Nervous System - Term 1 Y9 Flashcards
What does the nervous system do? How does it do it?
The nervous system is the body system that sends messages around the body regarding the external environment. Messages are sent via electrical impulses that run along the nerves. The nervous system is split into two sections: the CNS (central nervous system) and PNS (peripheral nervous system).
What is the CNS (central nervous system) and the PNS (peripheral nervous system)?
- The central nervous system (CNS) is composed of the brain and spinal cord. They receive process and respond to sensory information.
- The peripheral Nervous System (PNS) is comprised of three types of neurons; sensory neurons, motor neutrons and interneurons (which are sometimes known as relay neurons).
What is the structure of a nerve cell?
A nerve cell is comprised of a cell body, dendrite, axon and myelin sheath. Dendrites are branches that receive messages from other nerve cells. This message is then sent to the cell body where the nucleus is located. Messages are sent via impulses which are then carried through the axon. The axon is protected by the myelin sheath.
What is the Reflex Arc?
The reflect arc refers to the body’s reflexes. This occurs when a person acts on an impulse before that impulse reaches the brain - the spinal cord makes this decision.
How does the Reflect Arc work?
1)Receptors detect a change in stimulus.
2)This information is sent to the spinal cord through the sensory neuron.
3)The spinal cord sends the response (rather than the brain)
4)This response reaches the effector through the motor neuron.
5)The response is given by the effector (muscle of the organ)
What are the types of neurons?
- Sensory neurons: transmit messages from sensory organs to the central nervous system.
- Interneurons: transmit messages from sensory neurons to motor neurons.
- Motor neurons: transmit messages from the central nervous system to “effectors” such as muscles and glands to initiate a response.
