Biology Form 5 Notes Chapter 2 Human Skeletal

8/18/2019 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

Biology Form 5 Notes Chapter 2 Human Skeletal

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