Reflexes

Question 1

2.80: How are organisms able to respond to changes in their environment?

Answer 1

Synapse
————————
/ \
Sensory Relay Motor
Stimulus —> Receptor ———————-> ————————-> CNS —————-> Effector —> Response

Receptor detects the stimulus and sends an electrical impulse along the sensory neurone which then travels across the synapse and to the relay neurone through the CNS and across another synapse to the motor neurone which travels to the effector causing a response.

Question 2

2.87: what is the CNS made up of?

Answer 2

The brain and the spinal chord. It is linked to the body by nerves.

Question 3

2.82: what does a co-ordinated response require?

Answer 3

A co-ordinated response requires a stimulus which is detected by a receptor and a response caused by an effector.

Question 4

2.88: what happens when a receptor is stimulated?

Answer 4

The receptor sends an electrical impulse along nerves into an out of the central nervous system. This results in rapid responses.

Question 5

2.89: what is the role of neurotransmitters at synapses?

Answer 5

Neurotransmitters are chemicals that are diffused across the synapse to set off a new electrical impulse in the next neurone. So their role is t carry information from the first neurone to the next.

Question 6

2.90: describe the structure and function of a simple reflex arc.

Answer 6

Structure: Stimuli —> Receptor across sensory, relay, motor —> Effector —> Response (skips the CNS)
Function: quicker response than when travelling through the CNS, protects the body from harm, eg. Burns