Cardio-toxicology - WIP

Question 1

what is cardiotoxicity?

Answer 1

a deleterious effect on the heart, due to poisoning of the cardiac muscle or its conducting system

Question 2

What are the three layers of cardiac muscle?

Answer 2

Endothelium – inner layer which lines entire circulatory system

Myocardium – heart muscle

Epicardium – outer layer

Bundles of cardiac muscle are arranged spirally around the ventricle

Question 3

How does the heart beat? *

Answer 3

A simultaneous dual pump, triggered by depolarisation via an action potential.

SA node -

AV node -

Bundle of His -

Purkinje fibres -

Question 4

Describe the normal pacemaker activity

Question 5

Describe abnormal pacemaker activity

Question 6

What are the effects of altered extra-cellular K+ and Ca2+ concentrations?

Answer 6

Abnormal levels of K+ change resting potential, leading to decreased cardiac contractility
– Rise in K+ reduces resting potential (less negative)
– Inactivates Na+ channels
– Arrythmias and fatalities
– Decrease in K+ increases resting potential (hyperpolarisation)

Elevated Ca2+ causes longer contractions
– Ca2+ blockers reduces force of contraction (inotropy)
– Digoxin increases Ca2+ and contractility

Question 7

What is an ECG and how does it help diagnosis?

Question 8

Describe some cardiotoxic drugs *

Answer 8

theophylline ?
beta blockers ?
aphetamine ?
cocaine ?
digoxin ?