Absorption of nutrients

Question 1

Which part of the GIT has most capacity of absorption?

Answer 1

Jejunum

Question 2

What are the 4 routes of nutrient absorption?

Answer 2

passive, active transport, solvent drag and pinocytosis

Question 3

What is the main difference between simple diffusion and facilitated diffusion?

Answer 3

simple does not use energy or a carrier protein and is not saturable, while facilitated is the opposite

Question 4

What is the main difference between passive and active transport?

Answer 4

Passive is passage of molecules along concentration gradient without spending any energy while active is against and thus require energy spenditure

Question 5

How does the Na-glucose co-transporter protein work?

Answer 5

The protein is in the brush border membrane and transports glucose and Na into the cell along Na concentration gradient, and the Na-K pump in the cell uses ATP to remove 3 Na in exchange for 2 K ions in order to maintain the Na concentration in the cell constant. Thus it is a secondary transport because it spends energy indirectly.

Question 6

What are the three forms of transporting glucose into the cell?

Answer 6

Na-glucose co-transporter protein, facilitated diffusion and passive diffusion

Question 7

What are the two routes that Nutrients may take to go into body?

Answer 7

hepatic portal system and lymphatic vessels

Question 8

What are the main defects in absorption of carbohydrates?

Answer 8

Lactase or sucrase defficiency, disaccharidiuria and monosaccharide malabsorption

Question 9

What are the end products of lipid digestion?

Answer 9

Fatty acid and 2 monoacylglycerol

Question 10

What are the main factors that affect lipid digestion?

Answer 10

Viscosity of glycocalyx, passage of mycelles through glycocalyx (size of micelles (longer chain length and saturation decreases passage rate)), coalescence of micelles with plasma membrane (longer chain length and saturation decreases coalescence and absorption)

Question 11

Maltose is composed of

Answer 11

2 gucose units by alfa 1,4

Question 12

isomaltase is composed of

Answer 12

2 glucose units by alfa 1,6

Question 13

sucrose is composed of

Answer 13

glucose and fructose by alfa 1 beta 2 link

Question 14

trehalose is composed of

Answer 14

2 glucose by alfa 1-1

Question 15

How is lipase-colipase complex activated?

Answer 15

procolipase is secreted and is activated by trypsin into colipase, then it merges with prolipase to form the lipase-colipase complex

Question 16

What are the bile salts in pigs and chickens?

Answer 16

Sodium or potassium taurocholate or glycocholate in pigs, in chickens only the taurocholate forms are present

Question 17

saturated FA are ________ absorbed than unsaturated

Answer 17

less

Question 18

Shorter chain FA are ________ absorbed than longer chain

Answer 18

more

Question 19

Regarding saturation, Soybean oil is

Answer 19

unsaturated

Question 20

Unsaturated _______ double bonds

Answer 20

have

Question 21

Unsaturated have _______ melting point than saturated FA

Answer 21

Lower

Question 22

Shorter chain and unsaturated FA are ______ absorbed

Answer 22

better, because of smaller micelle size and lower melting point gives high coalescence of micelles with plasma membrane

Question 23

How are tryglycerides transported in pigs and chickens

Answer 23

Triglycerides with 10 or less C are exported out of hepatic portal into liver and throughout body in both, tryglicerides with more than 10 C are repackaged into lipoproteins (chilomicrons and VLDL) and released from enterocytes into central lactea and then drained to lymphatic system then to general circulation in pigs (depositing the FA as they are ingested, saturated or unsaturated), while in poultry they are sent to hepatic portal and go to liver to be processed

Question 24

Why are pigs destined to for market fed diets with animal fat instead of soybean oil?

Answer 24

Because the fatty acids with more than 10 C will be absorbed and deposited as they are ingested, so to avoid deposition of liquid fat pigs are fed with more saturated fat

Question 25

Why may brown shelled eggs have fishy flavor?

Answer 25

Because of sinapine in diet, this is present in canola meal and is hydrolyzed in the hindgut by microbes into triethylamine that is then broken by triethylamine oxidase, however brown shelled layers dont have this enzyme and the triethylamine ends up in the eggs

Question 26

D form of amino acids is ______ to absorb than L form

Answer 26

slower

Question 27

Why may AA compete for absorption but not with dipeptides?

Answer 27

Because the active transport of AA can transport several amino acids but it is linked to Na transport by secondary transport while di and tripeptide transport is linked to proton gradient by tertiary transport

Question 28

Absorbed AA and CHO are transported by which system?

Answer 28

hepatic portal system

Question 29

How can some mammals transfer passive immunity to neonates through colostrum?

Answer 29

First is because neonates don’t have significant HCl production and the stomach closure is poorly regulated so the immunoglobulins in colostrum are not broken down and can move to be absorbed by pinocytosis, secondly colostrum also has some trypsin inhibitor which also decreases protein hydrolysis

Question 30

What are the primary substrates for fermentation?

Answer 30

dietary plant cell wall polysaccharides, endogenous loss (glycoprotein, gastric juice and mucus), simple sugars, resistant starch(regarded as fiber in some classifications) and di and oligosaccharides (raffinose, stachyose, etc)

Question 31

What is the fate of the VFAs produced from fermentation?

Answer 31

Acetate is transported to liver to be used as energy for muscle
Propionate: converted to glucose in liver
Butyrate: used as main energy source for colonocyte

Question 32

How are nitrogenous compounds used in fermentation, and what are the products?

Answer 32

Nitrogenous compounds in hindgut, come from diet, endogenous and microbial. They are hydrolyzed and deaminated into keto acids that are used in anaerobic respiration or in fermentation. Product are SCFA, BCFA (indicator of fermentation), H2S, phenols or ammonia that are toxic and harmful. Last fate of protein in hindgut is for bacterial proteins using ammonia or hydrogen sulfide

Question 33

What happens if dietary protein is provided in excess?

Answer 33

Besides the economic impact, the unabsorbed fraction will contribute to eutrophication, and in the hindgut the microbes (mainly E. coli) will ferment and produce ammonia, amines, H2S and other compounds that are toxic and can cause tight junction failure, compromising the barrier function(leaky gut syndrome), allowing pathogens to cross into blood stream and infect the host. Weaned piglets are more susceptible since they are exposed to various stress factors after weaning, antibiotic use is limited and require a diet with high protein content. Also, it increases the consistentcy of the digesta which increases occurance of diarrhea

Question 34

What are some of the functions of butyrate in the hindgut?

Answer 34

Activation of mucin release, increase of mucosa blood supply, generation of acidic environment, stimulation of electrolyte and water absorption, used as energy, anti inflammatory and protection of epithelial barrier.

Question 35

Where are ulcers more common in pigs and why?

Answer 35

In esophageal region of the stomach because it lacks protective mucus from the stomach acid, lower particle size of diets increases fluidity of gastric content, allowing bile reflux to proximal region of stomach where it can damage tissue working with stomach acids. Additionally housing density and season (higher density increases ulcers), parturition (lactating sows are more susceptible because of stress) and concurrent diseases increases ulcers

Question 36

5 factors that affect feed efficiency:

Answer 36

chemical composition of diet (fiber content, type of fiber, presence of antinutrients), processing of diet, ground diets increase the surface area of it for enzymes, heat treatment inhibits some antinutritional factors but decreases AA digestibility if too extreme, addition of exogenous enzymes