The Nervous System Flashcards
Describe the central nervous system (CNS)
- consists of the nerves of the brain and spinal cord
- responsible for coordinating information from PNS
Describe the peripheral nervous system(PNS)
- consists of nerves outside of the brain and spinal cord
- Responsible for relaying info between the CNS and the rest of body
What are the voluntary and involuntary components of the PNS?
- voluntary component called somatic nervous system and it relays sensory and motor info
- involuntary component called autonomic nervous system and it relays info between the internal organs of the body and the CNS
Describe glial cells
- supporting cell (non-conducting)
1. Insulate and protect neurons
2. Supply neurons with oxygen and nutrients
3. Facilitate transmission of nervous impulses - retain ability to divide throughout life to replace damaged cells
Schwaan cells
Type of glial cell
- form tightly wrapped layers of plasma membrane called myelin sheaths
- acts as electrical conductors to speed up messaging
- gaps in between called “nodes of Ranvier”
Describe Neurons
Conducting cells
-made up of enlarged cell body and two types of extensions or processes
Dendrite: projection that carries signals toward the nerve cell body
Axon: extension that carries nerve signals away from the nerve cell body
- bundles of axons (extremely thin) form nerve fibres
- nerves branch extensively to relay signals throughout body
Three main groups of neurons
Sensory neurons:
- also known as afferent
- carry info from sensory receptors to CNS
- May occur in clusters called ganglia
Interneurons:
- also known as associate
- major component of CNS
- relay info from sensory neurons to motor neurons
Motor neurons:
- also known as efferent
- carry info from CNS to effectors (muscles, organs, glands…)
Neural circuits/ reflex arc
-connections between axon terminals of one neuron and dendrites or cell body of another for a neuronal circuit
- receptor/afferent neuron/interneuron/efferent neuron/effector
- withdrawal reflex
