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nervous system
and sensory organs
40
Anatomy
Undergraduate 1
12/07/2009

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Term
What do neurons do?
Definition
Neurons transmit nerve impulses along   nerve fibers to other neurons
Term
what are nerves made of?
Definition
Nerves are made up of bundles of nerve   fibers.
Term
what does neuroglia do?
Definition
Neuroglia carry out a variety of   functions to aid and protect components   of the nervous system.
Term
What is the CNS made of?
Definition
the central nervous system (CNS),   made up of the brain and spinal cord
Term
What is the PNS made of?
Definition

and   the peripheral nervous system (PNS), made   up   of peripheral nerves that connect the   CNS to the rest of the body.

Term
What does the nervous system provide?
Definition
The nervous system provides sensory,   integrative, and motor   functions to the   body.
Term
what are motor functions divided into?
Definition
Motor functions can be divided into the   consciously controlled somatic nervous   system and the unconscious autonomic   system.
Term
central nervous system
Definition
brain and spinal cord
Term
peripheral nervous system
Definition

A) cranial nerves arising from the brain

1. somatic fibers connecting to skina nd skeletal muscles

2. autonomic fibers connecting it ciscera

 

 

B) spinal nerves arising from the spinal cord

1. somatic fibers connecting to skin and skeletal muscles

2) autonomic fibers connecting to viscera

Term
Functions of the nervous system (3)
Definition

 

  A.  Sensory receptors at the ends of peripheral   nerves gather information and convert it into   nerve impulses. Impulses sent to brain. 

  B.  When sensory impulses are integrated in the   brain as perceptions, this is the integrative   function of the nervous system.

  C.  Conscious or subconscious decisions follow,   leading to motor functions via effectors.

 

Term
what do neuroglial cells do?
Definition
Neuroglial cells fill spaces, support   neurons, provide structural frameworks,   produce myelin, and carry on   phagocytosis.  Four are in the CNS and   the last in the PNS
Term
What are miccroglial cells?
Definition
Microglial cells are small cells that   phagocytize bacterial cells and cellular   debris.
Term
Oligodendrocytes
Definition
Oligodendrocytes form myelin in the   brain and spinal cord.
Term
Astrocytes
Definition
Astrocytes are near blood vessels and   support structures, aid in metabolism,   and respond to brain injury by filling in   spaces.
Term
Ependyma
Definition
Ependyma cover the inside of   ventricles and form choroid plexuses   within the ventricles.
Term
Schwann cells
Definition
Schwann cells are the myelin-  producing neuroglia of the peripheral   nervous system.
Term
Neuron structure
Definition
A neuron has a cell body with   mitochondria, lysosomes, a Golgi   apparatus, chromatophilic substance   (Nissl bodies) containing rough   endoplasmic reticulum, and   neurofibrils.
Term
Nerve fibers
Definition
Nerve fibers include a solitary axon   and numerous dendrites
Term
Branching Dendrites
Definition
Branching dendrites carry   impulses from other neurons   (or from receptors) toward the   cell body.
Term
The axon transmits the impulse where?
Definition
The axon transmits the impulse   away from the axonal hillock of   the cell body and may give off   side branches.
Term
Larger axons are enclosed by what?
Definition
Larger axons are enclosed by   sheaths of myelin provided by   Schwann cells and are myelinated   fibers.
Term
The outer layer of Myelin is surrounded by what?
Definition
The outer layer of myelin   is surrounded by a   neurilemma (neurilemmal   sheath) made up of the   cytoplasm and nuclei of the   Schwann cell.
Term
Nodes of Ranvier
Definition
Narrow gaps in the myelin   sheath between Schwann   cells are called nodes of     Ranvier
Term
What do the smallest axons lack?
Definition
The smallest axons lack a myelin   sheath and are unmyelinated   fibers
Term
White matter
Definition
White matter in the CNS is due to   myelin sheaths in this area.
Term
unmyelinated nerve tissue
Definition
Unmyelinated nerve tissue in the   CNS appears gray.
Term
Peripheral neurons
Definition
Peripheral neurons are able to   regenerate because of the   neurilemma but the CNS axons   are myelinated by   oligodendrocytes thus lacking   neurilemma and usually do not   regenerate.
Term
how can nuerons be grouped
Definition
  Neurons can be grouped in two   ways:   on the basis of structural differences   (bipolar, unipolar, and multipolar   neurons), and by   functional   differences (sensory neurons,   interneurons, and motor neurons).  
Term
Bipolar neurons
Definition
Bipolar neurons are found in the eyes,   nose, and ears, and have a single axon   and a single dendrite extending from   opposite sides of the cell body.
Term
Unipolar neurons
Definition

Unipolar neurons are found in ganglia   outside the CNS and have an axon and a   dendrite arising from a single short fiber   extending from the cell body.

  

Term
Multipolar neurons
Definition

Multipolar neurons have many

   nerve fibers arising from their   cell bodies and are commonly   found in the brain and spinal   cord.

Term
Sensory neurons (afferent   neurons) 
Definition
Sensory neurons (afferent   neurons) conduct impulses from   peripheral receptors to the CNS   and are usually unipolar, although   some are bipolar neurons
Term
Interneurons
Definition
Interneurons are multipolar   neurons lying within the CNS   that form links between other   neurons.
Term
motor neurons
Definition
Motor neurons are multipolar   neurons that conduct impulses   from the CNS to effectors. 
Term
cell membrane
Definition
A cell membrane is usually polarized,   with an excess of negative charges on   the inside of the membrane; polarization   is important to the conduction of nerve   impulses.
Term
A distribution of ions is determined by:
Definition
The distribution of ions is determined   by the membrane channel proteins   that are selective for certain ions.
Term
Potassium ions more readily...
Definition

 

Potassium ions pass through the   membrane more readily than do   sodium ions, making potassium ions a   major contributor to membrane   polarization.

  

 

Term
Resting potential
Definition

1.  Due to active transport, the cell   maintains a greater concentration of   sodium ions outside and a greater   concentration of potassium ions   inside the membrane.

  2.  The inside of the membrane has   excess negative charges, while the   outside has more positive charges.

  3.  This separation of charge, or   potential difference, is called the   resting potential.

Term
Potential changes
Definition

D.  Potential Changes

  1.  Stimulation of a membrane can locally   affect its resting potential.

  2.  When the membrane potential becomes   less negative, the membrane is   depolarized.

  3.  If sufficiently strong depolarization   occurs, a threshold potential is achieved   as ion channels open.

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