Targeted Sensory Organs

Briefly describe the path of information from the targeted sensory organs (eye, ear, skin, and nose) to the brain.

Eye to the brain. pg. 88-89

There are rods and cones in the back of your eye that are in the retina, these are connected to the bipolar cells and a set of nerves called the interneurons. The first step is the bipolar cells to hook up with the ganglion cells that lead out of the eye. From there the axons and the ganglion cells join with the optic nerve carrying messages from the eye to the brain. Next the axons of all of the ganglion cells join to form the optic nerve. This is taken to a place in the eye on the retina called the blind spot. The blind spot is a place where there are no receptor cells, so when light hits it there will be no imagine seen. After the nerves are made into fiber they leave the eye and enter the brain where they split to either side of the brain at the optic chiasm. The nerve fibers from the

pg. 96

When you hear a sound there are six stages that the ear goes through to get that sound that you heard to your brain. The first step is sound going into your external ear, this serves as a channel for the sound to go into. The sound that you hear travels in vibrations. Those vibrations make the eardrum start to vibrate. When the eardrum starts to vibrate it makes three small bones bump into each other and a signal is sent to the inner ear. The signal is then sent to the cochlea, which is the Greek word for snail. In the cochlea there is a fluid, and from all the vibrations it pushes the fluid through the coil. This then activates the receptor cells or the hair cells to send a signal to the brain.

Skin to the brain.

When you touch a hot pan you pull away very quickly because it hearts. The pain that you feel goes through some steps that tells your brain that it is hot. Information goes to the motor cortex in your brain, down the spinal cord, and then to the motor nerves. This is what makes you pull your hand