Biology Form 5 Notes Chapter 2 Human Skeletal
Transcript of Biology Form 5 Notes Chapter 2 Human Skeletal
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BIOLOGY FORM 5 NOTES
CHAPTER 2 : LOCOMOTION AND
SUPPORT2.1 SUPPORT AND LOCOMOTION IN HUMANS AND ANIMALS
2.1.1 Introduction
1. Locomotion = The ability of an organism to move in a particular direction in itsenvironment.
2. Support and humans and animals is provided by a framework called askeleton.
3. There are 3 types of skeleton:
(a _________________________________________________ ! The support is derived from the body fluid contained within the body cavity! The fluid maintains the body shape and provide support for internal organs! "#amples: earthworms$ leeches and caterpillars
(b _____________________________________ ! %ound in the bodies of arthropods$ the shell of molluscs and the bony plates of
tortoise.
! The e#oskeleton supports important body organs$ protects the internal structure fromdamage and allows the animals to move from place to place.
! "#amples: insects$ crabs$ snails
(c ______________________________________________ ! %ound in the bodies of all vertebrates! The endoskeleton consists of hard skeleton of bones found inside the body.! The endoskeleton supports the body and also protects the organs! "#amples: human$ fish$ amphibians and birds
4. The functions of skeleton:
(a _____________________________________________ ! The skeleton protects the organs! "#ample: The skull protects the brain$ the vertebral column protects the spinal cord
and the rib cage protects the heart and lungs
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(b _____________________________________ ! The skeleton acts as a framework to support soft body parts$ to maintain the upright
position and to keep the body stable.(c --___________________________________
! &ones interact with the skeletal muscle to enable the movement of the body.
(d &lood cell formation! 'ost of the blood cells are formed in the bone marrow of the long bones
(e 'ineral storage! &ones act as a reservoir for calcium and phosphorus.
.). The human skeletal system
1. The skeletal system can be divided into the a#ial skeleton and the
appendicular skeleton.
2. The a#ial skeleton:
! 'ade up of the bones that form the vertical a#is of the body.! *t supports and protects the organs of head$ neck and trunk.! *ncludes: the skull$ vertebral column and rib cage
3. The appendicular skeleton:
! 'ade up of the bones that are attached to the a#ial skeleton! *ncludes: bones of the limbs (forelimb and hind limb$ the pectoral girdle and the
pelvic girdle
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+. ,#ial skeleton
Type of skeleton -haracteristics e#planation
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/. Structure of a typical vertebra
Structure %unction
Transverse foramen
0ertebral foramen
Spinous processes$Transverse processes
-entrum
1. Type of vertebral
Type of vertebral -haracteristics e#planation
,tlas
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,#is
3rd!2th cervical vertebrae
Thoracic vertebrae
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Lumbar vertebrae
Sacrum and -occy#
2. ,ppendicular skeleton
Type of skeleton -haracteristics e#planation
ectoral girdle
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elvic girdle
4pper limb
Lower limb
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5. Structure of a 6oint
• , 6oint is a place where or more bones meet.
• Structures of a 6oint:
a 77777777777777777777
b muscles
c 77777777777777 (elastic fibres$ prevent dislocation of the 6oints during movement.
d 7777777777777777 ( absorb shock$ reduce friction
e 7777777777777777 ( reduce friction$ protect the bones from wearing away.
• Two types of 6oint:
(a ______________________________
- ,llow movement of bones in one plane only (door hinge
- "#amples: elbow 6oint$ knee 6oint and some of the 6oints between the finger or toe
bones
(b --_____________________________________-----
- ,llow rotational movement of bones in 3 planes ( all directions
- "#amples: shoulder 6oint and hip 6oint.
8. Ligaments$ Tendons and 'uscles
(a ________________________
• 9oints two or more bones together at a 6oint.
• Ligaments are tough and strong connective tissues.
• They are elastic and allow the movement of bones at a 6oint
(b ____________________________________
• 9oints muscles to the bones
• Ligaments are tough and strong an d inelastic strands of dense connective tissues.
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(c 7777777777777777
i. Skeletal muscles
- can only contract when there are impulses. *f the nerve to the skeletal muscle is
damaged or blocked$ the muscle will completely paralysed.
- roduce movement by e#erting the force to pull on the tendons which are attached
to bones. ,s muscle contracts$ it becomes shorter as it pulls on the attached bone.
- roduce movement by e#erting the force to pull on the tendons which are attached
to bones. ,s muscle contracts$ it becomes shorter as it pulls on the attached bone.
ii. ________________________________________-
- can contract spontaneously even in the absence of nervous stimulation.
iii. -ardiac muscles
- can contract spontaneously even in the absence of nervous stimulation.
The structure of skeletal muscles
• -onsists of bundles of muscle fibres$ nerves and blood vessels.
• 'uscle fibres is a long cylindrical cell that contain numerous nuclei.
• "ach muscle fibre is made up of many myofibrils
• "ach myofibril has section of sacromere.
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• , sacromere consists of myosin and actin which interact to bring about muscle
contraction
)). ___________________________ muscles
• , pair of muscles work together to allow coordinated movement of the skeletal
6oints.
• hen one muscle contracts$ the other muscle rela#es.
• ;ne muscle pulls the bones in one direction and the other pulls it in the opposite
direction.
). ,ction of ligaments$ tendons and muscles in the moving of a limb.
(c alking
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The calf muscle of right leg contracts to raises the heel.
The fle#or muscle at the thigh (biceps femoris < hamstring muscle
777777777777777while the e#tensor muscle (uadriceps femoris rela#es to pull the
tibia and fibula backwards and bend the leg at knee.
The leg is raised. The weight of the body is now supported by the left leg which is
still in contact with the ground.
Then$ the uadriceps femoris contracts while the biceps femoris rela#es to pull tibia
and fibula the forward and e#tends the leg.
The tibialis contracts to lower the heel onto the ground.
The right leg regains contact with the ground. The weight of the body is now
supported by the right leg.
The whole process is repeated with the left leg.
.).3 -onseuences of impaired musculoskeletal system
*mpaired
musculoskeletal
system
-auses Signs and
syndromes
revention and
treatment
'uscle cramp
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*mpaired
musculoskeletal
system
-auses Signs and
syndromes
revention and
treatment
;steoporosis
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'uscular
dystrophy
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*mpaired
musculoskeletal
system
-auses Signs and
syndromes
revention and
treatment
,rthritis
(a ;steoarthritis
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(b >heumatoid
arthritis
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.).+ The mechanism of locomotion in animals
). The locomotion of earthworm
• "arthworms have two antagonistic muscles: circular muscles and longitudinal
muscles.
• hen circular muscles contract$ the longitudinal muscles rela#$ the earthworm
becomes thinner and longer.
• hen longitudinal muscles contract$ the circular muscles rela#$ the earthworm
becomes shorter and thicker.
• ?uring locomotion$ the circular and longitudinal muscles contract rhythmically to
produce peristaltic waves along the body.
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• The waves begin at the front and move towards the end of the body.
• The earthworms have bristles called chaetae which anchor parts of the body to the
ground so that other parts can be pulled towards.
. Locomotion in an animal with an e#oskeleton
• , grasshopper has antagonistic muscles: fle#or muscle and e#tensor muscle.
• hen fle#or muscle contracts and the e#tensor muscle rela#es$ the leg is bent at
6oint.
• hen e#tensor muscle contracts and the fle#or muscle rela#es$ the leg is
straightened.
(a alking
• , grasshopper uses three legs to support the body off the ground$ while the other
three legs move together to make successive steps while walking.
(b 9umping < @opping• The rear legs (hind legs of a grasshopper are adapted for hopping. The legs are
long and muscular.
• hen the fle#or muscle contract$ the lower leg is pulled towards the body. The long
hind legs are folded in shape of A. The grasshopper is ready for a 6ump.
• hen the e#tensor muscle contracts$ the leg 6erks backwards.
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• The grasshopper is propelled forward and upwards to the air.
3. Locomotion in an animal with an endoskeleton
(, Locomotion in fish
• roblems faced by fish in locomotion:
(a water is viscous and dense
(b gravity
• The adaptations of fish in locomotion:
(a %ish have streamlined body shapes to overcome water resistance.
(b The overlapping scales on the body of a fish facing backwards to reduce resistance
when swimming.
(c The body of fish is covered by a slimy coating to minimiBe frictional drag and
maintains a smooth flow of water over the body.
(d The vertebral column of the fish is fle#ible to allow the movement of the body.
(e The movement of the fish is controlled by the contraction and rela#ation of
myotomes (!shaped muscle which causes different parts of the body to be swept
from side to side pushing the water backwards and sideways and the body forwards.
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• %orward movement
(a ?uring swimming$ the tail is swept from side to side to bend the body on either side
alternately and produce a thrust that propels the fish forward.
(b The contraction of the myotome on the right side of the body will bend the tail to the
rightC the contraction of the myotome on the left side of the body will bend the tail to
the left.
(c The continuous sweeping movement of the tail from side to side produces a thrust
that propels the fish forward on a straight path.
• &alancing the body
(a The function of fins of fish is to maintain the balance of the body during swimming.
(b The paired fins consist of ectoral fins and elvic fins:
i ectoral fins: used for steering$ to change the direction and as a brake to slow
down or stop the movement.
ii elvic fins: used for balance and to keep the fish steady by preventing diving and
rolling.(c The unpaired fins consist of one dorsal fin$ one ventral fin and one caudal fin or tail.
i Tail: propulsion organ
ii ?orsal fin and ventral fin: prevent yawing and rolling
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(a 'any bony fish have swim bladders to help them maintain buoyancy in the water.
The swim bladder is a sac inside the abdomen that contains gas. &y controlling the
amount of gas in the swim bladder$ a fish can change its buoyancy.
(& Locomotion in birds
• The adaptations of birds in flying:
(a &irds have streamlined body shapes to reduce resistance in the air when flying.
(b The body is light as the bone is hollow$ the head is small and the body is free of fats.
Some of the internal organs such as kidney and testis are reduced to one to reduce
weight.
(c The feathers on the tail and wings provide a large surface area for flight.
(d The body is covered by waterproof feathers to prevent it to become wet.
(e The feathers are arranged to overlap one another and pointed backwards to keep
the body its streamlined shape and to prevent it from being ruffled by the wind.The wings are aerofoiled in shape to provide an upward thrust that carries the bird
forward and upward
5 Whole
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• %light
(a hen the wings move down:
i The ma6or pectoralis muscle on both wings contract.
ii The wings are pulled down during downstroke.
iii The air resistance produced as a result of lowering the wings provides an upward
thrust on the wings.
iv The thrust is transmitted from the wings to the coracoid.
v The whole body is lifted up.
(b hen the wings move up:
i The minor pectoralis muscle on both wings contract.
ii The wings are pulled up during upstroke.iii The air resistance is very low.
iv This returns the wings to the starting position for the ne#t downstroke.
(c The wings which move up and down rhythmically generate the forward thrust as well
as provide the lift for the flying bird.
2.1 APPRECIATING A HEALTHY MUSCULOSKELETAL SYSTEM
). The various ways to care for the musculoskeletal system:
(a @aving a well!balanced diet
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(b @aving a good posture
(c 4sing proper attire for daily activities
(d Taking appropriate precautions during vigorous activities
(e racticing correct and safe e#ercise techniue