B13.1 Coordination and response

What is a stimuli, a receptor and an effector?

1. Stimuli: changes in organism’s environment

2. Receptors: specialised cells that detect stimuli

3. Effectors: muscles and glands that respond to stimuli

What are the 2 parts of the nervous system called?

• Central Nervous System:

  • Brain and spinal chord

  • Responsible for coordinating all reactions and nervous communication around the body

• Peripheral Nervous System:

  • Nerves in the rest of the body

  • Transmits impulses from CNS to the rest of the body

What are neurones and its 3 main types?

• Specialised cells that carry impulses around the body 

• Types:

  • Sensory

  • Relay

  • Motor

What is the role of a sensory neurone? Identify in a diagram

• Sensory neurones transfer nerve impulses away from receptor cells when a stimulus is detected

Adaptations of a sensory neurone

• Can be long because they may need to transmit nerve impulses from receptors in distant parts of the body towards the spinal cord

• Cell body outside so electrical impulses can move along faster

What is the role of a relay neurone? Identify in a diagram

• Short to connect one neurone to the next (sensory to motor)

What is the role of a motor neurone? Identify in a diagram

• Motor neurones transfer nerve impulses from the brain or the spinal cord to effectors

What are the adaptations of a motor neurone?

• Long, thin fibres of cytoplasm to quickly carry electrical signals

• Have dendrites which are shorter fibres that can pick up electrical signals from nearby neurones and pass them to the axons

• Have axons which are long fibres to communicate neurone to neurone

• Have myelins which insulate axons so the electrical impulses can travel faster

Describe a reflex arc

• Reflex actions are fast, automatic and involuntary

  • 1. Receptors: detect stimulus and converts it into nerve impulse, connects with sensory neurone

  • 2. Sensory neurone: carries electrical impulse from receptor to spinal cord

  • 3. Relay neurone: receives impulse from sensory neurone and passes it to motor neurone

  • 4. Motor neurone: carries impulse away from CNS to the effector

  • 5. Effector: receives impulse and carries out response

What is a synapse?

• Ends of the two neurones and the gap in between is called a synapse