Hormones which interact with the membrane - bound receptors normally do not enter the target cell but generate second messengers. These second messengers are referred as

Options

A. Calcium ion the inositol - 3 phosphate
B. Inositol 3- phosphate and CAMP
C. cAMP and calcium ion
D. All of above

Answer

To solve the question regarding hormones that interact with membrane-bound receptors and generate second messengers, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding Hormones and Their Types**:
- Hormones can be classified into two main types: lipid-soluble hormones and water-soluble (proteinaceous) hormones.
- Lipid-soluble hormones can easily pass through the lipid bilayer of cell membranes, while water-soluble hormones cannot.

2. **Interaction with Membrane-Bound Receptors**:
- Water-soluble hormones (such as insulin, FSH, and adrenaline) bind to specific receptors on the cell membrane.
- Since these hormones cannot enter the cell directly due to the lipid nature of the membrane, they rely on membrane-bound receptors to initiate their action.

3. **Generation of Second Messengers**:
- Upon binding to their receptors, these hormones trigger a cascade of intracellular events, often leading to the generation of second messengers.
- Common second messengers include cyclic AMP (cAMP) and calcium ions (Ca²+).

4. **Identifying Second Messengers**:
- Cyclic AMP (cAMP) is a well-known second messenger involved in various signaling pathways.
- Calcium ions (Ca²+) and inositol trisphosphate (IP3) are also recognized as second messengers in the signaling pathways of certain hormones.

5. **Analyzing the Options**:
- The question provides multiple options for the second messengers generated by these hormones.
- The correct answer must include all relevant second messengers associated with the proteinaceous hormones mentioned.

6. **Conclusion**:
- Given that both cyclic AMP and calcium ions are involved in the signaling pathways of various proteinaceous hormones, the answer to the question is that the second messengers referred to are indeed all of the above mentioned in the options.

### Final Answer:
The second messengers generated by hormones that interact with membrane-bound receptors are referred to as **all of the above** (including cyclic AMP, calcium ions, and inositol trisphosphate).

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