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KS4 Biology
B3a / Side 1
Human Skeleton
The skeleton has a number of functions:
1.
2.
3.
4.
It keeps the shape of the animal
It protects vital organs such as the brain, heart, lungs and spinal cord
It supports the animal’s weight
It provides a framework for the attachment of muscles for movement
Using the Internet, CD-Rom’s and books, try to find out:
1. How many bones are in the human body
2. The names of the longest and shortest bones
You should be familiar with some of the main bones found in the human skeleton.
Label the following diagram using your textbooks.
P236 Applin
P214 Nelson
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KS4 Biology
B3b / Side 1
The skeleton is made up of mainly two types of tissue, bone and cartilage.
Bone is covered at joints by cartilage.
1. Bone is both hard and flexible o some extent. Bone cells are specially arranged
in cylindrical layers. This makes the bone hard. Bone cells are living and they
secrete calcium phosphate, which is a mineral that gives the bone hardness.
Bone cells are attached to a network of fibres and this gives the bone a
degree of flexibility.
2. Cartilage is a rubbery protein secreted by special cartilage cells. It cushions
the ends of bones at special areas called joints. It has a smooth, shiny
surface.
Each type of tissue has its own specific properties.
A property describes the physical appearance and chemical nature of the material.
Make a copy of the table below and complete using the following statements.
Rubbery protein; structural fiber arrangement; smooth; hard minerals (calcium
phosphate); shock absorber; structural support; protection of organs
Types of Tissue
Property
Job/Function
Bone
Cartilage
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KS4 Biology
B3c / Side 1
Joints
One of the main roles of the skeleton is movement. This happens at areas where the
bones are linked together. These areas are called joints.
Different joints in your body allow you to carry out different types of movement.
These moveable joints are called synovial joints and are specially designed to enable
easy movement.
Examples of synovial joints are:
Complete the following table using your textbook as a reference
Type of joint
Type of movement possible
Examples
Ball and socket
Hinge
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KS4 Biology
B3c / Side 2
Synovial Joints have special features that allow them to move easily.
Using the following words, label the human elbow joint and answer the questions.
Synovial fluid, cartilage, humerus, radius, synovial membrane,
ligament, ulna
What job does each of these do:
1. Synovial membrane
2. Synovial fluid
3. Cartilage covering the ends of the bones
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KS4 Biology
B3d / Side 1
Connective Tissue
There are two kinds of connective tissue that help movement of bones and muscles.
1. Ligaments
2. Tendons
Copy and complete the following table
Type of tissue
Property
What it connects
Function
Inelastic
Bone-to-bone
Structure and movement of the forearm
Muscles move bones. A muscle works by pulling on a bone. To do this the muscle has
to contract. Muscles only shorten in length. They do not lengthen. Using your
textbook, answer the following questions
Q1.
What attaches muscles to bone?
Q2.
Why is this design important?
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KS4 Biology
B3d / Side 2
The diagrams below show the muscles and bones of a person’s arm in two different
positions.
Muscles work by contracting. Muscles of ten work in antagonistic pairs. This means
when one contracts the other relaxes.
Label the following diagrams.
Diagram 1 – Arm Extended
Diagram 2 – Arm Flexed
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KS4 Biology
B3d / Side 3
Answer the following questions:
1. What type of joint is shown?
2. Which muscle in diagram 1 contracts to lower the arm?
3. Which muscle in diagram 2 contracts to raise the arm?
4. Why are these muscles known as antagonistic pairs?
5. What role is played by the bones of the skeleton in movements of the arm?
Complete the following paragraph using the words provided below. You can use these
words once or more than once.
Contracts, antagonistic, tendons, levers, ulna, push, biceps, arm,
raised, extend, synovial, opposing, pull, elbow, muscles, triceps,
forearm, extends
Muscle can only
they cannot
. As a consequence,
two muscles are required to operate ( both flex and
These are called the biceps and the
arranged to have
pair. The
)
muscles,
and
the
they
lies on the front of the humerus and is attached by
the forearm is
. When it
and the
is flexed. When the
contracts, it pulls the forearm down and
elbow. The bones of the arm act like
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are
actions. They are called an
to the shoulder and
by
elbow.
the
which
are
moved
pulling on tendons.
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KS4 Biology
B3e / Side 1
Dissection of a Pig’s trotter
This dissection will allow you to see a joint in action.
Over the top of the joint there are four white tough tendons. Make sure that you
can see these. Ask your teacher!
1. Hold the trotter and waggle the toes from left to right.
2. Now bend the toes downwards. You should see a second joint further down,
away from the toe. ( Like a knuckle )
3. Using scissors cut down the length in-between the toes and the second big
joint on the front surface of the trotter. Ask if you are not sure!
4. Then cut across this area at right angles to the first cut
5. You should have a cross shape cut
6. Peel back the skin and remove any hair. Cut this piece of skin off
7. You should be able to see the tendons.
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KS4 Biology
B3e / Side 2
1. Bend the toes down and expose the knuckle.
2. Cut across the knuckle. You will cut through the tendons.
3. Underneath the tendons, close to the bone, you will find a membrane, which is
loose. Behind this is fluid.
4. When you cut through the membrane the fluid should trickle out. This is synovial
fluid.
5. Cut towards the tow now and you should expose the shiny white surface on the
lower part of the joint.
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KS4 Biology
B3e / Side 3
6. Now cut sideways. You should cut through the joint capsule and ligaments. Don’t
worry if you are not sure. Ask your teacher and compare group samples.
7. When the joint is exposed feel the cartilage and press your scissors into the
cartilage.
8. Slice a piece of cartilage off and you should see pinkish bone underneath.
9. If time discuss the differences in texture between, muscle, bone, cartilage,
tendons and membranes. Think how these differences may be related to their
functions.
Answer the following questions:
1. Describe what cartilage is like?
2. Why is it necessary to have cartilage in joints?
3. What would happen if two bones rubbed together?
4. What does synovial fluid do?
5. Why are tendons tough and not elastic?
6. What happens when a joint swells up?
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Science Department - June 17
KS4 Biology
B3f / Side 1
Practical – Using a model arm to investigate the action of
the biceps muscle
It would be easier to raise the arm if the biceps muscle was attached to the wrist
since the further away from the joint, the smaller the force is required to lift the
arm. Muscles compensate by being very strong and able to exert large forces over
small distances.
1. Copy the title and results table.
2. Hang a 100g weight on the hook at the end of the ‘forearm’ of the model.
3. Attach a spring balance to hook 1. Pull upwards with the spring balance,
parallel to the humerus until the forearm is exactly horizontal. Take the
reading on the spring balance and fill it on the results table.
4. Repeat with the balance pulling on hooks 2, 3 and 4.
5. Repeat using a different weight.
Results table
Remember 10N=1Kg
Weight in Newtons
(N)
1
1
1
1
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Hook Number
Distance from
elbow (cm)
Force exerted by
spring balance (N)
1
2
3
4
1
2
3
4
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KS4 Biology
B3g / Side 1
Supplementary Questions
1. What does the spring balance represent?
2. At which position was the force needed to lift the weight greatest?
3. Which position most closely represents the actual position of the biceps to the
radius?
4. Striated muscles are able to exert considerable forces but they cannot shorten
by a very large amount.
Can you suggest why the biceps is attached in this
position?
The forces acting on a forearm when lifting a weight can be shown diagrammatically
like this:
When the arm is horizontal and not moving
W x D1 = F x D2
5. What does W stand for?
6. What does F stand for?
7. Use your equation to explain your answer to question 2.
8. Where are the following muscles found in the human body?
(a)
Voluntary muscle
(b)
Involuntary muscle
(c)
Cardiac muscle
9. What are the main differences between these 3 muscles?
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KS4 Biology
B3h / Side 1
Core questions
1. Cartilage in a synovial joint serves to:
(a)
Give the body its shape
(b)
Protect the muscles at the joint
(c)
Reduce fiction
(d)
Allow for extra movement
2. The structures which attach muscle to bones are called:
(a)
Tendons
(b)
Nerves
(c)
Ligaments
(d)
Cartilages
3. When the arm is flexed:
(a)
The biceps relaxes and the triceps expand
(b)
The biceps expands and the triceps relax
(c)
The biceps expands and the triceps contracts
(d)
The biceps contracts and the triceps relaxes
Short answer questions
1. The diagram below shows the elbow joint.
1. Name the parts labeled A to G
2. What is a joint?
3. State two features of a joint which help
to reduce friction
4. What do we mean
antagonistic muscles?
by
the
term
5. Name and explain how antagonistic
muscles can cause the arm to bend at
the elbow
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