Topic 3 - part 1 and a bit more Flashcards

1
Q

Who should absolutely not be on a low CHO diet? Why?

A

Pregnant women, because glucose is crucial for the fetus

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2
Q

Name an exemple of pentose

A

Ribose, deoxyribose

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3
Q

What is a general recommendation concerning sugar consumption?

A

Reduce simple sugars consumption

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4
Q

True or false fructose is a hexose

A

TRue, but 5 membered ring

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5
Q

What disaccharide has a beta glycosidic bound?

A

Lactose

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6
Q

List in order of sweeteness (from high to low) mono (fructo and gluose) and disaccharides (3)

A
  • Fructose
  • Sucrose
  • Glucose
  • Maltose
  • Lactose
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7
Q

What is the differences in glycosidic bounds in amylose and amylopectin?

A

Amylose : alpha (1-4) chains

Amylopectin : alpha (1-4) chains with alpha (1-6) branches

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8
Q

What is the recommendation for fibre?

A

25-35 g/day

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9
Q

What is the difference in soluble and insoluble fibre?

A

SOLUBLE:

  • Pectin
  • Forms a gel
  • Glycemic control
  • Delays intestinal emptying
  • Binds to cholesterol and bile acids
  • Fermented by colonic bacteria

INSOLUBLE :

  • Hemicellulose, cellulose
  • Bulk (retains water-> laxative effect)
  • Delays intestinal emptying
  • Some glycemic control
  • Binds to cations
  • Minor fermentation by bacteria
  • Increased motility in GI tract, speeds up transit (even if slows digestion and absorption..)
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10
Q

What are enzymes involved in carbohydrate digestion in mouth, stomach, and small intestine?

A

Mouth:
- Salivary amylase

Stomahc:
- Salivary amylase denatured, inactive…

Small intestine:

  • Pancreatic amylase
  • Glucoamylase

Small intestine brush border

  • Sucrase- isomaltase
  • Lactase
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11
Q

How does glucose enter and exit enterocytes?

A

Enters through SGLT1 (using secondary active transport, no energy, but by symport with Na+ => Na+/K+ pomp…)

Exits: GLUT 2 (uniport, from high concentration in enterocytes, to lower concentration in blood)

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12
Q

True or false, GLUT is responsive to insulin?

A

false

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13
Q

true or false, galactose enters by using GLUT 5 and exits through GLUT 5 or GLUT 2

A

false, galactose uses SGLT1 (enter) and GLUT 2 to exit as glucose

It is fructose that uses GLUT 5

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14
Q

What does insulin do (to glucose) ?

A
  • Increases glucose uptake by cell by GLUT 4
  • Increases storage
  • Increases conversion to fat
  • Increases glucose oxidation

Inhibits glucose production

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15
Q

How do we call period after ingesting high GI CHO, when glucose goes under normal concentration? How does it happen?

A

Rebound hypoglecymia
- Increased insulin response to high GI food increase glucose uptake and can lead to low glucose concentration in the blood, can cause ENERGY CRASH

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16
Q

What are 2 enzymes involved in glycogen synthesis from glucose?

A

UDP- glucose pyrophosphorylase (converts glucose-Pi to UDP-glucose)

GLycogen synthase

17
Q

What is the key enzyme involved in gycogen breakdown to form glucose? Where can we find this enzyme?

A

Glucose-6-phosphatASE

  • In liver and kidney
  • So only liver and kidney can export glucose… because G?P cannot cross cell membrane, only glucose can
18
Q

What are the 3 glucose precursor?

A

Amino acid, pyruvate, glycerol

19
Q

What are the 3 end-products (ketones) from ketogenesis?

A

Acetate
Acetoacetate
B-hydroxybutyrate

20
Q

When are ketones made?

A

During (prolonged) fasting

When low or no glucose => so high b-oxidation of Fatty acids will produce high levels of acetyl-CoA=> build up of acetyl-coA, no anapleurosis of TCA cycle=> acetyl-Coa converted to ketones

21
Q

Where does gluconeogenesis take place?

A

In the liver

22
Q

What are the 3 main actions of glucagon?

A
  • Glycogen released and converted to glucose by liver and muscles
  • Adipose tissue release FA for FA oxydation
  • Breakdown of muscle to provide glucogenic a.a. for gluconeogenesis
23
Q

What does indirect calorimetry measure?

A

Measures CO2 and O2 concentration and flow of air

Measures RQ (respiratory quotient) : CO2 produced / O2 produced

24
Q

What are the 4 components of total energy expenditure, and how much % do they represent (approx)?

A

Basal metabolic rate ( 67%)
Activity (23%)
Diet induced thermogenesis - Energy to digest nutrients from diet (10%)
Adaptive thermogenesis (…%)

25
Q

Where do you find GLUT 1? When is it efficient?

A

RBCs, blood brain barrier (bbb), fetus

- it increases at low glucose concentration

26
Q

Where do you find GLUT 2? when is it effiencient?

A

Small intestine, Liver, Beta-cell, kidney

  • High capacity transporter
  • High efflux and efflux of glucose
27
Q

Where do you find GLUT 3? When is it efficient?

A

Placenta, Brain, (neurons)

- High affinity, even if low concentration

28
Q

Where do you find GLUT 4? When is it efficient?

A

Heart, muscle, adipose tissue

- insulin mediated

29
Q

What is GLUT 5 used for? Where?

A

Found in small intestine

- Fructose transporter

30
Q

Insulin is a _________ hormone

A

anabolic, protein hormone