Lecture 21- Energy Generation & Metabolism

studied byStudied by 0 people
0.0(0)
get a hint
hint

What is the main difference in energy yield between oxidative phosphorylation & glycolysis alone?

1 / 118

Tags and Description

119 Terms

1

What is the main difference in energy yield between oxidative phosphorylation & glycolysis alone?

Oxidative phosphorylation yields more energy than glycolysis alone.

New cards
2

What are carbohydrates in the context of metabolism?

Main sources of energy in metabolism.

New cards
3

Where does glycolysis occur in the cell?

Cytosol of the cell.

New cards
4

What is glycolysis?

Glycolysis is a metabolic pathway that converts glucose into pyruvate.

New cards
5

What role do fats & proteins play in metabolism?

Sources of energy in metabolism.

New cards
6

What is pyruvate?

End product of glycolysis.

New cards
7

What is lactate?

Byproduct of anaerobic metabolism that can be produced from pyruvate.

New cards
8

What happens to ADP during oxidative phosphorylation?

ADP is phosphorylated to form ATP during oxidative phosphorylation.

New cards
9

What is the role of CO2 in metabolism?

Byproduct of metabolism that is released during oxidative phosphorylation.

New cards
10

Where does the Krebs cycle occur in the cell?

Mitochondria of the cell.

New cards
11

What is the Krebs cycle?

Series of biochemical reactions that produce energy in the form of ATP.

New cards
12

What is the main product of oxidative phosphorylation?

ATP

New cards
13

What is the role of coenzyme-2H in metabolism?

Transfer of electrons during oxidative phosphorylation.

New cards
14

What is the role of oxygen in metabolism?

Necessary for oxidative phosphorylation to occur.

New cards
15

What is oxidative phosphorylation?

Process that produces ATP from the energy released by the transfer of electrons from NADH & FADH2 to oxygen in the mitochondria.

New cards
16

What is the end product of oxidative phosphorylation?

water (H2O).

New cards
17

What are the two ways to process nutrients?

Glycolysis & the tricarboxylic acid cycle (also known as the Krebs cycle).

New cards
18

What is the energy yield of glycolysis?

2 ATP molecules.

New cards
19

What is the starting molecule for glycolysis?

Glucose.

New cards
20

Where does oxidative phosphorylation occur in the cell?

Oxidative phosphorylation occurs in the mitochondria of the cell.

New cards
21

What are the products of oxidative phosphorylation?

ATP, water, & carbon dioxide.

New cards
22

What is the role of NADH + H+ in oxidative phosphorylation?

Source of electrons for oxidative phosphorylation.

New cards
23

What is the role of FADH2 in oxidative phosphorylation?

Another source of electrons for oxidative phosphorylation.

New cards
24

What is the tricarboxylic acid cycle?

Series of biochemical reactions that generate energy from the oxidation of acetyl CoA.

New cards
25

Where does the tricarboxylic acid cycle occur in the cell?

Occurs in the mitochondria of the cell.

New cards
26

What is the energy yield of the tricarboxylic acid cycle?

ATP molecules, as well as NADH + H+ & FADH2, which are used in oxidative phosphorylation to produce more ATP.

New cards
27

What is the starting molecule for the tricarboxylic acid cycle?

Acetyl coenzyme A.

New cards
28

What are the products of the tricarboxylic acid cycle?

NADH + H+, FADH2, ATP, carbon dioxide, & water.

New cards
29

How many ATP molecules are produced in total from the processing of glucose through glycolysis, the tricarboxylic acid cycle, & oxidative phosphorylation?

34-38 ATP molecules.

New cards
30

What are the main nutrients consumed & used by the myocardium?

Fatty acids, glucose, lactate, & ketone bodies.

New cards
31

What percentage of the myocardium's energy needs come from fatty acids?

Approximately 60%

New cards
32

What percentage of the myocardium's energy needs come from glucose?

Approximately 27%

New cards
33

What percentage of the myocardium's energy needs come from lactate?

Approximately 10%

New cards
34

What percentage of the myocardium's energy needs come from ketone bodies?

Approximately 2%

New cards
35

What is the role of pyruvate in myocardial metabolism?

Converted into acetyl-CoA, which enters the tricarboxylic acid cycle to produce energy in the form of ATP.

New cards
36

What is the storage capacity of glycogen in the myocardium compared to skeletal muscle?

Equivalent to 1/5 of that in skeletal muscle.

New cards
37

What is the role of phosphorylated creatine in myocardial metabolism?

Serves as a small reserve of phosphate in the myocardium.

New cards
38

Why is the myocardium completely reliant on lipid & glucose supply by the coronary circulation?

The myocardium is unable to synthesise lipids, thus making it completely reliant on lipid & glucose supply by the coronary circulation.

New cards
39

How do the limited nutrient reserves & continuous function of the cardiac pump affect myocardial metabolism?

These features make the myocardium a supply-limited tissue from the metabolic perspective, thus tightly linking nutrient & oxygen supply with cardiac function or dysfunction.

New cards
40

How does the myocardium maintain ATP levels?

Sustained mitochondrial respiration.

New cards
41

What are the O2 & ATP consumption levels of the heart with respect to its mass?

The heart has very high O2 & ATP consumption levels with respect to its mass.

New cards
42

What is the reason for the high O2 & ATP consumption levels of the heart?

The high O2 & ATP consumption levels of the heart are due to a high density of mitochondria in each cardiomyocyte.

New cards
43

What happens to cardiomyocytes when O2 consumption exceeds supply?

When O2 consumption exceeds supply (hypoxia), cardiomyocytes have no other option than breaking down glucose (glycolysis) to produce ATP.

New cards
44

Why is glycolysis insufficient in the mid-to-long term?

Glycolysis is insufficient in the mid-to-long term, which is the metabolic basis for cardiac failure.

New cards
45

What do the red & grey regions in the image represent?

The red regions represent mitochondria, while the grey regions represent sarcomeres.

New cards
46

Why are O2 levels crucial for cardiac metabolism & function?

Heart is highly dependent on O2 supply & consumption.

New cards
47

What are some factors that affect O2 supply in cardiac metabolism?

Myocardial arterial venous oxygen content difference (MAVR) Diastolic time, Pump function Coronary flow Ventilation Haemoglobin saturation.

New cards
48

What is MAVR in cardiac metabolism?

Difference in oxygen content between arterial & venous blood in the myocardium.

New cards
49

What is the role of diastolic time in cardiac metabolism?

Filling of the coronary arteries, which can affect O2 supply in the myocardium.

New cards
50

How does pump function affect O2 supply in cardiac metabolism?

Determines the cardiac output, which affects blood flow to the coronary arteries.

New cards
51

What is the role of coronary flow in cardiac metabolism?

Delivering O2 & nutrients to the myocardium.

New cards
52

How does ventilation affect O2 supply in cardiac metabolism?

Affects the oxygenation of arterial blood.

New cards
53

What is the role of haemoglobin saturation in cardiac metabolism?

Delivering O2 to the myocardium.

New cards
54

What are some factors that affect O2 consumption in cardiac metabolism?

Heart rate Myocardial mass Contractility Sympathetic activity Pre/afterload.

New cards
55

What is the percentage of total O2 consumption at rest that is attributed to the heart?

At rest, the heart is responsible for approximately 10% of total O2 consumption.

New cards
56

Why is the myocardium considered a supply-limited tissue from a metabolic perspective?

It is a terminally vascularized organ where O2 supply depends exclusively upon coronary blood flow, & the cardiac pump must function continuously.

New cards
57

What are the two main processes that the myocardium distributes ATP expenditure between?

Contractile apparatus & maintenance of ion gradients.

New cards
58

What are some sources of fatty acids in the myocardium?

Albumin, chylomicrons, & fatty acid transporters such as CD36 & MCT.

New cards
59

What is the role of glucose in myocardial metabolism?

Source of energy in the myocardium through glycolysis & the tricarboxylic acid cycle.

New cards
60

What is the role of GLUT in myocardial metabolism?

Glucose transporter that helps transport glucose into the myocardial cells.

New cards
61

What is the role of acetyl-CoA in myocardial metabolism?

Intermediate molecule that enters the tricarboxylic acid cycle to produce energy in the form of ATP.

New cards
62

What is the role of the carnitine shuttle in myocardial metabolism?

Transporting fatty acids into the mitochondria for oxidation.

New cards
63

What is the role of the citric acid cycle (Krebs cycle) in myocardial metabolism?

Series of biochemical reactions that generate energy from the oxidation of acetyl-CoA.

New cards
64

What is the energy yield of oxidative phosphorylation compared to glycolysis?

The energy yield of oxidative phosphorylation is 18 times higher than glycolysis.

New cards
65

How does the heart obtain ATP from different energy substrates?

The heart obtains 60-90% of its ATP from lipids through beta-oxidation, while 10-30% comes from the breakdown of glucose through glycolysis.

New cards
66

What are some of the processes that require ATP in the myocardium?

⅔ of ATP is used by the contractile apparatus

⅓ s used to maintain ionic gradients, such as the Na+/K+ ATPase & SERCA pump.

New cards
67

What happens to the myocardium when coronary blood flow is impaired?

Myocardium relies on glycolysis, which consumes most ATP on the maintenance of ionic gradients, thus starving contractile apparatus & further aggravating cardiac pump function

New cards
68

What is the preferred source of ATP in a non-hypoxic, well-perfused heart?

Most of the ATP in a non-hypoxic, well-perfused heart is derived from fatty acid beta-oxidation.

New cards
69

What is the role of myosin ATPase in myocardial metabolism?

Producing force in the myocardium.

New cards
70

What is the role of ion gradients in myocardial metabolism?

Maintaining the proper function of cardiac cells, including the regulation of calcium ions & the Na+/K+ ATPase.

New cards
71

What happens to ATP usage in a failing heart?

Glucose oxidation becomes the dominant source of ATP More ATP is used for ion homeostasis instead of force production → ↓↓↓ cardiac efficiency.

New cards
72

What are some sources of energy substrates in myocardial metabolism?

Fatty acids, glucose, lactate, & ketone bodies.

New cards
73

What are some transporters involved in myocardial metabolism?

GLUT for glucose, MCT for lactate, & CD36 for fatty acids.

New cards
74

What is the role of glycolysis in myocardial metabolism?

Source of energy for the myocardium, especially during times of hypoxia or low nutrient perfusion.

New cards
75

What is the role of beta-oxidation in myocardial metabolism?

Process of breaking down fatty acids for energy production in the myocardium.

New cards
76

What is the tricarboxylic acid (TCA) cycle?

Series of biochemical reactions that generate energy from the oxidation of acetyl-CoA.

New cards
77

What is oxidative phosphorylation in myocardial metabolism?

Process of producing ATP through the electron transport chain in the mitochondria.

New cards
78

What are some ATP-dependent processes in the myocardium?

Contractile element (myosin ATPase), calcium regulation (SERCA2 & sarcolemmal Ca2+ ATPase), & ion homeostasis (Na+/K+ ATPase).

New cards
79

What is myosin ATPase?

Enzyme that hydrolyzes ATP to produce force in the myocardium.

New cards
80

What happens in a hypoxic, poorly perfused (ischaemic) heart?

Supply of oxygen & nutrients is reduced → ↑↑↑ in lactate production & a ↓↓↓ in fatty acid beta-oxidation.

New cards
81

Why is glycolysis less efficient than oxidative phosphorylation?

Produces fewer ATP molecules per glucose molecule.

New cards
82

What happens to myosin ATPase in a hypoxic, poorly perfused heart?

More ATP is used to maintain ion homeostasis rather than force production by myosin ATPase → ↓↓↓ cardiac efficiency.

New cards
83

What is the role of lactate in myocardial metabolism?

Source of energy in hypoxic conditions where fatty acid beta-oxidation is impaired. However, high levels of lactate can also be detrimental to cardiac function.

New cards
84

How does ↓↓↓ fatty acid beta-oxidation affect myocardial efficiency?

A shift towards glycolysis, which is less efficient in producing ATP.

As a result, the heart is less efficient in producing force & more ATP is used to maintain ion homeostasis, leading to ↓↓↓ cardiac efficiency.

New cards
85

What is the electron transport chain?

Series of protein complexes in the inner mitochondrial membrane that transfer electrons & protons to generate a proton gradient for ATP production

New cards
86

How does impaired energy generation & metabolism in the heart affect its function?

Lead to impaired contractile function, which can manifest as decreased cardiac output or impaired relaxation (diastolic dysfunction) → lead to changes in the electrical activity of the heart, which can manifest as arrhythmias.

New cards
87

How can arrhythmias be an early sign of heart failure?

Occur as a result of impaired energy generation & metabolism, & can be an early sign of heart failure before changes in the pulse. So the electrical signalling fails before the anatomical pumping

New cards
88

What is the main pathway for ATP generation in myocardial metabolism under hypoxia/ischaemia?

Glycolysis

New cards
89

What is glycogen in the context of myocardial metabolism?

Storage form of glucose that can be broken down into glucose molecules for use in glycolysis.

New cards
90

What is ppp in the context of myocardial metabolism?

Pentose phosphate pathway, which is an alternative pathway for glucose metabolism that generates NADPH & ribose-5-phosphate.

New cards
91

What is NADPH in the context of myocardial metabolism?

Coenzyme that is involved in the production of fatty acids & the removal of ROS (reactive oxygen species) in the cell.

New cards
92

What is ROS in the context of myocardial metabolism?

Reactive oxygen species, which are harmful molecules that can cause cellular damage & contribute to various diseases.

New cards
93

What is FADH in the context of myocardial metabolism?

Coenzyme that is involved in the electron transport chain, which generates ATP through oxidative phosphorylation.

New cards
94

What is NADH in the context of myocardial metabolism?

NADH is a coenzyme that is involved in the electron transport chain, which generates ATP through oxidative phosphorylation.

New cards
95

What is ATP synthase in the context of myocardial metabolism?

ATP synthase is an enzyme that synthesises ATP from ADP & inorganic phosphate during oxidative phosphorylation.

New cards
96

What is glutamate in the context of myocardial metabolism?

Amino acid that is involved in the TCA cycle & can generate FADH2 for use in oxidative phosphorylation.

New cards
97

How does hypoxia affect myocardial metabolism?

Reduces the availability of oxygen for oxidative phosphorylation, leading to a shift towards glycolysis for ATP production.

New cards
98

What is the energy yield of metabolism under hypoxia compared to aerobic metabolism?

Only 2 ATP molecules per glucose molecule, whereas aerobic metabolism yields 36 ATP molecules per glucose molecule.

New cards
99

What is the relationship between NAD+ & NADH in myocardial metabolism?

NAD+ is the oxidised form of the coenzyme, while NADH is the reduced form. The balance between the two is important for energy production in the cell.

New cards
100

What is the role of sympathetic activation in myocardial glycolysis?

Simulates myocardial glycolysis.

New cards

Explore top notes

note Note
studied byStudied by 3 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 34 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 67 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 10 people
Updated ... ago
5.0 Stars(2)
note Note
studied byStudied by 5 people
Updated ... ago
4.5 Stars(2)
note Note
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 181259 people
Updated ... ago
4.8 Stars(731)

Explore top flashcards

flashcards Flashcard23 terms
studied byStudied by 1 person
Updated ... ago
5.0 Stars(1)
flashcards Flashcard21 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard24 terms
studied byStudied by 9 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard101 terms
studied byStudied by 239 people
Updated ... ago
5.0 Stars(3)
flashcards Flashcard111 terms
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard30 terms
studied byStudied by 1 person
Updated ... ago
5.0 Stars(1)
flashcards Flashcard57 terms
studied byStudied by 91 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard34 terms
studied byStudied by 4 people
Updated ... ago
5.0 Stars(1)