5.4 The nervous system part 2

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

Bs 4: The nervous system part 2

Planning for today

• Look back at last class 


• Bs 4: The nervous system part 2


• Homework

Learning goals

• You can describe the structure and functions of the nervous system,
  
• You can describe the structure of nerve cells and nerves.
• You can describe a reflex arc.

Senses of humans

Summary:

Stimuli

Impuls 

Touch

Light

Sound

Taste

smell

The nervous system

The nervous system is made up of:

• the central nervous system 

--> Brain + spinal cord

• the nerves.  

the nerves connect the central nervous system to all parts of the body.

How the nervous system works

1.  The sensory cells in the senses organ makes an impulse. 
2. Impulses travel through the nerves to the brain. 
3. Brain processes the impulses.
4. Brain makes new impulses.
5. Impulses travel through nerves to the salivary glands and arm muscles. 
6. Salivary glads start making saliva and muscles contract to pick up chocolate.

Nerve cells

The nervous system contains millions of nerve cells. 

Each nerve cell consists of a cell body and its protrusions (uitsteeksels) 

• Axons conduct the impulses. There are axons that conduct impulses to the cell body, away from the cell body and to other cells
  

Axon

Dendrites

Nerves

Impulses are passed via thousands of axons at the same time.

The axons are bundled together in a nerve (zenuw) 

Each axon in a nerve is surrounded by a thin layer. This layer insulates the axons from each other.

A nerve has a tough protective layer around it.

The nerves connect the central nervous system to all parts of the body.

Impulses are passed to the brain through nerves in the spinal cord. The spinal cord starts at the brain and ends in the lumbar vertebrae in the lower back. 

Spinal cord

Vertebra

Nerve

Path taken my impulses

Nerves can be very long, sometimes as much as a metre.

When reacting to stimuli, impulses can travel through the nervous system in various ways.

• In a conscious reaction, impulses first go from your senses to your brain.
  
• In a reflex,a fixed, fast and involuntary reaction to a certain stimulus In a reflex. The impulses do not go through your brain

The spinal cord and the brain have interneurons. These are nerve cells that conduct impulses within the central nervous system, from one nerve cell to another.

Homework

Read 5.4         (10 min silence)

Make exercise: 1,2, 3 ab,c, 5 and 6

Done:

Make summary B4