Biology Chapter 14: Coordination and response

What travels along the neurones

Electrical impulses

Describe the mammalian nervous system

• Central Nervous System ( CNS) -Brain and spinal cord

• Peripheral nervous system (PNS) -nerves outside brain and spinal cord

What is the role of nervous system ?

Coordination and regulation of body functions

Describe the 3 neurones

• Sensory ( from sense organs ( or receptors ) to CNS )

• Relay ( from sensory neurones CNS to Motor neurones CNS)

• Motor ( from CNS to effectors)

Describe a simple reflex arc

• Receptors dectect stimulus and generate impulse

• It travels to sensory neurone, then relay neurone , then to motor neurone then to the effector

What is a reflex action

Automatically and rapidly integrating and coordinating stimulus with the responses of effectors ( muscles and glands)

What is a synapse ?

A junction between two neurones

Describe the structure of a synapse

• The presence of vesicle containing nerotransmitter molecules

• The synaptic gap

• Receptor protein

Describe the events at a synapse

• An impulse stimulates the release of neurotransmitter molecule from vesicles into the synaptic gap

• The neurotransmitter molecules diffuse across the gap

• The neurotransmitter molecules bind with receptor proteins on the next neurone ( complementary to each other)

• An impulse is then stimulated in the next neurone

Statement about the function of synapse

• Synapse ensures that impulses travel in one direction only

• Because the vesicles containing the neurotransmitter are only present in the presynaptic neurone, while the receptors are only present in the presynaptic neurone

• Impulse cannot go backwards