Cells (Division of Labour)

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Cells(Division of Labour)

• Chapter 24

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In this chapter, you will learn

• that cells of similar structures are organised
  into tissues
• that several tissues may make up an organ
• that organs are organised into systems
• to explain the significance of division of labour

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Unicellular Organisms
Paramecium
Amoeba
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Unicellular Organisms

• Paramecium
• Microscopic organism
• Found on surface of water (eg pond, river)
• Has hair surrounding the body for movement
• Has a mouth

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Unicellular Organisms

• Amoeba
• Often found at bottom of ponds or under rocks
• Does not move fast
• No arms, legs, eyes, mouth
• Eats by surrounding its prey with its body
• Lives only for 2 days
• Reproduce by spliting itself into 2 new amoebas

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Multicellular Organisms

• Have many different cells
• Different cells perform different functions
• Examples
• Plants
• Humans

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Cells in a Human

• Examples
• Red blood cell (transport oxygen)
• Nerve cell (have nerve fibres to transmit signals
  to and from the central nervous system)

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Cells in a Plant

• Examples
• Root hair cell
• Leaf guard cell

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From cells to tissues

• Tissue
• Group of similar cells that are specialised to
  perform a particular function

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Tissues in a Human

• Epithelial tissue
• Covering or lining tissue to protect structure
  beneath it
• Connective tissue
• Joins, stores or supports all parts of an organism

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Tissues in a Human

• Muscle tissue
• Cause movement
• Nerve tissue
• Carry messages from one part of body to another
  by conducting electrical signals

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Tissues in a Plant

• Epidermal tissue
• Protects plant against injury and losing too much
  water
• Vascular tissue
• Transports materials within a plant

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Tissues in a Plant

• Photosynthesis tissue
• Carries out photosynthesis in a plant

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From Tissues to Organs

• Organ
• Group of specialised tissues that are gathered in
  a certain part of the body to perform a
  particular function together

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Organs in a Human

• Examples
• Skin
• Lungs
• Heart

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Organs in a Plant

• Examples
• Leaves
• Stem
• Roots
• Flowers

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From Organs to Systems

• System
• Different organs working together to perform a
  major function in an organism

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Main Organ Systems in a Human

• Respiratory system
• Digestive system
• Blood circulatory system
• Skeletal system
• Muscular system

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Respiratory System
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Respiratory System

• Respiration
• Process in which cells release energy from the
  food we eat
• Oxygen is required
• Carbon dioxide is removed

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Respiratory System

• Mechanics of breathing

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Digestive System
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Digestive System

• Digestion
• Process in which large, insoluble food substances
  are broken down into smaller, soluble food
  substances for absorption into blood

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Blood Circulatory System
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Blood Circulatory System

• Transports nutrients, gases, water and hormones
  to different parts of the body
• Include red blood cells, white blood cells,
  heart, blood vessels

Red blood cells
White blood cells
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Skeletal System
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Skeletal System

• Supports our body
• Gives us shape
• Protects our organs
• Enables movement

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Muscular System
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Muscular System

• Enables movement by contraction and relaxation of
  muscles
• 3 muscle types
• Skeletal muscles
• Smooth muscles
• Cardiac muscles

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Other systems in Human

• Reproductive System
• - Produces sex cells (sperm, ovum)
• For reproduction
• Nervous System
• - Consists of the brain, spinal cord and nerves
  found throughout our body
• - Controls and coordinates functions throughout
  our body
• - Enables us to respond to changes around us

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Male Reproductive System
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Female Reproductive System
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Nervous System
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Plant Transport System
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From Systems to Organisms

• Organism
• Made up of different systems working effectively
  in a coordinated manner

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The Human Body - An organism
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Division of Labour

• Each cell in a multicellular organism does not
  perform all the bodily functions.
• Each type of cell specialises in performing one
  particular function.
• Different functions in a multicellular organism
  can be performed at the same time by division of
  labour.

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Division of Labour

• Division of labour
• Sharing different functions in an organism among
  its cells, tissues, organs and systems
• Ensures smooth running and effective working of
  the different parts in an organisms as well as
  the organism as a whole