Nervous System and Reflex Assignment - KNES 191A LAB The...

Info icon This preview shows pages 1–2. Sign up to view the full content.

KNES 191A LAB: The Nervous System & Reflexes INTRODUCTION The function of the nervous system, among other things, is communication between the various regions of the body, coordination of body functions (as in digestion and walking), orientation to the environment, and assimilation of information. The neuron , or nerve cell, consists of three main parts, the axon , the dendrite , and the nerve cell body , or soma . The receptive end of the neuron is the dendrite or the nerve cell body. Dendrites are so named because they have branching structures that resemble a tree ( dendros = tree). DIVISIONS OF THE CENTRAL NERVOUS SYSTEM The nervous system can be divided into two general divisions based on location. The central nervous system (CNS) consists of the brain and spinal cord. The peripheral nervous system (PNS) is composed of 12 pairs of cranial nerves and 31 pairs of spinal nerves. The peripheral nervous system has an afferent, or sensory, division and an efferent, of motor division. The afferent division conducts impulses from the regions of the body to the central nervous system. The efferent division conducts impulses from the central nervous system to the various regions of the body. The efferent division has two subunits – the somatic motor nervous system , which takes impulses from the CNS and innervates muscles, and the autonomic nervous system (ANS), which innervates glands, smooth muscle, cardiac muscle, and organs. The ANS has centers in the central nervous system ( midbrain, pons, medulla oblongata , and the spinal cord ) and has peripheral branches that function independently and provide automatic controls for activities normally under subconscious direction. When you walk upstairs, your heart rate increases automatically, along with your breathing rate, without your having to think about controlling these activities. FUNCTIONS OF NEURONS There are three types of neurons based on function. Afferent or sensory, neurons conduct impulses to the central nervous system. They convey information from the external or internal body environment to the spinal cord and/or the brain. Efferent, or motor, neurons conduct impulses away from the central nervous system. Association neurons, or interneurons , occur between afferent and efferent neurons. They also transmit information to the brain for processing.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 2
This is the end of the preview. Sign up to access the rest of the document.
  • Fall '15
  • MicheleBarr
  • Michele L. Barr

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern