key term - Target cells

Definition

Target cells are specific cells in the body that are affected by particular hormones. These cells have receptors that bind to the hormones, allowing them to respond to hormonal signals. The interaction between hormones and their target cells is crucial for regulating various physiological processes, including growth, metabolism, and homeostasis.

5 Must Know Facts For Your Next Test

1. Target cells can be located far from the hormone-producing gland, as hormones circulate throughout the bloodstream.
2. Not all cells in the body are target cells for a given hormone; only those with specific receptors will respond to the hormone's signal.
3. When a hormone binds to its receptor on a target cell, it can initiate various cellular responses, such as changes in gene expression or enzyme activity.
4. The sensitivity of target cells to a hormone can change due to factors like hormone levels, receptor density, and cellular context.
5. Target cells play a key role in maintaining homeostasis by responding appropriately to hormonal signals based on the body's needs.

Review Questions

• How do target cells differ from non-target cells regarding hormonal signaling?
  • Target cells are specifically equipped with receptors that allow them to respond to certain hormones, while non-target cells lack these receptors and therefore do not react to those hormones. This distinction is crucial for ensuring that hormones exert their effects only where needed, allowing for precise regulation of bodily functions. For instance, insulin primarily affects muscle and fat cells because they have insulin receptors, while other cell types do not respond to insulin.
• What role do receptors on target cells play in the effectiveness of hormonal signaling?
  • Receptors on target cells are essential for hormonal signaling because they determine which hormones a cell can respond to. When a hormone binds to its specific receptor, it triggers a cascade of biochemical events inside the cell, leading to a physiological response. The number and sensitivity of these receptors can influence how effectively a cell responds to hormone levels in the bloodstream. If there are too few receptors or if they are desensitized, target cells may not respond properly to hormonal signals.
• Evaluate the implications of altered target cell sensitivity in disease conditions, providing examples.
  • Altered sensitivity of target cells can have significant implications for health and disease. For example, in type 2 diabetes, target cells become less sensitive to insulin due to a decrease in receptor function or number, leading to impaired glucose uptake and elevated blood sugar levels. Similarly, in conditions like hyperthyroidism, an excess of thyroid hormone can lead to increased sensitivity of target cells, resulting in heightened metabolic activity and symptoms such as weight loss and anxiety. These alterations illustrate how changes in target cell responsiveness can profoundly affect overall physiology and contribute to disease states.

Related terms

Hormones:

Chemical messengers produced by glands in the endocrine system that travel through the bloodstream to regulate various functions in the body.

Receptors:

Proteins on the surface or inside target cells that specifically bind to hormones, triggering a response in the cell.

Endocrine System: The system of glands and organs that produce hormones and regulate bodily functions through chemical signaling.