Nervous system Flashcards
Central Nervous System (CNS)
What does this contain?
Spinal cord, brain, neural tissue, Connective tissue, blood vessels
Function of the Central Nervous System (CNS)
Sensory Data, Motor Commands, Higher Functions
Peripheral Nervous System (PNS)
What does this contain?
Cranial Nerves
Spinal Nerves
What are the functions of the Peripheral Nervous System (PNS) ?
Delivers sensory information to the CNS
Afferent Division (sensory info only)
PNS sensory receptors to CNS
Interoceptors
Internal Environment
Externoceptors
External Environment
Proprioceptors
Body Position
Efferent Division (Motor commands only)
CNS to PNS
Somatic (skeletal)
Controlling voluntary/involuntary skeletal muscles contraction
Autonomic
Subconscious Actions
Sympathic
Fight or flight stimulate
Parasympathic
Relax
Neurons
Functional unit
How does a Neuron flow?
In One Direction (toward the cell body)
Axon hillock
Initial segment (thick)
Colladerals
Branch of a single axon
Telodendria
Extension of the distal axon
Synaptic terminal
Tips of the Telodendria
Ana
Absence
Anaxonic
Small dendrites axons also look alike
Bipolar
Small, 1 large dendrite, 1 main large Axon
Unipolar
Very long axon, fused dendrites and axons
Where are Anaxonic found in?
Brain, sense organs
Where are bipolar found in?
Sensory organs
Where are multipolar found in?
CNS
Multipolar
Very long axon, many dendrites
What is the function of sensory?
Afferent PNS, signals to CNS
What is the function of Motor units?
Efferent PNS, Takes signals to effectors
where are Interneurons found?
Only found in CNS
What is the function of Ependymal Cells in the CNS?
Form epithelial tissue lining the central channel
What is the function of Astrocytes in the CNS?
Creates framework and scar tissue
These also are projections that wrap capillaries to form the blood brain barrier which isolated the CNS.
What is the function of Oligodendrocytes in the CNS?
Insulates axons
Increase speed of propagation
Makes the axon white
What is the function of Microglia in the CNS?
Clean up things that do not belong
What is the function of Satellite in the PNS?
Regulates the environment around the neurons.
What is the function of Schwann Cells in the PNS?
Forms the Myelin sheath
Produces myelin or separates Axons
If a Injury occurs to the PNS…
Distal Axons degenerate and Schwann cells replicate.
If a injury occurs to the CNS…
Limited repair, no regrowth, scar tissue, astrocytes release chemicals that prevent growth.
Neurons conduct information through..
Action Potentials
Action Potential
Sodium-Potassium Exchange Pump
Electro-Chemical Gradiant
When Na+ wants to enter the cell
When k+ wants to exit the cell
Positive ion entering cell (less neg)
Action potential
Positive ion leaving the cell (more neg)
No Action Potential
Passive channels are..
Leak channels that are always open
Active Channels are..
Gated channels that open and close with stimuli
What are the 3 types of active channels
Close inactivated (locked)
Close capable to open (unlocked)
Open
Repolarization
When a stimulus is removed, transmembrane potential returns to normal
Hyperpolarization
further away from resting potential K+ channel opens
Action Potential Steps
- ) Depolarzation to threshold
- ) Activation of Na+ channel
- ) Inactivate of Na+ channel, K+ channels activated
- ) return to normal permeability K+ channel close at -70 mv
Absolute Refractory Period
No AP Possible, Na+ Open or Inactive
Relative Refractory Period
Large Stimulus 2nd AP
What do Anesthetics do?
Locks all Na+ channels in inactive sites
Continuous Propagation Steps
- ) Action Potential
- )Depolarize second segment to Threshold (Develop AP)
- ) First Segment Refractory Period
- ) Local Current Depolarization Next Segment
What is a Salutary Propagation?
Myelinated Axon, faster/less energy
Nodes of Ranvier
Local Current Jumps Node to Node
Larger Axon Diameter
High Speed
Myelinated Axon
High speed
Synapse
Junction, Neuron and Cell
Presynaptic
Sends a message
Postsynaptic
Receives a Message
Synaptic Cleft
Gap increases
Electrical Synapse has..
Direct Connections, Gap Junctions
Chemical Synapse
No Direct Connections, neurotransmitters, AP Not Guaranteed
Steps of a Synapse
- ) AP Arrives, Depolarizes Synaptic Knob
- ) Ca2+ Channels Open and Dumps ACh
- ) ACh Bind to receptors, Depolarizes Postsynaptic
- ) ACh. Removed By Enzyme AChE
Synaptic Delay
.2-.5 Milliseconds
Acetylcholine
SM (excitory) CM (inhibit)
Norepinephrine
Brain/ ANS (excitory)
Dopamine
Both Excitory and Inhibtory CNS
Serotonin
Excitory CNS
Gamma Aminobutyncacid (GABA)
Inhibtory CNS
Neuropeptides
Bind to receptors which activate enzymes
Opiods
Found in CNS, Relieves pain
Inhibition
Further Away From Threshold
Facilitation
Raised Closer Toward Threshold
Temporal Summation
Many Times
Rapid, Repeated Stimuli at 1 Synapse
Spatical Summation
Many Locations
Many Stimuli At Many Synapse