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Question 1

What do cells take in when absorbing nutrients?

Answer 1

The building blocks of major macromolecules.

Question 2

Main stages of digestion? (4•)

Answer 2

•Ingestion
•Digestion
•Absorption
•Elimination

Question 3

Type of digestion in mouth? •3

Answer 3

•Ingestion
•Mechanical Digestion
•Enzymatic digestion

Question 4

Salivary amylase is important for?

Answer 4

The digestion of carbohydrates into disaccharides (maltose, sucrose, and lactose). It also digests glucose polymers such as starch and glycogen into disaccharides.

Question 5

Parasympathetic and sympathetic nervous system?

Answer 5

•Sympathetic: Fight or Flight
•Parasympathetic: Rest and digest

Question 6

Salivary reflex?

Answer 6

Thought of food -> higher brain centres-> salivary control in hypothalamus (increases parasympathetic activity and decreases sympathetic activity) -> salivary glands

Food in mouth -> Mechanoreceptors and taste receptors in mouth -> salivary control in hypothalamus (increases parasympathetic activity and decreases sympathetic activity) -> salivary glands

Question 7

HCL breaks?

Answer 7

Hydrogen bonds that stabilize secondary and tertiary structures of food to denature the protein.

Question 8

Why is HCL super important for digestion?

Answer 8

It activates pepsin which can only be activated between 1-4 pH.

Question 9

Chief cell?

Answer 9

Produces pepsinogen

Question 10

Parietal cells?

Answer 10

Produce HCl

Question 11

Goblet cells?

Answer 11

Produce mucus

Question 12

How does pepsinogen get activation and the role of pepsin?

Answer 12

Pepsin is synthesized in an inactive form called pepsinogen. The low pH causes pepsinogen to change shape by attacking itself and cuts out a part of the protein. That active pepsin can expose its active site and digest proteins. It can also digest pepsinogen and active them.

Question 13

Helicobacter Pylori?

Answer 13

Penetrates the mucus layer lining and damages the goblet cells responsible for much of the production and the loss of stomach mucus occurs.

Question 14

HCl secretion?

Answer 14

Parietal cells are generally in pH of ~7-8 and the lumen of stomach has a pH of ~2. There is a proton concentration gradient and the highest proton concentration is inside the stomach canal. However, the parietal cell needs to move protons against the concentration gradient. Therefore, the cell uses ATP to pump protons to the canal by using a proton ATPase with potassium being exchanged. The protons inside the cell comes from bicarbonate, which comes from carbonic acid, and the reaction requires an enzyme, carbonic anhydrase. The reaction: (CO2 + H2O <-> H2CO3) -> (HCO3- + H+). Because of this, the pariental cell becomes very basic and the protons need Cl- to make HCl. HCO3- needs to be pumped to the blood vessel and the vessel pumps Cl- into the pariental cell without ATP (going down its concentration gradient).

Question 15

Carbonic anhydrase?

Answer 15

An enzyme that assists in the reversible reaction of CO2 + H2O <-> H2CO3 which gets converted into HCO3- + H+

Question 16

Presence of food in intestine _____ HCl secretion?

Answer 16

Inhibits

Question 17

Molecules that can stimulate stomach acid secretion? (3•)

Answer 17

Acetylcholine, histamine, and gastrin

Question 18

Acetylcholine?

Answer 18

Neuron makes contact with acetylcholine which makes contact with pariental cell and secrets HCL. Histamine also makes contact with acetylcholine that secrets histamine.

Question 19

Enteric neurons also release a peptide called?

Answer 19

Gastrin releasing peptide (GRP)

Question 20

GRP binds to receptors on ECL cells. What releases?

Answer 20

Histamine and stimulate acid secretion.

Question 21

How to turn off acid secretion?

Answer 21

•Cells in stomach lining sense stomach pH. When pH is low, these cells release the chemical messages somatostatin.

Question 22

Stomatostatin?

Answer 22

Decreases the release of gastrin and histamine which decrease stomach acid secretion.

Question 23

When does this cells Release somatostatin?

Answer 23

When food enters the small intestine which decreases the activity of parasympathetic neurons leading to the stomach.

Question 24

What does the pancreas release? 2•

Answer 24

•Bicarbonate to increase the pH in the stomach acid so it doesn’t burn the small intestine.

•Pancreatic Protease

Question 25

!!!Enzymes on intestinal wall digest the disaccharides?

Question 26

Pancreatic proteases?

Answer 26

Secretes and inactive form of the enzyme (proteases).

Question 27

Final step of protein digestion?

Answer 27

In the small intestine where carboxypeptidase, trypsin and chymotrypsin continue to break down the peptide bonds.

Question 28

Lipase?

Answer 28

Breaks down lipids into their dependents (fatty acid tails, glycerol backbone, phosphate group)

Question 29

Protease?

Answer 29

Digest proteins in small intestine

Question 30

!!!Digestive proteins that exist in the small intestine?

Answer 30

Amylase, protease, …..

Question 31

Digestion of fats?

Answer 31

Requires both pancreatic and gall bladder secretions. Bile salts from the gall bladder break large fat droplets into small ones. Pancreatic lipases digest into glycerol and fatty acids.

Question 32

The roles of large intestine?

Answer 32

•Regulation (re-absorption) of water
•There is some absorption of nutrients.

Question 33

What does the large intestine mainly consist of?

Answer 33

Symbiotic bacteria

Question 34

Cellulase?

Answer 34

Digests cellulose but no animal expresses the cellulase enzymes.

Question 35

How does cellulose get digested in the gut of an animal?

Answer 35

By a bacteria found in the large intestine inside the caecum (appendix in humans).

Question 36

The bacteria inside the cecum have ______respiration?

Answer 36

Anaerobic since it makes glucose after the cellulase digests cellulose and the glucose undergoes anaerobic respiration.

Question 37

If you have a cecum, why is a large colon important?

Answer 37

To absorb the waste product of the bacteria that lives inside the cecum.

Question 38

In animals with a large cecum but a small colon, how do they absorb the by products of the bacteria that live inside the cecum?

Answer 38

They eat their feces to absorb the byproducts inside the small intestine again.

Question 39

Foregut fermenters (ruminants)?

Answer 39

Organisms that have a specialized pocket (rumen) before the stomach that houses bacteria and acts as a fermentation chamber to digest cellulose, then passes the food to another stomach (after further chewing) to absorb the byproducts of the bacteria (in small intestine).

Question 40

!!!Large hindgut fermenters?

Answer 40

Large colon and may or may not have a large colon.

Question 41

Must nutrient absorption occurs in the?

Answer 41

Small intestine.

Question 42

What does the wall of small intestine consist of?

Answer 42

Have folds called “villi” and have microvilli to increase surface area.

Question 43

Why is surface area important for absorption in the small intestine?

Answer 43

To absorb more nutrients.

Question 44

Secondary active transport to pump glucose out of intestinal lumen?

Answer 44

Inside the lumen of small intestine, glucose needs to go to the blood vessel against its concentration gradient. It needs energy from ATP. To achieve this, there needs to be a sodium potassium pump with ATP (to pump Na+ out and K+ in intestinal cell both against their concentration gradient). Na+ also gets pumped from the lumen to the cell, and this carries glucose with it.

Question 45

Secondary active transport to pump Amino Acids out of the intestinal lumen to blood vessel work similar to?

Answer 45

Glucose secondary active transport.

Question 46

How does water get regulated?

Answer 46

By moving water against the walls of the colon.

Question 47

Where does most water get absorbed?

Answer 47

In the surface of the colon.

Question 48

Water moves from?

Answer 48

Low solute to high solute