Carbs, Their digestion and metabolism

Question 1

types of polysaccharides

Answer 1

starch, glycogen, cellulose (fiber)

Question 2

the goal of breaking down glycosidic bonds

Answer 2

using dietary foods to produce energy for body processes through digestion; various enzymes break down starch and disaccharides to monosaccharides for absorption

Question 3

carbohydrate digestion

Answer 3

salivary amylase at the mouth, enzymatic digestion by hydrolysis rxns

Question 4

starch digestion

Answer 4

salivary alpha amylase at the mouth and at the small intestines

Question 5

pancreatic alpha amylase

Answer 5

digests starch into disaccharides, containing bicarbonate ions to raise the pH of stomach contents as they move into the duodenum

Question 6

starch digestion in the small intestine

Answer 6

enzymes in the brush border hydrolyze disaccharides into monosaccharides, each. with activity toward a diff. glycosidic bond/oligosaccharide structure

Question 7

what type of proteins are carbohydrate-digesting enzymes?

Answer 7

integral membrane proteins which are highly glycosylated to prevent digestion from intestinal proteases

Question 8

what can the body not digest?

Answer 8

dietary fibre (cellulose), which is insoluble (not to be confused w/ soluble fibres such as pectin and gums)

Question 9

lactose intolerance

Answer 9

impaired ability to digest lactose due to reduced amounts of the enzyme lactase as you age; secondary lactase deficiency occurs w/ injurt to intestinal absorptive cells (e.g. celiac disease)

Question 10

what occurs with inability to break down lactose?

Answer 10

metabolism of lactose by colonic bacteria (lac operon) into gases and lactic acid

Question 11

glucose absorption

Answer 11

secondary active transport with sodium ions (sodium-glucose cotransporter, also facilitative diffusion)

Question 12

glucose transport

Answer 12

secondary active transport; glucose is polar and cannot freely diffuse through the lipid bilayer

Question 13

GLUTs (glucose transporters)

Answer 13

mechanism used in some glucose transport into the intestine

Question 14

GLUT4

Answer 14

isoform of GLUT that is insulin-sensitive and important for uptake into muscle and adipose tissue

Question 15

GLUT3

Answer 15

isoform of GLUT that is NOT insulin-sensitive and important for uptake into brain; can account for potential for low blood glucose in brain (transported at rate not much faster than it is used)
- less glucose transport = less metabolism = situations associated w/ hypoglycemia

Question 16

how is glycogen synthesized?

Answer 16

in response to blood glucose level signals

Question 17

what does insulin signal?

Answer 17

glucose uptake by muscle and adipose and promotion of glycogen synthesis

Question 18

what does glucagon signal?

Answer 18

glycogenolysis in the liver to control regulate blood sugar levels

Question 19

glycogen utilization

Answer 19

• fuel source in the muscle when ATP is needed
• glycogen in the liver controls blood glucose; muscle glycogen cannot contribute to blood glucose
• the liver (and kidneys) have glucose-6-phosphatase from C6 so glucose can enter the bloodstream

Question 20

cholera

Answer 20

toxin causes Cl- channels to remain open resulting in watery diarrhea
- oral rehydration/rice takes advantage of secondary active transport to return Na+ to the cell and slow the release of water into the intestines

Question 21

Starch

Answer 21

long polymer (many subunits) of glucose

Question 22

Lactose

Answer 22

glucose + galactose- disaccharide

Question 23

Sucrose

Answer 23

glucose + fructose- disaccharide

Question 24

T/ F: Animal products contain very little carbohydrate?

Answer 24

true

Question 25

Where do carbohydrates exist?

Answer 25

fruits, vegetables, and grains

Question 26

What stores glycogen?

Answer 26

liver and muscles

Question 27

Cellulose has what type of bond?

Answer 27

B-14 bonds; dont have enzyme for so bond between glucose cant break so it becomes dietary fibre

Question 28

Amylases breaks down

Answer 28

starch into individual glucose molecules

Question 29

Sucrases breaks down

Answer 29

glucose and fructose (Sucrose)

Question 30

Galactose breaks down

Answer 30

galactose and glucose (lactose)

Question 31

Where is bile salt stored?

Answer 31

made in liver and stored in gallbladder and released in presence of fats in GI tract

Question 32

T/F: cellulose is soluble?

Answer 32

false; insoluble

Question 33

T/F: Pectins and gums are solube?

Answer 33

true

Question 34

How do soluble fibres reduce blood cholesterol?

Answer 34

by binding bile salts or reducing absorption in the intestines

Question 35

Type One Diabetes

Answer 35

- beta cells are destroyed by autoimmunity - GLUT are locked inside cell and can only come to surface of cell - cells are starving and go into ketoacidosis - blood glucose drops too low- brain not getting enough - want glucose out of blood stream and stored back in liver or muscle - want GLUT to go back into the cell so glucose is not being taken out of the blood so glucose wont keep dropping

Question 36

Does the brain have insulin sensitive glucose transporters?

Answer 36

no

Question 37

Type Two Diabetes

Answer 37

- insulin circulates but receptors arent as sensitive - results in hypergylcemia - drops in blood glucose= less glucose transport and therefore metabolism

Question 38

What transport does the brain normally use?

Answer 38

GLUT 3; not insulin sensitive

Question 39

What is broken down in response to blood glucose level signals?

Answer 39

glycogen

Question 40

Ribonucleotide

Answer 40

source of energy

Question 41

What is salivary amylases optimal pH? and when is it inactivated?

Answer 41

6; by the acidity in the stomach

Question 42

When does starch begin to be digested?

Answer 42

in the mouth due to salivary amylases

Question 43

What breaks starch down into smaller units until maltose is produced?

Answer 43

alpha amylase in the pancreas

Question 44

Where does maltose reside?

Answer 44

intestinal wall

Question 45

Villi and microvilli

Answer 45

contain a capillary network and nutrients can get into the rbc and then into the capillary

Question 46

Carb digesting enzyme function

Answer 46

wait for disaccharides to come by in order to break them down

Question 47

What happens to the disaccharides that are not digested?

Answer 47

enzymes distributed along here not digested may be metabolized by bacteria in the colon to prod. gases or short chain FAs

Question 48

Where should lactose never be?

Answer 48

large intestine- it should be digested in the small intestine

Question 49

too much LDL

Answer 49

get rid of some bile salts so that the liver takes more LDL out of the blood to remake bile salts

Question 50

Secondary lactase deficiency

Answer 50

results from injury to intestinal absorptive cells; lactase is first to shed and last to come back

Question 51

Osmotic diarrhea is caused by?

Answer 51

lactose being in small intestine and dragging in water with it to balance the osmolality

Question 52

What happens when you cant break down lactose?

Answer 52

metabolism by colonic bacteria by lac operon

Question 53

treatment for diarrhea

Answer 53

rehydration of fluids needs to contain glucose and sodium in water in order for absorption to occur

Question 54

symptoms of hypoglycemia

Answer 54

- headache - blurred vision - hunger - irritability - weakness, fatigue, feeling tired - sweating - dizziness - fast heartbeat - shaking - anxiety

Question 55

Blood glucose levels after eating

Answer 55

drop

Question 56

Can muscle use glycogen to contribute to blood glucose?

Answer 56

NO only use it for energy within the muscle