Chapter 45

Chapter 45 - Chapter 45 Neurons and Nervous Systems Nervous...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 45. Neurons and Nervous Systems Nervous systems are composed of two types of cells: neurons and glia. Neurons: excitable (can generate and transmit action potentials) Axons: long extensions that enable them to conduct action potentials over a long distance. Glia do not conduct action potentials; they support neurons physically, immunologically, and metabolically. Nerve: a bundle of axons coming from many different neurons. Axons wrapped by glia 1. To electrically isolate them. 2. Increase speed of conduction of action potentials Neural network categories: Afferent neurons – carry sensory information into the nervous system. * Information comes from sensory neurons that convert sensory stimuli into action potentials (e.g., light, heat, pressure) Efferent neurons – carry commands to physiological and behavioral effectors such as muscles and glands. Interneurons – communicate between afferent and efferent neurons. Ganglia – clusters of neurons Information transmitted from sensory cells to the CNS and from the CNS to effectors via neurons that extend or reside outside the brain and spinal cord. Peripheral nervous system – neurons outside the brain and spinal cord. Synapses – information passed from one neuron to the next. 1. Presynaptic neuron – sends the information
Background image of page 1

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

View Full Document Right Arrow Icon
Chapter 45. Neurons and Nervous Systems 2. Postsynaptic neuron – receives the information Properties of individual neurons Plasma membranes generate action potentials Four regions: Cell body – contains nucleus and most organelles Dendrites – brings information from other neurons or sensory cells Axon(s) Axon terminals – comes very close but doesn’t touch target cell membrane Synapses can be chemical or electrical * Neurotransmitters – chemical messenger molecules released at axon terminal Bind to receptors on the plasma membrane of postsynaptic cell. Can inhibit or excite postsynaptic cells Glia More glia than neurons in the human brain Come in several forms with different functions Do not generate or transmit electrical signals – but they can release neurotransmitters Types of Glial Cells 1. Oligodendrocytes (in CNS)– wrap around axons; called Schwann cells in PNS . a. Myelin – cover produced; conduct action potentials more rapidly
Background image of page 2
Chapter 45. Neurons and Nervous Systems b. Multiple Sclerosis : most common demyelinating disease; “multiple scars” Causes impaired conduction of action potentials. Autoimmune disease produces antibodies to proteins in the myelin in CNS Motor impairment most common c. Guillain-Barre Syndrome : demyelinating disease affecting the PNS. d.
Background image of page 3

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

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 9

Chapter 45 - Chapter 45 Neurons and Nervous Systems Nervous...

This preview shows document pages 1 - 4. Sign up to view the full document.

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