the structure of the nervous system. divisions of the nervous system
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The Structure of the Nervous System
Divisions of the Nervous System
The Nervous System:
Central Nervous System
CNSPeripheral Nervous Systems
PNS
Central Nervous System (CNS): - brain
- spinal cord
Peripheral Nervous System (PNS)
• The nerves that connect the CNS to the rest of the body
• The system is subdivided into the somatic and autonomic nervous systems.
Autonomic Nervous System
• Monitors the autonomic functions (breathing, blood pressure, digestion)
• Divided into the sympathetic and parasympathetic nervous systems
Sympathetic Nervous System:
In charge of arousal responses such as
“fight or flight” (helps us deal with
perceived threats)
Parasympathetic Nervous System:
Calms the body and brings it back to a relaxed state
The Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System
HOW DOES THE
NERVOUS SYSTEM WORK?
I. Neuron - The basic building block of the nervous system (a
nerve cell)
• Receive, Carry, and Pass information on to the next neuron
Parts of the Neuron
Dendrites
• Receive information into the cell body.
Soma - cell body of a neuron
Nucleus: the organelle that is located in the center of the cell body of a neuron.
Axon - takes information away from the cell body.
Myelin Sheath: Fatty material that surrounds
some axons•its purpose is to protect the axon
and speed processing.
Axon Terminal: the end of the neuron, it releases neurotransmitters into the synaptic cleft
Neurons
Neuron
Neural Communication:
The Neural Impulse
1. Action Potential
• A brief electrical charge that travels down the axon of the neuron.
2. Neurotransmitters: Chemical messengers that are released into the synapse.a. Examples: Acetylcholine
(movement), Serotonin (mood)
b. Are also found in psychiatric medications and other substances
• Antagonists: block neurotransmitters if you have too much (ex: People with Schizophrenia have 6x the proper level of dopamine!)
• Agonists: mimic neurotransmitters when you don’t have enough (ex: Depression is caused by low levels of serotonin.)
3. Synapse: A space or “junction” between two neurons
• The gap where neurotransmitters are released by one neuron and absorbed by the next neuron
Neurotransmitters
How Do Neurons Communicate?
• First, neurotransmitters are received by the dendrites.
• Then, the information is processed by the soma.
• Next, an action potential occurs, sending information down the axon.
• Finally, neurotransmitters are released at the axon terminal for the next neuron to absorb.
C. Types of Neurons
• Sensory - carry information to the central nervous system from the sensory organs (eye, ear, skin, etc.)
• Motor - carry information from the central nervous system to the muscles and glands
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
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