Nutrition Chapter 9 Flashcards Preview

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Flashcards in Nutrition Chapter 9 Deck (23):
1

What do cells use energy for?

1. building compounds
2. contracting muscles
3. conducting nerve impulses
4. pumping ions

2

What is ATP?

adenosine triphosphate
the main form of energy the body uses
does mechanical, chemical and osmotic work

3

What are anabolic pathways?

building larger, more complex compounds from smaller ones

4

What are catabolic pathways?

break down compounds into small units

5

What are intermediates?

compounds formed in the steps of the metabolic pathway

6

How is a substance oxidized?

when it loses 1 or more electrons
when it gains oxygen or loses hydrogen

7

How is a substance reduced?

when it gains 1 or more electrons
when it loses oxygen or gains hydrogen

8

What is cellular respiration?

The process of of oxidizing food molecules to obtain energy.

9

What are the stages of aerobic cellular respiration?

1. glycolysis
2. transition reaction
3. citric acid cycle
4. electron transport chain (oxidative phosphorylation)

10

What happens in glycolysis?

glucose broken down to form pyruvate
6-C glucose --> 2, 3-C pyruvates
uses and produces ATP
can be reversed, but requires energy

11

What happens in the citric acid cycle?

pyruvate --> acetyl CoA
requires several B vitamins
generates NADH, FADH2, GTP, CO2
irreversible

12

What happens in the electron transport chain?

series of carrier molecules move hydrogen ions and electrons
oxidative phosphorylation
NADH, FADH2 converted to ATP
H2O generated

13

Where does energy metabolism occur?

in the cell - cytoplasm and mitochondria

14

What are the sources of glucose for glycolysis?

1. dietary CHO
2. glycogen stores
3. endogenous biosynthesis
4. lactate (anaerobic)

15

What happens in lipid metabolism?

triglycerides are broken into glycerol and fatty acids
glycerol --> pyruvate
fatty acids --> acetyl CoA (lipolysis)

16

What is lipolysis?

The breakdown of lipids.
lipids are cleaved at the beta bond and progressively broken into 2 C molecules
triggered by hormone sensitive lipase

17

How are ketones formed?

acetyl CoA molecules combine, ketones are products of incomplete fatty acid oxidation
results from low CHO intake or insufficient insulin
acetyl CoA can't enter the TCA cycle

18

When does ketosis occur?

fasting, diabetes
fasting - lack of glucose from CHO, fatty acids flood the liver, TCA cycle stops w/o oxaloacetate
diabetes - acetyl CoA builds up, more ketones, causes blood to become acidic, diabetic coma

19

How is protein metabolized?

amino acids become part of pyruvate, TCA cycle or acetyl CoA depending on side chain
in order to be used as fuel, AAs must be reanimated
ketogenic and glucogenic amino acids

20

How is metabolism regulated?

enzymes
hormones
blood glucose concentration
ATP concentration
mostly occurs in the liver

21

What happens in feasting?

store a little glycogen and a lot of fat
lipogenesis - build fat

22

What happens in fasting?

body draws on glycogen and fat stores for energy
stores last about 24 hours w/o strenuous activity

23

What happens in starvation?

after glycogen stores are used up
body begins to break down protein from AA to produce glucose --> lost muscle mass and organs shrink
eventually, to preserve tissue, fatty acids start being converted to ketones for energy
ketosis keeps you alive
adaptation keeps you alive for up to 2 months