Nervous system Flashcards
What does the CNS consist of?
- Brain
2. Spinal cord
What does the PNS consist of?
- Cranial nerves(from the brain)
2. Spinal nerves(from the spinal cord)
What is the function of the sensory neuron?
Transmits nerve impulses from the sense organs to the CNS
What is the function of the relay neuron?
Transmits nerve impulses from the sensory neuron to the motor neuron through the synapse.
What is the function of the motor neuron?
Transmits nerve impulses from the CNS to the effectors.
What is the function of cell body?
Cell body contains the nucleus, cytoplasm and organelles.
What is the function of dendron?
Nerve fibres that transmit nerve impulses towards the cell body are called dendrons. The end branches of the dendron are called dendrites.
What is the function of the axon?
The nerve fibres that transmit impulses away from the cell body are called axons.
What is the function of the Myelin sheath?
The layer of fatty substances enclosing many nerve fibres is the Myelin sheath. It insulates the axon.
What is the function of the Node of Ranvier?
The regions where myelin sheath are absent are called Node of Ranvier. Nerve impulses cannot be transmitted through the myelin sheath, so they ‘jump’ from one node to another. In this way, they help speed up the transmission of impulses along the neuron.
What is reflex action?
A reflex action is an immediate response to specific stimulus without conscious control.
What is reflex arc?
A reflex arc is the shortest pathway by which nerve impulses travel form the receptor to the effector in a reflex action.
