The document discusses the form and movement of the human body. It describes the key components of the skeletal and muscular systems including bones, joints, and muscles. The skeletal system is divided into the axial skeleton and appendicular skeleton. Bones provide structure, support, and protection. They are living tissues composed of calcium and cells. Joints connect bones and allow various ranges of movement. Muscles are attached to bones and facilitate movement via contraction. Regular exercise strengthens muscles and improves body function.
Edexcel IGCSE - Human Biology - Chapter 07 - Form & Movement
1. Chapter 07: Form & Movement
Edexcel IGCSE Human Biology
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2. Introduction
• Vertebrates – The organisms that composed of
a vertebral column
• Voluntary muscles/ skeletal muscles
– Muscles connected to bones
– Controlled consciously/voluntarily by the
brain
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3. Importance of the skeleton
• Support & movement
• Protect vital organs
– Cranium – Brain, eyes, ears
– Vertebrae – spinal cord
– Rib cage – heart, lungs
• Produce blood products(RBC, platelets) in long
bones (sternum, femur, pelvis)
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7. Bone Structure
• Bone;
– is hard
– it is made up by Calcium phosphate
– Can resist bending, compression forces
– Made of cells called osteocytes along with protein
fibers
• Middle of the bone is composed of spongy bones with
fewer Ca2+ salts and spaces
• Some larger bones contain cavities fill with bone
marrow store fats and produce blood cells
• The outside of the bone is made up with compact bone
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8. Bone Structure
• Ossification
– The process converting cartilages in to bones
– Nearly completed once the baby is born
• Haversian system
– The arrangement of osteocytes around cannels
containing blood vessels and nerves
– The osteocytes secrete Ca2+ ions and protein fibers in
order to make the bone matrix
– Watch this link :
https://www.youtube.com/watch?v=d9owEvYdouk
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9. Bone Structure
• Cartilages
– Can be seen at the end of long bones
– Act as a cushion between bones
– It is tough but, flexible
– Consists of cells called as chondrocytes which secrete various
proteins
• Periosteum
– Outer surface of the bone
• Long bones stop growing in late teens, but the internal structure
can be changed due to;
– Hormones
– Diet ( ex: Rickets due to Vit. D deficiency, less Ca2+ intake )
– Exercise
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10. Joints
• The point where two bones are
met/articulated
• Features ;
– Having a way to avoid
dislocation
– Having a way to reduce
friction
– Having a shock-absorbing
surface
• Movable joints are called as
synovial joints
• The oily Synovial fluid is
secreted by synovial membrane
to reduce friction
• The cartilage acts as the shock
absorber
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11. • The joint is surrounded by
tough fibrous capsule and
held together by ligaments
composed of fibers
• Ligaments have tensile
strength to resist stretching
and have elasticity to bend
Joints
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12. Classification of joints
Type of joint Movement Example
1. Freely movement
joints
One plane Hinge joint in elbow
Three planes Ball and socket joint in
hip & shoulder
2. Partially movable
joints
Some movement Vertebrae facilitated by
cartilages
3. Immovable (fixed)
joints
No movement Joints in skull
Cranium consist of 22 bones12
13. Muscles
• Muscles are attached to the bones and move them by
contracting
• Tendons
― attach muscles in to the bones
― have very high tensile strength
― not very elastic
• When a muscle is;
―contracted -> the length is shorten
― relaxed -> the length gets longer
• Antagonistic pairs - muscles work in pairs; one
contracting while other relaxes (Ex : biceps & triceps)
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15. Muscles
• In arm;
―flexion – biceps contracts, triceps relaxes
―Extension – triceps contracts, biceps relaxes
• When a muscle contracts,
― the bone at one end of the muscle moves and the
place where the muscle is attached to the stationary
bone is called the origin
―The bone at the other end stays still and the place
where the muscle is attached to the moving bone is
called as the insertion
― the insertion moves towards origin
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16. Bending the spine
• Spine is made of bones called vertebrae
• Joined by synovial joints which allow a slight
movement
• Rectus muscles responsible for bending the spine
• Types of vertebrae
1. Cervical vertebrae
2. Thoracic vertebrae
3. Lumber vertebrae
4. Sacrum (five fused vertebrae at the bottom)
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19. Muscle contraction and exercise
• Skeletal muscle made up
of highly specialized
muscle cells or fibres
arranged in bundles
• Adopted to contraction
• Composed of fine protein
filaments
• Thin filaments slide past
the thick filaments,
making fibers shorter
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20. Muscle contraction and exercise
• Contraction of muscles needs energy comes from
respiration
• In respiration glucose and O2 are converted into CO2 ,
water and release the energy
• Some energy is lost as heat
• In vigorous exercises;
– HR increases to provide more oxygenated blood to
muscles
– RR and volume of breath is increased to receive
more O2 and to release more CO2
– Blood in gut is diverted towards muscles
– Vasodilatation and sweating happens in the skin
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21. Muscle contraction and exercise
• Even when a muscle is relaxed, some of its fibres are
contracted and this state of partial contraction called as
muscle tone
• It keeps muscles taut, but don’t cause movement ( Ex:
Sitting & standing)
• Regular exercises;
― keeps muscle toned
― develops muscles
― Avoid stiffness and soreness of muscles
―Improves blood circulation
―Keeps joints working smoothly
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