MYP Biology 4.6 Receptors Notes

How Do Systems Know When to Act?

1. Systems only work when they receive accurate information about what is happening inside or outside your body.
2. Receptors help them detect those changes, things like temperature shifts, pressure, chemicals, or light, and alert the nervous or endocrine system.
3. Once that signal arrives, the system knows exactly when to speed up, slow down, or take action.

What Exactly Do Receptors Detect?

1. Receptors are built to detect very specific kinds of changes.
2. Some look outward (light, sound, touch), others monitor your internal state (oxygen levels, temperature, pressure).
3. Each type gives the body a different stream of information so systems can react in the right way.

1. To help you see the pattern, here’s a quick overview:

How Do Receptors Convert Stimuli Into Signals?

1. The basic idea of transduction is that once a stimulus hits the receptor, the receptor changes its electrical activity, which causes a signal to be sent onward.
2. That signal travels through nerves or hormone pathways until it reaches the brain or spinal cord.
3. At that point, the body decides what to do, such as adjusting breathing rate or releasing hormones.
4. This is how a tiny external or internal change becomes a full-body response.

How Do Receptors Guide Growth, Development, and Life Cycles?

1. Receptors do more than just sense the environment, they also control long-term processes inside the body.
2. Hormone receptors guide growth, puberty, and repair.
3. In plants, receptors detect light and gravity to guide seedling growth and flowering.

1. These responses shape the entire life cycle of an organism.