Support and Movement | Biology Form 4

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Support and Movement - Biology Form 4

Background

In earlier studies you learnt that all living orgasms carry out movement. Animals move from place to place in search of food, territory, mate or escape danger. Plants movements are not locomotory in nature. Their movement is mainly by growth responses. They grow towards useful stimulus or away from injurious ones. All organisms have support structures which enables them to bear their body weight as well as maintain their body forms. Both plants and animals possess a variety of structures that helps in support and movement.

Objectives.

By the end of this topic you should be able to:

    Explain the necessity of support and movement in animals and plants
    Describe the arrangement and the role of supporting tissues in young and old plants
    List functions of the exoskeleton and endoskeletons
    Describe locomotion in a named finned fish
    Identify the bones of the axial and appendicular skeleton in a mamma
    Describe the structure and functions of different types of joints in a mammal and explain how muscles bring about movement
    Distinguish between the different types of muscles, their location and functions

SUPPORT AND MOVEMENT IN PLANTS AND ANIMALS

Introduction

Support is the ability of an organism to bear its weight and maintain its body form. Movement on the other hand refers to displacement of parts of the body or the whole organism from one position to another. Plants mainly display localized movement while animals display both localised and locomotory movement. In this topic, we will look at the following: -

  • The necessity for support and movement in plants and animals
  • Locomotion in finned fish
  • Structure of bones
  • Axial and appendicular skeletons
  • Types and functions of movable joints
  • Structure, functions and locations of cardiac, smooth, and skeletal muscles
  • Role of muscles in movement of the arm in human.

Click on the play button to view the aniation.







Support and movement in plants Movement enables plants to adequately adjust to the environment. The movement occurs at cellular level and at organ level. Play the animation to see different types of movement in plants

Necessity for support in plants

Support tissues enable plat parts to be held upright for maximum light absorption.

Play the animation to see sun rays reaching broad leaved plant.

Support tissue position the flower appropriately for pollination.

The video clip shows an insect reaching a brightly colored flower and carrying the pollen. Click on the play button to watch the video.


 

Support tissues position the fruits and seed for dispersal by agents.

Play the animation to see seeds on the mother plant being blown away by wind.

 

 

 

Enables the transport tissues to transport materials from the soil through the stem to the branches without collapsing.

The animation shows water moving from the soil through the xylem of stem to branches. Click on the play button to view the animation.

 

 

 

 

 

Through a support framework plants are able to withstand strong external forces of winds and water currents.

Play the animation to see trees swaying due to strong wings

 

 

 

 

 

 

Necessity for movement in plants

Movement in plants is important during fertilization e.g. in flowering plants growth of pollen tube down the style towards the embryo sac, swimming of male gametes in bryophytes and pteridophytes.

Play the animation to see the growth of pollen tube down the style towards the embryo sac


Tropic movements enable plants to obtain raw materials from the environment e.g. light (phototropism) water (hydrotropism).

The Photograph shows a sunflower plant bending towards sunlight.

Movement in plants helps plants to avoid harmful stimuli e.g. strong winds and high temperature.

The Photograph shows trees bending in the direction of wind to avoid opposing the strong currents.


Arrangement of tissues in monocot and dicot stems.

The Illustration shows the arrangement of tissues in a monocot stem.

The Illustration shows the arrangement of Arrangement of tissues in dicot stems

Tissues and organs involved in support in plants

Tissues

  • Parenchyma
  • Collenchyma
  • Sclerenchyma
  • Xylem tissue.

Organs

  • Stems
  • Sendrils
  1. Parenchyma

Parenchyma tissue cells are spherical and elongated. They are found in the cortex and pith regions of the stem. When turgid they provide mechanical support to stems of herbaceous plants.

The illustration shows parenchyma tissue.

  1. Collenchyma

Collenchyma tissue cells are spherical and they are thickened with cellulose especially at corners. They provide mechanical support in leaves, herbaceous plants and young woody plants.

The illustration shows collenchyma tissue.


  1. Sclerenchyma

Sclerenchyma tissues cells are dead and are often long fibres found in stems. They are thick and lignified is a polysaccharide.

The illustration shows sclerenchyma tissue.

4 Xylem tissue (Vessels and Tracheids)

a) Vessels

They are made up of dead cells composed of thick unevenly magnified walls. The light is deposited on the walls to form rings, spirals or patches. This enables them to give strength and support to the stem.

The illustrations show different types of xylem vessels

b) Tracheids

Tissue Made up of long dead cells which have tapered ends which are deposited with evenly deposited lignin. Unlike vessels they have cross walls. The illustrations show different types of tracheids.


5. Stems

Some herbaceous plants obtain support by twinning round other plants e.g. passion fruit stems and morning glory.

The photographs show different types of stems.

6. Tendrils

Other herbaceous plants use tendrils to support themselves e.g. pumpkins. The photograph shows tendrils twisting around a support material.






Support and movement in animals is dependent on a skeleton frame work and muscles attached to it to enable the animal to carry out many of its life processes. Play the video below to see animals moving.


Necessity for support in animals

To hold the tissues and organs in the rightful position so as to carry out their functions.

To provide a rigid framework against forces such as compression, tension and gravity.

The photograph shows a new born animal trying to stand against gravitational pull.

  • To escape from harmful conditions and enemies in the environment.
  • To obtain food since they are heterotrophic

Click on the play button to watch the video.


To Search for shelter.

The video clip shows a weaver bird building a nest.


To look for mates.

The photograph shows a cock mating with a hen.

Types and functions of skeletons.

A skeleton is a supportive frame work in animals bodies that enables them to maintain their body foams. They are of two types namely

    Exoskeleton
    Endoskeleton

All arthropods posses an exoskeleton while chordates have an endoskeleton.

Exoskeleton

This is a skeleton found on the outside of the bodies of some animals e.g. arthropods. In arthropods the exoskeleton is called chitin. Chitin is a tough, light and flexible material containing cellulose and proteins. In some arthropods it is hardened by deposits of calcium ions.

Functions of exoskeleton.

    Prevents dehydration since it is impermeable to water
    Forms protective layers against mechanical injuries since it is tough.
    Allows movement as it provides joints and points for muscle attachment
    The cuticle has outgrowth which act as appendages used for locomotion, copulation feeding and sensory purposes
  1. Provides ,support for soft body parts

Endoskeleton.

This is a support framework which is internal to the muscles. In vertebrates the skeleton is composed of bones and cartilage. Since it consists of living tissue it grows at the same rate with the body.

Functions of the endoskeleton

    It supports the body and its internal organs.
    It provides protection for certain internal organs such as brain, heart, lungs, and spinal cord from injury.
    Protects parts of the ear that is inner ear and the eye.

The illustration shows a human skeleton with some protected organs


  • Provides surfaces for attachment of muscles
  • Produces locomotion in conjunction with muscles
  • It is important in the formation of blood cells.

The illustration shows the human skeleton and attachment of muscles.

Locomotion in a fined fish.

Fish move in water by swimming. The fish body is covered with scales which face /point backwards to reduce resistance to locomotion in water. The body tapers both backwards and forward to provide a streamlined shape which minimises resistance to water.

The swim bladder controls buoyancy thus determines the depth at which the fish swims. Fish have blocks of muscles called myotomes which arranged on either side of the vertebral column that contract and relax alternately generating wave like thrust from side to side.

This propels the fish forward in water. During locomotion in water the fish experiences the following forces in water.
Play the animation (page 2) to see external features that adapt the fish to locomotion.

Play the animation to see external features that adapt the fish to locomotion.

Pitching - this is the tendency of the fish to plunge with head downwards .It is controlled by paired fins namely pectoral and pelvic fins. Play the animation to see pitching movement in fish.


Rolling - this is the tendency of the fish to turn about its horizontal axis. It is controlled by the dorsal and ventral fin. These fins are referred to as median or unpaired fins. They increase the surface area to prevent rolling. Play the animation to see rolling in fish.

Yawing - this is the lateral deflection of the body due to the contraction of the myotomes. It is controlled by the head inertia and the unpaired fins dorsal and ventral. Play the animation to see yawing in fish.

The tail has muscles and tail fin (caudal) which together causes for steering the fish. Play the animation to see the steering action in fish tail.

Axial skeleton

The axial skeleton consists of the skull, the sternum, ribcage and the vertebral column.

The animation shows various parts of the axial skeleton. Click on the play button to view the parts.

The skull

The skull is made up of many bones joined together to form the cranium as shown in the graphic.

.

The cranium encloses and protects the brain. It contains orbits that house and protect the eyes. It also protects the middle and the inner ears and the olfactory organs responsible for smelling. The skull has on it the upper and the lower jaws. The upper jaw is called maxilla and is rigidly attached to the skull.

The lower jaw is called mandible and forms a movable joint with the skull. Jaws house the teeth. There are openings on the cranium through which nerves and blood vessels pass to serve the brain. At the posterior end of the cranium are two smooth rounded extensions called occipital condyles. These articulate with the first bone of the vertebral column, the atlas to form a joint which allows for nodding of the head.

Play the animation to show how the atlas articulates with the occipital condyles of the cranium.


The vertebral column.

The vertebral column is made up of bones called vertebrae. In humans there are 33 vertebrae. Vertebrae have the following features in common:

    Neural spine which provides a large surface area for attachment of muscles
    Neural canal which houses and protects the spinal cord
    Centrum which supports weight and produces red blood cells.
    Transverse processes for attachment of muscles.
    Neural arch
    Paired smooth facets called zygapophyses. Those at the anterior are prezygapophyses while those at the posterior are post zygapophyses.

The illustration shows a typical vertebrae.

The vertebrae are separated from each other by cartilaginous discs called intervertebral discs. The discs act as cushions that absorb shock and reduce friction during movement. They also make the vertebral column flexible by allowing for some movement between vertebrae. This facilitates bending and swinging movements. The vertebral column has five types of vertebrae. These are:

    Cervical vertebrae
    Thoracic vertebrae
    Lumbar vertebrae
    Sacral vertebrae
    Caudal vertebrae

The illustration below shows a vertebral column


Cervical vertebrae

These are found in the neck region. There are seven cervical vertebrae in humans. The first of this is called the atlas. It articulates with the occipital condyles at the posterior end of the cranium to form a joint that allows for nodding movements of the head.

The illustration below shows an atlas

The animation shows the articulation of atlas and cranium. Click on the play button to view the animation.

The second is the axis. This forms a joint with the atlas that allows for side to side movement of the head, allowing one to face to the left or the right.

The Illustration shows the structure of axis.

The animation shows the articulation of atlas and axis. Click on the play button to view the animation.

The remaining five cervical vertebrae have the following characteristics;

a) Short neural spine

b) Have openings through which blood vessels and nerves enter or leave the spinal cord at the neck.

c) The outer part of each transverse process is divided into two.

The photograph shows a standard cervical vertebra

 


Thoracic vertebrae.

These are found in the thoracic area. There are 12 thoracic vertebrae in humans The neural spine of the thoracic vertebrae is prominent to provide a large surface area for attachment of shoulder muscles. The transverse processes are well developed and have facets to articulate with ribs. The facets that articulate with the capitulum of the rib is called capitular facet and the one that articulates with the tuberculum is called tubercular facet. The photograph shows thoracic vertebrae.

Play the animation to see the various parts of a thoracic vertebrae

Lumbar vertebrae

Lumbar vertebrae are found in the abdominal region. They are five in humans. Lumbar vertebrae have well developed transverse processes projecting forwards and downwards from the centrum, to offer a large surface area for attachment of abdominal muscles.

A number of processes from the centrum called metapophyses, anapophyses and hypapophyses provide more surface area for attachment of abdominal muscles.

The illustration shows Lumbar vertebrae

Play the animation to see the various parts of Lumbar vertebrae.

Sacral vertebrae

These are located in the pelvic region. Four sacral vertebrae are fused together to form a broad structure, the sacrum.

The illustration below shows the structure of a sacrum.

The most anterior sacral vertebrae have well developed transverse processes which are fused to the pelvic girdle.

The illustration shows position of the sacrum in the pelvic girdle.

Caudal vertebrae

These are small. They support the tail. In man they are reduced to form coccyx.

The Illustration shows caudal vertebrae.

Appendicular skeleton.

The appendicular skeleton comprises of the pectoral girdle and the pelvic girdle. The fore limbs articulate with the pectoral girdle while the hind limb articulates with the pelvic girdle. Girdles also provide surface for muscle attachment.

Play the animation to view the appendicular skeleton.

The pectoral girdle

The pectoral girdle is the part of the skeleton of a vertebrate animal that provides the attachment points support for the fore limbs. It is made up of two halves each of which consists of three bones namely the scapular, the coracoid process and clavicle.

Play the animation to view the position of pectoral girdle in human skeleton.

The scapula is a flat triangular shaped bone which overlies a number of ribs on the anterior side. At the tip of the scapula is a depression called the glenoid cavity, which articulates with the head of the humerus to form a ball and socket joint. The joint formed allows movement in all the directions. The scapula has a projection known as the spine which runs parallel to it. The spine provides a surface for muscle attachment. Close to the glenoid cavity are two projections, the acromion and metacromion. Both are used for muscle attachment. The clavicle articulates on one end with acromion process and the other with sternum. It is for muscle attachment and aids in the movement of the arms.

Play the animation below to see the various parts of a scapula.

Fore limb

The fore limb is made up of the humerus, ulna and radius and the bones of the hand.

The illustration shows the humerus, ulna and radius and the bones of the lower hand.

Humerus

Humerus is the single bone of the upper arm. It consists of a long shaft whose upper end has a rounded smooth projection known as the head. There are two projections near the head. The uppermost is known as the greater tuberosity while the lower one is the lesser tuberosity. Between the tuberosities is a groove that the tendons of the biceps muscles pass. At the lower end is the trachea which articulates with the fore arm to form hinge joint at the elbow.

The illustration shows the humerus.

The head of the humerus articulates with the glenoid cavity to form the ball and socket joint.

Play the animation to see the articulation of the head of the humerus with the glenoid cavity.

Ulna and radius

Ulna and radius are two bones found in the fore arm. The radius is found on the side of the thumb while the ulna is on the side of the small finger. The photograph shows ulna and radius.

The ulna is longer than the radius and has a depression known as sigmoid notch found at the upper end. The sigmoid notch articulates with the humerus. A projection known as the olecranon process extends beyond the sigmoid notch. This process provides surface for muscle attachment as well as preventing overstretching of the forearm when straightened.

The illustration shows various parts of ulna and radius.

Bones of the hand

The distal end of the ulna and radius articulates with the small bones of the wrist known as the carpals. Carpals articulate with the five longer bones known as the metacarpals which form the palm. Metacarpals on the anterior side articulate with the phalanges which are the bones of the fingers. The thumb has two phalanges while the fingers have three phalanges each.

The illustration shows Carpals, metacarpals and phalanges.

The pelvic girdle.

The pelvic girdle is made up of two halves which are fused at the pubic symphysis. Each half is made up of three fused bones i.e. Ilium, ischium and pubis.

The photograph shows pelvic girdle of a human.

The three bones are collectively known as the innominate bone. Each half has a depression known as acetabulum which articulates with the head of femur to form a ball and socket joint.


Play the animation to see how the head of femur articulates with the acetabulum.

The Ilium is above the acetabulum and provides a large surface to which thigh muscles are attached. Between the ischium and pubis is a hole called orbturator foramen through which blood vessels, nerves and muscles pass. The pubic symphysis is composed of flexible cartilage which permits widening of the females girdles when giving birth.

The illustration shows the orbturator foramen in pelvic girdle.

The hind limb bones

The hind limb consists of the femur, tibia and fibula and bones of the foot.

The illustration shows femur, tibia and fibula and bones of the foot.

Femur

Femur is a long bone found between the hip and the knee. It is the longest and the strongest bone in the body. The head of the femur fits into the acetabulum forming the hip joint. Below the head of femur is a projection known as the lesser tronchanter. On the upper side is the greater tronchanter. Both tronchanters provide surface for muscle attachment. The distal end of the femur has two curved protrusions known as condyles with patella groove. The condyles articulate with tibia to form a hinge joint at the knee. They also articulate with the patella.

The structure of femur is shown on the illustration below.

Tibia and fibula

The lower part of the leg consists of two bones known as tibia and fibula. Tibia is larger than fibula and has condyles at its proximal end for articulation with femur. The fibula is attached to the distal part of the tibia. The illustration below shows tibia and fibula.

Bones of the lower foot

The bones of the lower foot are the tarsals, metatarsals and phalanges. The tarsal's are the bones of the ankle and articulate with tibia and fibula at the proximal end and metatarsals at the distal end. Metatarsals are longer and articulate with the phalanges on the lower side. The bones of the lower foot support the weight of the body. They also act as a lever when one is walking.

The illustration shows tarsals, metatarsals and phalanges.

JOINTS

A joint is the location at which two or more bones make contact. Joints can be classified into three categories namely

    Immovable joints /sutures
    Partially moveable joints
    Freely movable joints.

Immovable joints

These are joints that are characterised by presence of tissues between the joining bones that tightly hold the bones together in position to allow very little movement or no movement. Examples of immovable joints

Joints between cranial bones.

The photograph shows the joints between cranial bones

Joints between pelvic girdle bones.

The photograph shows the joints between pelvic girdle bones.


Partially movable joints

These are joints characterised by cartilaginous pads between the joining bones. They are of two types: Gliding and Pivotal joints.

Gliding joints

Examples are: Joints between vertebrae bones, carpals, and tarsals.

Play the animation to see movement in the gliding joints of the vertebral column.

Pivotal Joints

This is a joint in which a bone rotates around another permitting only rotating movement

Examples are: Joint between atlas and axis, vertebrae bones.

Play the animation to see movement in a pivot joint.

Freely movable joints.

These are called synovial joints. They are characterised by the presence of a cartilage covering the surfaces of the articulating bones. They have a synovial fluid secreted by the synovial membrane separating the articulating bones. The joints allow a wide degree of movement of t he articulating bones. The articulating bones are connected to each other by ligament. Movable joints are of two types:

  1. Ball and socket
  2. Hinge joint

The illustration shows a synovial joint

Ball and socket joint

This is a type of joint with two bones with one with round head and the other one with a depression or cavity into which the head of the first bone fits and moves freely. In ball and socket joints movement is possible in all directions that is 360 degrees. However the joint bears little weight.

The photograph shows a ball and socket joint.

Examples of ball and socket joint are: Joint between head of femur bone and acetabulum cavity of Ilium bone.

The Photograph shows a hip joint.

Joint between head of head of humerus bone and glenoid cavity of scapula bone.

The Photograph shows a shoulder joint.

The animation shows the head of humerus moving into a socket and subsequently rotating at 360 degrees.


Hinge joint

This joint allows the movement only in one direction .The smooth condyles of one bone fit in the depression of another and articulates to allow movement in one plane of backward and forward at 180 degrees. Examples of hinge joint are:

Elbow Joint Joint between distal end of humerus bones and proximal end of ulna at the sigmoid notch. This can be called the elbow joint. The photograph shows the elbow joint.

The animation shows movement of the hinge joint through 180 degrees

Joint between the distal end of the femur bone and the proximal end of the tibia and fibula bones. This can also be called the knee joint. The photograph shows knee joint.

Joint between phalanges, metatarsals and carpals. The illustration shows a joint between carpals, metacarpals and phalanges.

Muscles

Muscles are tissues made up of cells that are specialised for contraction the cells contain two proteins actin and myosin. Which glide on each other to bring about contraction and relaxation of muscles play a crucial role in movement of parts or whole organism. There are 3 types of muscles

    Skeletal
    Smooth
    Cardiac muscles.

1. Skeletal muscles.

These are the muscles attached to the bones or skeleton. They are sometimes referred to as striated or voluntary muscles.

The microscopic appearance of a striated muscle is shown below

The illustration shows the locations of skeletal muscles in human body.



2. Cardiac muscles.

Consists of short cells with centrally placed nuclei. They have numerous striated myofibrils whose end of the cells is marked by thickened regions called intercalated discs. They only occur in the heart. They are capable of generating contractions from within without nervous stimulation hence referred to as a myogenic. Cardiac muscles can contract rhythmically continuously without fatigue. They have a very high concentration of mitochondria to provide the energy required.

The microscopic appearance of a cardiac muscle is shown below.

Play the animation to see the pumping action of the heart due to presence of the cardiac muscles

3. Smooth muscles

They contain myofibrils enclosed by a plasma membrane. Unlike skeletal muscle they lack striations. They are capable of slow involuntarily contractions unlike skeletal muscles. They are found in most internal organs e.g. Reproductive organs, blood vessels, intestines and respiratory tract.

The illustration shows a smooth muscle.

Role of muscles in movement of the arm in humans

At the joint muscles are attached to the bones by in tendons. A muscle is attached at two points: the origin of an immovable bone and the insertion of a movable bone. Muscles which move joint occur in pairs. These muscles work in an antagonistic manner to each other. Flexor muscles bend the joint while extensor muscles straighten the limb.

The Illustration shows the biceps and triceps muscles of the arm.

The animation shows movement of the arm by contraction and relaxation of the extensor and flexor muscles

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