Chapter 9, Problem 1QC

Summary Introduction

To determine:

The cells in the body that respond to the hormone if it is released into the blood stream and therefore comes into contact with many cells.

Concept Introduction:

Hormone is chemical messenger molecule which has a specific function in the cell. This molecule binds to the specific receptor present on the different cells after its release from the cells which synthesize it. It is then transported in the blood stream and reaches the target cell where it exerts its action. The receptors for the hormones are present in the target cells throughout the body.

Explanation of Solution

The cells of the body respond to the release of the hormones from the specific gland. These released hormones reach the target receptors present on the various organs of the body. The receptor-ligand complex activates the cell signaling response. The receptor protein kinases are activated which transfer the signal from the membrane to the nucleus. The example includes that of epinephrine or adrenaline.

This hormone is released from the adrenal glands and is transported in the blood stream to reach the various other target organs in the glands like stomach and heart. This hormone ligand binds to the receptor and modulates the structure of this receptor-ligand complex. The cell signaling gets activated.

Conclusion

The hormone chemical has a specific structure and binds to specific receptor molecules according to the affinity of binding. These molecules are transported in the blood stream and reach the receptors present in the various organs of the body. The hormone has a specificity of binding of the receptor, according to the chemical structure of the hormone and the conformation of the binding site on the receptor. Every hormone molecule will not bind to every receptor on the membrane.