1. Section A: An Overview Of Nervous Systems
CHAPTER 48
NERVOUS SYSTEMS
Section A: An Overview Of Nervous Systems
Dr. Hesham Sharaf

2. Nervous system Peripheral N.S. Central N.S.
(PNS) composed of peripheral nerves
(CNS) composed of Brain & Spinal cord is responsible for integration
Dr. Hesham Sharaf

3. Nervous systems perform three overlapping functions (sensory input, integration and motor output)
Fig. 48.1, Page 1023
Dr. Hesham Sharaf

4. Networks of neurons build connections to form nervous systems
Neuron Structure and Synapses التشابكات العصبية.
The neuron (nerve cell) is the structural and functional unit of the nervous system.
Nerve impulses are conducted along a neuron.
Dentrite  cell body  axon hillock  axon
Some axons are protected by a myelin sheath.
Axon endings are called synaptic terminals.
They contain neurotransmitters الموصلات العصبية which conduct a signal across a synapse.
Synapse: is the junction between a presynaptic and postsynaptic neuron.
Presynaptic cell: is the transmitting cell.
Postsynaptic cell: is the target cell.
قبل التشابكات
بعد التشابكات
التشابكات
Dr. Hesham Sharaf

5. تفرعات شجرية
الغمد العصبى
Dr. Hesham Sharaf
Fig. 48.2, Page 1023

6. Sensory receptors المستقبلات الحسية: a responsive to external and internal stimuli.
Such sensory input is conveyed to integration centers (CNS) in which the input is interpreted and associated with a response.
Sensory neuron: الخلية الحسية receives information from the sensory receptor (e.g. eye) and passes it to the motor neuron.
Motor output is the conduction توصيل of signals from integration centers (CNS) to effector cells (e.g. muscular cells).
Effector (motor) neuron: carries out the body’s response to a stimulus.
Interneuron الخلية العصبية البينية: intermediate cell between the sensory and motor neuron (exists in spinal cord الحبل الشوكى)
Dr. Hesham Sharaf