Final answer:
When feeling cold, thermoreceptors such as Krause end bulbs detect the temperature change and send signals through the spinal cord, thalamus, and finally to the primary somatosensory cortex. Intense cold sensations may also trigger pain responses due to shared pathways, and the body takes actions like shivering to maintain core temperature.
Step-by-step explanation:
When you feel something that's cold, the sensation is detected by thermoreceptors in your skin, particularly through structures called Krause end bulbs that are sensitive to cold temperatures. These receptors are also located in the dermis, skeletal muscles, liver, and hypothalamus.
From the initial sensory receptor sites, the cold sensation is transmitted via nerve fibers to the spinal cord and then travels through the thalamus to the primary somatosensory cortex in the brain. In the case of cold sensations from the face, this information is transmitted via a cranial nerve.
If the cold stimulus is intense, it may also be perceived as pain because pain sensations and temperature sensations share common neural pathways. Moreover, it's important to consider that your body has several mechanisms, such as shivering and reducing blood circulation to extremities, to maintain homeostasis and thereby protect core body temperature against the cold.
Conduction also plays a role when you step onto a colder surface, such as a tile floor, from a warmer one, like a carpet, due to different rates of heat transfer that enhance the sensation of cold.