5.9 Neurons

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

5.9 Neurons

The Nervous system

The nervous system controls your muscles 

-walk / write / exercise 

-swallowing / blinking / breathing

-Central nervous system vs. 

-Peripheral nervous system

The central nervous system (CNS)

Nerve cells / neurons 

• Sense organs (receptors) send messages to the CNS

via Sensory neurons

• Muscles and glands (effectors) CNS send messages telling them wat to do 

via Motor neurons

• Interneurons  are the connections between sensory and motorneurons.(in the spine and the brain)

The message

-Nerve impulses (electrical signals)

-Via the axon of the nerve cell

-Fatty sheat around axons make the impuls travel faster

Dendrite

Cell body

Nucleus

Axon

Fatty sheath

Synapse

You get an itch in your elbow. What is the stimulus in this reaction?

1. Receptors in your skin
2. The itch itself
3. muscles that move your arm to scratch
4. The brain that decides to scratch the elbow

You get an itch in your elbow. What is the response in this reaction?

1. Receptors in your skin
2. The itch itself
3. muscles that move your arm to scratch
4. The brain that decides to scratch the elbow

Which will send a message along sensory neurons?

1. Receptors in your skin
2. The spinal cord
3. The muscles in your arm
4. The brain

Which will receive a message by motor neurons?

1. Receptors in your skin
2. The spinal cord
3. The muscles in your arm
4. The brain

Sensory neurons carry information

1. away from the brain.
2. both to and from the brain.
3. towards the brain.
4. within the brain

True

False

Motor (efferent) neurons carry messages to the central nervous system.

The nucleus of a neuron is found outside the cell body (soma)

Motor Neuron

Relay neuron

Sensory neuron

Found in visual system, brain, and spinal cord, pass informatiion on

carry electrical impulses away from the brain and spinal cord

Take information from sense organs to the brain and spinal cord

homework

tuesday: study page 136/137 (5.9)

do excercises 45 till 50, write down difficult words!

friday: study 5.9 completely

do excercises 51 till 56

questions?

• about page 136, 137 
• difficult words?
• the workbook?

Dendrite

Cell body

Nucleus

Axon

Fatty sheath

Synapse

nerves

spinal cord - grey and white matter

Reflex arcs

• You take away your hand from an hot object very fast
  Automatically, why? 
  
  
• Reflexes protect you 
• Why do you think a reflex is unconscious? 
  
  
• Signal does not go to the brain immediately
• It goes to the spinal cord and back (short circuit) 

Reflex arcs

W

Stimulus? 

Receptor? 

Effector? 

Response? 

Reflex arcs

Stimulus = hot flame 

Receptor = heat sensor in the skin 

Effector = muscles in your arm

Response = moving your hand away from the hot object. 

Reflex or not???

Reflex

Reflex

concious

trained reflex