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Patho 2 > 2 - Energy and Metabolism > Flashcards

2 - Energy and Metabolism Flashcards

1
Q

ATP is comprised of:

A

Adenine

Ribose

Three Phosphate Radicals

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2
Q

90% of the carbohydrates utilized by the body are used to:

A

create ATP

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3
Q

Once fructose and galactose are reabsorbed, what happens to them?

A

They are converted to glucose in the liver

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4
Q

How does glucose get through the cell membrane?

A

It cannot easily diffuse. It’s molecular weight is prohibitive.

Passes via facilitated diffusion

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5
Q

The rate of carb utilization in most cells is controlled by:

A

the amount of circulating insulin

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6
Q

What chemical process allows cells to capture glucose?

A

Phosphorylation

As soon as glucose enters most cells it combines with a phosphate radical via

Glucokinase or hexokinase

This bond is usually irreversible

In specialized cells (liver, kidneys, intestines) flucose phosphatase attaches the phosphate group in a reversible bond

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7
Q

Why is it so beneficial to store glucose as glycogen rather than as loose glucose?

A

High concentrations of low molecular weight soluble monosaccharides would wreak havoc on the osmotic relationship of the ICF and ECF

One large high molecular weight insoluble polysaccharide will not

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8
Q

Which two hormones can activate phosphorylase?

A

Epinephrine and Glucagon

Phosphorylase breaks down glycogen and releases glucose

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9
Q

What does “glycolysis” mean?

A

Splitting of a glucose molecule to form two molecules of pyuvic acid

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10
Q

The net gain in ATP molecules from the glycolytic process is:

A

2 moles of ATP for every 1 mole of glucose utilized

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11
Q

1 ATP = ________ calories

A

12,000

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12
Q

Only 47% of the energy expended in glycolysis results in ATP. What happens to the other 57%?

A

Released as heat

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13
Q

Glycolysis yields two molecules of pyruvic acid. What comes next?

A

Pyruvic acid is converted into two molecules of Acetyl CoA

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14
Q

The Krebs Cylce begins and ends with ________, allowing it to repeat over and over again

A

Oxaloacetic acid

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15
Q

What happens in the Kreb’s Cycle?

A

The Acetyl portion of Acetyl CoA is degraded to CO2 and H+ by the addition of H2O

2 ATP are formed

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16
Q

Why does cellular respiration result in CO2 formation?

A

At three points in the Decarboxylases cut CO2 from a substrate to release

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17
Q

For each two electrons that pass through the entire electron transport chain, up to _____ ATP molecules are synthesized

A

three

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18
Q

Fill in the numbers:

_____ hydrogen atoms are released during glycolysis and the citric acid cycle. _____ of these are oxidized, with the release of ____ ATP molecules per ____ atoms of hydrogen metabolized, yielding ______ ATP molecules

A

24

20

3

2

30

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19
Q

How many ATP are formed from each molecule of glucose degraded to carbon dioxide and water?

A

38

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20
Q

How does ATP control energy metabolism?

How do ADP and AMP?

A

It inhibits phosphofructokinase, which catalyzes one of the initial steps in the glycolytic cycle

ADP/AMP have the exact opposite effect on phosphofructokinase

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21
Q

What is the law of mass action?

A

As the end products of a chemical reaction build up in a reacting medium, the rate of the reaction decreases, approaching zero

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22
Q

What are the two end products of glycolysis?

What happens when they build up?

A

pyruvic acid

hydrogen (as H+ and NADH)

When they build up they bind react with eachother to form lactic acid

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23
Q

Why is it important that NADH and Pyruvic Acid react to form lactic acid in anaerobic states?

A

It allows for clearance of the end products of glycolysis in anaerobic states, when those products aren’t going on to be used by the Kreb’s Cycle

If they didn’t form lactic acid they would just sit there, and glycolysis reactions would come to a hault

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24
Q

What happens to lactic acid once oxygen is available again?

Where does this occur?

A

It’s reconverted to pyruvic acid + NADH + H

It’s immediately oxidized to form ATP

Once there’s excess ATP, the remaining pyruvic acid is converted back into glucose

IN THE LIVER

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25
Q

Which organ is particularly capable of converting lactic acid to pyruvic acid for energy?

A

the heart

occurs to a great extent during heavy exercise

when lactic acid is released into the blood from the skeletal muscles, the heart uses it as an extra energy source

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26
Q

What is the pentose phosphate pathway?

A

An alternative oxidation pathway that can provide energy independently of all the enzymes in the citric acid cycle

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27
Q

During pentose phosphate oxidation, hydrogen joins to _____ instead of NAD.

Why does that matter?

A

NADP

Only hydrogen bound to NADP can be used for the synthesis of fats from carbohydrates

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28
Q

The Pentose Phosphate Pathway uses the energy in the glucose molecules not for the formation of ATP, but for:

A

the formation and storage of fat in the body

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29
Q

The body stores enough glycogen to last how long?

What happens to the rest?

A

12-24 hours

converted to fat in the liver and stored as fat in fat cells

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30
Q

What happens when normal quantities of carbs are not available to the cells?

A

Anterior pituitary secretes ACTH

adrenal cortex releases cortisol

cortisol mobilizes proteins from all the cells of the body, making these proteins available in the form of amino acids

these amino acids are deaminated in the liver and are converted into glucose

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31
Q

Neutral fats are also known as:

A

triglycerides

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32
Q

There are three kinds of lipids. Which ones contain fatty acids?

A

Triglycerides and phospholipids

cholesterol does not

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33
Q

Triglycerides are primarily used for ______

Cholesterol and phospholipids are used for ______

A

provide energy for metabolic processes

form the membranes of all cells and perform cellular functions

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34
Q

A triglyceride is three _____ bound to one ______

A

long-chain fatty acids

glycerol

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35
Q

What are the three most common human triglycerides?

A

Stear acid

Oleic Acid

Palmitic Acid

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36
Q

Describe the transport of triglycerides from the GI tract to the blood

A

broken down into monoglycerides and fatty acids

converted back into new molecules of triglycerides in the epithelial cells

Formed into chylomicrons

transported through the lymph into thoracic duct and into the venous circulation

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37
Q

What is the half life of a chylomicron?

A

Less than an hour

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38
Q

How are most chylomicrons absorbed from the blood stream?

A

removed by adipose tissue, skeletal muscle, and cardiac muscle

tissues produce lipoprotein lipase which sits on the surface of capillary endothelial cells and sticks to any circulating chylomicrons

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39
Q

How do adipose cells know when to release fatty acids into the blood stream?

A
  1. alpha glycerophosphate is a breakdown product of glucose that is requred to maintain triglycerides. When glucose is low, this product is also low and triglycerides start to fall apart (hydrolyze).
  2. Endocrine activation can cause cellular lipase to hydrolyze triglycerides
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40
Q

What happens when fatty acids enter the plasma?

A

They ionize

ionic portion binds with albumin (these are called free fatty acids)

other fatty acids circulate as esters of glycerol, cholesterol, or others

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41
Q

Any condition that increases the rate of fat utilization also increases ___________ in the blood.

What conditions would this include?

A

free fatty acid concentration

DM, starvation

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42
Q

When all the chylomicrons have been cleared from the plasma, 95% of all lipids in the plasma are in the form of _________

A

small lipoprotein

particles containing triglycerides, cholesterol, phospholipids and protein

(Chylomicrons are very, very large lipoproteins)

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43
Q

How are lipoproteins classified?

A

By their density

44
Q

Define the following:

VLDL

IDL

LDL

HDL

A

VLDL: mostly triglycerides

IDL: VLDLs from which some triglycerides have been removed, so the concentrations of cholesterol and phospholipids are increased

LDL: almost all triglycerides removed, leaving especially high concentration of cholesterol and phospholipids

HDL: high concentration of protein and very little cholesterol and phospholipids

45
Q

Where are lipoproteins (other than chylomicrons) formed?

A

In the liver

46
Q

Large quantities of fat are stored in which two tissues?

A

Adipose and the liver

47
Q

How are fatty acids and glycerol used for energy in cells?

A

Fatty acids are broken down and oxidized in the mitochondria, formed into Acetyl CoA which enters the citric acid cycle

Glycerol is converted to glycerol-6-phosphate and enters glycolysis

48
Q

Why does fat oxidation produce so much more ATP than glucose?

A

Way more hydrogen is released during the breakdown of stearic acid into acetyl coA

A total of 148 molecules of ATP are formed during the complete oxidation of 1 molecule of stearic acid

The net gain is 146

49
Q

When the liver breaks down lipids and produces more acetyl CoA than it can use, what happens?

A

Two molecules of the Acetyl CoA condense to form on molecule of acetoacetic acid

Acetoacetic acid is transported in the blood to other cells that can use it for energy

50
Q

Some of the acetoacitic acid produced in the liver is converted to ______ and _____

A

Beta hydroxybutyrate

Acetone

51
Q

Acetoacetic acid is a _______ acid

A

keto

made of three ketone bodies

52
Q

What is the rate limiting reaction in cellular ketone usage?

A

oxaloacetate is required to bind acetyl-CoA before it can enter the citric acid cycle

oxaloacetate is derived from carb breakdown

deficiency of oxaloacetate limits how much acetyl CoA can be used in the the citric acid cycle

53
Q

Why is it so important that the body be able to store excess glucose as fat?

A

cells don’t have that much capacity to store glycogen (a few hundred grams)

But adipose tissues can store pounds and pounds of fat

54
Q

In the average person, the amount of energy stored as fat is _______ that the amount of energy stored as carbohydrates

A

150x greater!

55
Q

How does insulin impact fat synthesis?

A

If insulin is absent, fats are poorly synthesized

glucose can’t enter the fat and liver cells

lack of alpha glycerolphosphate makes it diffuclt to form triglycerides

56
Q

Why is hyperglycemia fat sparing?

A

Excess alpha glycerophosphate makes hydrolysis of fats almost impossible

when carbs are available in excess, fatty acids are synthesized more rapidly than they are degraded

57
Q

The most darmatic increases in fat utilization is seen when?

A

During exercise, due to norepi and epi from adrenal medullae

activate hormone-sensitive triglyceride lipase

Non-exercise stress has the same effect

58
Q

Which two hormones are said to have a ketogenic effect?

Why?

A

Increases lipolysis by releasing ACTH

ACTH stimulates glucocorticoid release from adrenal cortex

Both ACTH and glucocorticoids activate the same hormone sensitive triglyceride lipase that NE and Epi do

In Cushings, when ACTH and glucocorticoids are extremely high, fats are mobilized to the point of ketosis

59
Q

All phospholipids bear what characteristics?

A

all lipid soluble

all transported in lipoproteins

all used throughout the body for structural purposes

60
Q

Phospholipids always contain ____ and ____

A

one or more fatty acid molecules

one phosphoric acid radical

usually also contain a nitrogenous base

61
Q

Where are phospholipids synthesized?

A

essentially all cells in the body, but 90% in the liver

62
Q

What are the uses of phospholipids? (5)

A
  1. essential component of lipoproteins
  2. Thromboplastin is composed of cephalin
  3. Sphingomeylin is an electrical insulator in myelin sheaths
  4. donate phophate radicals for chemical reactions in tissue
  5. structural formation in the cell
63
Q

What happens to lipid transport when phospholipids are absent?

A

seriously abnormal

lipoproteins can’t form without phospholipids

64
Q

The basic structure of cholesterol is:

A

sterol nucleus

multiple molecules of acetyl-CoA

65
Q

Why doesn’t plasma cholesterol increase dramatically with cholesterol ingestion?

A

high levels of cholesterol inhibit

3-hydroxy-3-methylglutaryl CoA synthase

if plasma cholesterol is high, liver synthesis of cholesterol is inhibited

66
Q

A diet high in cholesterol doesn’t spike cholesterol levels. A diet high in ______ does.

A

saturated fats

increased fat deposition means more acetyl-CoA for production of cholesterol, bypassing the normal feedback

67
Q

Ingestion of ________ fat actually depresses blood cholesterol concentration

A

unsaturated

we actually have no idea why

68
Q

Lack of which hormones increases blood cholesterol concentration?

A

insulin and thyroid hormone

69
Q

What is the function of cholesterol in the body?

A

Forms cell membranes

80% is converted into cholic acid in the liver, which is conjugated to form bile salts

Hormone formation

Deposits in skin to help protect the skin from water evaporation

70
Q

The ratio of _________ determines the fluidity of cell membranes

A

cholesterol to phospholipids

71
Q

What’s the difference between arteriosclerosis and atherosclerosis?

A

atherosclerosis is the deposition of fatty lesions in large and intermediate arteries

arteriosclerosis is the thickening and stiffening of any blood vessel, regardless of size

72
Q

When vascular endothelium is injured, ________ cells aggregate on the blood vessel and form fatty streaks

A

macrophage foam

73
Q

What is the pathogenesis of familial hypercholesterolemia?

A

defective genes for formation of LDL receptors on cell membranes

Without these receptors the liver can’t absorb IDLs or LDLs

Since these lipoproteins can’t be detected by the liver, it cranks out VLDLs because the liver thinks fat levels are low

74
Q

What kills people with familial hypercholesterolemia?

A

if untreated, die by age 30 of atherosclerosis MI

75
Q

How do HDLs protect against atherosclerosis?

A

may absorb cholesterol crystals that would otherwise be deposited

may inhibit oxidative stress and prevent inflammation

76
Q

when a person has a high ratio of ______ to ____ the likelihood of developing atherosclerosis is reduced

A

HDL

LDL

BUT exogenously increasing HDLs doesn’t really reduce the risk of cardiovascular disease

77
Q

How are amino acids taken up by cells?

A

They are too large to diffuse

have to have facilitated or active transport

78
Q

When are amino acids excreted?

A

When there are more amino acids in the kidney that there are active transport proteins

79
Q

How are amino acids stored in cells?

A

As rapidly-exchangeable proteins, never as free amino acids

80
Q

_____ and ____ hormones increase the formation of tissue proteins

_____ hormones increase the concentration of plasma amino acids

A

GH and insulin

adrenocortical glucocorticoids

81
Q

The major types of protein present in the plasma are:

A

Albumin

Globulin

Fibrinogen

82
Q

What are essential and non-essential amino acids?

A

Amino acids that cannot be synthesized by the cells

refers to amino acids that are essential to the diet

Non-essential amino acids are essential to cellular function, but not essential in the diet because they can be synthesized

83
Q

Without Vitamin ______, amino acids are poorly synthesized and protein formation cannot proceed

A

Vit B6 (pyridoxine)

84
Q

Degradation of amino acids occurs in the ________ by a process called _______

A

liver

deamination

85
Q

Describe deamination

A

amino group from amino acid is transferred to alpha ketoglutaric acid

this forms glutamic acid

flucatmic acid transfers the amino group to another substance or releases it as ammonia

when the amino group is removed, glumatic acid because alpha ketoglutaric acid again and can pick up another amino acid

86
Q

All urea formed in the body is formed in the ________ by _______

A

liver

deamination

87
Q

Why is it important to check an ammonia level, not just BUN?

A

The BUN only tells you excretion (if something is wrong with the kidney)

If the liver is malfunctioning, ammonia isn’t being processed into urea, so the BUN may not be that elevated

88
Q

Deaminated alanin is ______

why is this important?

A

pyruvic acid

This is how the body uses proteins to make energy

89
Q

The conversion of amino acids into glucose is called ______

the conversion of amino acids into keto acids is called ______

A

gluconeogenesis

ketogenesis

90
Q

How many types of amino acids are there?

A

20

10 essential

10 nonessential

18 can be converted into glucose

19 can be converted into fatty acids

91
Q

A minimum of 60-75 g proteins is recommended each day. Why?

A

When you don’t eat protein, body proteins will be degraded

the body has an obligatory loss of about 20-30 g protein each day, so you have to eat more than that to make sure you’re not losing net proteins

92
Q

Growth hormone _______ the synthesis of proteins

A

increases

93
Q

What is the effect of insulin deficiency on protein synthesis?

A

Insulin is required for protein synthesis

accelerates the transport of amino acids into the cell and reduces protein degradation by increasing the availability of glucose

total lack of insulin reduces protein synthesis to zero

94
Q

Cortisol ________ plasma amino acid concentration

A

increases

encourages the breakdown of cellular proteins

95
Q

ATP is generated by _______

A

combustion

96
Q

What is the role of phosphocreatine in the body?

A

It holds high-energy phosphate bonds (more so even than ATP)

It can’t interact with cellular functions directly, but it can interact with ADP

When there’s excess ATP, phosphate is bound to phosphocreatine

When ATP stores are low, phosphocreatine releases these phosphate to form ATP+creatine

97
Q

The best source of energy during anaerobic conditions is:

A

stored glycogen, NOT circulating glucose

Glucose brought into the cell has to be phosphorylated before it can be put into glycolysis, using ATP and decreasing the net ATP gain. Glycogen does not.

98
Q

Anaerobic exercise is derived from:

A

glycolysis

99
Q

What happens to lactic acid once exercise is over?

A

4/5 of it is converted into glucose

the rest becomes pyruvic acid and is sent into the citric acid cycle

100
Q

After we quit exercising, we still breathe hard for quite a while. Why?

A

Your body is “repaying the oxygen debt”:

the extra oxygen is used to convert lactic acid into glucose

convert AMP/ADP to ATP

Convert creatine and phosphate to phosphocreatine

re-establish normal concentrations of Hgb binding

raise O2 concentration in the lungs to its normal level

101
Q

What is the major rate-limiting factor for almost all energy metabolism in the body?

A

ADP concentration

102
Q

How is metabolic rate normally expressed?

A

In terms of the amount of heat liberated during chemical reactions

103
Q

How much energy in the body is eventually converted to heat?

A

Pretty much all of it

Even energy that’s expended as muscle movement causes friction between muscles, which generates heat

104
Q

What is a calorie?

What is a Calorie?

A

quantity of heat required to raise the temperature of 1g of water by 1 degree C

a kilocalorie (1000 calories)

105
Q

What are the four categories of energy output?

A
  1. Basal metabolic rate
  2. physical activity
  3. digestions
  4. maintaining body temp
106
Q

At rest, skeletal mm accounts for __% of BMR

A

20-30

Patho 2 (24 decks)

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