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Nervous System
The master controlling and communicating system of the body
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Functions of the nervous system (3)
- Sensory input (stimuli)
- Integration (interpretation)
- Motor output (response)
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The two principal cells of the nervous system
Supporting Cells
Neurons
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Supporting Cells
Cells that surround and wrap neurons
Not invovled in communication and controlling
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Neurons
Excitable cells (neuroglia and glial cells) that transmit electrical signals.
Signaling cells can react
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Astrocytes (stars)
Most abundant, versatile (has many functions), and highly branched glial cells
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Function of Astrocytes
- Without astrocytes neurons cannot live
- Support and brace neurons
- Anchor neurons to the nutrient support
- Guide migration (brings neursons together to make tracks)
- Control the chemical environment
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Microglia
Glia cell, small, ovoid cells with spiny processes
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Phagocytes
Monitor the health of neurons
Eat foreign bugs that come into the brain
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Ependymal Cells
Glial cell, line the cavities in brain
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Oligodendrocytes
Covers neurons tail in the central nervous system (brain and spinal cord)
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Schwann Cells (neurolemmocytes)
Surround neurons tail in the PRN (peripheral nervous system)
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Satellite Cells
Surround neuron cell bodies with ganglia
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Nerve Cells
Structural units of the nervous system
Composed of body, axon, and dendrites
Amitotic (dont divide) long lived
No centrioles
Has well developed Nissl bodies (rough ER)
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Multiple Sclerosis (MS)
Deteration of Schwann Cells
Autoimmune Disease
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Node of Ranvier (Neurofibral Nodes)
Gabs in the myelin sheath between adjacent Schwann cells
Distribute elecity to the next node
Increases speed
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Saltatory Conduction
Jumping of electrical activity from node to node
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Action Potentials are triggered....
Only at the nodes and jump from onbe node to the next
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Voltage-gated Na+ channels are concentrated at
In the gaps between the nodes
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Multipolar neurons
Three or more process (multidirection)
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Bipolar neuron
Two processes (2 directions)
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Unipolar neuron
Single, short process (1 direction)
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The three functional neurons
- Sensory (afferent)
- Motor (efferent)
- Interneurons (association neurons)
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Sensory (afferent) neurons
transmits stimuli to toward the CNS
Stimuli to brain
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Motor (efferent) neurons
Carries impulse away from the CNS
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Intermeurons (association neurons)
- Shuttle signals through the CNS pathways
- In spinal cord
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Central Nervous System (CNS)
Composed of the brain and spinal cord
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Cephalization
Formation of the brain in uterus/fetal
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Three parts of the brain
- Cerebal hemispheres
- Cerebellum
- Brain Stem
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Cerebral Hemispheres
Make up 83% of the brain
Contains peaks (gyri) and shallow vallies (sulci)
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Cerebral Cortex
Outside of the cerebral hemisphere
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Brain Stem
Consists of midbrain, pons, and medulla oblongata
Controls automatic behaviors necessary for survival
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Cerebellum
Makes up 11% of the brain's mass
Plays a fole in language and problem solving
Center of balacing
Ceremellum Ataxia- cannot move
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Meninges
Three layers that surround the brain and spinal cord
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The three connective tissue membraines that lie external to the CNS
- Dura mater
- Arachnoid mater
- Pia mater
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Blood-brain barrier
Shields the brain from harmful substances.
Consist of three layers and fluid
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Two things that can pass through the blood-brain barrier
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Three functions of Cerebrospinal Fluid (CSF)
Prevents brain from crushing
Protects the CNS from trama
Nourishes the brain and carries chemical signals
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Vertebral column
Encloces the CNS tissue
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Spinal Nerves are located in the________ and contains____pairs.
Peripheral Nervous System
31
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Epidural Space
Space between the vertebrae and tghe dural mater and it is filled with fat and a network of veins
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Paralysis
Loss of motor function
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Transection
Stright horizontal break of the spinal cord, leads to paraplegia and quadripelgia
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Peripheral Nervous System (PNS)
Outside the brain and spinal cord
Toward the side
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Autonomic Nervous System
Cannot control, involuntary
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Somatic Nervous System
Controled, voluntery
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Two parts of the Autonomic nervous system (ANS)
Sympathetic and Parasympathetic
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Parasympathetic
Mobilizes the body during extreme situations
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Sympathic
Performs maintenance activties and conserves body energy
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How many pairs of cranial nerves are there?
12
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The 31 pairs of spinal nerves
- 8 cervival
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coocylgeal
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Reflex Arc
rapid, predictable motor responce to a stimulus
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