Pathology in Sport Med. Lecture 1
Evidence based medicine is the conscientious, explicit and judicious
use of the best available information. It is used to make decisions
about the care of patients.
Example: Cardiac Arhythmia Supression Trail (~late1980’s/early
Problem- a 8-15% mortality rate post heart attack (MI), half of which
died of heart rate problems (arrhythmias).
- SA node (innervated by vagus nerve X) = primary control
Parasympathetic nervous system decreases HR via acetacholine
Sympathetic NS increases HR via epinephrine.
[Fight or flight vs Rest and digest]
Options for Controlling HR:
• Beta-blockers (CLASS II)—reduce sympathetic input to cells
(which decreases HR). They do this by binding/interfering with
receptors for norepinephrine and epinephrine.
• NA+ channel blockers (CLASS I)—NA+ initiates depolarizations of
a nerve cell (from a negative resting potential (-70mv)). There is
more NA+ outside the cell. NA+ blockers cause it to take longer
to depolarize (for NA+ to rush into cell) which slows HR.
• K+ channel blockers (CLASS III)—More K+ inside cell, K+
initiates repolarization (K+ rushes out, decreases conc.
Gradient= cell becomes negative). K+ blockers prevent/increase
the time to repolarize (prevents 2 ndaction potential), which
• Ca+ channel blockers (CLASS IV)—CA+ initiates muscle
contractions in skeletal and cardiac muscle. Sarcoplasmic
Reticulum= troponin- tropomyosin-actin/myosin. In cardiac
muscle, Ca+ helps