Salivary Amylase

Pepsin Pancreatic Lipase

Source salivary glands stomach cells pancreas cells

Substrate amylose (starch) proteins (polypeptides)

lipids

Products maltose and glucose

amino acids glycerol and fatty acids

Optimum pH

neutral (pH 7) acidic (pH 3) neutral (pH 7)

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Myogenic muscle contraction: heart muscle can contract and relax without nervous system

SA node: tissue sends an electrical signal to stimulate atrial contraction (nearly every second)

AV node: tissue responds to SA node sending an electrical signal to stimulate ventrical contraction 0.1 seconds after it gets SA node signal

These act as the heart’s pacemaker to keep it “in time”

When you exercise, CO2 levels in your blood increase

This increase is sensed by the medulla in your brain which sends a nerve signal through your cardiac nerve to the SA node which increases your heart rate

When you stop exercising, CO2 levels fall, and the medulla sends another signal to the SA node through the vagus nerve to return rate control to the SA node, slowing down the rate.