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Describe the nervous System?
- The master control and communication center of the body
- and controls cells of the body using nerve cells called neurons and chemical and electrical signals
What are the functions of the Nervous System?
- Sensory Input
- Motor Output
Monitoring changes in the chemical environment ( iNside and outside of the body)
Processing and interpreting the information and making a decision about how to respond
The response usually involving control of muscles and glands
Central Nervous System
CNS- the integration and command center to include the brain and spinal cord
Peripheral Nervous System
PNS-The sensory (afferent) and motor (efferent) nerves that receive/relay information to organs and glands communication lines
(sensory)- carry toward
(motor)- carry away
Somatic Nervous System
Voluntary movement or control using skeletal muscles
Autonomic Nervous System
(ANS)- involuntary actions including digestion, heart rhythm, breathing and other subconscious commands
Sympathetic Nervous sysem
- The accelerator system for flight or fight
- Hype up
Parasympathic Nervous System
- The brake system for fight or flight
- Calms down
What is the nervous tissue made up of?
- The active cells that transmit electrical and chemical signals
- extreme longevity if given nutrition
- Amitotic (dont divide or replace)
- High Metabolic rates (require continuous supplies of oxygen and glucose
- Conduct impulses from one part of body to another
- The structural unit of nervous system
(Glial Cells) The cells that support and maintain neurons
What are some of the Neurogila in the CNS?
- Ependymal cells
- most abundant
- attaches to capillaries and to neurons and their synaptic endings
What are Astrocytes function?
- determines capillary permeability
- the migration of young neurons and in synapse formation
- Deects neuron injury and differentiates into macrophages which engolf dead cells, pathogens and debris
- Defensive cells
the cavities of the brain and spinal cord and when ciliated, aids in the movement of the cerebrospinal fluid (produced by this cell)
- Covers the axons of the nerves in the CNS and formsan insulating covering called the Myelin sheath.
- Helps speed up
What are the Neuroglia in the PNS?
- Satellite Cells
- Schwann Cells
- Surrounds cell bodies of the nerves and aids in gathering nutrients for the Neurons
- (Simillar to the Astrocytes in CNS)
- Surround the axons of neurons and forms the myelin sheath and aids in the regeneration of damaged peripheral nerve fibers
- (Similiar to the Oligodendrocytes in the CNS)
- The Cell Body or Prokaryon
- contains the nucleous and the majority of the cytoplasm and organelles
The rough ER of a neuron is called
- Maintain the cell shape and integrity
- Bundles of intermediate filaments within the cell body
What are clusters of cell bodies within the CNS called?
What are clusters of cell bodies within the PNS called?
What are processes?
- They extend from the cell bodies of all neurons
- Myelin Sheath
What are the bundles of Neuron processes within the CNS called?
What are the bundles of Neuron processes within the PNS called?
- Short branching extensions that act as a receptor for incoming inforation and convey info toward cell body
- May contain spiky dendritic spines which are points synapse with other neurons
- uses graded potential to relay info to cell body
A long single process that directs information away from the cell body toward the synaptic terminal (other end of the axon)
A long axon is called
a branched axon contains terminal branches (telodendria) with axon terminals
The ___1___ generates nerve impulses at the _____2______ along the _____3______ to the _______4_____ where neurotransmitters are secreted into the __________5_________ to excite or inhibit another neuron or some organ or gland.
- 1. Axon
- 2.Axon hillock (next to cell body)
- 3. Axolemma (plasma Membraine)
- 4. Axon terminal
- 5. Synaptic cleft (extracelluar space)
What does the Axon lack?
- Nissl Bodies and the Golgi apparatus
- and proteins must be made and transported from the cell body through the length of the axon and items for degredation and recycling must be transported back to the cell body
A whitish fatty segmented covering that protects nerve fibers (axons) and electrically insulates the fiber to speed up nerve impulses
Regions of the brain and spinal cord that contain dense collections of myelinated fibers are referred to as
Regions of unmyelinated fibers are referred to as
Which propagate impulses faster Myelinated or Unmyelinated fibers?
The sheath cells wrap around the axon the exposed portion is called the............
Nodes of Ranvier
- One sheath cell does not connect to its neighbor forming gaps along the axon that are not covered.
- This is where axon callaterals can emerge and the signal is propagated in leaps rather than small steps
What are the Structural Classifications of Neurons?
- Mutipolar Neurons
- Bipolar Neurons
- Unipolar Neurons
- Contains 3 or more processes with only one axon.
- 99% of all neurons
- are the major neuron type of the CNS
- Contains an axon and a dendrite that extend from opposite sides of the cell body
- Located in the optic and olfactory areas
- A single process that divides into a distal and proximal branch where the distal branch is normally associated with a sensory receptor (peripheral process) and the central process entering the CNS
- should be considered as a single long axon that propagates info to the CNS
What are the Functional Classifications of Neurons?
- (Afferent) receives sensory stimuli and propagates that info to the CNS
- unipolar with sensory ganglia outside the CNS
- (Association Neurons) Receives info from sensory Neurons, Processes that info, Makes a decision which it propagates to motor neurons.
- Multipolar Neurons residing within the CNS
- (Efferent) receives info on the decision and responds (usually by inhibiting or exciting a musccle group)
- Multipolar with cell bodies located within the CNS
A Nerve Impulse
Or Action Potential is an electrical impulse that is generated in and conducted through the length of the axon
energy that is stored, that has the potential to do work
for cells- the charge difference across the cell membraine
- is the difference in charges separated by some device (semipermeable membrane)
- The greater the potential difference the higher the Voltage
- when work is done and the potential is relieved, the charge difference is increased or decreased
- (in motion)
Is the energy generated by a separation of charges
Is the flow of electrical charge (electrons or ions) from one point to another for the purpose of doing work
Is the opposition to flow of electrons or ions from one point to another that decreases the current and is determined by the material for which current passes through
- is a poor electrical conductor
- rubber, plastic, plasma membrane
- Is a good electrical conductor
- Metal, water, Open ion channels
Proteins, Nucleic acids and potassium within the cell to give the inside of the cell a net negative charge in respect to the more positive, sodium- dominated extracellular fluid
Ion Channels can _________1_________a potentialdifference across the________2________.
- 1. Increase or decrease
- 2. Membrane
What are the ion channels?
- These channels within the membrane are selective for a particular ion to pass and may allow these ions to pass only under certain circumstances.
are always open (not gated or closeable)
open when a chemical stimulus binds to the channel, otherwise it remains closed
Open and close in respones to changes in the Membrane Potential
Open in respone to physical deformation of the receptor
Ion Channels allow substances to cross the membrane when open to follow their _______________________________ and prevent transport of those ions when closed.
is the desire of positive and negative to attract one to one another
is the desire of an equilibrium of chemicals such that a high concentration of a substance moves to an area of lower solute concentration following its own Kinetic energy