Adrenaline dilates the airways of the lungs so that air will flow more easily in and out of the lungs. Breathing becomes more rapid and deeper so that adequate oxygen can be transferred to the blood. The oxygen-carrying capacity of the blood is increased by adding more red blood cells (the oxygen-carrying cells) to the bloodstream. This is done by the sympathetic nervous system: it stimulates the spleen which contracts, releasing red blood cells from its store.
Obtaining more fuel
Glucose and fats are quickly mobilized from the body’s sugar and fat stores by the action of adrenaline and noradrenaline on the liver and fat tissues. Supplies are maintained by the action of other hormones, including cortisol, released during the stress response.
Increasing alertness and sharpening the senses
Noradrenaline enhances alertness and sensory activity: smell hearing, taste, touch and sight. The pupils of the eye increase in size to allow more light to enter, thus improving vision, especially in poor light conditions. Hearing becomes more acute and the skin is more sensitive to touch, both clear advantages when fighting. Mental alertness increases, leading amongst other things to quick thinking.
Obtaining more oxygen Photo Gallery
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