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2.2 CELL ORGANISATION
What is cell organisation?
Cell organisation – cell that was organise to give orderly structure
Unicellular and multicellular organism
Unicellular organism – made up of one cell
Multicellular organism – made up of many cells, larger in size and more complex
Living processes in Amoeba sp. Living Process Description
1. Locomotion -Using cytoplasmic projection-extending its pseudopodia, anchoring the tips to the ground and followed by the flow of cytoplasm
2. Feeding - Engulfs food by phagocythosis, feeds on microscopic organism
3. Respiration -Exchange of gases through plasma membrane
4. Excretion -By diffusion through plasma membrane
5. Respond to stimuli
-Retreating from adverse stimuli and moves towards favorable stimuli
6. Reproduction -By binary fission (favorable environment) and by spores ( not conductive environment)
7. Growth - By synthesising its cytoplasm
Living process in unicellular organism
Carry out vital functions and perform living process within a cell
Example: Amoeba sp.
Cell specialisation in multicellular organism
Multicellular organism begins life as a single cell
Cell divide repeatedly to form embryo and grow, change shape and adapt to carry out specific functions
To perform specific task, cells differentiate and specialised
Cell specialisation – a process of change and adaptation that a cell undergoes to give it special structures and specific function
Cell organisation in multicellular organism
The same type of cells which carried out a common function are organised into tissues
Different type of tissues group together to form an organ
Several organs group together to form a system
All systems work together to make up an organism
Cell organisation can be summerised as follows
Cell Tissues Organ System Organism
The importance of cell organisation:
a group of cells work efficientlydivision of labour enables organism to do
various tasks and function efficiently and systematically
achieve higher growth rateable to adapt and survive in diverse habitat
and environmentcarry out all living process more efficiently
Cells Organisation In Humans
Tissues
four major types:
1. Epithelial tissues
2. Muscle tissues
3. Connective tissues
4. Nerve tissues
1.Types of epithelial tissues in human
For protection, secretion and absorptionExamples: form the surface of the skin
act as a protective barrier, line the alveoli of the lungs the walls of blood capillaries are thin to allows the exchange of gases to take place efficiently (absorption) and form glands in the skin to secrete sweat glands and oil-secreting glands (sebaceous glands).
Functions of epithelial tissues
2. Muscle tissues Three types:a) smooth muscle – found along the wall of
digestive tract, blood vessels, bladder and reproductive tract which responsible for the involuntary actions of the body
b) skeletal muscle – attached to the bones of the skeleton which responsible for the voluntary movements of the body
c) Cardiac muscles – form the contractile wall of the heart which contract to pump blood to all parts of the body
3. Connective tissues
Loose connective tissues – widespread in the body, binds epithelia to underlying tissues and holds organs in place (E.g. adipose tissue
Dense fibrous connective tissues – a large number of collagenous fibres which are packed closely together (E.g. tendons and ligaments
Functions:• binds structures together, provide support
and protection to other tissues• Examples: tendons - connect muscles to
bones, ligaments - join bones together at joints, cartilage provide support to the nose, ears, cover ends of bones at joints and disc between the vertebrae act as cushion to absorb pressure, bones - provides protection to organs and support the body, blood cells - regulating, transporting and protective functions, adipose tissues acts as energy reserve and provides insulation and protection
4. Nerve tissues
Composed of neurone/nerve cells Consist of a cell body and nerves fibres
(dendrone, dendrites and axon) Three types: afferent, efferent and
interneurones Functions:
1. transmit impulses/signals
2. controls and coordinates all activities of the body
Exercise• Complete the table below about the functions of each tissue.
Types of tissues
Functions
1. Epithelial tissues
2. Muscle tissues
3. Connective tissues
4. Nerve tissues
AnswersTypes of tissues Functions
1. Epithelial tissues
ProtectionSecretionAbsorption
2. Muscle tissues Smooth muscles – involuntary actionsSkeletal muscles – voluntary actionsCardiac muscle – pump blood to all parts of the
body
3. Connective tissues
Bind structures togetherProvide support and protection
4. Nerve tissues Transmit signals Controls and coordinate all activities of the body
formed by two or more types of tissues working together to perform particular functions
individual tissues can’t carried out specific function of an organ
examples of organs – skin, heart, lungs, kidneys, eyes and ears
Organs
- Example :Skin
consist of several organs that work together to perform a common function
System
11 major system:1. Integumentary system2. Circulatory system3. Endocrine system4. Lymphatic system5. Nervous system6. Digestive system7. Muscular system8. Excretory system9. Skeletal system10.Respiratory system11.Reproductive system• Body system.doc