sense organs and their functions pdf
Sense organs for kindergarten
The eyes are the first organ we have that helps us perceive our environment. We use them to see things around us and they allow us to see colors, shapes, movement, and size. Our eyes are located at the front of our head and are composed of two parts; the cornea and the lens. The cornea is the clear outer layer of the eye that refracts light rays coming into the eye. The lens focuses these rays onto the retina where the optic nerve connects to the brain. The retina is the innermost lining of the eye that contains photoreceptors (rods and cones) that detect light. These photoreceptors send signals to the brain via the optic nerve.
Our nose detects odors and identifying smells. It is composed of three sections; the olfactory bulb, the nasal cavity, and the sinuses. The olfactory bulb is located inside the brain and is connected to the limbic system. The limbic system controls emotions and memory. The nasal cavity is the passageway between the nostrils and the back of the throat. The sinuses are air-filled cavities behind each cheekbone. The sinus cavities help warm and moisten incoming air before it enters the lungs.
The tongue is a muscular structure that is attached to the roof of the mouth. Its primary function is to taste food and drink liquids. I divided the tongue into four distinct regions; the tip, sides, root, and back. The tip is the pointy end of the tongue and is used to identify tastes. The sides are the sides of the tongue and are used to identify textures. The root is the base of the tongue and is primarily used to identify temperature. The back is the largest portion of the tongue and is mainly used to identify flavors.
Ears are on either side of the head and are responsible for hearing sounds. There are three types of ears; external, middle, and internal. External ears are located outside of the skull and are used to hear high frequencies. Middle ears are located inside the skull and are used for low frequency sounds. Internal ears are located inside the cranial cavity and are used to hear both high and low frequencies.
Skin is the largest organ of the body and is composed of three layers; epidermis, dermis, and hypodermis. The epidermis is the top layer of skin and is made up of dead cells called keratinocytes. Keratinocytes are constantly being shed off of the surface of the skin and replaced with new ones. The dermis is the second layer of skin and is composed of connective tissue, blood vessels, hair follicles, sweat glands, and oil glands. The hypodermis is the deepest layer of skin and is comprised of fat, muscle, bone, and cartilage.