The Nervous System (chpt. 33) Flashcards
What is the nervous system made up of
Central nervous system (CNS)
Peripheral nervous system (PNS)
What makes up CNS
Brain + spinal cord
What makes up PNS
Neurons
Stimulus
A change to the environment that can cause a response
Steps to respond to a stimulus
- Reception - stimulus is detected
- Transmission - message passed along neurons
- Integration - messages are sorted and processed to decide on a response
- Response - carried out by effectors when stimulated by neurons
Neurons
A nerve cell
Role of sensory neuron
Carry impulses from sense organs to CNS
Role of motor neuron
Carry impulses from CNS to efector
Role of interneuron
Link sensory with motor neutrons
Smallest type
Role in neuron: dendrite
Carry impulses to cell body
Role in neuron: axon
Carry impulses away from cell body
Axon - Away
Role in neuron: cell body
Make neurotransmitter cells
Contains nucleus and organelles (mitochondria)
Role in neuron: myelin sheath
Insulated the message
Speeds up transport
Role in neuron: Schwann cell
Produce myelin sheath
Role in neuron: node of ranvier
Gaps in myelin sheath which speed up transport of message
Role in neuron: neurotransmitter swellings
Release neurotransmitters
Describe the transmission of nerve impulses across the synapse
- neurotransmitters activated by ions
- released into synapse
- impulse passed to next neuron
- transmitter remains for a short period of time before it is inactivated by enzyme
- it is then reabsorbed and its parts are reused
Threshold
The minimum stimulus required to start a nervous impulses
All or nothing law
The size of the stimulus has no effect on the size of the impulse
How is the speed of the message increased
Wide diameter axons
Myelin sheath
Refactory period
The length of time needed by a nerve cell to recover before it can pass a second impulse