Problem 4 - Biology of Humans: Concepts, Applications, and Issues

Question

The area of the sensory cortex in the cerebrum devoted to each part of the body a. is exactly the same as the area of the motor cortex devoted to each region of the body. b. depends on how far away that region of the body is from the brain. c. is greater for regions of the body that are most sensitive to touch. d. is smaller on the left cerebral hemisphere than on the right cerebral hemisphere.

Step-by-Step Solution

Answer

Option c is correct. The area of the sensory cortex is greater for regions of the body that are most sensitive to touch.

Step 1 - Understand the Question

The question asks about the area of the sensory cortex in the cerebrum devoted to different parts of the body. It provides four different options, and the task is to identify the correct one.

Step 2 - Analyze Option A

Option a suggests that the area of the sensory cortex is exactly the same as the area of the motor cortex devoted to each region of the body. Review if there is any scientific basis for this.

Step 3 - Analyze Option B

Option b suggests that the sensory cortex area depends on the distance of the body region from the brain. This needs to be evaluated based on anatomical knowledge.

Step 4 - Analyze Option C

Option c states that the area of the sensory cortex is greater for regions that are most sensitive to touch. Consider what is known about the sensory homunculus and the fact that more sensitive areas like the hands and face occupy larger portions.

Step 5 - Analyze Option D

Option d suggests the area is smaller on the left cerebral hemisphere than on the right. Reflect on whether there is lateralization in terms of the sensory cortex area.

Step 6 - Choose the Correct Answer

Summarize the evaluation of the options. Option c is consistent with the understanding of the sensory homunculus where sensitive regions like hands and lips have more representation in the sensory cortex.

Key Concepts

sensory homunculus

The sensory homunculus is a visual representation of the sensory cortex mapping in the brain. It illustrates how different body parts are represented by different regions of the primary somatosensory cortex. This mapping is quite specialized, reflecting the areas that are more sensitive to touch. Regions such as the hands, lips, and face have larger representations on the sensory homunculus compared to less sensitive areas like the back or legs. This difference in representation sizes stems from the density of sensory receptors in each body part. For instance, the hands and lips are rich in touch receptors, making them extremely sensitive. The sensory homunculus helps us understand why these areas of the body can detect fine textures and subtle touch stimuli more effectively.

cerebral cortex

The cerebral cortex is the outer layer of the cerebrum and is critical for many high-level brain functions, including sensation, perception, memory, association, thought, and voluntary physical action. In terms of sensory information processing, the cerebral cortex is where the primary somatosensory cortex is located. This region of the brain is specifically involved in processing tactile information from the body. It's divided into different areas, each responsible for processing sensory information from different parts of the body. These areas work in tandem to interpret the external world accurately. The cerebral cortex is divided into two hemispheres - the left and the right - and each hemisphere is responsible for sensory information from the opposite side of the body.

somatosensory system

The somatosensory system is a network that enables the body to perceive physical sensations. It involves a series of receptors spread throughout the skin, muscles, and joints that detect stimuli such as pressure, temperature, and pain. The information collected by these receptors is transmitted to the spinal cord and then to the brain for processing. Once this information reaches the sensory areas in the cerebral cortex, particularly the primary somatosensory cortex, it is interpreted and recognized as a specific sensation. This process allows us to respond to our environment effectively, helping us navigate and interact with the world around us. The functionality and efficiency of the somatosensory system are crucial for our daily activities and overall survival.