Why Do Multicellular Organisms Need To Respond To Their Environment

Question 1

Receptor

Answer 1

A receptor is a part of a cell or organ that responds to a specific signal such as light, heat or a particular chemical.

Question 2

Thermorecpetor

Answer 2

A receptor that responds to heat and cold.

Question 3

Stimulus

Answer 3

Anything that activates a sensory cell in the nervous system or a response in the endocrine system.

Question 4

Central Nervous System (CNS)

Answer 4

The brain and spinal cord.

Question 5

Peripheral Nervous System (PNS)

Answer 5

All parts of the Nervous System apart from the brain and spinal cord.

Question 6

Neuron

Answer 6

A single nerve cell.

Question 7

Effector

Answer 7

A structure or organ that brings about a response.

E.g. Muscles and glands

Question 8

Cell body

Answer 8

The enlarged part of a neuron that contains the nucleus.

Question 9

Dendrite

Answer 9

The branching neuron extension that brings impulses towards the cell body.

Question 10

Axon

Answer 10

The neuron extension that conducts impulses away from the cell body.

Question 11

Myelin Sheath

Answer 11

A fatty covering around the axon that insulates it.

Question 12

Synapse

Answer 12

A tiny gap separating two neurons.

Question 13

Neurotransmitter

Answer 13

A chemical that defuses across synapses to transmit a message.

Question 14

Presynaptic membrane

Answer 14

The membrane that releases neurotransmitters.

Question 15

Postsynaptic membrane

Answer 15

The membrane that receives neurotransmitters.