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Unit 13 Flashcards

1
Q

What is the structure of ATP?

A

Adenine
Ribose
3 x phosphate radicals

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2
Q

What are the final products of CHO metabolism? Which is present in the largest quantity?

A

Glucose - 80%
Fructose
Galactose

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3
Q

What happens to fructose and galactose following absorption from the GIT?

A

Mostly converted to glucose in the liver

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4
Q

How is the liver able to convert other monosaccharides into glucose?

A

Large quantity glucose-6-phosphatase

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5
Q

How is glucose transported into cells in the a) GIT, b) kidneys, c) peripheral tissues

A

A and B - sodium glucose co-transport
C - facilitated diffusion

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6
Q

What happens to glucose following entry into a cell? What enzyme is involved? How does the process differ in the liver/kidneys?

A

Phosphorylated by hexokinase (glucokinase in liver)
Reversible in liver (not in other cells) - liver cells have glucose phosphatase

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7
Q

Describe glycogenesis

A

Glucose ==> glucose-6-phosphate ==> glucose-1-phosphate ==>uridine diphosphate glucose ==> glycogen

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8
Q

Describe glycogenolysis

A

Glycogen ==> glucose-1-phosphate ==> glucose-6-phosphate ==> glucose

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9
Q

In glycolysis, which enzyme is responsible for converting glycogen into glucose-1-phosphate?

A

Phosphorylase

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10
Q

How is phosphorylase activated?

A

Epinepherine
Glucagon

Both promote cAMP production

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11
Q

Where is glucagon released?

A

Alpha cells of pancreas

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12
Q

Describe glycolysis

A

Glucose ==> 2x pyretic acid

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13
Q

What are the net ingredients and products of glycolysis?

A

Glucose + 2 ADP + 2 P ==> 2 pyruvic acid + 2 ATP + 4H

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14
Q

What happens to the pyruvic acid formed in glycolysis? What else is formed in this reaction?

A

Concerted to acetyl-CoA
2 pyruvic acid + 2 CoA ==> 2 acetyl-CoA + 2CO2 + 4H

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15
Q

What happens following acetyl-CoA formation? Where does this reaction take place?

A

Acetyl degraded to CO2 and H in the CAC
Matrix of mitochondria

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16
Q

What is the net result of the CAC?

A

2 Acetyl CoA + 6 H20 + 2 ADP ==> 4CO2 + 16H + 2CoA + 2ATP

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17
Q

How many hydrogen ions are produced per glucose molecule?

A

24

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18
Q

What happens to the H ions produced during CHO metabolism?

A

20 pair with NAD+
4 pass directly into oxidative process

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19
Q

What happens to H+ produced during CHO metabolism?

A

Oxidative phosphorylation

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20
Q

Briefly describe oxidative phosphorylation

A

H split into H+ and e-
e- + H2O => OH-
H+ + OH- => H2O + ATP

21
Q

Where is ATP produced in the oxidative phosphorylation
process?

A

ATP synthetase - H+ passes down concentration/electrical gradient in mitochondria through ATPase molecule

22
Q

How much ATP is formed per glucose molecule metabolised?

23
Q

How is the rate of glycolysis controlled?

A

ATP and citrate inhibit phosphofructokinase - presently glycolytic pathway
ADP enhance phosphofructokinase
Once all ADP used, further ATP cannot be formed

24
Q

Describe anaerobic glycolysis

A

If quantities of pyruvic acid and NADH become excessive, combine with one another to form lactic acid

25
What happens to lactic acid formed during anaerobic glycolysis?
Converted back to pyruvic acid and NADH once oxygen is available again
26
What is the alternative pathway of glucose metabolism? Where does it occur? Why is it important?
Pentose phosphate pathway Liver and adipose Releases NADP - can be used for fat synthesis
27
Briefly describe gluconeogenesis
Amino acids and glycerol portion of fat combined to form glucose
28
What stimulates gluconeogenesis?
Reduced cellular CHO and low BG ACTH secreted = ^cortisol Mobilises proteins
29
What promotes hydrolysis of stored fat?
1 - alpha-glycerophosphate - glucose breakdown product - maintains glycerol portion of triglycerides. When reduced glucose availability - insufficient quantity 2 - hormone sensitive lipase activated
30
What is the function of a) chylomicrons and b) lipoproteins?
a) Transport lipids from GIT to tissues b) Transport lipids between tissues
31
What are the 4 types of lipoproteins? How do they differ in composition?
VLDLs - high concentration triglycerides, moderate cholesterol and phospholipids IDLs - some triglycerides removed LDLs - almost all triglycerides removed HDLs - high concentration protein, smaller concentration cholesterol/phospholipids
32
Where are lipoproteins formed?
The liver
33
Which tissues cannot use fatty acids for energy?
Brain and RBCs
34
Briefly, how are triglycerides used to produce energy?
Triglyceride hydrolysed Glycerol - converted to glycerol-3-phosphate - enters glycolytic pathway Fatty acids - degraded and oxidised in mitochondria - converted into acetyl CoA - beta oxidation
35
What limit the rate of utilisation of ketone bodies?
Oxaloacetate - product of CHO metabolism needed to bind to acetyl-CoA before it can be processed in the CAC
36
Why are fats poorly synthesised in diabetes?
Little cellular glucose: - little acetyl-CoA and NADPH available for fat synthesis - reduced availability of alpha glycerophosphate
37
What prevents fat metabolism when excess CHO is available?
- Excess CHO = excess alpha-glycerophosphate - binds FFA in form of stored triglycerides - Excess CHO = excess acetyl-CoA and low quantities FFA - favours FFA formation - Acetyl-CoA-carboxylase - controls rate of acetyl CoA => malonyl CoA for FA synthesis. Activity accelerated in presence of CAC intermediates
38
What hormones are most important in promoting fat utilisation?
Ep/NEp => activate hormone sensitive lipase Cortisol and glucocorticoids => activate HSL GH => => activate HSL Thyroid hormone - overall increase in metabolism
39
What process allows amino acids to be used for energy?
Deamination
40
Draw a liver lobule
pg 872
41
What substances encourage hepatic growth?
Hepatocyte growth factor TNF IL-6
42
What substances terminate hepatic growth?
Transforming growth factor beta
42
How does the liver contribute towards CHO metabolism?
Glycogen storage Conversion of galactose/fructose to glucose Gluconeogenesis Formation of chemical compounds from intermediate products of CHO metabolism
42
What is the respiratory quotient for the metabolism of CHO?
1.0
42
What is the respiratory quotient for the metabolism of protein?
0.8
43
What is the respiratory quotient for the metabolism of fat?
0.7
43
What is the respiratory quotient?
Ratio or CO2 output to O2 usage
44
Where are the hunger and satiety centres located?
Hypothalamus

Guyton (10 decks)

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