Video Transcript
The figure shows some of the body’s
responses to fear and stress, which are coordinated by one main hormone X. What is hormone X? (A) Glucagon, (B) insulin, (C)
adrenaline, (D) testosterone, or (E) thyroxine.
Hormones are chemical messengers
that travel throughout the body via the bloodstream to cause an effect. They have diverse functions, and
each hormone has a specific target. Some hormones can be involved in
reproduction, growth, homoeostasis, and some in response to fear and stress caused
by dangerous situations. Hormones are secreted by endocrine
glands, an example of which are the adrenal glands. Humans typically have two adrenal
glands, one of which sits above each of our kidneys. Depending on the situation, the
adrenal glands can produce two main responses to cope with stress. One of these responses involves the
release of the hormone cortisol. Cortisol is used in more long-term
responses, modulating our metabolism and immune response.
The other response involves the
hormone adrenaline. It’s a short-term response produced
to react to acute stress or immediate danger. Adrenaline induces the
fight-or-flight response, which has many functions in the body. It can increase the blood flow to
muscles, increase the heart rate, and can even dilate the bronchioles, which are the
air passages leading to the lungs, allowing more oxygen to enter the
bloodstream. This is how our body prepares to
fight through or escape from a dangerous situation. Therefore, we’ve worked out that
hormone X is adrenaline.
