Flashcards
5. Nervous System
Cards in this deck (38)
- 1Characteristics of the Nervous SystemFast acting control system
Responds to internal and external change (Stimuli)
Activates muscles and glands - 2—
- 3—
- 4—
- 5Neurons = nerve cells JobMajor regions of neurons
Cell body – nucleus and metabolic center of the cell
Processes – fibers that extend from the cell body - 6What does the Cell body contain? Nucleus
Mitochondria - 7What does the Extensions outside the cell body contain? Dendrites – conduct impulses toward the cell body
Axons – conduct impulses away from the cell body - 8Nerve Axon Coverings Schwann cells – produce myelin sheaths in jelly- roll like fashion
Nodes of Ranvier – gaps in myelin sheath along the axon - 9Axons Starts at the axon hillock
Axons end in axonal terminals
Axonal terminals contain vesicles with neurotransmitters
Axonal terminals are separated from the next neuron by a gap - 10Axonal terminals gaps Synaptic cleft – gap between adjacent neurons
Synapse – junction between neurons - 11Neuron Cell Body Location p.1. Most are found in the central nervous system
Gray matter – cell bodies and unmyelinated fibers - 12Neuron Cell Body Location p.2. Nuclei – clusters of cell bodies within the white matter of the central nervous system
Ganglia – collections of cell bodies outside the central nervous system - 13Key Terms related to the Neuron• Neuron – Dendrites – Cell body – Axon – Myelin sheath – Schwann cells – Axon terminals – Synapse – Neuromuscular junction
• Neuroglia
– Supporting cells in the
CNS “nerve glue” - 14Functional Classification of Neurons Motor (efferent) Carry impulses from the
central nervous system
Signals muscles to move - 15Functional Classification of Neurons Sensory (Afferent) Carry impulses from the
sensory receptors
Cutaneous sense organs
Proprioceptors – detect stretch or tension
Tells you what is happening in your body - 16Two Functional Classification of Neurons?Sensory (Afferent)
Motor (efferent) - 17Three Structural Classification of Neurons?Multipolar
Unipolar
Bipolar - 18Multipolar neurons– many extensions from the cell body, most common
- 19Unipolar neurons– have a short single process leaving the cell body, sensory
- 20Bipolar neurons– one axon and one dendrite, rare in adults eye & ear
- 21Interneurons (association neurons) Found in neural pathways in the central nervous system
Connect sensory and motor neurons - 22Functional Properties of NeuronsIrritability – ability to respond to stimuli
Conductivity – ability to transmit an impulse (electricity)
The plasma membrane at rest is polarized
Fewer positive ions are inside the cell than outside the cell - 23Resting Membrane PotentialThe plasma membrane of a neuron at rest is polarized.
Fewer positive ions are inside the cell than outside the cell - 24Resting Membrane PotentialSlightly more positive ions outside the cell compared to inside.
As long as the inside stays more negative
will be inactive
 - 25Resting Membrane Potential Major ions inside and out?Major positive ion inside the cell is K
Major positive ion outside the cell is Na+
 - 26Importance of Resting Membrane Potential
- 27Starting a Nerve ImpulseDifferent stimuli excite neurons to become active and produce an impulse.
Most neurons are excited by neurotransmitters from other neurons
Regardless of type of stimuli the result is the same - permeability of the membrane alters - 28Starting a Nerve Impulse p.1 Normally very small amounts of Na+ diffuse through the membrane
Na+ concentration higher outside cell than inside cell
With adequate stimulation sodium gates open - 29Starting a Nerve Impulse p.2 Na+ rushes into the cell (no Na+ entry no action
potential)
Na+ changes membrane polarity - inside more positive
This is called depolarisation - 30The Action Potential p.1 If the action potential (nerve impulse) starts, it is propagated over the entire axon and never goes part way along axon
Immediately after Na+ rushes in membrane permeability changes again. - 31The Action Potential p.2 Membrane become impermeable to Na+ but permeable to K+. Remember more K+ inside cell than outside.
Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane - 32The Action Potential p.3 Repolarisation restores the membrane electrical conditions to resting.
The sodium-potassium pump restores the original configuration of Na+ and K+
This action requires ATP - 33Nerve Impulse Propagation p.1 The impulse continues to move away from the cell body
This shows events in an unmyelinated axon
Impulses travel faster when fibers have a myelin sheath
Impulses travel faster when fibers are large - 34Nerve Impulse Propagation p.2 Impulses travel faster when fibers have a myelin sheath
Nerve impulse jumps from node of Ranvier to node of Ranvier along the length of the axon
No electrical current can flow across the membrane where there is fatty myelin insulation
This is called Saltatory conduction - 35Continuation of the Nerve Impulse between NeuronsImpulses are able to cross the synapse to another nerve
Neurotransmitter is released from a nerve’s axon terminal
The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter
An action potential is started in the dendrite - 36The synapse stage 1,2,31. Action potential arrives
2. Vesicle fuses with plasma membrane
3. Neurotransmitter is released into synaptic cleft - 37The synapse stage 4,5,64. Neurotransmitter binds to receptor on receiving neurone's membrane
5.
6. - 38—
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- 5 HAP 1 Flashcards on 5. Nervous System, created by Jonathan Cash on 10/08/2015.
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- Jonathan Cash
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