1: When you enter the kitchen, you smell and see freshly baked chocolate chip cookies cooling on a plate. You know you shouldn't eat one because you're trying to lose weight, but you decide to eat one anyway, so you reach out to grab one. By the time they reached your mouth, you started to salivate. Particles from the cookies enter your nose and are deposited on the olfactory mucosa by binding to olfactory receptor proteins on olfactory receptor neurons. When these particles bind to the receptor, the protein changes shape, which causes an action potential in the neuron. This signal travels along the olfactory nerve (cranial nerve 1) to the olfactory bulb in the brain. From the olfactory bulb, neurons are sent to many different areas, including via the anterior olfactory cortex to the priform cortex which is primarily used to identify odor. Neurons are also sent to the amygdala, which is associated with social functions such as partner identification (this is a more primary instinctive use of smells). Neurons are also sent to the entorhinal cortex which links the odor to a specific memory. This is why smells make you think of things from the past. Visually, light from the cookies enters your eye and causes a reaction in the photosensitive retinal ganglion cells in the retina. This causes an action potential in the optic nerve. Most neurons move to the lateral geniculate nucleus located in the thalamus (some neurons move to other areas as described in question 2). This serves as a relay and processing center. The signal is then sent via “optical radiation” (a bundle of neurons in the brain) to the visual cortex. The visual cortex processes the information that the eye sees. The orbitofronta...... middle of paper ......y nerve (ipsilateral side). This causes the foot to suddenly move away from the source of pain. Additionally, the sensory nerve synapses with a motor neuron on the contralateral anterior horn (opposite side). This contralateral motor neuron stabilizes the uninjured leg. This way, when the foot is removed, the other side can help balance and support the weight of the body. Along with all this, the sensory neuron sends a signal down the spinal cord. This signal is used to tell the body to move the center of gravity away from the injured side so that the person does not tip over. This entire process of controlling contralateral motor neurons to stabilize the body is called the cross-extension reflex. The process of seeing the bleeding is done by the optic nerve via the lateral geniculate nucleus and the visual cortex as described in question. 1.