Nervous System Flashcards
What is the nervous system?
The nervous system allows the body to respond to changes in the environment in a process usually coordinated by the brain.
What are reflex actions?
Reflex actions are extra-rapid responses to stimuli; this process involves the nervous system but bypasses the brain.
What are receptors?
They are groups of specialised cells that can detect changes in the environment called stimuli.
Give some examples of receptors and what they are sensitive to.
Eyes are sensitive to light.
Ears are sensitive to sound and the positioning of the head.
The tongue is sensitive to chemicals in food.
The nose is sensitive to chemicals in the air.
The skin is sensitive to touch, pressure, pain and temperature.
What are neurones?
Neurones are nerve cells that carry information as tiny electrical signals.
What are the three different types of neurones?
Sensory
Relay
Motor
What is the job of the sensory neurone?
Sensory neurones carry signals from receptors to the spinal chord and the brain.
What is the job of the relay neurone?
Relay neurones carry messages from one part of the central nervous system to another.
What is the job of the motor neurone?
Motor neurones carry signals from the central nervous system to effectors.
What is a synapse?
Where two neurones meet there is a tiny gap called a synapse. Signals cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal.
What happens when a receptor is stimulated?
It sends a signal to the central nervous system where the brain coordinates the response; but sometimes a very quick response is needed, one that does not involve the brain: this is called a reflex action.
What is the sequence of a simple reflex action?
Stimulus - Receptor - Sensory Neurone - Relay Neurone - Motor Neurone - Effector
What is an effector?
Any part of the body that produces the response.
Give two examples of effectors.
- A muscle contracting
- A gland releasing a hormone
