What do we call things that directly affect all activities of cells?

The correct answer to this question is stimuli. All activities of the cells respond to stimuli in a bid to detect any changes in their internal and external environment. Stimuli are what make organisms to be sensitive to any changes in their environment.

All cellular activities respond to stimuli in order to control all conditions in the body so that the body can function effectively. For instance, when there is a low amount of oxygen in the blood, a stimulus is sent to the kidneys for them to be aware of the situation. And the kidneys respond to this at the cellular level by producing more red blood cells in the bone marrow.

Receptors are part of the cell, and they make it easy for cells to respond to changes in the environment. The moment stimuli are received, the affected part of the body responds to this and adjust to the changes, and this usually happens at the cellular level.

Something that will affect the activity of all cells will be called stimuli. When you say stimulus, you would mean to say that this is a change in the physical or chemical structure of the organism in an internal or external environment. There is a need for an organism to detect external stimuli.

The more sensitive the person is, the easier it will be for the organism to do some changes. Some say that this is also an interesting quality. You need to know what the definition is for so that you will be able to use it properly. Take note that there are some objects that will only start to move or do a reaction when they get a certain type of stimulus.