Unit 6 Flashcards
What is a receptor ?
Specialised cells or proteins in cell membrane which detects a stimulus.
They are specific to one type is stimulus
What is a stimulus ?
A change in the internal or external environment
What is an effector ?
Cells which produce a response to a stimulus.
They include muscles and glands
How many neurones does a simple reflex arc consist of ?
What are the names of these neurones?
Only 3 neurones used:
Sensory, relay and motor
What is the order of a simple reflex arc ?
Stimulus
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Give the importance’s of a reflex arc
- Rapid and automatic
- Protects against/prevents damage to body tissues
- Do not have to be learnt/innate
- Help escape from predators
- Enable homeostatic control
What is the function of a sensory neurone ?
Transmit impulses from receptors to the CNS or relay neurone
What is the function of a relay neurone ?
Transmit/carries impulses from sensory to motor neurone
What is the function of a motor neurone ?
Transmit/carries impulses from CNS/relay to the effectors
What is taxis ?
Directional response
Organisms move towards or away from a directional stimulus e.g. light
Positive taxis: move towards favourable stimulus
Negative taxis: move away from unfavourable stimulus
What is kinesis ?
Non directional response to a stimulus
Organism shows random movement
Both the speed and frequency of direction change increase
What is tropism ?
A response in a flowering plant to a directional stimulus
Plants respond to this stimulus by regulating their growth
