Cells, in general, are designed to respond to specific signals.
But, all the body cells do not respond to all the chemical signals.
They respond differently to different signals based on the receptors on their surfaces.
Cells generally respond to bio-molecules like hormones, ions, vitamins, etc. They also respond to drugs, heavy metals, and poisons.
- To put it in another way, we can say that cells respond to the signals for which they are required.
- However, these cells sometimes do not respond to specific signals to which they ought to respond.
- This condition of non-responsiveness to regular signals is either a permanent condition leading to a disease condition like diabetes.
Or, it could also be a temporary condition that could be revoked.
Permanent non-responsiveness of cells
- In disease conditions, the cells might lack the receptor to respond.
- One of the best examples of such non-responsiveness in disease conditions is type-II diabetes.
- Here, the cells of the muscles and other tissues do not respond in particular to the insulin hormone.
- Insulin is a hormone that enhances glucose uptake from the blood into the cells and tissues.
- Due to insulin resistance, cell receptors do not respond to the insulin signal.
- This leads to a lack of energy in the tissues and muscles, and at the same time, the accumulation of glucose in the blood leads to high blood glucose levels.
- Hence, people with cells that lack insulin sensitivity have diabetes.
Due to this, they cannot utilize the glucose in the blood, leading to weakness, weight loss, and enhanced sugar levels in urine.
Temporary lack of cell response to stimuli.
- Here, the cells do not respond for a short period but will start responding later.
- This condition is due to a phenomenon called receptor down-regulation.
- The receptors are presented on the cell surface and hidden or exhausted.
- This leads to a lack of response. So, one has to wait for the cell receptors to up-regulate again.
- After up-regulation, these cells again respond to the stimuli.
- One example of such a disease condition is breathing insufficiency.
- Doctors prescribe drugs that act on the β2-adrenergic receptors to facilitate respiration.
- But after the use of these drugs for five days, then the response goes down.
- Then, the patient is given steroids to up-regulate the β-receptors, and then they again start to respond.
- So, here, β-receptors show temporary non-responsiveness.
- For more details on the signal receptors, check our article on types of receptors.
There are also many diseases or other conditions when cells do not respond to signals.
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