Nervous System Part 1 Flashcards
What are the functions of the Nervous system?
Sensory input, integration, motor output
What is the central nervous system composed of?
Brain and spinal cord
What is the function of the central nervous system?
Integration, interpreting incoming sensory information, and issuing outgoing information
What is the Peripheral nervous system composed of?
Nerves
What is the function of the spinal nerves?
To carry impulses to and from the spinal cord
What is the function of the cranial nerves?
To carry impulses to and from the brain
What is the function of the peripheral nervous system?
To serve as communication lines among sensory organs, brain, spinal cord, and glands or muscles
How is the PNS organized?
Sensory (afferent) Division and Motor (efferent) Division
What is the function of the sensory division?
carry info to the CNS
What is the function of the motor division?
Carry info away from the CNS
What are the subdivisions of the Motor Division?
Somatic and Autonomic
What is the function of the Somatic Nervous System?
Consciously controls muscles
What is the function of the Autonomic Nervous System?
Automatically controls smooth and cardiac muscles and glands
What is the Autonomic Nervous System divided into?
Sympathetic and Parasympathetic
What are the functions of Support Cells?
Support, insulate and protect neurons
What do astrocytes do?
Star-shaped cells that brace neurons, form a barrier between neurons and capillaries, and control the chemical environment of the brain
What do microglia do?
Spiderlike phagocytes that dispose of debris
What do ependymal cells do?
Line the cavities of the brain and spinal cord; cilia assist with the circulation of cerebral spinal fluid
What do oligodendrocytes do?
Wrap around nerve fibers in the CNS, produce myelin sheaths
What do satellite cells do?
Protect neuron cell bodies
What do Schwann cells do?
Form myelin sheath in the PNS
What is the function of Neurons?
Transmit messages
What is the Nissl Bodies
Specialized endoplasmic reticulum
What are the neurofibrils?
Intermediate cytoskeleton, maintains shape
What are the dendrites?
Long extensions conduct impulses toward the cell body
What are the Axons?
conduct impulses away from the cell body and have only one axon arising from the cell body at the axon hillock
What is the Axon Terminal?
The end of Axons that contain vesicles with neurotransmitters
What is the Synaptic Cleft
Gap between adjacent neurons
What are Synapses?
The junction between nerves
What are Synapses?
The junction between nerves
What is the Myelin Sheath?
Whitish, fatty material covering axons, composed of Schwann cells, nodes of ranvier, and oligodendrocytes
What are Schwann cells?
produce myelin sheaths in jelly roll-like fashion around axons (PNS)
What are the nodes of ranvier?
Gaps in the myelin sheath along the axon
What are Oligodendrocytes?
Cells that produce myelin sheaths around axons of the CNS
Where are most neurons located
The CNS
What is gray matter?
cell bodies and unmyelinated fibers
What are nuclei?
clusters of cell bodies within the white matter of the central nervous system
What are glanglia?
collections of cell bodies outside the central nervous system
What are Sensory (afferent) neurons?
Carry impulses from the sensory receptors to the CNS
What are Motor (efferent) neurons?
Carry impulses from the central nervous system to viscera, muscles, or glands
What are Interneurons (association neurons)?
Found in neural pathways in the central nervous system and connect sensory and motor neurons
What are multipolar neurons
many extensions from the cell body, All motor and interneurons are multipolar, Most common structure
What are bipolar neurons?
One axon and one dendrite
What are unipolar neurons?
Have a short single process leaving the cell body
What are the properties of neurons?
Ability to respond to stimuli and transmit an impulse
When is the plasma membrane polarized?
At rest
What is the extracellular ion at rest?
Sodium
What is the intercellular ion at rest?
Potassium
What is depolarization?
The stimulus depolarized the membrane, and sodium channels opened, causing sodium to enter the membrane
What is action potential?
the movement of ions initiates an action potential due to a stimulus
How does action potential transmit?
If enough sodium enters the cell, the action potential starts and is sent through the entire axon
How do nerves repolarize?
Potassium ions rush out of cells after sodium ions rush in
How are signals transmitted at the synapses?
1.) When the action potential reaches the axon terminal, the electrical charge opens calcium channels 2) Calcium causes the tiny vesicles containing the neurotransmitter chemical to fuse with the axonal membrane 3.) Entry of calcium into the axon terminal causes pore-like openings to form, releasing the transmitter 4.) Neurotransmitted molecules diffuse across the synapse and bind to receptors on the membrane of the next neuron. 5.) If enough neurotransmitter is released, the graded potential will be generated-> an action potential will occur in the neuron beyond the synapse. 6.) The electrical changes prompted by neurotransmitter bindings are quick-> neurotransmitter is quickly removed from the synapse
