Term
| Four step process to animal nutrition |
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Definition
1. Ingestion
2. Digestion
3. Absorption
4. Incorporation into tissues or elimination |
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Term
| How ingestion works with the mouth |
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Definition
Capture food
Initial digestion |
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Term
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Definition
| live in or on fluid form host |
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Term
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Definition
| suck nutrition rich fluid from host |
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Term
| Suspension and filter feeds |
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Definition
| Eat particles in the water column |
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Term
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Definition
| Ingest large pieces of food |
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Term
| Pathway to Carbohydrate digestion |
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Definition
Salivary amylases
Pancreatic amylases (in the stomach and Small intestine from pancreas)
Diaccharidases (in small intestine from the epithelium) |
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Term
| Pathway to protein digestion |
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Definition
Stomach: pepsin
Small intestine: Pancreatic trypsin and chymotrypsin, pancreatic carboxypeptidase
Small intestine from the epithelium: dipeptidases, carboxypeptidase, aminopeptidase |
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Term
| Pathway to nucleic acid digestion |
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Definition
Small intestine: pancreatic nucleases
Small intestine from the epithelium: nucleotidases, nucleosidases and phosphatases |
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Term
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Definition
| Small intestine: Pancreatic lipase |
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Term
| Where are the digestive enzymes from when they go to the small intestine? |
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Definition
1. Pancreas
2. The intestinal epithelium [image][image] |
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Term
| Explain how mutualisms between microbes and animals aid digestion |
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Definition
| Example: cellulose digestion in some animals (No animal expresses the cellulase enzymes needed to digest cellulose) |
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Term
| Foregut fermenters (ruminants) |
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Definition
Modified stomach: bacteria in modified stomach (rumen) and cecum digest cellulose
bacterial waste products and dead bacteria are digested in the rest of the intestine |
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Term
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Definition
| bacteria in cecum and colon |
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Term
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Definition
| a large cecum where commensal bacteria digest cellulose |
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Term
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Definition
| a large colon where commensal bacteria digest cellulose |
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Term
| Purpose of the human colon |
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Definition
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Term
| What is the role of microbes in the human colon? |
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Definition
Repress the growth of pathogenic microbes
Digest nutrients into forms that can be absorbed
omnivores such as humans can do some hindgut fermentation, but are not efficiently |
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Term
| Explain how proteins are digested and compare this to carbohydrate digestion |
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Definition
Stomach secretes acid (HCl) and enzymes
Proteins are digested by the enzyme pepsin (low pH)
Move to small intestine: digestion by Intracellular peptidase enzymes
then to blood as amino acids
[image]
[image] |
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Term
| Path of enzymatic digestion in the stomach |
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Definition
Pepsin synthesized in an inactive form (pepsinogen)
Low pH causes pepsinogen to change conformation
Attacks itself and cuts out the “masking sequence”
Exposes the active site in pepsin, which digests proteins
Pepsin can also digest pepsinogen and activate it --- positive feedback |
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Term
| How is stomach acid secreted? |
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Definition
1. the sight, smell, taste, or thought of food
2. the prescence of food in the stomach |
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Term
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Definition
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Term
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Definition
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Term
| Gastric pits/gastric gland |
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Definition
| Part of the stomach lining |
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Term
| What is the method of HCl Secretion? |
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Definition
[image]
HCl needs to enter the Canal to go to the lumen of the stomach.
H+ ions are moved from the parietal cell to the canal with the use of ATP to ADP
Protons are from the Carbonic Anhydrase reaction (CO2+H2O->H2CO3)
HCO3- (after losing the proton) goes through a CL-/HCO3- symporter to move Cl- into the cell
Cl- goes through a protein channel and moves into the Canal |
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Term
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Definition
esophageal sphincter does not close tightly
allows stomach acid to leak into the esophagus
Causes the feeling of “heartburn”
Damages the cells of the esophagus
Can lead to esophageal cancer |
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Term
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Definition
| Very long, highly folded surface to increase surface area for absorption of nutrients |
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Term
| Explain how glucose is taken up in the small intestine |
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Definition
[image]
You must move glucose from the intestinal lumen (low conc of gluc) to the intestinal cell (high) to the blood (low)
So from the cell to the blood, glucose can just flow along it's concentration gradient through a channel
But from the lumen to the cell, glucose is transported through a symporter with Na+
The symporter is powered by Na+, which wants to move along it's concentration gradient into the cell
This gradient is created by the active transport of K+into the cell and Na+ into the blood (with the use of ATP) |
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Term
| Explain how amino acids are taken up in the small intestine |
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Definition
[image]
Amino acids enter the blood stream the same way that glucose does (facilitated transport of aa into blood, symporter into the intestinal cell, and active transport of Na+ out of the intestinal cell to create a concentration gradient). |
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Term
| Explain how the large intestine helps to regulate water balance |
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Definition
water needs to get from the lumen to the ECF
water goes through the paracellular pathway (between cells)
Therefore, water absorption is regulated by the solute concentration in the ECF as water will flow into the ECF by osmotic or solute pressures.
[image] |
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Term
| Explain how saliva secretion is regulated |
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Definition
Thought, taste, texture of food can stimulate saliva secretion
Regulated by the autonomic nervous system
[image] |
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Term
| What are the two branches of the autonomic nervous system? |
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Definition
Parasympathetic (calm)
Sympathetic (stress) |
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Term
| Explain how stomach acid secretion is regulated |
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Definition
Thought, smell, taste of food will trigger the parasympathetic neurons, which stimulates enteric neurons (in gut), causing them to release acetylcholine into the parietal cell which stimulates acid secretion
If actual food is in the stomach, the stomach is stretched by the food, stimulates enteric neurons to release acetylcholine, and stimulates acid secretion
The peptides in the food are detected by G cells, which release gastrin, which stimulates the ECL cells that release histamine and stimulates acid secretion. [image]
To stop all the secretion, when food enters the intestine, various nervous and hormonal reflexes shut down production of gastrin and histamine
This reduces acid secretion from parietal cell |
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Term
| What are some negative regulators of acid secretion in cells? |
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Definition
HCl (maybe excess?) stimulates stomatostatin releasing cells to release stomatosatin, which is a negative regulator of the parietal cell secretion of HCl, ECL cell secretion of histamine, and G cell secretion of gastrin
https://www.youtube.com/watch?v=ifDp57pvKOg |
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Term
| Compare the regulation of digestion and absorption in animals with different feeding modes |
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Definition
| Ex. Pythons: eat their prey whole, 6 days of digestion, and change the size of their intestine through changing the length of their microvilli |
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