Senses (vertaling stercollectie)

Senses (vertaling stercollectie)

Chapter: Senses

Intro

Watch the movie clip below. 

Josh's story

When you are blind, life is different.

For somebody who is able to see normally, light is a stimulus which can be recieved and reacted to.

 

Light falls onto your face and stimulates your eyes. In this case, light is a stimulus.

To recieve stimuli from the world around you, you use your senses.

You have different senses for seeing, hearing, feeling, tasting and smelling.

 

At the end of this chapter you will make a quartets (card game) game about the different senses.

 

Before you start, you should know more about how senses work and how stimuli are recieved.

Planning

In this chapter you are going to make five assignments plus a final one.

In the table you can see how many lessons you will need for each one.

Activity Number of lessons
Introduction 0,5
Assignment: Stimuli and impulses 1
Assignment: Feeling: the skin 2
Assignment: Watching 2
Assignment: Hearing 2
Assignment: Smelling and tasting 3
Final Assignment 2
Total 12,5

 

Stimuli and impulses

Intro

Watch the video.

The central nervous system includes your brain and all your nerves.
The central nervous system includes your brain and all your nerves.

In the video they are talking about stimuli and response. Everything you can sense are stimuli (e.g.: light, sound, touch, heat, cold, taste and smell). These stimuli are recieved and transported to your brain by a network called your nerve system.

In the first assignment of this chapter, the nerve system is the subject.

Good luck!

Final product & assessment

Final product

You will finish this subject with a quiz 'nervous system'.

The test will consist of multiple choice questions.

Assessment

You will have succeeded when you answer 80% of the questions correct.

Learning goals

The central nervous system includes your brain and all your nerves.
The central nervous system includes your brain and all your nerves.

After this assignment:

  • You know the most important senses in our body.
  • You know the difference between a stimuli and an impulse.
  • You know how information travels from the senses to the brain.
  • You know the difference between conscious and unconscious actions.
  • You know what a reflex is.

Method

The central nervous system includes your brain and all your nerves.
The central nervous system includes your brain and all your nerves.

Group size

This assignment is done alone. Sometimes you may have to discuss with a classmate.

 

Materials

Nothing special.

 

Time

For this assignment you will need approximately 1 hour.

 

Extra

If you are done within 1 hour you have to make the extra parts.

Step1

Senses

Study the following:

 

Stimuli

You recieve stimuli from the environment through your senses. Senses are made from nerve cells. These nerve cells pass on the stimuli to your brain. This is why you can react to stimuli. The senses are in your eyes, ears, tongue, nose and skin. With these senses you can see, hear, taste, smell and feel.

 

Correct stimulus

Every sense has a stimulus it is sensitive to. So every sense has a correct stimulus.

  Sense Stimulus
Sight eyes light
Hearing ears sound
Smell nose odors*
Taste tongue chemicals
Touch skin pressure

* An odor is a chemical suspended in the air, like a fart.

 

 

Now answer the following five questions.

 

Which word should be placed in the open space?

1. You recieve ... from your environment with the help of your senses.

A. stimuli

B. impulses

C. reflex

 

2. Senses bring the stimuli through the nerves to the ... .

A. brain

B. muscles

 

3. A fast reaction which you didn't need to think about is called a(n) ... .

A. impulse

B. reflex

C. stimulus

 

4. The ... from the sun is the correct stimulus for the eyes.

A. sound

B. smell

C. light

 

5. The odors in the classroom were picked up by my ... .

A. ears

B. nose

C. skin

 

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.

 

Step2

The central nervous system includes your brain and all your nerves. The peripheral nervous systems is everything outside the central nervous system.
The central nervous system includes your brain and all your nerves. The peripheral nervous systems is everything outside the central nervous system.

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.

Step3

The patellar reflex

When somebody hits your petallar tendon (just underneath your patella), your lower leg will kick up by itself! This is known as the patellar reflex (also called the knee-jerk reflex). In normal situations, the patellar reflex helps to stand up straight and balance without having to think about it.

For more information watch this video.

When somebody hits your patellar tendon, sensory neurons in your thigh pick up the stretch and send an impulse to your spinal cord (to the right you see a cross-section of the spinal cord). In the spinal cord the impulse is sent directly to the motor neurons which activate the muscle.

 

 

Below you will see a couple of parts of the human body.

A. leg muscle (quadriceps)

B. cerebrum

C. cerebellum

D. sensory neuron

E. motor neuron

F. clavicle

G. interneuron

 

Of these words, only four are involved with the patellar reflex.

Which of the parts are involved?

Put those parts in the right order.

 

Answer: ... - ... - ... - ...

 

Extra assignment:

If you focus, you can stop the patellar reflex from taking place. A man named Ernő Jendrassik observed something strange. When a patient would hold their hands like in the picture below, they were not able to stop the leg from kicking up.

When a patient is holding their hands like in the picture and focus on pulling outwards, this inhibits the knee-jerk reflex. This is called 'the Jendrassik maneuver' after its inventor.

 

Try the following things yourself:

  • Have your partner hit your patellar tendon with a small object.
  • Try not to move your leg while somebody hits the patellar tendon.
  • Do the Jendrassik maneuver and try not to move your leg while somebody hits the patellar tendon.

Step4

Pupillary reflex

When you look at a human eye, you will see a white part, a coloured part and a dark spot. This dark spot is called the pupil. Actually the pupil is a hole in your eye where the light falls through. The pupil can become bigger and smaller to control the amount of light going in.

Watch the following videos:

Pupillary reflex in a human

Papillary reflex in the W-shaped pupil of the cuttlefish

 

Your pupil will automatically become smaller when there is a lot of light and become bigger when there is very little light. This way the pupillary reflex makes sure there is a more or less constant amount of light entering our eyes. This is called a negative feedback loop, these negative feedback loops makes sure something stays at the same level without us having to think about it. Make sure to study the picture below to understand the negative feedback loop in our pupillary reflex.

The negative feedback loop of the pupillary reflex.

 

Now with a partner, try to answer the next questions:

1. What happens with the pupil when there is a lot of light?

2. What happens with the pupil when there is not much light?

3. What does this sentence mean?: 'The pupillary reflex is an example of negative feedback loops.'

Step5

Quiz

You will end these assignments with a quiz.

The quiz consists of several multiple choice questions. Afterwards you will see which questions you answers right and which were wrong.

Klick the button below to start the quiz

Good luck!

 

 

Quiz: Stimuli and impulses

 

Extra 1: Senses

Using other senses

Animals often use other senses than humans do. Try and guess which senses belong to which animals in the assignment below.

Extra 2: External material

If you want to know more about this subject, follow the following links to external study material:

 

 

 

http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_2011/ourselves/3_keeping_in_touch1.shtml

http://leavingbio.net/the%20senses_files/the%20senses.htm

 

 

Feeling: the skin

Intro

Commercial Acupunctuur (2006) - Even Apeldoorn bellen - Centraal Beheer

Human skin
Human skin

 

 

 

On the outside of your body is your skin.

You use the skin to feel a lot of different things from your environment. Your sweater feels soft against your skin, a needle point feels sharp and hurts, the radiator feels hot to the touch and the metal chair leg feels cold.

How does the skin do all that? You are about to find out.

Good luck!

Final product

Final product

You will finish this part with the practical 'sense of touch'.

You will have to make a lab report of this practical.

 

In the report will be:

  • The research question
  • The method
  • The results
  • The conclusion
  • The evaluation

 

Assessment

You will assess the lab report yourselves, but make sure to let your teacher take a look at it when you are done. Your teacher will check if the report is sufficient and if it is neat enough.

Learning goals

After finishing this task:

  • You will know how the different senses in the skin work.
  • You will know how information travels from the senses to the central nervous system.
  • You will understand how the warm and cold senses work.

Method

Group size

Studying the theory and the practical about warm and cold senses you will do by yourself. You are allowed to work together with a classmate on the final product (the lab report).

 

Materials

 

Time

To study the theory and answering the questions you will need about 30 minutes. To do the practical and finish the lab report you will need another 60 minutes.

Step1

The skin

Study the text below:

Structure and function

The skin covers your entire body on the outside. The skin offers protection against different dangers from the outside, like a flu virus. In this way the skin is part of your defense system.

The different parts of the human skin.

 

The epidermis is the upper 1-2 mm of our skin. This is where the colour of our skin comes from, it is pigment. Pigment protects you from UV-radiation. The epidermis is covered with a layer of dead skin cells called corneum. This layer stays in place because the skin cells keep growing outwards.

Right underneath the epidermis lies the dermis. The dermis is a thick layer of skin where the sweatglands, oil glands and senses lie.

Under the dermis there is a final layer of skin called the subcutaneous tissue. This includes a layer of fat which functions as insulation, food reserve and cushions us from knocks and falls.

 

These three layers of skin contain another number of parts. Hairs serve as insulation and protection. The oil glands keep your skin supple and stops it from drying out. Lymph vessels help keep you healthy. The nerves connect to different sensory nerve cells imbedded in the dermis. Hair follicles grow hairs. Veins and arteries supply blood to the skins, this blood brings oxygen and nutrients which are needed by all the cells in the human body. Finally the sweat glands produce sweat which cools you down as it evaporates from your skin.

 

Answer the following six questions:

True or false?

1. The outer layer of your skin is covered in corneum.

2. The corneum is made up of dead skin cells.

3. The corneum contains pigment (colour).

4. The entire epidermis is made of dead skin cells.

5. Pigment protects the skin against UV-radiation.

6. Warmth and cold senses give your information about the temperature of your surroundings.

Step2

Practical: cold and warmth senses

During the following experiment you will study how cold and warmth senses work.

 

Material:

  • a beaker with cold water (with ice cubes)
  • a beaker with warm water (about 40 degrees Celcius)
  • a beaker with lukewarm water (about 20 degrees Celcius)
  • a thermometer to measure the temperature of the different beakers of water

 

Method:

  • put the index finger of your left hand in the beaker with warm water.
  • put the index finger of your right hand in the beaker with cold water.
  • wait for 60 seconds
  • now put both index fingers in the beaker with lukewarm water

 

What did you notice when you put both of your fingers in the lukewarm water?

Finish the assignment below:

 

Step3

What happens with the skin in warmth or cold?

To the right you see the same bit of skin two times.

 

In one of those drawings the skin is in a warm environment, the other is in a cold environment. In the drawing you see a hair, a muscle (for erecting the hair), a sweat gland and some blood vessels.

 

Take a good look at the differences between both of the drawings. Write the differences down.

 

Which drawing do you think is from a cold environment? And which is from a warm environment?

 

Discuss your answer with a classmate. Do you agree with eachother? If not, ask a third classmate.

Step4

Practical 'sense of touch'

Together with a classmate you are going to perform the practical 'sense of touch'. You will make a lab report about this practical.

Do you know how to write a lab report?

No? Watch the following:

 

Are you writing a lab report for biology, physics or chemistry? Then you are writing a scientific paper. A real scientific paper includes the following:

Introduction

Start with the explanation about why you are doing the experiment. Include the things you already know and the theories you have already learned.

Research question

Write down the question you are trying to answer with the experiment. This is your research question. Explain what you are investigating and how you are going to get an answer to your research question.

Material

Write down the materials somebody would need if they wanted to do the same experiment. If the setup is quite complicated you should also make a drawing of how everything is put together.

Method

In your own words, explain how you perform the experiment. Keep in mind, somebody else must be able to re-do the experiment by reading your lab report!

Results

Write down what you observed during the experiment. Everything you: saw, heard, smelled, measured, counted, etc. In the results there should be either a drawing, a graph or a table (sometimes multiple). If you needed to calculate something show your calculations in the results.

Conclusion

In the conclusion you answer the research question. Answer the question in a full sentence. Make sure the conclusion matches the results.

Discussion

In the discussion you explain why the results lead to your conclusion. Also you give tips on how to improve the experiment. This way somebody who reads your research can make an even better experiment!

Are you finished?

When you are finished make sure your lab report includes the following:

  • a title
  • the subject
  • your first and last name
  • your class
  • the date
  • if there are multiple pages, include a contents page

If you have used information from a book or the internet, make sure to mention which sources you used at the end.

 

 

Now we remember how to write a lab report we can move on with the following:

  • Download the handout: Practical skin senses
  • Read the handout
  • Get all the materials ready at your station (so you won't have to walk during the experiment)
  • Execute the practical as instructed
  • Make a lab report about the experiment
  • Dont forget to fill in the evaluation
  • Before handing in your work, take a look at it and think about how you would grade your work
  • Hand in the lab report to your teacher

Good luck!

Vision

Intro

Please watch the video below. It is about a young man going to college. There is one problem for him, he is blind. While watching this video think about what would be different in YOUR life if you were blind.

 

A day in the life of Chris Wright

Now together with a classmate discuss which three things you would miss most.

Final product & Assessment

Final product

You will finish this assignment with the test 'eyes and vision'.

This test consists of a number of multiple choice questions.

 

Assessment

You have a sufficient mark if you answered 80% of all questions. As proof you did this, you have to save the certificate 'eyes and vision'.

Learning goals

After this assignment:

  • You should be able to name the following parts of the eye, and know what their function is: Iris, Pupil, Lens, Sclera, Cornea, Retina, Choroid, Macula lutea, Optic disc (blind spot), Optic nerve, Vitreous body.
  • You can explain how your eyes are being protected by your eyebrows, your eyelids and your eyelashes.
  • You can describe tears being formed in the Lacrimal glands and the tears being wiped across the eyes by the eyelids.
  • You can describe the following terms: accomodation, near-sightedness (or short-sightedness), far-sightedness (or long-sightedness).

 

Method

Group size

Most of these assignments you will do by yourself. Sometimes you will need the help of a classmate.

 

Materials

  • Computer with internet
  • Paper and (colour)pencils
  • Ruler

 

Time

To make all the assignments and the final test you will need about 2 lessons.

 

Extra

When you are finished, ask your teacher if you have to do the extra assignment about colour blindness.

Step1

Look into eachother's eyes

You will start this assignment with looking at and drawing the eye of one of your classmates. You will make a detailed drawing of his/her eye.

 

While drawing remember the drawing rules:

A biological drawing is a good way to show how something looks. A biological drawing is NOT a fantasy drawing, but a detailed description of what you see.

Materials

  • Paper
  • Pencil
  • Eraser
  • Ruler
  • Pencil sharpener

Method

  • Make sure your pencil is sharpened
  • Before you start make sure you know what you are going to draw. For instance just draw the eye, the eyebrow, the eyelids, the eyelashes. Do not draw the nose or the mouth.
  • To make sure even small details are clear, draw BIG.
  • Draw everything you see, dont imagine extra things. While drawing keep looking at the thing you are observing.
  • Make horizontal lines from the different parts and write down what it is.
  • Note what the magnification is and give your drawing a title.

 

Make sure to name all the parts you know.

 

When you are finished, show your drawing to a classmate. Look at their drawing. Who was able to name the most parts? Are there any other major differences? Discuss.

At the end of the section about eyes, take another look at your drawing and see if you can name more parts.

Step2

Anatomy of the human eye

Study the following:

 

Eye lid - a thin fold of skin that covers and protects the human eye

Tear duct - a tube that carries tears from the eye to the nasal cavity

Sclera - also known as the white of the eye, is the protective outer layer of the eye, it is very tough

Iris - the coloured bit of the human eye, it controls the amount of light that enters the eye

Pupil - a hole located in the centre of the iris of the eye that allows light to pass through

Cornea - the transparent part of the eye that covers the pupil and the iris

Ciliary body - the part of the eye that contains muscles that control the shape of the lens, which makes you focus your vision

Lens - light falls through the pupil into the lens, the lens then focusses the light so you can see clearly

muscle - the muscles that control movement of the eye (eye muscles / ocular muscles)

Choroid - the layer of the eye which contains the blood vessels, this is what you see when people have red eyes in a flash photograph

Retina - this is the light-sensitive layer of the eye, this is where the sensory cells are located

Macula lutea - the place on the retina with the most sensory cells, this is the place you see with then you focus on something

Vitreous body - a clear gel that fills the space between the lens and the retina of the eye

Optic disc (blind spot) - the point of exit for all sensory nerves leaving the eye, there are no light sensitive cells so this is your blind spot

Optic nerve - the nerve that transmits visual information from the retina to the brain

 

 

After studying the picture and text above, do you know the anatomy of the eye? 

Start the assignment: "anatomy of the eye"

 

 

Test:Anatomy of the eye

Step3

Pupil

You are going to look into the eyes of a classmate again. Your classmate will look in the direction of a lightsource, like the window or near a lamp. Do not look directly into the sun. The classmate will cover one eye with a hand, but does not close the eye!

After 30 seconds remove the hand. Now look at the pupils. What do you notice? Discuss with your classmate.

 

Complete the text below by filling in the missing words:

 

dark - retina - less - contracted - big - small

 

When you look at the light, your pupil is ..1.. . This is because the muscles of the iris are ..2.. . This way ..3.. light will fall into the eye, onto the retina. This makes sure the ..4.. does not get damaged. In a ..5.. environment your pupil is ..6.. . Because of this you are able to still see a lot when it is dark.

 

1= ...

2= ...

3= ...

4= ...

5= ...

6= ...

 

Step4

Around the eye

Study the text and do the assignment below:

Your eyes are being protected by your eyebrows, eyelids and eyelashes. The eyebrows stop sweat running down your forehead from getting in your eyes. The eyelids and eyelashes stop most of the other things that would otherwise get in your eyes. The eyelids also 'wipe' tears across the eyes. Tears keep the eyes clean and moist, kills bacteria and gathers dust. The tears are formed by tearglands above your eyes. After cleaning the eye the tears drain down the tearduct into the nasal cavity.

 

Complete the text by entering the missing words below:

 

reflex - eyebrows - eyelashes - tears - dirt - tear glands - eye

 

Around the eye

Above the eye you will find the ..1.. , it stops the sweat running down our forehead from entering our eye. Behind the eyebrows just above your eyes are the ..2.. . These glands make ..3.. all day long, which are being 'wiped' across the eye by blinking the eyelids. The tears make sure the ..4.. doesn't get dry and make sure dust and dirt are washed out. On the eyelids are the ..5.. . The function of the eyelashes is to keep ..6.. out of the eye. Eyelashes are very sensitive to touch. When they are touched, the eye will be closed in a ..7.. .

 

1 = ...

2 = ...

3 = ...

4 = ...

5 = ...

6 = ...

7 = ...

Step5

The lens

Study the text and do the assignment below:

The lens makes sure the light is refracted (refracted means 'to bend light'). Straight rays of light falling onto the eye will pass through the focal point. The ciliary body can change the shape of the lens to change the focus. On the retina a sharp image will be shown. Inside the retina light sensitive cells will create an impulse to be sent to the brain through the optic nerve.

Your eye and you! A lesson in lens accommodation, by Maxwell Yeager.

 

When the lens in your eye isn't the right shape, or has become rigid with age, the focal point might not be exactly on your retina and you might need glasses. There are two types of lenses for glasses, concave and convex. In the picture below you see the difference.

Near-sightedness is corrected with a concave lens, far-sightedness is corrected with a convex lens.

 

The lens

 

near-sighted - concave - convex - brain - focal point - far-sighted - retina

 

Light rays enter the eye through the pupil and pass through the lens. In the back of your eye the light falls onto the ..1.. . The light is refracted in such a way, a clear image appears on the retina, but upside down! Your ..2.. turn this image around. Sometimes the lens does not work properly. You might be ..3.. or far-sighted and need glasses. In near-sighted people the lens bends the light too much. The ..4.. will not reach the retina. Somebody who is near-sighted needs glasses with ..5.. lenses. In ..6.. people it is just the other way around. The lens does not bend the light enough. The focal point will be behind the retina. Somebody who is far-sighted, needs glasses with ..7.. lenses.

 

1 = ...

2 = ...

3 = ...

4 = ...

5 = ...

6 = ...

7 = ...

Step6

Study the text and do the assignment below.

Upside down

The lens focuses the image but also turns it upside down. This is no problem for our brain because it can just flip it right side up again. After all we are seeing everything right side up right now? right? Watch the video to see how the lens works.

 

Blind spot

There are two important parts of the retina, the macula lutea and the blind spot. The macula lutea is the part where the light falls when we focus on something. The blind spot is where the optic nerve enters the eye and we can't see anything. Then how come we dont have a blind spot in our vision? We do! but our brain fills it in for us. Don't believe me?

  • Cover your right eye with your hand while sitting about 50cm away from your screen.
  • Now with your left eye focus on the eyes of the girl.
  • Now slowly move your face (while holding your hand over your right eye) towards your screen.
  • If you keep focusing on the eyes, at a certain moment the flower will disapear!

The reason this happens is the light from the eyes is falling directly onto your macula lutea, so you see it clearly. However the light from the flower is falling directly onto your blind spot and you can't see it at all.

 

 

 

 

 

Step7

Quiz

You will end these assignments with a quiz.

The quiz consists of several multiple choice questions. Afterwards you will see which questions you answers right and which were wrong.

Klick the button below to start the quiz

Good luck!

 

 

Quiz: Vision

Toets:Quiz: Vision

Extra

Colour blindness

Some people think all people who are colour blind can't see colours. This is not true. People with colour blindness usually have problems with seeing the difference between two colours. In some rare cases they can't see any colour.

Most people who are colour blind only find out later in life. People who are red-green colour blind usually think that is what red and green are surposed to look like!

So how do you find out?

 

Do the test below:

http://enchroma.com/test-150401.2/#&ui-state=dialog

Hearing

Intro

Hearing

Most people are perfectly able to hear and never realise how precious hearing is. Imagine watching a movie without sound or trying to talk to somebody without hearing what they say. You might think experiencing music would be impossible for deaf people, but this is not true. Watch the video below to see how deaf people experience music.

 

 

Concert for the Deaf

Final product & Assessment

Final product

You will finish this assignment with the test 'hearing'.

This test consists of a number of multiple choice questions.

 

Assessment

You have a sufficient mark if you answered 80% of all questions. As proof you did this, you have to save the certificate 'hearing'.

Learning goals

After this assignment:

  • You can name the parts of the ear and the order in which they convey information about sound.
  • You can explain how the ear transforms the vibrations in the air to impulses and how those impulses travel to the brain.
  • You can explain what the term 'decibel' means.
  • You can describe how the limit of our hearing is determined.

 

Method

Group size

Most assignments you will do by yourself.

The practical assignments will require you to work together with a classmate.

 

Materials

  • Headphones
  • Alarmclock
  • Cotton (to plug your ears)
  • Decibelmeter (you can download one onto your phone from the app store)

 

Time

To do this assignment you will need about one and a half hours.

 

Extra

When you are finished with the test on hearing ask your teacher if you should do the extra assignment.

Step1

Hearing

Study the text and do the assignment below:

 

 

The parts and their functions in the order the information about sound travels through:

Pinna - Acts as a kind of funnel which assists in directing the sound into the auditory canal.

Auditory canal - Transmits sound from the pinna to the eardrum.

Eardrum - A membrane at the end of the auditory canal. Its is extremely sensitive and pressure from sound waves makes the eardrum vibrate.

Hammer - First of three bones in the middle ear. The bones in the middle ear amplify the sound.

Anvil - Second of three bones in the middle ear. The bones in the middle ear amplify the sound.

Stirrup - Third of three bones in the middle ear. The bones in the middle ear amplify the sound.

Oval window - This membrane recieves vibrations from the stirrup and covers the entrance to the cochlea. The oval window makes the fluid in the cochlea move.

Cochlea - Transforms sound waves into electrial impulses which are sent to the brain through the auditory nerve.

Auditory nerve - A bundle of nerve fibres that carry information between the cochlea and the brain.

Organs of balance - Has no function in hearing. These organs make sure we are able to keep balance.

Eustachian tube - Has no function in hearing. Makes sure the pressure on the outside of the eardrum stays the same as the pressure on the inside. 

 

 

 

Do you now the parts of the ear? Test your knowledge with the assignment below:

 

Step2

The way sound travels

Watch the movies and do the assignment.

Because of your ears you are able to hear sounds. Before you actually hear the sound, a lot happened to the soundwave entering the ear.

In the movies below you can see what happens:

 

How your ears work

How the ear works

Step3

Floppy ears

Most people can't move their ears. However many animals can! Watch the ears in the next video:

The smallest fox with the biggest ears! - Super cute animals: Preview - BBC one

Think about the advantages of being able to move your ears.

 

Then do the next experiment:

  • Put the volume of your computer at LOUD.
  • Listen to this sound: 
  • Put your hands behind your ears like in the picture in the top right of this page.

 

Was the sound louder the second time around? Why do you think this is?

Step4

Earwax

In the pinna is an opening into the auditory canal. The soundwaves travel through the auditory canal into the ear. In the back of the auditory canal is the eardrum and on the sides are the glands which produce earwax.

The glands produce earwax. The function of earwax is to keep the eardrum supple and the bacteria out. When the eardrum is supple it can vibrate to soundwaves. Soundwaves can make the eardrum vibrate between 20 and 20.000 times per second!

Sometimes the earwax dries up and turns into a hard lump or ball. Because of this the eardrum can't vibrate well and you will hear less. By having a doctor clean your ear with a syringe.

 

True or false?

 

1. Earwax keeps the eardrum supple.

2. Dried up earwax can reduce your ability to hear because it can stop the eardrum from vibrating.

 

Watch the video to see how ear syringing works.

Earwax removal

You can also get an ear infection. The middle ear is the part right behind the eardrum, where the hearing bones are. The Eustachius tube connects the middle ear with your throat. Normally the Eustachius tube is closed. But... When you swallow or blow your nose it opens. When you have a cold, sometimes bacteria can go up the Eustachius tube and into the middle ear. When this gets infected you have an ear infection.

In young children they sometimes fit tubes which go through the eardrum. This way moisture and pus can get out of the middle ear.

 

True or false?

3. Bacteria from the throat can cause infection in the middle ear.

4. By placing tubes through the eardrum, moisture and pus can no longer get into the middle ear.

 

Watch the video to see how and why tubes are placed in the eardrum.

Tubes in your ear

Step5

Pressure

The eardrum is the border between the air outside and the middle ear. The middle ear also has air inside it. When the air pressure is not the same on both sides, the eardrum can either be concave or convex.

When the air pressure is not equal on both sides of the eardrum something happens. The Eustachian tube closes and the eardrum bulges inward or outward (depending on which side the pressure is higher).
When the air pressure is not equal on both sides of the eardrum something happens. The Eustachian tube closes and the eardrum bulges inward or outward (depending on which side the pressure is higher).

Watch the video.

How does ear pressure work?

These ear pressure problems might be caused by a number of things like driving up or down a mountain, flying in an airplane or scuba diving. By swallowing yawning you can force the Eustachius tube to open for a moment. This way the air pressure will be equal on both sides again. This also causes the eardrum to move more easily and will probably increase your hearing.

Step6

Volume

Study the text and do the assignment below.

Decibel

The loudness of sound -also called volume- is measured in decibel (dB). A classroom with a murmur produces about 50 dB, a disco often more than 100 dB. Sounds louder than 80 dB damage your hearing. If you listen to loud noise for a longer period of time the damage increases. This is because every time you listen to a sound which is too loud, sensory cells in the cochlea die. Each time a sensory cell dies, you lose a bit of hearing.

Playing loud music through earphones can be damaging to your ears.

 

 

 

 

 

Because your ears get damaged from listening to loud sounds for too long, employers need to make sure there isn't enough noise at the workplace. If there is too much noise they have to make employees wear hearing protection. Every 3 dB above 80 dB halves the time you should be exposed to the sound.

 

Volume (in dB) Maximum time
80 8 hours
83 4 hours
86 2 hours
100 5 minutes
110 30 seconds

 

The sofstest sound humans can hear is 3 decibel. This 'softest' sound is called the absolute threshold of hearing.

The volume of sound can be measured with a decibelmeter. Your smartphone should have a free app in the app store which works as a (not very accurate) decibelmeter. The volume of a vacuum cleaner is around 70 dB. If two vacuum cleaners make twice as much noise, you might expect the volume to be 140 dB. However, this isn't true. When a sound is twice as loud, it is only 3 dB louder. So if one vacuum cleaner produces a volume 70 dB, two vacuum cleaners produce a volume of 73 dB.

Remember: When the sound is twice as loud, the volume is 3 dB louder.

 

 

Step7

Final test

You will end the 'hearing' lessons with a test.

The test consists of a number of multiple choice questions.

After the test you will see which questions you answered correctly and what you did wrong on the questions you answered incorrectly.

 

Click the button below to start.

 

Good luck!

Extra

Hearing damage

Damage to your hearing is called noise-induced hearing loss. Watch the video below

 

 

 

Now test your own hearing on the following site:

 

http://www.hear-it.org/Online-Hearing-Test

 

Discuss the results of your hearing test with your classmates. What did you learn?

Smell & taste

Intro

Intro

Having a nice meal, this is something we all like to do.

Look at the four bowls of soup. Which one would you like to eat?

Did you choose bowl 1 or bowl 4? Then you chose the same bowls most people choose. People aren't used to eating blue or purple foods, so they don't look good to us.

 

Final product & assessment

Final product

You will finish this assignment with a practical.

The practical is called 'tasteless'. You will write a lab report about this practical.

 

Assessment

First you will assess your own lab reports. After this you will hand it in to your teacher to let him/her assess it. Your teacher will assess the correctness of the lab report and look at how neat it is.

Learning goals

After this assignment:

  • You can describe the parts of the nose and tongue.
  • You can describe which flavours you taste and which flavours you smell.
  • You can explain how you use all your senses when recognising food.
  • You can describe how the smell and taste senses work.

Method

Group size

Most of these steps you will do by yourself. When you are ready to do the practical (step 6) you will work together with a classmate.

 

Materials

-Practical materials 'tasteless' plus the handout 'practical tasteless'

 

Time

To do all the assignments, the practical and writing a lab report you will need about 2 lessons.

 

Extra

Discuss with your teacher if you are going to do the extra assignment.

Step1

Smelling & tasting

Study the text and answer the questions below.

Tasting isn't only done with the tongue. Smelling actually plays a large part in what you taste.

The nose has two holes called nostrils. The nostrils open up into the nasal cavity which in turn opens up into the throat. The nasal cavity is covered in mucus called the nasal mucosa. The fragrances that enter the nostrils disolve in the nasal mucosa, much like sugar disolves in tea.

The taste senses are located on the tongue. 

The sensory cells in the tongue can discern five kinds of flavors: sweet, sour, salty, bitter and umami.

When you are eating or drinking the flavors disolve in the saliva. They come into contact with the taste buds and impulses travel to the brain. This is how you can taste food.

When you are eating a banana, a piece of candy or an ice cream, the taste senses taste something sweet every time. Still you can taste the difference between these sweet foods. The reason for this is you really taste with all your senses. 

The tongue also has a sense of touch and hot and cold senses. This way you can 'feel' what food you are eating.

Before and while you are eating you can also smell the fragrances entering your nasal cavity.

Your eyes can identify the food before it even comes close to your mouth.

Your ears can hear the soft sizzling of a carbonated drink.

 

 

Answer the following questions about the text:

 

1. True or false?

Tasting is only done with the tongue.

A. True

B. False

 

2. What is the name of the mucus that covers the inside of the nasal cavity?

A. Smelling mucus

B. Nasal mucosa

C. Hollow slime

 

3. How many different tastes can we taste?

A. 2

B. 5

C. 12

 

4. When you eat and drink flavors dissolve in the saliva. Why is this important?

A. Because they are dissolved in the saliva they can come into contact with the taste buds.

B. Because they are dissolved in the saliva they can get swallowed more easily.

C. Because they are dissolved in the saliva they can go through the Eustachian tube into the nasal cavity.

 

5. Which senses do you use when identifying different flavors?

A. Your sense of hearing, smell and taste.

B. Your sense of hearing, feeling, taste and sight.

C. Your sense of feeling, smell, hearing, taste and sight.

Step2

Salivating

Does it happen to you? You see or smell something good and it makes your mouth water. What about something you don't like? Do you walk away from it?

 

At trainstations people take advantage of this 'mouth watering' to create an appetite with hungry travelers: croissants spreading a lovely scent or big billboards advertising burgers.

 

Test if you are sensitive for this sort of advertising by looking at the burger in the top right hand corner. Does that make your mouth water? Does the burger make you hungry?

 

 

Step3

Smell

The next assignment is about the sense of smell and the nervous system. Complete the text by dragging the words into the correct spot.

 

Word list

nerve system = a system containing all the nerves in your body (NL: zenuwstelsel)