Responding to the Environment Flashcards
What is any change in temperature, light intensity or pressure called?
A stimulus
What is tactic response?
Directional movement in response to a stimulus.
The direction of the stimulus affects the response.
What is kinetic response?
Non-directional (random) movement in response to a stimulus.
What are receptors?
Receptors detect stimuli- they can be cells, or proteins on cell surface membranes.
What are effectors?
Cells that bring about a response to a stimulus, to produce an effect.
Receptors communicate with effectors via the nervous system or the hormonal system, or both.
What are the three main neurones?
Sensory neurone
Motor neurone
Relay neurone
What is the role of the sensory neurone?
Transmit electrical impulses from receptors to the central nervous system (CNS).
What is the role of the motor neurone?
Transmit electrical impulses from the CNS to effectors.
What is the role of the relay neurones?
Transmit electrical impulses between sensory neurones and motor neurones.
Give the simple 5 step sequence to nervous communication.
Stimulus Receptors CNS Effectors Response
What are the chemicals that allow for a signal to cross a synapse?
Neurotransmitters.
Why is a nervous response short lived?
When an electrical impulse reaches the end of a neurone, neurotransmitters are secreted directly onto cells so the response is localised.
Neurotransmitters are quickly removed once they’ve done their job.
Electrical impulses are very fast.
What is a simple reflex?
A simple reflex is a rapid, involuntary response to a stimulus , the pathway of response goes through the spinal cord but not the conscious parts of the brain so its automatic.
What is the reflex arc?
The pathway of neurones linking receptors to effectors in a simple reflex is called a reflex arc.
Three neurones are involved: a sensory neurone, a reflex neurone and a motor neurone.
What is a gland?
A group of specialised cells that are specialised to secrete a useful substance, such as a hormone e.g the pancreas secretes insulin.