Nervous System
The Nervous System functions as a control center and coordinates all actions and reactions, sending immediate and specific information as electrical impulses. Organs of the Nervous System: brain, spinal cord, and nerves The brain uses information received from the nerves to coordinate actions. Thin threads of nerve cells, called neurons, carry messages throughout the body. Sensory nerves carry these messages to the brain through the spinal cord, while motor nerves carry them from the brain to all of the various muscles and glands.
A tiny electrical pulse generates when a neuron is stimulated by heat, cold, touch, sound, or vibrations. Chemicals help carry the electrical pulse from the finger-like projection or dendrites of one neuron to the next cell.
Central Nervous System Central Nervous System is made up of the brain and spinal cord. The brain coordinates all of your body activities. The brain is made up of three parts, Cerebrum, Cerebellum and Brain Stem. The Cerebrum is the largest part of the brain that interprets impulses from senses, stores memory and controls movement. The Cerebellum part of the brain is located behind and under the cerebrum. Cerebellum interrupts stimuli from the eyes, ears, muscles and tendons. It also coordinates voluntary muscles movements and maintains muscle tone as well as maintain balance. The Brain Stem part of the brain extends from the cerebrum and connects to the spinal cord. Here you will find the medulla which controls involuntary actions such as heartbeat, breathing and blood pressure.
Peripheral Nervous System Peripheral Nervous System connects your brain and spinal cord to the rest of the body. The somatic system controls voluntary actions. The autonomic system controls involuntary actions.
Fun facts about the Nervous System There are more nerve cells in the human brain than there are stars in the Milky Way. The left side of the human brain controls the right side of the body and vice-versa. As we get older, the brain loses a gram of brain mass per year.
Your body has 5 senses: vision, hearing, smell, taste and touch Vision light enters your eye and the cornea and lens focus it onto the retina. The light is stimulates two types of cells, rods and cones, in the retina. The rods and cones send impulses to the optic nerve, which carries them to the visual cortex, which interprets the image you see. Hearing when an object vibrates, it produces sound waves necessary for hearing sound. Your outer ear catches sound waves and funnels them down the ear canal to the middle ear. In the middle ear the waves cause the ear drum to vibrate. The vibrations move through tiny bones called, hammer, anvil and stirrup. In the inner ear, vibrations cause fluid in the cochlea to vibrate, stimulating nerve ending. The nerve endings send impulses to the brain, were it is interpreted. The cristae ampullaris and maculae in the middle ear control balance. Smell food and other objects give off molecules into the air. These molecules stimulate nerve cells, olfactory cells, in your nasal passages. These olfactory cells send impulses to the brain where it is interpreted. Touch sensory receptors are found in internal organs and skin. Sensory receptors pick up changes in touch, pressure, pain, and temperature and send impulses to the brain or spinal cord.
A= Cornea - helps focus light rays on the retina THE EYE PUPIL B= Optic Nerve - carries images from the retina to the brain C = Rods & Cones - rods detect movement, cones allows you to see color Vitreous Cavity D= Retina - nerve layer, creates the visual impulse and sends it to the brain E = Lens - focuses light onto the retina IRIS Pupil changes sizes to adjust for the amount of light entering the eye Iris color part of the eye, regulates the amount of light entering the eye
THE EAR A = Eardrum - sound waves cause eardrum to vibrate B= Hammer - vibrations are transferred C = Anvil - vibrations are transferred B C Auditory Nerve E D = Stirrup - rest on the cochlea of the inner ear, smallest bone in the body E = Cochlea - fluid filled structure where vibrations are sent to the brain A D F = Outer Ear - intercepts sound waves and funnels them through the canal G = Middle Ear - consists of the eardrum, hammer, anvil, stirrup Tube H = Inner Ear - cochlea and nerve F G H