Movement is a characteristic of all living organisms.
- Most animals move from place to place but some are sessile (i.e. fixed to the substratum).
- However, though not easily observed all living protoplasm shows movement of one type or another.
Necessity for support and movement in plants
- They enable plants to be held upright to trap maximum light for photosynthesis and gaseous exchange.
- It enables animals and plants to adjust to their environment.
- To hold flowers and fruits in appropriate position for pollination and dispersal respectively.
- To enable plants to grow to great heights and withstand forces of environment e.g. strong winds.
- Movement of male gametes to effect fertilization and ensure perpetuation of a species.
- Plant parts move in response to certain stimuli in the environment of tropisms.
Tissue distribution in Monocotyledonous and Dicotyledonous plants
- Vascular bundles are the main support tissues in plants.
- In monocotyledonous stem they are scattered all over the stem.
- while in dicotyledonous stem they are found in a ring or rings.
- In monocots the xylem and phloem alternate around with pith in the centre.
- In dicots of the xylem forms a star in the centre – there is no pith.
- Phloem is found in between the arms of xylem.
- Dicotyledonous plants have cambium which brings about secondary growth resulting in thickening of the stem and root hence providing support.
- Secondary xylem becomes wood, providing more support to the plant.
Role of support tissues in young and old plant
Plants are held upright by strengthening tissues ;
- xylem tissue.
- Parenchyma and collenchyma are the main support tissues in young plants.
- They are found below the epidermis.
- They form the bulk of packing tissue within the plant between other tissues .
- They are tightly packed and turgid they provide support.
- Their cell walls have additional cellulose deposited in the corners.
- This provides them with extra mechanical strength.
- Their cells are dead due to large deposits of lignin on the primary cell wall.
- The lignified wall is thick and inner lumen is small, hence provide support.
- Sclerenchyma fibres are arranged in elongated and in longitudinal sheets giving extra support.
- They are found in mature plants.
- Has two types of specialised cells.
- Vessels and tracheids.
- Vessels are thick-walled tubes with lignin deposited in them.
- They give support and strength to the plant.
- Tracheids are spindle-shaped cells arranged with ends overlapping.
- Their walls are lignified.
- They help to support and strengthen the plant.
Plants with weak stems obtain their support in the following ways.
- Some use thorn or spines to adhere to other plants or objects.
- Some have twinning stems which grow around objects which they come into contact with.
- Others use tendrils for support.
- Tendrils are parts of a stem or leaf that have become modified for twinning around objects when they gain support.
- In passion fruit and pumpkin, parts of lateral branches are modified to form tendrils.
- In the morning glory, the leaf is modified into a tendril.
Support and Movement in Animals
Necessity for support and movement in animals.
Animals move from place to place:
- In search of food.
- To escape from predators.
- To escape from hostile environment.
- To look for mates and breeding grounds.
- The skeleton, which is a support structure helps to maintain the shape of the body.
- Movement is effected by action of muscles that are attached to the skeleton.
Types and Functions of Skeletons
- Two main types will be considered.
- These are exoskeleton and endoskeleton.
- Exoskeleton is hard outer covering of arthropods made up of mainly chitin.
- Which is secreted by epidermal cells and hardens on secretion.
- It is strengthened by addition of other substances e.g. tannins and proteins to become hard and rigid.
- On the joints such as those in the legs the exoskeleton is thin and flexible to allow for movement.
Functions of Exoskeleton
- Provide support.
- Attachment of muscles for movement.
- Protection of delicate organs and tissues.
- Prevention of water loss.
- It forms an internal body framework.
- This is a type of skeleton characteristic of all vertebrates.
- The endoskeleton is made of cartilage, bone or both.
- It is made up of living tissues and grows steadily as animal grows.
- Muscles are attached on the skeleton.
- The muscles are connected to bones by ligaments.
- The functions of endoskeleton include support, protection and movement.
- Locomotion in a finned fish e.g. tilapia.
- Most of the fishes are streamlined and have backward directed fins to reduce resistance due to water.
External features-of Tilapia
- Scales tapers towards the back and overlap forwards to provide a smooth surface for a streamlined body.
- The head is not flexible.
- This helps the fish to maintain forward thrust.
- Slimy mucous enables the fish to escape predators and protects the scales from getting wet.
- The pectoral and pelvic fins are used mainly for steering, ensuring that the fish is balanced.
- They assist the fish to change direction.
- The dorsal and anal fins keep the fish upright preventing it from rolling sideways.
- The caudal or tail fin has a large surface area, and displaces a lot of water when moved sideways creating forward movement of the fish.
- In order to change position in water the fish uses the swim bladder.
- When filled with air the relative density of the body is lowered and the fish moves up in the water.
- When air is expelled, the relative density rises and the fish sinks to a lower level.
- Swimming action in fish is brought about by contraction of muscle blocks (myotomes).
- These muscles are antagonistic when those on the left contract, those on the right relax.
- The muscles are attached to the transverse processes on the vertebra.
- The vertebra are flexible to allow sideways movement.
The mammalian skeleton is divided into two:
- Axial and appendicular.
- Axial skeleton is made up of the skull and the vertebral column.
- Appendicular skeleton is made up of the pelvic and pectoral girdles and limbs (hind limb and forelimbs).
The Axial Skeleton
This consists of the ;
- the sternum,
- the vertebral column.
- The skull is made up of cranium and facial bones.
- The cranium; encloses and protects the brain.
- It is made up of many bones joined together by immovable joints.
- The facial bones consists of the upper and lower jaws.
- At the posterior end of the cranium are two smooth rounded protuberances, the occipital condyles.
- These condyles articulate with the atlas vertebra to form a hinge joint, which permits the nodding of the head.
Sternum and ribs –
- They form the rib-cage.
- The rib-cage encloses the thoracic cavity protecting delicate organs such as the heart and lungs.
- The ribs articulate with the vertebral column at the back and the sternum at the front.
The Vertebral Column
- The vertebral column is made up of bones called vertebrae placed end to end.
- The vertebrae articulate with one another at the articulating facets.
- In between one vertebra and another is the cartilaginous material called intervertebal disc.
- The discs act as shock absorbers and allow for slight movement.
- Each vertebra consists of a centrum and a neural arch which projects into a neural spine.
- The neural canal is the cavity enclosed by the centrum and the neural arch.
- The spinal cord is located inside the canal.
- The neural spine and other projections e.g. transverse processes serve as points of attachment of muscles.
- These are found in the neck region of a mammal.
- The distinguishing feature is a pair of verte-braterial canals in the neural arch, through which the blood vessels of the neck pass.
- Another feature is the structure of the transverse processes.
- They are flattened out and are known as cervical ribs.
- The fIrst cervical vertebra is known as the Atlas.
- It has a large neural canal and no centrum.
- The second cervical vertebra, is called axis.
- The other five cervical vertebrae have no specific names.
- They have the same structure.
- The cervical vertebrae possess numerous processes for muscle attachment.
- Each thoracic vertebra has a large centrum ,a large neural canal, neural arch and a long neural spine that projects upwards and backward.
- There is a pair of prezygapophyses and postzygapophyses for articulation with other vertebra .
- They have a pair of short transverse process.
- The thoracic vertebra also articulates with pair of ribs at tubercular and capitular facets.
- Each lumbar vertebra has a large, thick centrum for support of the body.
- It has a neural spine that projects upwards and forwards.
- There is a pair of large transverse process that are directed forwards.
- Above the prezygapophyses lies a pair of processes called metapophyses,
- Below postzygapophyses lies the anapophyses.
- Metapophyses and anapophysis serve for attachment pf muscles of the abdomen.
- In some mammals, there may be another process on lower side of centrum called hypapophysis also for muscle attachment.
- The sacral vertebrae are fused together to form a rigid bony structure, the sacrum.
- The centrum of each vertebra is large, but the neural canal is narrow.
- The neural spine is reduced to a small notch.
- The transverse processes of the first sacral vertebra are large and wing-like
- They are firmly attached to the upper part of the pelvic girdle.
- Human beings have only four of these vertebrae which are fused together to form coccyx.
- Animals with long tails have many caudal vertebrae.
- A typical caudal vertebra appears as a solid rectangular mass of bone.
- The entire bone consists of the centrum only.
- The appendicular skeleton consist of the limbs and their girdles.
Bones of Fore-limbs
- Pectoral girdle is made of scapula, coracoid and clavicle.
- A cavity known as glenoid cavity occurs at the apex of the scapula.
- The humerus of the fore limb fits into this cavity.
- The clavice is a curved bone connecting the scapular to the sternum.
- Humerus is found in the upper arm.
- It articulates with the scapula at the glenoid cavity of the pectoral girdle and forms a ball and socket joint.
Ulna and radius
- These are two bones found in the forearm.
- The ulna has a projection called olecranon process and a sigmoid notch which articulates with the humerus.
Bones of hind limb
- The pelvic girdle consists of two halves fused at the pubic symphysis.
- Each half is made up of three fused bones:
- the ilium,
- Each half has cup-shaped cavity for the acetabulum for articulation with the head of the femur.
- Between the ischium and pubis is an opening obturator foramen where spinal nerves, blood vessels and a tough inflexible connective tissues pass.
- The ilium, ischium and pubis are fused to form the innominate bone.
- The femur is the long bone joining the pelvic girdle and the knee.
- The head of the femur articulates with acetabulum forming the ball and socket joint at the hip.
- The femur has a long shaft.
- At the distal end it has condyles that articulate with the tibia to form a hinge joint at the knee.
- The patella covers the knee joint and prevents the upward movement of the lower leg.
Tibia and Fibula
- The tibia is a large bone, and the fibula a smaller bone is fused to it on the distal part.
- In humans the tibia and fibula are clearly distinguishable.
Joints and Movement
- Ajoint is a connection between two or more bones.
- Joints provide articulation between bones making movement possible.
- However some joints do not allow any movement e.g. the joints, between bones of the skull.
- Movable joints are of three main types:
- g., joints which occur between the vertebrae wrists and ankles.
- The ends of the bones that make the joint are covered with cartilage.
- The bones are held together by tough ligaments.
- The joint is enclosed by fibrous capsule lined by synovial membrane which secretes synovial fluid into the synovial cavity.
- The synovial fluid lubricates the joint.
- They are called synovial joints.
- They include hinge joint and ball and socket joint.
- g. knee joint.
- The joint allows movement in one plane.
Ball and socket joint.
- e.g., hip joint.
- The joint allows rotation in all directions.
Types, Locations and Function of Muscles
- There are three types of muscles, located at various parts of the body.
- In order to function all use energy in form of ATP.
- These include smooth, skeletal and cardiac muscles.
Smooth Muscle (Involuntary Muscles)
- These are spindle-shaped and contain filaments with myofibrils.
- Each muscle is bound by plasma membrane.
- They are found lining internal organs such as alimentary canal, bladder, and blood vessels.
- They are controlled by involuntary part of the nervous system.
- They are concerned with movement of materials along the organs and tubes.
- They contract slowly and fatigue slowly .
Skeletal Muscle (striated or voluntary muscle)
- Skeletal muscles are striated and have several nuclei.
- They are long fibres each containing myofibrils and many mitochondria.
- They have cross-striations or stripes.
- They are also called voluntary muscles because the contraction is controlled by voluntary nervous system.
- They are surrounded by connective tissue and are attached to bones by tendons.
- Their contraction brings about movement of bone, resulting in locomotion.
- They contract quickly and fatigue quickly.
- Consist of a network of striated muscle fibres connected by bridges.
- Are short cells with numerous mitochondria and uninucleate.
- They are found exclusively in the heart.
- Contractions of cardiac muscles are generated from within the muscles and are rhythmic and continuous hence they are myogenic.
- They do not tire or fatigue.
- The rate can be modified by involuntary nervous system.
- Their contractions result in the heart pumping blood.
Role of muscles in movement of the human arm
- Muscles that bring about movement are antagonistic, i.e. when one set contracts the other relaxes.
Antagonistic muscles of human forelimb
- The biceps muscles of the forelimb act as flexors while the triceps muscles act as extensors.
- The biceps has its point of origin on the scapula and the point of insertion on the radius.
- The triceps has its points of origin on the scapula and humerus and is inserted on the ulna.
- When the muscles contract, the limb acts as a lever with the pivot at the joint.
- Contraction of biceps muscles bends (flexes) the arm while contractions of triceps extends the arm.
To observe prepared slides of transverse section of stems of herbaceous and woody plants.
- Permanent slides of transverse sections of:
- Herbaceous plant and Woody plant are obtained.
- The permanent slide of a herbaceous plant is placed onto the stage of the microscope.
- Observations under the low power and medium power objective is made.
- A plan diagram is drawn and labelled.
- The permanent slide of a woody plant is placed on the stage of the microscope.
- Observations under the low power and medium power objectives are made.
- A plan diagram is drawn and labelled.
- In both cases, support tissues such as parenchyma, collenchyma, sc1erenchyma and xylem are observed.
To observe wilting in young herbaceous plants.
- A herbaceous potted plant e.g. bean plant is obtained.
- The plant is placed on the bench near a window and left for 3 days without watering on the third and subsequent day.
- The shoot droops due to fall in turgor pressure; caused by water loss.
To examine the exoskeleton in an arthropod.
- Obtain a beetle and observe the external structure.
- The exoskeleton is on the outer surface with muscles attached on inner side.
- The exoskeleton is hardened by chitin.
- Movement is due to joints on the limbs.
- Also examine various shed cocoons of insects e.g., butterfly.
To observe the external features of a finned fish.
- Fresh Tilapia is obtained and placed on a tray.
- Observations are made on the external features of the fish.
- A labelled drawing is made.
- Features like scales, fins a streamlined body and an operculum are seen.
- Opened operculum reveals the gills.
To examine bones of the axial skeleton of a rabbit.
- Bones of the vertebra column are obtained.
- These are cervical, thoracic, lumbar and sacral.
- For each of the bones the distinguishing features are listed down.
- Labelled drawings of the anterior and lateral views is made.
To observe bones of appendicular skeleton.
- Bones of pectoral girdle and fore limb are obtained i.e., scapula, humerus, ulna and radius.
- Labelled drawing of each bone is made.
- Observations on how the bones articulate with one another is made.
- Bones of pelvic girdle and hind limbs are obtained i.e., pelvic girdle, femur, tibia and fibula.
- Labelled drawings of each, bone is made.
- The distinguishing features of each bone is noted.
- Observations on how the bones articulate with one another is made.