Nervous System

1. Nervous System Sagar Patel Mustafa Azam SanjnaChoshi SrutiSomani

2. Functions of the Nervous System • The basic function of the nervous system is to send signal from one part of the body to another using different organs. • The nervous system consists of the brain, ear, eyes, brain stem, nerves, spinal cord, taste buds, and olfactory cells.

3. Olfactory Cells • They are sensory cells that are receptors of smells. • They are found in your nose.. • All olfactory cells are made up of basal cells that reproduce olfactory cells when they die. • The olfactory epithelial cells are the only group of neurons capable of regeneration. • Olfactory cells can detect smells in the air. • When the saliva in your mouth mixes with food and smells travel from your nose to your throat, the olfactory cells are stimulated. • First, the smells go to your olfactory bulb from your olfactory nerves. • In the olfactory bulb, all the different smells are recognized and sent to the brain through olfactory nerves.

4. Tastebuds • You might call the little knobs dotting the surface of your tongue taste buds, but those are papillae. The actual taste buds cluster together in packs of 2 to 250 within the papillae. • The taste buds consist of up to 100 cells, either receptor or basal. • They are not only found on your tongue, but also on the roof of your mouth. • They are the receptors of taste and are able to detect four basic tastes: salty, sweet, bitter, and sour. • Usually, the taste buds close to the tip of your tongue are sensitive to sweet tastes, whereas those in the back of the tongue are sensitive to bitter tastes. • The taste buds on top and on the side of the tongue are sensitive to salty and sour tastes. • At the base of each taste bud there is a nerve that sends the sensations to the brain. • The number of taste buds varies substantially from individual to individual, but greater numbers increase sensitivity.

5. Ears • Three Sections- • Inner Ear • Middle Ear • Outer Ear • Sound waves travel through the ear canal and hit the eardrum. • The eardrum then starts vibrating. These vibrations are then passed on to the hammer. The hammer then transfers the vibrations to the anvil and then to the stirrup. • Vibrations are passed from the stirrup to the cochlea where small hairs bend detecting the volume of the noise. • In the final phase electrical impulses are sent to the brain over the Auditory nerve. The brain then processes and interprets the sound received.

6. Eye • Without light seeing through the eye is not possible. • Eyes allow us to see objects, color, and shadows. • To have vision, light first enters the eye through the corona. The light waves then move through the pupil a round opening in the Iris. The pupil regulates the amount of light entering the eye by expanding or closing. Then light hits the eye’s lens which bends the light and flips it 180 degrees. The light then comes in contact with the retina and is put back into focus. Inside the retina the light is converted to electrical impulses that are sent to the brain through the optic nerve. The brain the interprets the information received.

7. Spinal Cord • The spinal cord heals slower than the rest of the body. • Spinal column • The spinal cord is made up of 31 segments and 31 spinal nerves. • Usually 45 cm long. • The spinal cord is the pathway that the brain sends messages to the rest of the body. • Conducts information from the body.

8. Nerves • Located all over the body. • Made up of neurons. Cell body, dendrites, myelin sheath, and axon. • Sensory neurons, motor neurons, and interneurons. • Pass electrical and chemical messages from neuron to neuron.

9. Brain Stem • The brain has 4 main parts: • Cerebrum-largest part of the brain. It sits on top of the rest of your brain. It has a folded grey surface, which has a pattern that’s different for each person. The cerebrum has 4 main lobes-frontal, parietal, occipital, & temporal lobes. Frontal controls speech, thought, emotion, and movements. The parietal lobe interprets sensations (touch, temperature, and pain). The occipital lobe detects & interprets visual images. On both sides of the cerebrum are the temporal lobes are involved in hearing and storing memory. The cerebrum is split into two halves (called hemispheres) that connect with each other. • Cerebellum-second largest part of your brain. It’s underneath the back of your cerebrum & coordinates control of balance & muscles to allow movements. • Diencephalon-is beneath the middle of your cerebrum and on top of your brain stem. It contains the thalamus and the hypothalamus. Thalamus-sends sensory nerve impulses to the appropriate regions of the brain for processing. It lets the brain know what’s happening outside of the body. Hypothalamus-keeps conditions inside the body constant by regulating body temperature, thirst, hunger, and by controlling the release of hormones from the pituitary gland. • Brain stem-controls when you feel sleepy or awake, reflexes, & crucial life functions like heart rate, breathing, digestion, and blood pressure

10. Brain • The brain is a jellylike mass of fat and protein that weighs about 3 pounds. It’s one of the body's biggest organs, having about 100 billion nerve cells. These put together thoughts and highly coordinated physical actions &regulate our unconscious body processes, such as digestion and breathing. • The brain is really sensitive and delicate. The skull & three tough membranes called meninges protect it. There is fluid between the spaces of the membranes so that it can cushion the brain and keep it from being damaged by contact with the skull. • It’s pale grey & the size of a small cauliflower.

11. Interactions Between Other Organs • Eyes and ears tell where you are. • Brain, spinal cord, and nerves tell body what to do. • Olfactory cells and taste buds helps you to eat food.

12. Interactions Between Other Systems • Cardiovascular system • Immune system • Respiratory system

13. Bibliography • Human Ear. (n.d.). In Encyclopedia Britannica. Retrieved September 17, 2012, from Encyclopedia Britannica. • Human Nervous System. (n.d.). In Encyclopedia Britannica. Retrieved September 17, 2012, from Encyclopedia Britannica. • Chudler, E. (1996, July). The Spinal Cord. Neuroscience for Kids. Retrieved from http://faculty.washington.edu/chudler/spinal.html. • Budgell, B. (2009, February). Nerve Structure and Function. BMHLinguistics. Retrieved from http://www.bmhlinguistics.org/joomla2/introductory-human-biology/nerve-structure-and-function. • Brain. (n.d.). National Geographic. Retrieved September 18, 2012, from http://science.nationalgeographic.com/science/health-and-human-body/human-body/brain-article/ • Organs-Brain. (n.d.). Science: Human Body & Mind. Retrieved September 18, 2012, from http://www.bbc.co.uk/science/humanbody/body/factfiles/brain/brain.shtml