Response To Changes In Environment. Flashcards
Define stimulus.
A change in internal or external environment.
Define receptors.
Specialised cells or proteins in cell membranes which detect stimuli - they are specific to one type of stimuli.
Define effector.
Cells which bring about a response to a stimuli.
Define sensory neurons.
Transmit impulses from receptors to the CNS or relay neuron.
Define motor neurons.
Transmit impulses from CNS/rely to the effectors.
Define relay neurons.
Transmits impulses from sensory to motor neurons.
Which part of the nervous system controls unconscious activities?
Autonomic Nervous System.
Define reflex.
A rapid, automatic response which does not need to be learnt.
Describe the process of the reflex arc.
- Receptors detect stimuli.
- Sensory neuron sends an impulse to the spinal cord via the dorsal root.
- Relay neuron connects the sensory neuron to the motor neuron.
- Motor neuron sends impulse to an effector via the ventral root.
- Effector receives impulse and carries out movement.
Give 5 importance’s of a reflex arc.
- Rapid.
- Protect against damage to body tissues.
- Do not have to be learned.
- Help escape from the predators.
- Enables homeostasis control.
Define taxes.
Organisms move towards or away from a directional stimulus.
What is the difference between a positive and a negative taxis?
Positive taxis are when organisms move towards stimulus, whereas negative taxis are when organisms moves away from stimulus.
Define kinesis.
The organisms’ movements is affected by a non-directional stimulus.
How does an organism respond to a kinesis?
By increasing speed of movement and more rapid change in direction, both slow down when favourable conditions are met.
