BIOL 109 1st Edition Lecture 11Outline of Last Lecture I. Describe the three kinds of musclesII. List the four traits that all muscle types have in commonIII. Attachment Outline of Current Lecture I. Two main divisions of the nervous systemII. Neuron and neuroglial cells function and structureIII. Three major categories of neuronIV. Myelin sheath Current LectureI. Nervous system: - Receives input form the surrounding world- Processes that information - Initiated responses to the environment when necessary - In all verberbrates, the nervous system is divided into two components: The central nervous system -Made of the spinal cord and the brain -The central nervous system processes information that is receives from sensory cells about the organism’s surroundings and sends out instructions toother nervous tissue to act in response.Peripheral nervous system- Network of sensory cells that receive information from the environment and - The cells that transmit signals to effectors, the organism’s muscles and glandsII. Cells of the Nervous system The nervous system is composed of two types of specialized cells: - Neurons – excitable cells that generate and transmit messages- Neuroglial cells (glial cells) – more numerous and provide structural support, nourishment, and insulating sheaths around the nerves. Able to reproduce, unlike neuronsIII. Function and structure These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Types of Neurons: - Sensory Neurons- carry information toward the CNS from sensory - Motor neurons – carry information away from the CNS to muscle or gland- Interneurons- located between sensory and motor neurons within the CNS, where they integrate and interpret signals. Account for more than 99% of the body’s neuronsStructure : the shape of a typical neuron is specialized for communicating with other cells. It has: - Dendrites – many short, branching projections (one or more). Carry information toward the cell body of a neuron - Axon – single long extension of the neuron (one). Carries information away from the cell body- Axon terminals – releases chemicals called neurotransmitters that affect the activity of nearby neurons or muscle or gland - Cell body (one) which contains the nucleus and other organelles, and functions tomaintain the neuron- ONLY TRAVEL IN ONE DIRECTION !Nerves: - Consist of parallel axons, dendrites, or both from many neurons- Covered with tough connective tissue- Classified as sensory, motor or mixed (sensory and motor together) depending onthe type of neurons they contain Neurons :-Most axons are electrically insulated by a myelin sheath which increases the rate of conduction of a nerve impulse-Schwann cells form the myelin sheath, insulating in and allowing messages to travel faster as they jump from one node of Ranvier to the next in a type of transmission called salutatory conduction IV. Myelin sheaths – the fatty coating that surrounds axons – are white, so areas of the brain rich in axons appear white. Brain regions rich in cell bodies and dendrites appear gray-The lack of myelin on an axon can be seen in babies when they first start trying towalk - At the time, myelin hasn’t completely formed around all of their axons and their gross motor control isn’t very