The Nervous System Flashcards
What do cells called receptors detect?
Stimuli (changes in the environment)
Which receptors detect which stimuli?
Receptors in the eyes that are sensitive to light
Receptors in the ears that are sensitive to sound
Receptors in the ears that are sensitive to changes in position and enable us to keep our balance
Receptors on the tongue and in the nose that are sensitive to chemicals and enable us to taste and to smell
Receptors in the skin that are sensitive to touch, pressure , pain and to temperature changes
What do light receptor cells have?
Nucleus
Cytoplasm
Cell membrane
What are neurones and what types of neurones are there?
Neurones are nerve cells. They carry information as tiny electrical signals. There are three different types of neurones, each with a slightly different function:
sensory neurones carry signals from receptors to the spinal cord and brain.
relay neurones carry messages from one part of the CNS to another.
motor neurones carry signals from the CNS to effectors.
What is synapse and what does it do?
Where two neurones meet, there is a tiny gap called a synapse. Signals cross this gap using chemicals released by a neurone. The chemical diffuses across the gap makes the next neurone transmit an electrical signal.
What does the nervous system enable humans to do?
To react to their surroundings and coordinates their behaviour
What happen one the neurone receives an impulse?
When receptors sense a change, the sensory neurone sends an electric impulse from the receptor to the spinal cord or brain
The brain then decides what to do
Motor neurones carry impulses from the CNS to effector organs which may be muscles or glands.
The muscles respond by contracting.
The glands respond by secreting (releasing) chemicals
Describe a simple reflex system
Impulses from a receptor pass along a sensory neurone
At a junction (synapse) between a sensory neurone and a relay neurone in the central nervous system, a chemical is released that causes an impulse to be sent along a relay neurone
A chemical is then released at the synapse between a relay neurone and a motor neutrons in the nervous system, causing impulses to be sent along the motor neurone to the organ (the effector) that brings about the response
The effector is either a muscle or a gland, a muscle responds by contracting and a gland responds by releasing (secreting) chemical substances
What happens with the information from the receptors?
They pass along cells (neurones) in the nerves to the brain coordinates the response. Reflexes actions are automatic and rapid. They often involve sensory, relay and motor neurones
What is a reflex?
It is a fast, automatic respond that occurs without conscious thoughts
