neurophysiology of the central nervous system dr. loai alzghoul loai.physiology@yahoo.com
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Neurophysiology of the central nervous system
Dr. Loai AlzghoulLoai.physiology@yahoo.com
Organization of the nervous system
Organization of the nervous system
Levels of the CNS
1) Spinal cord2) Brain stem and sub cortical3) Cerebral cortex
3 Major Levels of CNS Function
• The spinal cord level.– more than just a conduit for signals from
periphery of body to brain and vice versa.– cord contains:
• walking circuits.• reflexes circuits.
The brain stem and subcortical
• Contains:– medulla, pons, mesencephalon,
hypothalamus, thalamus, cerebellum and basal ganglia.
• Controls subconscious body activities:– arterial pressure, respiration, equilibrium,
feeding reflexes, emotional patterns.
The Higher Brain or Cortical Level
• Higher order functions : language, thoughts and personality
• Large memory storehouse.• Each portion of the nervous system
performs specific functions, but it is the cortex that opens the world up for one’s mind.
Organization of the Nervous System
• Sensory Division– tactile, visual, auditory, olfactory.
• Motor Division– respond to and move about in our
environment.• Integrative Division
– process information, creation of memory.
Figure 45-2
SomatosensoryAxis of the Nervous System
Figure 45-3
Skeletal Motor Nerve Axis of the Nervous System
Terminology:
Afferent
VS
Efferent
Terminology:
1st order , 2nd order and 3rd order neurons
Histology of the NS
NeuronStructure
Types of neurons
Neuroglia
Neuroglia
Myelination
Neuroglia
Myelination
In PNS = Schwann cell
Neuroglia
Form the blood-cerebrospinal fluid barrier
Neuroglia
Neuroglia
Phagocytize
Neuroglia
Astrocytes
Astrocytes
Astrocytes
1) Support for neurons
2) Form the blood –brain barrier
3) Maintain the prober environment for the neurons
Nervous tissue
Nervous tissue
Gray matter : neuron cells White natter: myelinated axons
Synapses and Neurotransmitters
Communication Between Neurons
• Synapse:
Communication Between Neurons
• Synapse: A specialized site of contact, and transmission of information between a neuron and an effector cell
Figure 45-5
Anterior Motor Neuron
Communication Between Neurons
• Electrical synapse
Communication Between Neurons
• Electrical synapse Chemical synapse
Communication Between Neurons
• Chemical synapse
Neurotransmitter: is a messenger of
neurologic information from
one cell to another.
Synaptic Transmission
Action of Neurotransmitter on Postsynaptic Neuron
• postsynaptic membrane contains receptor proteins for the transmitter released from the presynaptic terminal.
• The effect of neurotransmitter on the post synaptic neuron depend on the type of the receptor
Action of Neurotransmitter on Postsynaptic Neuron
• Two types of receptors– Ion channels receptors
Action of Neurotransmitter on Postsynaptic Neuron
• Two types of receptors– Ion channels receptors– Second messenger receptors
Ion Channels receptors
• transmitters that open sodium channels excite the postsynaptic neuron.
• transmitters that open chloride channels inhibit the postsynaptic neuron.
• transmitters that open potassium channels inhibit the postsynaptic neuron.
Seconded messenger receptors(as example G-protein)
Ion Channel
1. Opening specific ion channels
2. Activation of cAMP or cGMP
3. Activation of one or more intracellular enzymes
4. Activation of gene transcription.
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