Nerve Cells and Nerve Impulses PDF

Nerve Cells and Nerve Impulses CHAPTER 1 Santiago Ramón y Cajal Pioneer of Neuroscience  CN I – Olfactory Nerve, sends sensory information to your brain about smells that you encounter.  CN II – Optic Nerve, sensory nerve that involves vision.  CN III – Oculomotor Nerve, two diff...

Nerve Cells and Nerve Impulses CHAPTER 1 Santiago Ramón y Cajal Pioneer of Neuroscience  CN I – Olfactory Nerve, sends sensory information to your brain about smells that you encounter.  CN II – Optic Nerve, sensory nerve that involves vision.  CN III – Oculomotor Nerve, two different motor functions: muscle function and pupil response. 1. Muscle Function - provides motor function to four of the six muscles around your eyes. These muscles help your eyes move and focus on objects. 2. Pupil Response - helps to control the size of your pupil as it responds to light.  CN IV – Trochlear Nerve - controls your superior oblique muscle. This is the muscle that’s in charge of downward, outward, and inward eye movements.  CN V – Trigeminal Nerve - largest of your cranial nerves and has both sensory and motor functions. The trigeminal nerve has three divisions, which are: 1. Ophthalmic - The ophthalmic division sends sensory information from the upper part of your face, including your forehead, scalp, and upper eyelids. 2. Maxillary - This division communicates sensory information from the middle part of your face, including your cheeks, upper lip, and nasal cavity. 3. Mandibular - The mandibular division has both a sensory and a motor function. It sends sensory information from your ears, lower lip, and chin. It also controls the movement of muscles within your jaw and ear.  CN VI – Abducens Nerve - controls another muscle that’s associated with eye movement called the lateral rectus muscle. This muscle is involved in outward eye movement. For example, you would use it to look to the side.  CN VII – Facial Nerve - provides both sensory and motor functions, including: 1. moving muscles used for facial expressions as well as some muscles in your jaw 2. providing a sense of taste for most of your tongue 3. supplying glands in your head or neck area, such as salivary glands and tear- producing glands 4. sending sensations from the outer parts of your ear  CN VIII - Vestibulocochlear Nerve - sensory functions involving hearing and balance. It consists of two parts, the cochlear portion and vestibular portion: 1. Cochlear portion. Specialized cells within your ear detect vibrations from sound based on the sound’s loudness and pitch. This generates nerve impulses that are sent to the cochlear nerve. 2. Vestibular portion. Another set of special cells in this portion can track both linear and rotational movements of your head. This information is transmitted to the vestibular nerve and used to adjust your balance and equilibrium.  CN IX - Glossopharyngeal Nerve - has both motor and sensory functions, including: 1. sending sensory information from your sinuses, the back of your throat, parts of your inner ear, and the back part of your tongue 2. providing a sense of taste for the back part of your tongue 3. stimulating voluntary movement of a muscle in the back of your throat called the stylopharyngeus  CN X – Vagus Nerve - It has both sensory and motor functions, including: 1. conveying sensation information from your ear canal and parts of your throat 2. sending sensory information from organs in your chest and trunk, such as your heart and intestines 3. allowing motor control of muscles in your throat 4. stimulating the muscles of organs in your chest and trunk, including those that move food through your digestive tract 5. providing a sense of taste near the root of your tongue  CN XI – Spinal Accessory - motor nerve that controls the muscles in your neck. These muscles allow you to rotate, flex, and extend your neck and shoulders.  CN XII – Hypoglossal Nerve - 12th cranial nerve. It’s responsible for the movement of most of the muscles in your tongue. Neuron Fundamental units of the brain and nervous system. Parts and Function of Neuron  Dendrite - receive and process  Nucleus - contains the nucleolus signals from the axons of other and chromosomes, necessary for neurons. Neurons can have more the coded production of proteins than one set of dendrites, known within the cell. as dendritic trees.  Myelin Sheath - allows electrical  Axon - joins the cell body at a impulses to transmit quickly and specialized junction called the efficiently along the nerve cells. axon hillock. Many axons are  Schwann Cell - responsible for insulated with a fatty substance forming the myelin sheath around called myelin. Myelin helps axons the neurons of the peripheral to conduct an electrical signal. nervous system, and supplying  Soma - where the signals from the nutrients to individual axons. dendrites are joined and passed on. Motor Neuron Sensory Neuron  With its soma in the Spinal Cord,  Specialize to one end to be highly receive excitation through its sensitive to a particular type of dendrites and conducts impulses stimulation, such as light, sound or along its axon to a muscle. touch.