Adrenaline is a hormone that is secreted by the adrenal glands in response to stress or danger. When adrenaline is released into the bloodstream, our body undergoes several physiological changes to help us respond to the situation at hand.

Increased heart rate:
- Adrenaline triggers the heart to beat faster, increasing blood flow to the muscles and brain. This helps us react quickly to the stressful situation.

Dilated airways:
- Adrenaline causes the airways to relax and dilate, allowing for more oxygen to enter the lungs. This helps improve our breathing and oxygen intake.

Improved strength and speed:
- Adrenaline helps to increase the availability of glucose and oxygen to the muscles, providing a quick burst of energy. This can enhance our strength and speed, preparing us for fight or flight.

Heightened senses:
- Adrenaline can sharpen our senses, making us more alert and aware of our surroundings. This can help us react swiftly to potential threats.

Suppressed non-essential functions:
- When adrenaline is secreted, our body suppresses non-essential functions such as digestion and immune response. This allows all resources to be directed towards dealing with the immediate threat.
In conclusion, adrenaline plays a crucial role in the body's response to stress or danger by triggering a series of physiological changes that help us react quickly and effectively.