Functions of the central nervous system CNS. For your information THE FUNCTIONS OF THE BRAIN –The human brain is a complex organ that allows us to think,

Functions of the central nervous system CNS

For your information

• THE FUNCTIONS OF THE BRAIN

– The human brain is a complex organ that allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives information, analyzes information, and stores information (our memories). The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body.

Did you know?...

• Your brain uses 20% of your body's energy, but it makes up only 2% of your body's weight.

• Your brain is about 1300-1400 cubic centimeters in volume, about the size of a cantaloupe and wrinkled like a walnut.

• The brain feels like a ripe avocado and looks pink because of the blood flowing through it.

• Your brain generates 25 watts of power while you're awake---enough to illuminate a lighbulb.

• A newborn baby's brain grows almost 3 times in course of first year

• Humans have the most complex brain of any animal on earth.

• Your brain is divided into two sides. The left side of your brain controls the right side of your body; and, the right side of your brain controls the left side of your body.

CNS=central nervous system

• Central Nervous System (CNS) Introduction:

– Radiates throughout the body– Controls all body organs– Regulates all conscious and unconscious

actions

CNS=central nervous system

A. Main parts of the CNS:

1. BRAIN (cerebrum, cerebellum, brainstem) Hard drive of a computer where data is analyzed and

stored

2. SPINAL CORD Computer processor (pentium, intel centrino duo)

3. NERVES “wires” that carry messages to & from the brain

C.N.S.B. Anatomy of a neuron

The brain is made up of millions of individual cells called neurons.

• Neurons have specialized parts with specialized functions:

A. DendritesB. Cell body (nucleus)C. AxonD. Axon Terminals

Anatomy of a neuron

Dendrites• these are branched processes specialized

to receive input and carry information toward the cell body

The cell body • is the metabolic center of the neuron

(where energy is made)• contains the nucleus (center) of the cell • most proteins needed for functioning are

made here• incoming signals from dendrites meet here

Anatomy of a neuron

Axon• is larger in diameter than dendrites• is specialized to carry information

away from the cell body• may be very long, up to 1 m

Axon Terminals• the end of the axon• Sends the signal on to other neurons

Draw your own picture of a neuron here and label the 4 parts

A real neuron

Review questions

1) What does the CNS stand for?

2) What are the three main parts of the CNS and what are their main functions?

3) What is the brain made up of?

4) What are the 4 main parts of the neuron and what are their specialized functions?

Answers to review questions

1) What does the CNS stand for?Central Nervous System

2) What are the three main parts of the CNS and what are their main functions?Brain: analyses and stores informationSpinal Cord: processes the informationNerves: carry messages to and from the brain

3) What is the brain made up of?Millions of cells called neurons

Answers to review questions

4) What are the 4 main parts of the neuron and what are their specialized functions?Dendrites: receive inputs from other neurons and carry messages to towards the cell bodyCell body: Makes energy and proteins for the neuron, processes the inputs from the dendritesAxon: transmits the nerve impulse away from the cell bodyAxon terminals: relays (passes on) the nerve impulse to another neuron

How do neurons communicate?

• The connection between two neurons is called a synapse

• Neurons interact with other neurons through synapses

the axon terminals of one neuron will end near the dendrites of another neuron

• the Presynaptic neuron: sends out information• the Postsynaptic neuron: receives information• note: There is no physical connection between

the two neurons

Nerve impulses

When a neuron registers an external or internal stimulus (such as a sound, light, touch, odour) it will produce an electric current known as a nerve impulse or an action potential (AP).

For one neuron to send an impulse to another, it secretes a chemical messenger called a neurotransmitter (NT) into the gap (synaptic cleft) between it and the next neuron

It will then transmit the impulse (or AP) to different organs of the body

(animation- NIDA brain addiction)

Nerve impulses are:

1) _____________by the dendrites

2) _____________ by the cell body

3) _____________ through the axon

4) _____________ by the axon terminals

Fill in the blanks with the following words:

relayed, received, transmitted, processed,

Nerve impulses are:

1) received by the dendrites2) processed by the cell body3) transmitted through the axon4) relayed by the axon terminals

passed on to the next neuron

Fill in the blanks with the following words:

relayed, received, transmitted, processed,

Neurons interact with other neurons by synapses

Nerves

• A collection of neuronal axons forms a nerve.

• Many nerves radiate throughout the body, making it possible for nerve impulses to reach all parts of the body

• There are two main categories of nerves:– Sensory nerves– Motor nerves

Motor vs. Sensory Nerves

Sensory nerves send information from the sensory organs to the brain

Motor nerves send information from the brain to the muscles

vertebrae

synapse

synapse

Motor nerve: Start: brain, end: muscle

Sensory nerve: Start: sense receptor, end: brain

Review Questions

1) What is a synapse?2) Draw a picture of a synapse including pre and

postsynaptic neurons. Make sure to label all structures in your diagram.

3) What are two names for the electric current that travels down a neuron?

4) What is the name of the chemical messengers found at inside the axon terminal?

5) What part of the neuron receives the nerve impulse?6) What is a nerve?7) What two types of nerves exist and what are 2

differences between them?

1) Neuron 1 C

2) Neuron 4 D

3) Neuron 3 B

4) Neuron 2 A

5) Neuron 5 F

6) Neuron 6 E

Answers to review questions

1) What is a synapse?

The connection between 2 neurons through which they interact

2) Draw a picture of a synapse including pre and postsynaptic neurons. Make sure to label all structures in your diagram.

Answers to review questions

3) What are two names for the electric current that travels down a neuron?

- Nerve impulse, action potential4) What is the name of the chemical messengers

found at inside the axon terminal? - neurotransmitters

5) What part of the neuron receives the nerve impulse?

- the dendrite 6) What is a nerve?

- a collection of neurons

Answers to review questions

7) What two types of nerves exist and what are 2 differences between them?

- sensory nerves: - bring information from the sense receptors to the brain

- send sensory signals to the brain

- motor nerves: - bring information from the brain down to the muscles

- allow you to move

PBS clip: From Zzzz’s to A’s.http://www.pbs.org/wgbh/pages/frontline/sho

ws/teenbrain/view/

1. How many hours of sleep to you need to get in order to be fully alert?

2. What is the name of your Biological Timing System and how does it change during the teenage years?

3. What analogy does the announcer use for a teen that is trying to function with not enough sleep?

4. What are three daily life functions that sleep affects your ability to do?

5. What is REM sleep and what happens during this time?6. What is the best predictor of whether or not you will

succeed at school?7. What were the results of the study of the relationship

between learning and sleep in teens Charlie and Nicole?

From Zzzz’s to A’s (clip)1. How many hours of sleep to you need to get in order to be fully alert?

9 ¼2. What is the name of your Biological Timing System and how does it change

during the teenage years?The circadian clock: it shifts forwards (in the day) during the teenage years

3. What analogy does the announcer use for a teen that is trying to function with not enough sleep?It’s like a car trying to run on an empty tank.

4. What are three daily life functions that sleep affects your ability to do?Your mood, your ability to think and your ability to perform and react appropriately.

5. What is REM sleep and what happens during this time?Rapid Eye Movement. Dreaming and learning happens during this time.

6. What is the best predictor of whether or not you will succeed at school?Whether or not you get a good night’s sleep.

7. What were the results of the study of the relationship between learning and sleep in teens Charlie and Nicole? Nicole got more REM sleep than did Charlie and she also improved more on the learning tasks than Charlie did. Thus, the more REM sleep you get the better you learn.

Nova on Sleep

• Brain Trauma

Consequences of damage to nerve cells

A. The nerve cell does not regenerate itself

B. The transmission of impulses may diminish or stop

C. Interpretation of the impulse may be distorted, interrupted, or only partially completed

Damage to the C.N.S.

Concussion: temporary, hit to the head, may produce unconsciousness or bleeding in or around the brain.

Paralysis: injury to the spinal cord Cerebral palsy: lack of muscle control due to brain

damage before or soon after birth Epilepsy: muscular seizures and body convulsions

caused by abnormal action potentials Multiple sclerosis: hardening of the nerve tissue in

the brain or spinal cord

What happened to Phineas Gage? Reading

Questions

1) How did Phineas Gage change after the accident?

Gage’s personality changed. He was no longer the likable and respectable person he was before the accident. Instead he was irresponsible and used foul language.

2) How did Phineas Gage’s accident change scientists’ understanding of the brain?

Scientists learned that the brain does more than control the language and movement. It controls emotions and social behaviors.

Scientists also learned that specific parts of the brain control specific functions

The moral of the story is….

Different parts of your brain control

different senses and emotions

Lobes of the brain

Name of lobe Function

Lobes of the brainName of lobe Function

Frontal lobe “command center” =

decision making

Occipital lobe Processes vision

Parietal lobe Analyses sensation

Temporal lobe Hearing, understanding speech and integrating all senses

Probe the Brain

• Beginning in the 1940s, Canadian brain surgeon Wilder Penfield mapped the brain's motor cortex -- the area that controls the movement of your body's muscles.

• He did this by applying mild electric currents to the exposed brains of patients while they were in surgery.

• Brain Probing Activity

Other roles of the nervous system

A. Site of the intellectual processes Mostly found in the frontal lobe of the brain

B. Reflex centre The spinal cord serves as the body’s reflex

centre Reflex = an involuntary act that results when a

nerve impulse is sent out by the spinal cord in response to an unexpected stimulus.

You accidentally touch the burner on your stove at home….

What happens?

You automatically pull your hand away

HOW DOES THIS HAPPEN?

Reflex Response

1) The touch receptors in your hand relay information to the spinal cord in the form of a nerve impulse

2) BUT this nerve impulse doesn’t get send to the brain. WHY?

- Because it would take too long and this situation is urgent

3) Instead, a nerve impulse is commanded from the spinal cord to the hand muscles, telling them to draw away

- Processing the information at level of the spinal cord instead of the brain allows the response to occur faster

Reflex animation

Knee-jerk reflex

Ways to improve the power of your brain…(or, how to become more intelligent)

Lead a balanced lifestyle by:

A. Eating a Proper diet:

The nervous system needs a regular supply of B vitamins because these vitamins:

- strengthen the neurons

- facilitate the transmission of nerve impulses

Foods that are rich in B vitamins are:

- egg yolks, milk, whole grain cereals, fresh meat

B. Exercise regularly

The brain needs 20% of the body’s oxygen to function properly, so it’s important for your circulatory system be in tip-top shape. You can achieve this by exercising on a regular basis.

C. Get enough sleep

While you sleep your neurons reset themselves and prepare for a new day of activity.

If the body does not get enough sleep:– Intellectual performance will be impaired– Reflexes slow down– It becomes difficult to concentrate

Review Questions

1) What did the study of Phineas Gage teach us about the brain?

2) What lobe of the brain processes vision?3) Who is Wilder Penfield and how did he contribute to

our understanding of the brain?4) Where is the site of intellectual processes in the brain?5) What 3 types of neurons are involved in reflex

responses and in what order do nerve impulses travel through them?

6) What is the difference between a voluntary movement such as walking and an involuntary movement such as a reflex response?

7) What 3 things can you do to improve the power of you brain?

Answers

1) What did the study of Phineas Gage teach us about the brain?- that the brain is not only responsible for language and movement but it is also responsible for determining one’s emotions and personality

2) What lobe of the brain processes vision?- The occipital lobe

3) Who is Wilder Penfield and how did he contribute to our understanding of the brain?

- He was a brain surgeon who made of map of the motor cortex (which regions control which body parts)

4) Where is the site of intellectual processes in the brain?Frontal cortex

Answers to class starter questions

5) What 3 types of neurons are involved in reflex responses and in what order do nerve impulses travel through them?

1- Sensory neuron, 2- interneuron 3- Motor neuron

6) What is the difference between a voluntary movement such as walking and an involuntary movement such as a reflex response?Voluntary movements get processed by the brain whereas involuntary movements only get sent to the spinal cord and don’t reach the brain

7) What 3 things can you do to improve the power of you brain?Maintain a healthy diet rich in B vitamins, exercise regularly, and get enough sleep (9 ¼ hours/ night)

• Unit test on the CNS on Tuesday

• Pages 1,2,3,7 of drugs package