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Physiology of the heart - Coggle Diagram
Physiology of the heart
The heart’s natural pacemaker
group of special cells in the heart.
It automatically sends signals to make the heart beat — about 72 beats per minute normally
The Cardiac Cycle
Atrial systole
Top chambers squeeze blood into the lower ones
Isovolumetric contraction
Ventricles prepare to squeeze
Ventricular ejection
Ventricles push blood out to the body/lungs
Isovolumetric relaxation
Ventricles start to relax
Ventricular filling
Blood flows in passively before the next beat
Nervous system (automatic controls)
The brain and nerves help speed up or slow down the heart rate using two systems:
Sympathetic nervous system
Speeds up heart rate.
Active during exercise, stress, or excitement
Uses a chemical called norepinephrine
Parasympathetic nervous system
Slows down heart rate
Active when you're resting or sleeping
Uses a chemical called acetylcholine
Other Influences
Hormones like adrenaline increase heart rate
Temperature (fever increases it)
Chemoreceptors (sense blood oxygen or CO₂ levels)
Baroreceptors (sense blood pressure changes)