Question

Suggest some stimuli that might cause a cell to release a ligand and begin communication be-

tween cells.

Answer 1

There are many stimuli that can cause a cell to release a ligand and initiate communication between cells. Some examples include:

Physical damage or injury to the cell: When a cell is damaged or injured, it can release signaling molecules called cytokines to alert other cells to the presence of an injury and trigger the immune response.
Changes in the local environment: Cells can respond to changes in the local environment, such as changes in pH, temperature, or the presence of certain chemicals, by releasing ligands to communicate with other cells.
Changes in the internal state of the cell: Cells can also respond to changes in their own internal state, such as changes in gene expression or the availability of certain nutrients, by releasing ligands to communicate with other cells.
The presence of certain pathogens: Cells can release ligands in response to the presence of certain pathogens, such as bacteria or viruses, to alert other cells to the presence of an infection and trigger the immune response.
The presence of certain hormones: Hormones released by endocrine cells can stimulate other cells to release ligands and initiate communication.
Stimulation by neurotransmitters: Neurons can release neurotransmitters to stimulate other cells to release ligands and initiate communication.
Stimulation by growth factors: Growth factors released by certain cells can stimulate other cells to release ligands and initiate communication.

Answer 2

Some stimuli that might cause a cell to release a ligand and begin communication between cells are light levels, temperature of the environment, age of the cell, stress effects, a signal from another cell (hormones), sensory triggers (smells, tastes, touch).