Chapter 2Locomotion and Support

2.1 SUPPORT AND LOCOMOTION IN HUMANS AND ANIMALS

2.1 Support and Locomotion in Humans and AnimalsImportance of support and

locomotion◦Search for food◦Provide protection by escaping from

enemies or avoiding danger◦Search for more conducive living

environment◦Find mates for reproduction◦Avoid overcrowding which enables

the offspring to move to another place

2.1 Support and Locomotion in Humans and Animals (cont’d)Human skeletal system

◦ Consist of two main part; axial skeleton and appendicular skeleton

Human skeleton

Parts

Axial skeleton

1. Skull2. Vertebral

column (the backbone)

3. Ribcage

Cranium, bones of the face, jawCervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacrum, coccyxSternum and ribs

Appendicular skeleton

1. Pectoral girdle2. Arm

(forelimbs)

3. Pelvic girdle4. Leg (hind

limbs)

Scapula and clavicleHumerus, ulna, radius, carpals, metacarpals, phalangesIschium, pubis, ischiumFemur, tibia, fibula, tarsals, metatarsals. phalanges

2.1 Support and Locomotion in Humans and Animals (cont’d)Skull

◦Cranium – enclose and protect the brain

◦Facial bones and jaw Protect the eyes and ears Upper jaw is fixed

◦Skull is joined to the vertebral column at the base of cranium

2.1 Support and Locomotion in Humans and Animals (cont’d)

Rib◦Twelve pairs of ribs

Articulate with thoracic cavity dorsally, and sternum ventrally

◦Sternum is the front part

2.1 Support and Locomotion in Humans and Animals (cont’d)Vertebral column

◦Consists of 33 vertebrae, joined but separated by discs of cartilage

◦Five types of vertebrae1. Cervical vertebrae (7)2. Thoracic vertebrae (12)3. Lumbar vertebrae (5)4. Sacral vertebrae (5)5. Coccyx

2.1 Support and Locomotion in Humans and Animals (cont’d)

CentrumGives support

Neural archForms neural

canal

Neural spineMuscle

attachment

Neural canalProtects spinal

cord

2.1 Support and Locomotion in Humans and Animals (cont’d)

2.1 Support and Locomotion in Humans and Animals (cont’d)

Support head and neck

Sentrum is short and thick

Large and thick sentrum

2.1 Support and Locomotion in Humans and Animals (cont’d)Appendicular skeleton

◦Consists of1. Pectoral girdles and forelimbs (arms)2. Pelvic girdle and hind limbs (legs)

2.1 Support and Locomotion in Humans and Animals (cont’d)Arms

2.1 Support and Locomotion in Humans and Animals (cont’d)Legs

Pelvic girdle

2.1 Support and Locomotion in Humans and Animals (cont’d)

Joints◦Place where two

bones meet◦Bones are held

together by ligaments

◦Sinovial joints – joints that contains a cavity filled with fluid

◦End of bones are covered with cartilage.

2.1 Support and Locomotion in Humans and Animals (cont’d)Joints

◦Various types of joints1. Hinge joint

Allow movement in one plane

2. Ball-and-socket joint Allow movement in all directions

2.1 Support and Locomotion in Humans and Animals (cont’d)

Movement in a limb◦Skeletal muscles are attached to bones by tendons.◦Movements of cause by antagonistic movement of

muscles: One muscles is contracted, another is relaxed

2.1 Support and Locomotion in Humans and Animals (cont’d)

Structure of a muscle◦ Muscle fibre – single, long cylindrical cell that

contains many nuclei◦ Myofibrils – smaller units that made up muscle

fiber◦ Interaction of actin and myosin will cause

muscle contraction

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of earthworm◦Earthworms have a hydrostatic skeleton (the

force of contraction is applied to a coelum(fluid filled chamber).

◦Coelom is surrounded by two antagonistic muscle circular muscles – surround the chamber longitudinal muscles – extend from one end to the other.

◦Thinner and longer: When circular muscle contract and the longitudinal muscle relax. (and vice verca)

◦The muscles contract rhythmically to produce peristaltic waves which begins at the front and move towards the end of the body.

◦Earthworm has chaetae (bristles) which anchor parts of the body to the ground so that other parts can be pulled towards it.

2.1 Support and Locomotion in Humans and Animals (cont’d)

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of grasshopper◦The flexor and extensor (antagonistic) muscles

are attached to the internal surface of the exoskeleton.

◦Flexor muscles bend a joint.◦Extensor muscles straighten it.◦The rear legs of a grasshopper are long and

muscular and is adapted for hopping.◦Sitting position: When the flexor muscle contracts,

the lower leg is pulled towards the body. The hind leg is folded in a Z shape and ready for a jump.

◦ Jump: When the extensor muscle contracts, the leg jerks backwards, propelling the grasshopper forward and upward into the air.

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of grasshopper

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of grasshopper◦The flexor and extensor (antagonistic) muscles

are attached to the internal surface of the exoskeleton.

◦Flexor muscles bend a joint.◦Extensor muscles straighten it.◦The rear legs of a grasshopper are long and

muscular and is adapted for hopping.◦Sitting position: When the flexor muscle contracts,

the lower leg is pulled towards the body. The hind leg is folded in a Z shape and ready for a jump.

◦ Jump: When the extensor muscle contracts, the leg jerks backwards, propelling the grasshopper forward and upward into the air.

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of fish◦Fish has streamlined body shape◦Scales that overlap one another, with

free ends pointing backwards to reduce friction

◦Fish have W-shaped muscles called myotome

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of fish◦Fish move

forward from the contraction and relaxation (antagonistic) of myotome on either side of the body

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of fish◦Function of fins in fish – balance the body

◦Pectoral fins – for steering◦Pelvic fins – for balance, to prevent

diving and rolling

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of bird◦Bird can fly either by flapping their

wings or gliding

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of bird◦When wings move down

Pectoralis major contracts Wings are pulled down

◦When wings move up Pectoralis minor contracts

2.1 Support and Locomotion in Humans and Animals (cont’d)

Locomotion of bird◦During gliding,

wings are spread – act as aerofoil

◦Bernoulli principle – provide upward thrust

2.3 SUPPORT SYSTEM IN PLANTS

2.3 Support Systems in Plants

Support in plants is necessary to:◦Stay upright◦Obtain sufficient sunlight◦Bear the weight the plant◦Provide strength to withstand wind

ressistance

2.3 Support Systems in Plants (cont’d)

Plants

AquaticSubmerged Floating

TerrestrialHerbaceou

s Woody

2.3 Support Systems in Plants (cont’d)Submerged plants

◦Hydrilla sp. ◦Have thin, narrow and flexible leaves – provide little ressistance

◦Air sacs inside the leaves and stems - keep the plant floating close to the surface to obtain maximum sunlight.

2.3 Support Systems in Plants (cont’d)

Floating plants◦Lotus plant◦Have broad leaves that are firm but

flexible enough to resist tearing by wave action.

◦Aerenchyma tissues (spongy tissues with large air spaces between the cells) in the stems and leaves provide buoyancy so that the plants can float on the surface of the water

2.3 Support Systems in Plants (cont’d)Herbaceous plant

◦Support provided by the turgidity of the parenchyma and collenchyma cells.

◦Turgor pressure of the fluid content in the central vacuole pushes the cell membrane and the cell contents against the cell wall, creating support for the stem, root and leaves.

◦The thickening of the cell walls with cellulose and pectin in collenchyma cells provide additional mechanical strength

2.3 Support Systems in Plants (cont’d)Woody plants

◦Support provided through tissue modification

◦Xylem tissues Strenghtened by lignin Lignin – tough, not elastic and nor

permeable to water

◦Parenchyma tissues Store starch, sugars and water It become turgid – give support

2.3 Support Systems in Plants (cont’d)Woody plants

◦Collenchyma tissues Thickened with cellulose and pectin

◦Sclerechyma tissues Thickened with lignin