Additional Physiology Review Study Guide for McGraw-Hill's ASVAB
The senses are sight, hearing, touch, taste, and smell. There are specialized organs for each sense.
Sight Let's suppose that you are looking at an object. Light waves from that object enter the eye first through the cornea (a transparent section of the eye) and then through the pupil, the opening in the iris. Light waves are brought to convergence first by the cornea, and then by the lens. The lens directs the light through the vitreous humor (a gelatinous substance) onto the retina. The retina has two types of cells, rods and cones. Rods detect light intensity, and cones respond to color. At this point, the light waves are changed to electrical signals and then sent along the optic nerve to the brain. The brain then interprets the signals as the picture of the object.
Some people have vision problems. Two typical problems are nearsightedness and farsightedness. Nearsighted people have trouble seeing distant objects. Farsighted people have trouble seeing things that are close up. Nearsighted people can have their vision corrected with a concave lens, and farsighted people can have their vision corrected with a convex lens.
Hearing Sound is vibrating air. Vibrating air creates sound waves. These waves can pass through solids, liquids, and gases to eventually reach your ear. When the sound waves reach your ear, they stimulate nerve cells that send signals to the brain. The brain interprets these signals as sound.
The ear is made up of several different parts, each contributing to the process of transforming sound waves into signals. The ear has three basic sections: the outer ear, the middle ear, and the inner ear. The outer ear traps the sound waves and sends them down the ear canal to the middle ear, where the eardrum creates a vibration. This vibration then moves to some tiny specialized bones called the hammer, anvil, and stirrup. The stirrup bone rests against a membrane in the inner ear. The inner ear contains the cochlea, which is filled with fluid and is shaped like a snail. The cochlea vibrates when the stirrup vibrates, bending little hairs in the cochlea. The vibrating hairs send electrical signals to the brain, which in turn translates the signals into various sounds.
The semicircular canals in your inner ear are also responsible for maintaining your balance.
Smell Substances such as food, perfume, and gases give off molecules into the air. These molecules stimulate some nerve cells in your nose. These nerve cells are called olfactory cells. The olfactory cells are moist from mucus. Molecules are dissolved in the mucus, and, if there are a sufficient number of these molecules, a signal is sent to the brain. The brain then interprets these signals. If you have smelled this before, you may recognize the smell as a hamburger with onions, pumpkin pie, or your mother's favorite perfume.
Taste There are about 10,000 taste buds on your tongue. When you take food into your mouth, it begins to dissolve in liquid, your saliva. The mixture of saliva and food washes over your taste buds and stimulates the nerve fibers in the taste bud. The nerve fibers send a signal to your brain, and your brain translates the taste as sweet, sour, salty, bitter, or the taste of MSG (monosodium glutamate). The sense of smell and the sense of taste are related to each other.
Touch Your skin also has receptors allowing you to determine if something is hot, cold, rough, smooth, painful, hard, soft, and so on. The receptors send a signal to the brain, which in turn interprets the signals.
- Coats and Car Seats: A Lethal Combination?
- Kindergarten Sight Words List
- Child Development Theories
- Signs Your Child Might Have Asperger's Syndrome
- 10 Fun Activities for Children with Autism
- Why is Play Important? Social and Emotional Development, Physical Development, Creative Development
- The Homework Debate
- Social Cognitive Theory
- First Grade Sight Words List
- GED Math Practice Test 1