What are the effects of adrenaline on heart rate and blood pressure?

Adrenaline increases both heart rate and blood pressure by stimulating the heart and constricting blood vessels.

Adrenaline, also known as epinephrine, is a hormone produced by the adrenal glands in response to stress or danger. It is part of the body's 'fight or flight' response, preparing the body for physical action by increasing the heart rate and blood pressure.

When adrenaline is released into the bloodstream, it binds to receptors on the heart, causing an increase in the rate and strength of heart contractions. This is known as positive chronotropic and inotropic effects. The increased heart rate (tachycardia) and stronger contractions result in a higher cardiac output, which is the amount of blood the heart pumps per minute. This ensures that more oxygen and nutrients are delivered to the muscles, preparing the body for action.

Adrenaline also acts on the smooth muscles that line the walls of arteries and veins. It causes these muscles to contract, a process known as vasoconstriction. This narrows the blood vessels, increasing the resistance to blood flow and thereby raising blood pressure. The increased blood pressure helps to quickly distribute the blood, and therefore oxygen and nutrients, throughout the body.

Furthermore, adrenaline stimulates the release of glucose and fatty acids into the bloodstream, providing additional energy for the body to use. This is particularly important during periods of physical exertion or stress, when the body's energy demands are higher.

In summary, adrenaline plays a crucial role in the body's response to stress or danger. By increasing heart rate and blood pressure, it ensures that the body is prepared for action and can respond effectively to the situation at hand.