OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for the OCR GCSE Biology Exam with our comprehensive study resources. Practice with quizzes, flashcards, and detailed explanations to enhance your understanding. Ace your exam and secure your academic success!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

What effect does adrenaline have on the heart?

It decreases heart rate
It causes the heart muscle to contract more frequently
It reduces blood pressure
It increases oxygen supply to the lungs

The correct answer is: It causes the heart muscle to contract more frequently

Adrenaline, also known as epinephrine, is a hormone released by the adrenal glands in response to stress or danger, often referred to as the "fight or flight" hormone. When adrenaline enters the bloodstream, it has several physiological effects, particularly on the heart. The correct answer highlights that adrenaline causes the heart muscle to contract more frequently. This increased contraction rate, known as an increased heart rate, is a crucial response during stressful situations. As adrenaline binds to receptors on heart cells, it stimulates the heart to beat faster and with more force. This enhanced cardiac output ensures that more blood is pumped throughout the body, delivering oxygen and nutrients to vital organs and muscles, thus preparing the body for rapid physical activity. Additionally, adrenaline also acts to improve the efficiency of each heartbeat by increasing the stroke volume, which is the amount of blood the heart pumps with each contraction. Together, these effects optimize the body’s performance under stress, allowing for greater physical exertion. In summary, adrenaline's role in increasing the frequency and strength of heart muscle contractions prepares the body for action, making it a critical factor in the body's acute stress response.