Session 1 oxidative stress

Question 1

What is responsible for your hangover?

other than you

Answer 1

Acetaldehyde (ethanol broken down by alcohol dehydrogenase), which is a toxic metabolite which accumulates.

*eventually becomes acetate for ac-CoA via aldehyde dehydrogenase.

Question 2

Excessive alcohol oxidation has detrimental effects. name a few.

Answer 2

• Decrease in NAD+/ NADH ratio leading to accumulation of lactate, hypoglycaemia.
• Increased Acetyl-CoA leading to not efficiently exported so fatty liver buildup.

Question 3

Briefly describe how Disulfiram works.

Answer 3

• inhibits Aldehyde dehydrogenase causing accumulations of acetaldehyde, creating hangover effects with small amount of alcohol.
• Pavlovian association.

Question 4

What is oxidative stress?

Answer 4

Imbalance between free radicals and antioxidant defences in body.
- causes CVKS, cancer, MS, COPD, crohns, alzheimers.

Question 5

what are free radicals?

Answer 5

Atom or molecule that contains one or more unpaired electrons, making them very reactive.
(usually have an immune function).

Question 6

Name the reactive oxygen species.

ROS

Answer 6

Oxygen - relatively stable as electron in dif. orbitals.
Superoxide
Hydrogen peroxide - not a free radical but reacts with
Fe2+ to produce them.
Hydroxyl radical - most reactive and damaging.

Question 7

Name the reactive Nitrogen species.

NOS

Answer 7

Nitric oxide.

Peroxynitrite - superoxide and nitric oxide. not a free radical but powerful oxidant, damages cells.

Question 8

Name some endogenous biological oxidants.

Answer 8

• electron transport chain.
• nitric oxide synthases.
• NADPH oxidases.

Question 9

Name some exogenous biological oxidants.

Answer 9

• radiation ( cosmic, UV, X-rays)
• pollutants.
• drugs (primaquine)
• toxins ( herbicide)

Question 10

What is Respiratory burst?

Answer 10

• phagocytic cells like neutrophils and monocytes rapidly produce superoxide and H2O2, which destroy invading bacteria.

Question 11

Name some cellular defences our bodies have against these reactive oxidants.

Answer 11

• SOD : superoxide to H202 + O2.
• Catalase : H202 to water and O2.
• Gluthione : Utilises NADPH to transfer electrons.
• Vitamin E and C
• GSH

Question 12

Explain the link between heinz bodies and free radicals.

Answer 12

increase in free radicals causes disulphide bonds and the clumping of haemoglobin in RBC. removed by spleen.