1.12-14.Sinsitivity and responding to stimuli

Question 1

What is stimulus?

Answer 1

Anything your body is sensitive to including changes detected inside of the body.

Question 2

What do receptor cells do?

Answer 2

They detect stimulus and create impulses that trivial to the brain. The brain processes the information and sends impulses to other organs to change the way the body works.

Question 3

What is neurotransmission?

Answer 3

The transmission of impulses along neurons or nerve cells.

Question 4

How do impulses travel through a neurons? (6 steps)

Answer 4

1. Receptor cells detect stimulus
2. Stimulus creates impulses
   3.Impulses travel along the neurons
3. Neurons have a cell body and long extensions called Dendrons and their dendrites collect impulses from receptor cells
   Impulses moves along the Dendron, past the cell body to the axon
4. Pass along axon to the endings
5. Where it passes to other neurons

Question 5

What is the CNS and what does it do.

Answer 5

The central nervous system which is made up of the spinal cord and brain and contains many nerves packed together.
CNS is linked to sense organs by nerves.
CNS is bundles of neurons packed together.

Question 6

What do sense organs do?

Answer 6

The detect change inside and outside your body

Question 7

What happens in response to the brain receiving impulses from receptor cells?

Answer 7

In response, impulses are sent to effectors (muscles and glands) and these carry out the action.

Question 8

Name and explain the three different neurons.

Answer 8

1. Sensory neurons(long Dendron +axon) - neurons that receive impulses from receptor cells.
2. Motor neurons(no Dendron, dendrites on cell body)-neurons that take impulses to effectors.
3. Relay neurons- short neurons found in spinal cord cord where the link sensory and motor neurons and make up the brain.

Question 9

What is the myelin sheath and what does it do?

Answer 9

It is a fatty layer surrounding the axon.

Helps to insulate the neuron from surrounding tissue and other neurons and allows impulses to be carried faster.

Question 10

What is the synapses?

Answer 10

The small gap where one neuron connects with another.

Question 11

What are neurotransmitters?

Answer 11

Chemical substances that transmit impulses across the gaps in synapses.

Question 12

Why are synapses useful?

Answer 12

Because the chemicals are only released from axon endings and they make sure impulses can only travel in one direction.

Question 13

Reflex actions are automatic, quick responses that protect the body.
Reflex arcs are neurone pathways used by reflexes in which a sensory neuron directly controls a motor neurone.
State 2 characteristics of reflex arcs.

Answer 13

1. They are quicker than coordinated responses as they bypass the conscious thought in brain.
2. Reflex arcs contain 2 neurones although some have an interneurone to connect the sensory to the motor neurone.