A 10oC decrease in temperature causes decrease in cerebral metabolic rate by
**Core Concept**
The cerebral metabolic rate (CMR) refers to the rate at which the brain consumes oxygen and glucose to maintain its various functions. A decrease in CMR is associated with reduced brain activity and can be influenced by various factors, including temperature changes.
**Why the Correct Answer is Right**
A 10°C decrease in temperature causes a decrease in cerebral metabolic rate due to the reduction in neuronal activity and synaptic transmission. This is mediated through the inhibition of high-energy phosphate production, which is essential for maintaining neuronal function. The decrease in temperature also affects the activity of enzymes involved in glucose and oxygen metabolism, further contributing to the reduction in CMR.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the relationship between temperature and cerebral metabolic rate. A decrease in temperature does not increase CMR.
**Option B:** This option is incorrect because it is too vague and does not specify the mechanism by which temperature affects CMR.
**Option C:** This option is incorrect because it suggests that the decrease in CMR is due to an increase in the activity of certain enzymes, which is not accurate.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that hypothermia can have a protective effect on the brain by reducing its metabolic demands, which can be beneficial in certain clinical scenarios, such as cardiac arrest or traumatic brain injury.
**Correct Answer:** A.