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Nervous system

Study the following text:

#### Nerve system The nervous system is involved with everything you do. The nervous system process the stimuli recieved by your senses. The nervous system controls muscles and other things in your body. The nervous system is divided into parts. The central nervous system is made up of the brains and the spinal cord. These are connected with the rest of the body through nerves. Another part is the peripheral nervous system, this is everything outside the central nervous system. Peripheral means 'around the edge'. A nerve is made of nerve cells. There are three types of neurons (nerve cells): sensory neuron: These cells bring impulses from the senses to the central nervous system. interneuron: These cells bring impulses from one nerve cell to another nerve cell. motor neuron: These cells bring impulses from the central nervous system to the muscles or other parts of the body. The three types of neurons. #### Impulses through the brain In your nose and eyes there are sensory cells (sensory neurons). These sensory cells recieve the stimuli from our environment. When this happens the sensory cells create an impulse. An impulse is a small electric signal which travels through our nerves. The impulse travels through the sensory neurons to the central nervous system. Inside the brain the information is processed. You are able to think about the stimulus. The brain then sends an impulse back through the motor neurons to the muscles. These are the places the signal travels through: stimulus - sense - sensory neuron - spinal cord - brain - spinal cord - motor neurons - muscles - action An example: Somebody rings your doorbell. The sound reaches your ear and is picked up by sensory neurons. The sensory neurons create and impulse and send it to the spinal cord. The spinal cord contains interneurons which send the impulse to the brain. The impulse arives in the brain and you become concious of the sound. From the brain an impulse is sent to the spinal cord through the interneurons. From the spinal cord the impulse travels to the motor neurons. The motor neurons send the impulse to the muscles, which make you stand up to open the door. The central nervous system also manages other unconcious processes in your body, like your heartbeat and your breathing. #### Impulses through the spinal cord A reflex is an automatic reaction to a stimulus. After recieving a stimulus, impulses are made in your sensory neurons. The impulses travel through the sensory neuron to the spinal cord. There the spinal cord reacts directly. Even before the impulse reaches the brian, an impulse is sent to the muscles. This impulse travels through motor neurons. These are the places the signal travels through: stimulus - sense - sensory neuron - spinal cord - motor neurons - muscles - action Reflexes like the cough reflex, sneeze reflex, pupillary reflex and swallowing reflex are caused by the brain stem. Reflexes of the arms and legs, anus and urine bladder go through the spinal cord. An example: You accidentally touch something hot. Sensory neurons in your finger create an impulse. Impulse travels through the sensory neurons to the spinal cord. The spinal cord sends an impulse back to the hand and sends an impulse to the brain. The impulse to the hand travels through motor neurons and make the muscles in your arm/hand retract. The impulse to the brain travels through interneurons to the brain and you feel the pain of the hot object. #### #### #### Brain The brain is a very complicated organ. All your feelings, your thoughts and your skills are inside your brain. The brain has two halves, which are both wrinkled. The human brain, seen from above. The human brain has a couple of important parts which have different functions. The cerebrum is the big wrinkly part of your brain, it is made of the two halves seen in the picture above. It is responsible for sensing, movement and thought. The cerebellum is a smaller part of the brain located underneath the back side of your cerebrum. The cerebellum helps with coordination of voluntary movements. The brainstem looks like a thick part of spinal cord and is located between the cerebrum and the spinal cord. It is responsible for your heartrate, breathing, pain sensation and awareness. The three main parts of your brain. Watch this video to learn more about the brain. The cerebrum is the place where the impulses from the sensory neurons are recieved. Inside the cerebrum there are different locations for certain senses and other functions. In the picture below you can see different areas of the cerebrum with their functions. Different regions in your brain. The four lobes are part of the cerebrum.

Now answer the following nine questions:

1. The central nervous system contains:

A. brain and sensory neurons

B. spinal cord and motor neurons

C. brain and spinal cord

2. What is the name of the nerve cells which bring an impulse from the senses to the central nervous system?

A. sensory neurons

B. interneurons

C. motor neurons

3. What is the name of the nerve cells which bring an impulse from one nerve to another?

A. sensory neurons

B. interneurons

C. motor neurons

4. What is the name of the nerve cells which bring an impulse from the central nervous system to the muscles?

A. sensory neurons

B. interneurons

C. motor neurons

5. You recieve a stimulus and react to it.

What is the right order of events?

A. sense - sensory neurons - brain - motor neurons - muscles

B. sense - motor neurons - brain - sensory neurons - muscles

C. sense - sensory neurons - motor neurons - brain - muscles

6. True or false?

When a reflex takes place, the spinal cord reacts to the stimulus.

A. True

B. False

7. True or false?

When a reflex takes place, you react before you become concious of the stimulus.

A. True

B. False

8. The part of the brain which processes impulses from the senses is called ... .

A. cerebrum

B. cerebellum

C. brain stem

9. True or false?

Motor neurons are part of the central nervous system.

A. True

B. False

When you have answered all the questions, make sure to compare your answers with a classmate. If there is an question you have answered differently, try and figure out who was right.