
Q
muscularis
A
mixing and movement; also contains nerves
12
Q
serosa
A
smooth outside covering
13
Q
mucosa layer of stomach is subdivided into four zones
A
- cuticular region (non-glandular)
- cardiac gland region (mucus)
- fundic region (mucus, HCl, and enzymes)
- pyloric region (mucus)
14
Q
gastric glands are sometimes called ___
A
oxyntic glands
15
Q
gastric glands are located in the ___
A
fundic gland region
16
Q
Gastric glands
A
- mucous neck cells (secrete mucus)
- parietal cells (produce HCl)
- chief cells (produce gastric enzymes)
17
Q
B12 is not found in ___, only in ____
A
plants; animal proteins
18
Q
parietal cells produce…
A
HCl and Intrinsic factor.
19
Q
intrinsic factor
A
glycoprotein necessary for Vit B12 absorption. It binds to B12. Absorption occurs in ileum (last section of SI)
20
Q
B12 absorption may be decreased by…
A
- lack of intrinsic factor (aging, gastritis, or the partial removal of stomach; decreased HCl secretion- parietal cell problems) ; ileal resection or ileitis; deficiency of B12 in diet.
21
Q
small intestine divided into three parts
A
duodenum
jejunum
ileum
22
Q
two sets of muscles in SI
A
- circular: cause peristaltic movements
- longitudinal: aid peristaltic movements
23
Q
main functions of small intestine
A
- move chyme along its course
- continued digestion of chyme by secretions and enzymes secreted by the accessory glands and the SI’s own intrinsic factor
- absorption of nutrients into blood and lymph vessels
24
Q
chyme
A
semi-liquid, pulpy material produced by the action of gastric secretions in the stomach
25
villi and microvilli
surface anatomy of SI. Microvilli is also called the brush border and are on epithelial cells. These folds increase surface area. The main folds increase it by 3. Villi with epithelial cells increase it by 10. And microvilli increase it by 20. Combined surface area is 600X greater than just a round tube
26
___ of blood in liver enters through ____; and ___ enters through ___
80% through portal vein; 20% through hepatic artery
27
large intestine
- absorption of water and little minerals
- very few secretions (mucus only significant one)
- dehydrator in many species
- no digestive secretions
- cecum, colon, rectum
- cecum of horse and rabbit enlarged for microbial fermentation that permits utilization of forage
- sows on pasture also have enlarged cecum and significant microbial fermentation
28
three main pairs of salivary glands
- parotid: below ear
- submaxillary: base of the mandible
- sublingual: beneath tongue
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salivary amylase
- man and pig
- produced by parotid glands
- starch digestion enzyme
- starch -------> maltose and dextrin
- deactivated by HCl in stomach
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pre-gastric lipase
- from base of tongue
- produced by ruminants
- aids milk fat digestion
- also deactivated by HCl
31
composition of gastric secretions
- mucus
- gastric proteases
- HCl
- gastric lipase (minor importance)
32
protease
breaks down protein
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gastric proteases
pepsin (from chief cells of fundic region) and rennin (abomasum of nursing calf)
34
zymogen
precursor form. if chief cells secreted pepsin in active form, you would digest your own stomach.
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pepsin
- pepsinogen ---(HCl)---> pepsin
| - diet protein ---(Pepsin)---> long chain polypeptides
36
rennin
- prorennin ---(HCl)---> rennin
| - Casein ---(Rennin and Ca)---> Ca-paracaseinate (coagulated)
37
HCl
- activated pepsinogen and prorennin
- denatures dietary proteins
- stomach antiseptic
- promotes some hydrolysis (minor importance)
- stops action of salivary amylase
38
two sets of glands in small intestine
- brunner's glands and crypts of lieberkuhn
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Brunner's glands
- in mucosa/submucosa 1st few cm of duodenum
- secrete viscous alkaline mucus
- pH= 7-8
- neutralizes acid chyme
- also aids in fat emulsification
40
crypts of lieberkuhn
- enterokinase: activates trypsin
- amylase: breakdown of starch (minor role)
- mucus
41
small intestine intracellular enzymes
- located on surface or inside epithelial cells (on microvilli)
- several peptidases (split small peptides into AA)
- disaccharidases: sugar splitting enzymes (three primary are maltase, sucrase, and lactase)
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maltase
glucose + glucose
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sucrase
glucose + fructose
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lactase
glucose + galactose
45
horses do not have ___
gallbladder
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liver function with respect to digestion
secretes bile which is for fat emulsification and aids in absorption of lipids and fat soluble vitamins
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emulsification
breaks down fats into smaller pieces or droplets for more surface area for lipases to work with
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bile
- produced continually by liver
- formed from cholesterol (major route of cholesterol excretion from body)
- stored and concentrated in gall bladder
- empties into SI when digesta (especially fats) enters from the stomach
- about 94% of bile salts are reabsorbed and recycled back to gall bladder via enterohepatic pathway
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functions of bile
- emulsifies fat
- neutralizes acid
- excretes substances (cholesterol, fat soluble vitamins, drugs, toxins, some minerals)
50
composition of bile
- bile salts
- bilirubin
- cholesterol
- fatty acids
- lecithin
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bile salts
- cholic acid and chenodeoxycholic acid
- amphipathic - solubilize fats
- micelles
52
amphipathic
both polar and non polar regions; part hydrophilic and part hydrophobic
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bilirubin
- product of Hb breakdown
| - primary bile pigment- yellow color- modified by enzymes to give brown color in feces
54
types of tissue in pancreas
- acinar
| - islets of Langerhans
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acinar
- produce pancreatic secretions
| - released into duodenum
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islets of langerhans
- produce hormones
- released into blood
- beta cells: produce insulin
- alpha cells: produce glucagon
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pancreas secretions
- clear fluid, mostly water
- contains digestive enzymes
- contains bicarbonate to neutralize stomach acid
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digestive enzymes of pancreas
- proteolytic enzymes (trypsin, chymotrypsin, and carboxypeptidase)
- pancreatic amylase
- pancreatic lipase
- cholesterol esterase
- phospholipase
59
trypsin
- trypsinogen ---(enterokinase)---> trypsin
- trypsin, once formed, is autocatalytic
- enterokinase from crypts of lieberkuhn
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chymotrypsin
- chymotrypsinogen ---(trypsin)---> chymotrypsin
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carboxypeptidase
- procarboxypeptidase ---(trypsin)--> carboxypeptidase
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endopeptidases
- act on internal bonds, specific for certain AA
| - trypsin and chymotrypsin
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exopeptidase
- act on carboxyl group and releases free AA
| - carboxypeptidase
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pancreatic amylase
- hydrolyzes starch to maltose (G-G)
- major enzyme for starch digestion
- starch = major carbohydrate in grain
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pancreatic lipase
- hydrolyzes fats to fatty acids and monoglycerides
| - major enzyme in fat digestion
66
neural control of digestion
- salivary secretions: sight of food, smell, taste, etc. excite the salivary nuclei in the CNS
- HCl secretion: stomach distention
- pancreatic secretion: fat and protein products in SI
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origin of gastrin
pyloric region of stomach or abomasum
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releasing mechanism for gastrin
food in stomach, especially protein, caffeine, and spices
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function of gastrin
stimulates flow of stomach acid and enzymes
70
origin of gastric inhibitory polypeptide (GIP)
gastric antrum; duodenum; jejunum
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releasing mechanism for GIP
glucose in duodenum; fats, fatty acids, bile in duodenum
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function of GIP
insulin release; inhibit gastric secretion and motility
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origin of secretin
duodenum; jejunum
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releasing mechanism for secretin
acid chyme; large polypeptides
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function of secretin
secretion of pancreatic juice and reduce gastric motility
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origin of cholecystokinin
duodenum; jejunum
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releasing mechanism for cholecystokinin
fat, fatty acids, polypeptides in duodenum
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function of cholecystokinin
bile flow, synthesis of pancreatic juice and enzymes
79
places of absorption
1. mouth: no absn
2. esophagus: no absn
3. stomach: simple stomach (essentially no absn; water, alcohol, minerals); ruminant stomach (absn of VFA, NH3, gases and some AA; some absn from abomasum)
4. SI: primary site of absn
5. LI: primarily water; some minerals
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routes of absorption
- (hepatic) portal blood
- lymphatic system
- systemic blood
81
hepatic portal blood
- drains intestinal area and goes to the liver
| - "portal drained viscera"
82
lymphatic system
- flow much slower
- services stomach and SI
- empties into blood stream through thoracic duct (bypasses liver)
83
systemic blood
blood that serves the entire system
84
mechanisms of absorption
- passive transport (simple diffusion or diffusion through channels)
- facilitated transport (or facilitated diffusion)
- active transport
85
passive transport
- movement of molecules from an area of high concentration to an area of low concentration ("concentration gradient"; always down a gradient)
- requires no energy from cell
- molecules must be small enough to pass through the pores of membrane
- diffusion of water across membrane is osmosis
86
facilitated transport (facilitated diffusion)
- most molecules cannot cross membrane by simple diffusion
- some carried across by carrier proteins embedded in cell membrane (they change shape when molecules attach to them, the change in shape enables molecule to cross membrane)
- also occurs down a gradient
- molecules move in or out of cell
- requires no energy from the cell
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active transport
- cells often must move molecules up a concentration gradient (low to high)
- involves carrier proteins
- requires ATP
- carrier proteins act as pumps that use energy to move ions and molecules
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mechanism of absorption example
- transport of glucose into the villus epithelial cell is by active transport; requires energy ; glucose concentration in cell is greater than in SI
- transport across the basolateral surface of the cell (into the blood) is by facilitated diffusion; glucose concentration in blood is less than cell
89
carbohydrates
- CHO is major supplier of energy
- make up ~3/4 of weight of feed
- starch = major CHO in grain
- cellulose = major CHO in forages
- CHO <1% of body (glucose; glycogen; glycoproteins)
90
Three major classes of CHO
- monosaccharides (1 sugar molecule)
- oligosaccharides (2-10 monosaccharides; includes di, trisaccharides)
- polysaccharides (can have 100 to 1000+ monosaccharides)
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metabolically important monosaccharides
- trioses
- pentoses
- hexoses
92
trioses
- 3 C
| - mostly found in metabolic pathways
93
pentoses
- 5 C
- small amount in plants
- usually polymers
- xylose: usually associated with poorly digested material
- ribose: component of ATP, ADP, RNA, DNA
94
hexoses
- 6 C
- glucose (free in blood, required by nervous system and RBC, key sugar in CHO metabolism)
- fructose (in seminal fluid: normal energy source for sperm; found in honey and ripe fruits)
- galactose (seldom found free in nature, important in structure of brain and nervous tissue)
95
metabolically important oligosaccharides
- maltose (glucose + glucose)
- lactose (milk sugar; glucose + galactose)
- sucrose (table sugar; glucose + fructose)
96
metabolically important polysaccharides
- starch
- glycogen
- cellulose
- hemicellulose
97
starch
- amylose (straight, unbranched chain of glucose units; a-1,4-glucosidic bonds)
- amylopectin (branched chain every 24-30 units; a-1,6-glucosidic bonds)
98
glycogen
- similar to starch (branch points every 8-12 units)
| - liver and muscle
99
cellulose
- major component of plant cell walls
- straight, unbranched chain of glucose units
- b-1,4-glucosidic bonds
- strengthened by cross-linked H-bonds
- mammals: no digestive enzymes
100
hemicellulose
- part of cell wall of plants
| - xylose units (5 C) linked b-1,4
101
digestion of CHO (starch)
- amylase (hydrolyzes a-1,4-glucosidic bonds; forms maltose; cannot hydrolyze a-1,6-glucosidic bond; primary end products are maltose and limit dextrin)
- maltase, isomaltase, a-dextrinase
102
learn transporters from notes
...
103
sources and fates of blood glucose
- there are several needs that are met by blood glucose
- liver glycogen
- muscle glycogen
- tissue oxidation
- fat formation
104
feeding- what happens after you eat?
- dietary glucose enters blood
- some glucose used by liver to replenish liver glycogen supply
- other glucose goes to muscle and other extra hepatic tissues
- after in blood, 3 things can happen (energy production (1st), muscle glycogen, fat synthesis (last))
105
AA structures
...
106
composition of proteins
- contain C, H, O, N (15-19%), S and P
- mean N content of feed = 16%
- 100/16 = 6.25 (Kjeldahl CP)
- % N x 6.25 = % CP
- primary dry matter constituent of body organs
107
protein requirements as % of diet
- as a percent of diet, the amount of protein goes down as the animal matures
108
protein requirement per day
- the amount of protein per day will increase as the animal matures because they are gaining more muscle mass. they are eating more protein as they grow, but as a percent of their diet, it is less
109
weak calf syndrome
associated with the amount of portein consumed by the cow during the last 60 days of pregnancy (hay with less than 10% CP, the average amount if cows that will be weak is about 8.5%
110
general AA structure
- all proteins are made up of simple units called AA
- general structure of AA have an a-amino end and en a carboxyl end
O=C-OH O=C-O-
| |
H2N- C--H H2N+-C--H
| |
R R
general AA structure physiological pH
- proteins always use L-a AA
111
lysine has e-amino group
- extra NH2
- important for maillard reaction
- carpenter's available lysine test
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peptide bond
- AA linked together with peptide bonds
- couple carboxyl group with a-amino group
- dehydration synthesis
113
protein structure
1. primary = peptide bonds (sequence)
2. secondary = a-helix (stabilized by H-bond between (CO) and (NH))
3. tertiary = folding of polypeptide chains (3D): stabilized by disulfide bonds and H-bonds
4. quartenary = grouping of several tertiary units
114
functional categories of proteins
- structural proteins
- hormones
- enzymes
- immune system
- transport within body
115
structural proteins
- contractile: actin and myosin (muscle)
- fibrous proteins: collagen (bone, teeth, skin, tendons, cartilage), elastin (circulatory system), keratin protein (hair, nails, wool, feathers)
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hormones
- growth hormone, insulin, glucagon, thyroid hormone, ACTH are proteins
- regulate metabolism
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enzymes
almost all enzymes are proteins
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immune system
- antibodies are proteins
| - IgG, IgA, IgM
119
transport within body
- chylomicron, VLDL
- albumin (transports fat to blood)
- hemeproteins
120
other roles of proteins
buffers (look in notes)
121
protein digestion
- feed protein (plant and animal sources)
- proteins are hydrolyzed to AA
- protein ---> AA + di-,tripeptides
- exception: young animals absorb intact proteins (colostrum and immunoglobulins)
- proteins do not go into the blood as di-,tripeptides, but they can be absorbed and then broken down before blood
- born with little to no immunity, so important to get colostrum
- sows don't cycle until pigs are weaned
122
protein digestion in stomach
- gastric protease
- pepsin (from chief cells of fundic gland)
- pepsinogen --(HCl)-> pepsin
- diet protein --(pepsin)-> long chain polypeptide
- rennin (abomasum of nursing calf)
- prorennin --(HCl)-> rennin
- casein --(rennin & Ca)-> Ca-paracaseinate (coagulated)
123
protein digestion in small intestine
- proteolytic enzymes secreted from pancreas: trypsin, chymotrypsin, and chymotrypsin
- trypsinogen --(enterokinase)-> trypsin
- chymotrypsinogen --(trypsin)-> chymotrypsin
- procarboxypeptidase --(trypsin)-> carboxypeptidase
- brush border of villi epithelial cells (amino peptidases: N-terminal end of oligopeptides. Dipeptidases: N-terminal end of dipeptides. Tripeptidases: N-terminal end of tripeptides.
124
enzyme/activator for pepsinogen
HCl and also pepsin
125
active form of pepsinogen
pepsin
126
site of activity for pepsin
stomach
127
substrate for pepsin
most AA
128
enzyme/activator for trypsinogen
enterokinase and trypsin
129
active form of trypsinogen
trypsin
130
site of activity for trypsin
small intestine
131
substrate for trypsin
basic AA (lys, arg)
132
enzyme/activator for chymotrypsinogen
trypsin
133
active form of chymotrypsinogen
chymotrypsin
134
site of activity for chymotrypsin
small intestine
135
substrate for chymotrypsin
aromatic AA (phe, tyr, tryp,) & met, asn, his
136
enzyme/activator for procarboxypeptidase A & B
trypsin
137
Site of activity for Carboxypeptidase A & B
Small intestine
138
Substrate for Carboxypeptidase A
C-terminal neutral AA
139
Substrate for Carboxypeptidase B
C-terminal basic AA
140
Site of activity for amminopeptidases
microvilli brush border
141
substrate for aminopeptidase
N-terminal AA
142
AA antagonism
two structurally similar AA out of balance (too much of one could result in def of another)
143
fate of AA following following absoprtion
- tissue synthesis
- synthesis of enzymes and hormones
- deamination
144
tissue synthesis
- within 5-10 minutes after absoportion AA move from gut to cells where they are used for protein synthesis
- muscle, veins, brains, bone
145
synthesis of enzymes and hormones
- AA move to cells that secrete enzymes and proteins
| - pancreas, GI tract, liver, reproductive organs
146
deamination
- if AA not needed for protein synthesis, then deaminated
- used for energy or converted to fat
- no storage pool of AA
147
AA and nutrition
- >200 AA occur in nature
- only 20-22 commonly found in most proteins
- essential AA (also called indispensable)
- - 10 AA either cannot be synthesized or synthesis is inadequate to meet metabolic needs
- - must be supplied in the diet
148
essential (indispensable) AA
- refers to dietary essential; all are tissue essential
| - phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, arginine, leucine, lysine
149
exceptions to 10 essential AA
- chick requires glycine and proline
- cat requires taurine
- ruminants have no dietary requirement (microorganisms make them; as far as we know, the ten AA must be provided to the animal's tussues, enough N and enough energy so they can make them)
150
nonessential (dispensable) AA
- 12+ AA can be synthesized by body cells
- the 10 essential AA may be precursors for some of the others
- all 22+ are needed by body tissue
- alanine, aspartic acid, asparagine, cysteine, cystine, glutamic acid, glutamine, glycine, proline, hydroxyproline, serine, tyrosine
151
cannula
for testing things leaving the tract where its located (re-entrant or T-cannula)
152
sparing effect of CYS and TYR
- NRC lists MET + CYS requirement, MET can be used to form CYS, but CYS can only meet its own needs.
- same as PHE + TYR
153
protein requirements for nonruminants
- primary purpose is to suppl essential AA to the tissues for max performance at a minimum cost
- actually AA nutrition
- they require AA, not protein
- but NRC lists CP requirement
154
why a CP requirement then?
- we feed protein to get AA
- NRC based on corn-SBM diets
- meets the AA requirements of the most limiting AA (all other AA will be in excess)
155
limiting AA
- animal can perform no better than that allowed by the AA present in the lowest amount relative to the requirement
- barrel diagram
- 1st limiting AA is the indispensable AA present in the least amount relative to the requirement
- if you can synthesize it, it cant be limiting
156
usual order of rate-limiting AA in cereal grains
1. lysine
2. tryptophan (2nd in corn-SBM diet)
3. threonine (2nd in other grain based diets)
4. methionine
5. isoleucine
- legumes: methionine is 1st limiting, but also relatively high in lysine
157
requirement for lysine is high
- why does lysine have the highest dietary AA requirement
- highest concentration in muscle
- glutamic acid is actually in greatest concentration but can be synthesized
158
AA requirements
- are the net needs for tissue accretion and maintenance or replacement of net losses
159
why use the word "net" for AA requirement
- body proteins constantly turning over
- utilization of AA for protein synthesis is several times daily intake
- most AA are efficiently re-utilized
- some irreversibly lost (lost from AA pool)
- daily intake requirements reflect only the net needs of AA
- daily requirement of AA helps replacing lost AA
- in animals, it goes to replacing lost AA and storing muscle mass
160
does work increase CP/AA requirement?
- work and exercise do not increase requirements
- turnover rate increases
- more recycling
- needs more energy, so just feed more, which inevitably increases the protein anyways
161
what is protein quality?
- refers to the balance of AA to meet the needs of the animal
- perfect AA balance would equal ~7-8% CP
- egg is closest to being perfect
- biological value: measure of protein quality
162
high quality
proteins whose AA balance more nearly approximate the needs of the animal
- generally proteins of animal origins
- exception is gelatin (no tryp)
163
low quality
- low or lacking in one or more indispensable AA
| - plant proteins generally low quality
164
complementary proteins
- corn and SBM complement each other
| - Zein: primary protein in corn, practically devoid of lysine and tryptophan
165
Biological value
- % of absorbed N that is retained or utilized by the animal
- widely used method of expressing protein quality
- values expressed as a %
- 100 = perfect AA balance
- (NI - FN - UN) / (NI - FN) *100 = apparent BV
166
Apparent BV
(NI-FN-UN) / (NI-FN) *100
167
Actual BV
NI - (FN - MFN) - (UN - EUN) / NI - (FN - MFN)
- MFN is metabolic fecal nitrogen, and is nitrogen in feces that did not come from diet
- EUN is endogenous urinary nitrogen and is nitrogen in urine that did not come from the diet
168
PEM
protein energy malnutrition
169
kwashiorkor
- edema, fatty liver
- protein def, but not necessarily energy def
- eating enough carbs, but feed low in protein
170
marasmus
- skin and bones appearance
- def in protein and energy
- underfed
- starved
171
excess AA
- most diets have excess AA
- usually not a problem, but possible
- toxicity: rarely see adverse effects; methionine is most toxic (2.5% of diet, or 5x requirement); other AA have to be 5-10% of diet; growth reduction normally)
- long term could be kidney problem
172
antagonism
growth depression caused by excess amounts of naturally occurring AA that can be corrected by addition of structurally similar AA
