Grades K–2 · Organisms
Why can a sudden fright make your heart beat faster?
A sudden loud noise can make you jump and your heart beat faster because your brain and body begin responding to possible danger. Breathing can change too, before you know what made the noise.
Messages through your nervous system help coordinate these changes. Breathing brings oxygen into your lungs, and blood carries it to the body. Your heart pumps that blood. Faster pumping and breathing can help prepare muscles for quick movement. The changes fit together as preparation, even if you then discover there is no danger.
Arrows lead from sudden noise through brain + nervous system to heartbeat, breathing and muscles. The branches show several coordinated changes that can prepare the body for quick movement.
In the diagramA possible threat can coordinate a body responsesudden noisebrain + nervous systemheartbeatbreathingmusclesSeveral body changes work together; this is not every emotion.
A harmless dropped object may turn out to have made the noise, and the response can settle as the situation becomes clear. People respond differently, and quick heartbeats have other causes too. This picture follows one possible fright response, with body parts changing together.
About this explanation
Starting knowledge: Recognize a heartbeat and understand that nerves carry messages between the body and brain.
Sources
- National Institute of Mental Health — Guided Visualization: Dealing with Stress
- National Institutes of Health — Feeling Stressed?
- National Heart, Lung, and Blood Institute — How the Lungs Work — What Breathing Does for the Body
- National Heart, Lung, and Blood Institute — How the Heart Works — How the Heart Beats