BI 202 September 8 Chapter 7

BI 202 September 8 Chapter 7 - CHAPTER SEVEN: Introduction...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CHAPTER SEVEN: Introduction to the Nervous System Can divide the nervous system into two parts: o Central Nervous System (CNS) Brain and spinal cord o Peripheral Nervous System (PNS) All of the nerves and receptors outside of the CNS Functional units: neurons o o Three primary parts to a neuron Cell body Part of the neuron that has the nucleus and most of the organelles o Ribosomes, golgi apparatus, rough ER o Protein synthesis will occur in the cell body o Lipid synthesis will occur in the cell body Dendrites Transmit information towards the cell body o Conducted in the form of graded potentials most of the time Axon Carries information away from the cell body in the form of action potentials Axon hillock or initial segment: the site of action potential formation Axon terminal: site of neurotransmitter release o Neuron Classification By Function Afferent or Sensory Neurons: carry information (action potentials) toward the CNS o Are unipolar (see Structure) o Efferent Neurons or Motor: carry information away from the CNS o Multipolar (see structure) Interneurons or Association Neurons: carry information within the CNS o Typically also Multipolar o Found in the CNS ONLY By Structure Unipolar or Pseudounipolar neurons: cell body, one axon but no true dendrites o Only one process comes off the axon technically Multipolar Neurons: cell body, axon, many dendrites Bipolar Neurons: can only really be found in retina of the eye o IGNORE for this class!! o Look at one afferent neuron How many efferent neurons will there be for every afferent neuron? Approximately 10 efferent neurons for 1 afferent neuron How many interneurons would there be for those? 200,000 interneurons for 10 efferent and 1 afferent neuron o o Important Definitions (Table 7.1) o Central Nervous System (CNS): brain and spinal cord
Background image of page 1

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

View Full DocumentRight Arrow Icon
o Peripheral Nervous System (PNS): nerves, ganglia, and nerve plexuses (outside of the CNS) o Association neuron (interneuron): multipolar neuron located entirely within the CNS o Sensory Neuron (afferent neuron): neuron that transmits impulses from a sensory receptor into the CNS o Motor neuron (efferent neuron): neuron that transmits impulses from the CNS to an effector organ, for example, a muscle o Nerve: cablelike collection of many axons in the PNS; may be “mixed” (contain both sensory and motor fibers) No nerves in the CNS, called TRACTS in the CNS o Somatic motor nerve: nerve that stimulates contraction of skeletal muscles o Autonomic motor nerve: nerve that stimulates contraction (of inhibits contraction) of smooth
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/12/2012 for the course BI 202 taught by Professor Winn during the Fall '10 term at Northern Michigan University.

Page1 / 6

BI 202 September 8 Chapter 7 - CHAPTER SEVEN: Introduction...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online