Download TISSUES 1) DEFINITION: A group of cells that are similar in structure

TISSUES
1) DEFINITION: A group of cells that are similar in structure and work together to achieve a specific
function is called a tissue.
2) IMPORTANCE IN MULTICELLULAR ORGANISMS
a) Multicellular organisms are complex. Thus, they show division of labour.
b) A tissue is arranged and designed to give the highest possible efficiency of function.
3) DIFFERENCE IN PLANTS AND ANIMALS: There are differences in plants and animals that also
bring about a change their tissues.
Criteria
PLANTS
ANIMALS
Movement
They remain stationary.
They move for breeding,
nutrition etc.
Tisssue Function
The tissues are supportive in
The tissues are living and
function and provide structural require more energy to
strength. They are mostly dead. function.
Pattern of growth
The pattern of growth in plants The pattern of growth in
is limited to certain regions.
animals is uniform throughout
the body.
Structural organisation
The structural organization of
The structural organization of
organs and organ systems is not organs and organ systems is
very complex.
very very complex.
Form of existence
Plants have sedentary
Animals show active
existence.
locomotion..
4) TYPES: Based on dividing capacity
a) Plant Tissues
b) Animal Tissues
5) Plant Tissues
a) Meristematic Tissue
i) Structure
(1) Similar in structure, have thin cell walls.
(2) May be spherical, oval or rectangular in shape
(3) Compactly arranged with no intercellular space
(4) Dense cytoplasm
(5) No vacuoles
(6) Active cells
(7) Prominent nuclei (single and large)
ii) Occurrence
(1) Is found in the actively growing regions of the plant
(2) Is divided into apical, lateral and intercalary meristem on the basis of occurrence
iii) Types
(1) Apical Meristem
(a) Occurrence
(i) Present at the growing tips of stems and roots
(b) Function/Effect
(i) Increases the length of the stem and the root
(ii) Results in increase in height called “primary growth”
(2) Lateral Meristem
(a) Occurrence
(i) Found beneath the bark
(ii) Found in vascular bundles
(iii)
Occurs in thin layers
(b) Function/Effect
(i) Responsible for growth in girth and thickness
(ii) Known as cambium
iv) Intercalary Meristem
(1) Occurrence
(a) Base of leaves
(b) Present at internodes(on either side) on twigs
(2) Function
(a) Increase in length of the stem or root
b) Permanent Tissue
i) Tissue derived from meristematic tissues which have attained a definite shape, size and
form and lost the ability to divide
(1) The process of a meristematic taking up a permanent shape, size and function is called
differentiation.
ii) Types
(1) Simple permanent tissue
(a) Structure
(i) Made up of one type of cells
(ii) Structurally and functionally similar
(b) Types
(i) Parenchyma: [Greek word, (para - beside) + (enchyma – in filling)]
1. Its few layers form the basic packing tissue.
2. It is the bulk of a plant body.
3. Structure
a. Live cells
b. Thin cell wall
c. Dense cytoplasm
d. Isodiametric, that is equally expanded on all sides
e. Loosely packed with large intercellular spaces
4. Functions
a. Food storage tissue
i. Stores and assimilates food
b. If it contains chlorophyll, it performs photosynthesis. This type of
parenchyma is termed as chlorenchyma.
c. In aquatic plants, parenchyma has large air cavities which provide
buoyancy to the plant. This type of parenchyma is termed as aerenchyma.
d. Parenchyma of roots and stems also stores water
(c) Collenchyma
(i) Structure
1. Cells are living, elongated
2. Irregularly thickened at corners
3. Very little ntercellular space
(ii) Occurrence
1. Leaf stalks below the epidermis
(iii) Functions
1. It is a mechanical tissue. It provides mechanical support and elasticity.
2. It provides tensile strength with flexibility..
3. Allows easy bending in various parts without breaking
(d) Sclerenchyma
(i) Structure
1. Tissue cells are dead
2. Long and narrow
3. Cell walls are thickened with lignin.
4. They are closely packed with almost no intercellular space.
(ii) Occurrence
1. In stems around vascular bundles
2. In veins of leaves
3. In hard covering of seeds and nuts
(iii) Functions
1. This tissue is mechanical and protective in function
2. Makes the plant hard and stiff
3. EXCEPTIONAL ADDITIONS
a. Gives strength, rigidity, flexibility and elasticity
b. Enables it to withstand various strains
(2) Complex permanent tissue: These are conducting tissues and constitute a vascular
bundle.
(a) Structure
(i) Made of more than one type of cell
(ii) All cells coordinate for a single function
(b) Function
(i) Transportation of water, mineral salts (nutrients) and food material to various
parts of the plant body
(c) Types
(i) Xylem
1. Structure
a. Most cells are dead.
b. It has thick cell walls.
c. Made of four componenets:Tubular structures which help
i. Tracheids
in vertical transportation of
ii. Vessels
water and minerals.
iii. Xylem parenchyma
iv. Xylem fibres
2. Function
a. Transportation of water, soluble minerals and nutrients
i. Transportation only takes place from root to other parts, that is in the
up direction and not vice versa
(ii) Phloem
1. Structure:
a. Composed of four elements
i. Sieve tubes: Tubular cells with perforated walls
ii. Companion cells
iii. Phloem parenchyma
iv. Phloem fibres
b. Phloem has living cells except for phloem fibres.
2. Function
a. Transports food from to other parts
i. Transportation of materials takes place in both directions
(iii)
Difference between xylem and phloem
Xylem
Consists of mainly dead elements.
Conducts water and minerals from
the roots to the aerial parts of the
plant.
Phloem
Consists of living tissue.
Conducts prepared food from the
leaves to storage organs and growing
parts of the body.
c) Protective Tissue
i) Epidermis: The outermost layer of cells in plant bodies
(1) Structure
(a) Made of a single layer of cells
(b) With time epidermis is replaced by secondary meristem
(c) Cells on the outside get cut off from this layer. This forms thick cork, the bark of the
tree.
(i) Structure
1. Cells of cork are dead.
2. Cells are compactly arranged with negligible intercellular space.
3. Have a chemical called subernin in walls
a. Makes the cells impervious to gases and water
4. Simple tissue having only one type of cell
(d) Has small pores called stomata
(i) Stomata are enclosed by two kidney shaped cells called guard cells.
(ii) Functions
1. Gaseous exchange with the atmosphere
2. Transpiration
a. Loss of water in the form of water vapour
(2) Structure in desert plants
(a) Epidermis is thicker to prevent water loss
(b) It secretes waxy substance called cutin
(i) Cutin prevents loss of water, mechanical injury and invasion by parasitic fungi
(c) Less intercellular spaces
(d) Outer and side walls are thicker than inner wall
(3) Structure in Roots
(a) Bear long hair like parts
(i) To increase surface area for water absorption
6) Animal Tissues
a) The contraction and relaxation of these cells results in movement.
b) Types
i) Epithelial Tissue
(1) It is the It is the covering or protective tissue in the animal body.
(2) Structure
(a) Cells are very tightly packed with negligible intercellular space and form a
continuous sheet.
(b) Very little intercellular matrix is present OR
(c) Very little cementing material between the cells
(d) The cells are permeable to an extent.
(e) Seperated from the underlying tissue by an extracellular fibrous basement
membrane.
(3) Types
(a) Squamous Epithelium
(i) Strucure
1. Extremely thin and flat
2. Form a delicate lining
3. Arranged in a pattern of layers
a. This is known as stratified squamous epithelium.
(ii) Location
1. Oesophagus
2. Mouth lining
3. Skin
(iii)
Function
1. protect underlying parts from germs and injury
(b) Columnar epithelium
(i) Structure
1. They are tall
2. Has cilia (hair like projections) in the respiratory tract
a. Known as ciliated columnar epithelium
i. Cilia can move.
ii. This movement pushes the mucous forward and helps clear the
respiratory tract
(c) Cuboidal epithelium
(i) Location
1. Lining of kidney tubules
2. Ducts of salivary glans
(ii) Functions
1. Mechanical support
(d) Glandular epithelium
(i) Formation
1. Acquire specialization as gland cells
a. Secrete substances at the epithelial surface
2. This tissue folds inward, forming a multicellular gland.
(ii) Location
1. lining the intestine and various glands
(iii)
Function
1. Production of specific secretions
ii) Connective Tissue
(1) Structure
(a) Cells are loosely spaced
(b) Embedded in an intercellular matrix
(i) Matrx structure differs in correspondence with the function of the connective
tissue
(ii) May be dense, jelly like, fluid or rigid
(2) Function
(a) Tissues and organs in a body are supported and held in position.
(b) Binds organs and tissues together
(3) Types : areolar, adipose, compact bone, hyaline cartilage, types of blood cells
(a) Blood
(i) Structure
1. Fluid matrix called plasma
a. RBC (red blood cells), WBC (white blood cells) and platelets are suspended
b. Has proteins, slats and hormones
2. It flows
(ii) Function
1. Transports gases, digested food, hormones and waste materials to different
body parts
(iii)
Types of white blood cells(WBCs)
1. Neutrophil – Polynuclear leucocyte
2. Eosinophil
3. Basophil
4. Lymphocyte
5. Monocyte
6. Platelets
(b) Bone
(i) Structure
1. Strong tissue
2. Non flexible
3. Embedded in a hard matrix
(ii) Function
1. Forms the supportive framework of the body
2. Anchors the muscles
3. Supports the main organs
a. Composed of calcium and phosphorus
(c) Ligament
(i) Structure
1. Very elastic
2. Has considerable strength
3. Contain very little matrix
(ii) Function
1. It connects two bones to each other.
(d) Tendon
(i) Structure
1. Fibrous tissue
2. Great strength
3. Limited flexibility
(ii) Function
1. Connect muscles to bones
(e) Areolar Connective Tissue
(i) Location
1. Between skin and muscles
2. Around blood vessels and nerves
3. In the bone marrow
(ii) Functions
1. Fills space inside the organs
2. Supports internal organs
3. Helps in repair of tissues
(f) Adipose Connective Tissue
(i) Location
1. Below the skin
2. Between internal organs
(ii) Structure
1. Cells are filled with fat globules
(iii)
Functions
1. It stores fat.
2. Acts as an insulator due to fat storage
iii) Muscular Tissue
(1) Structure
(a) Elongated cells called muscle fibres
(b) Have contractile protein
(2) Functions
(a) movement of the body
(i) occurs by the contraction and relaxation of contractile protein present in muscle
cells
(b) Types
(i) Striated Muscles
1. Location
a. Limbs
i. These muscles can be moved according to will. Hence, they are termed
as voluntary muscles.
b. Mostly attached to body bones
i. Hence, called skeletal muscles.
2. Structure
a. Show alternate light and dark bands (or striations) when stained properly
i. Hence, called striated muscles
b. Cells are long and cylindrical.
c. They are unbranched and multinucleate (having many nucei).
(ii) Smooth Muscles
1. Location
a. In the ailamentary canal
b. In the iris of the eye
c. In ureters
d. In bronchi of lungs
2. Structure
a. Involuntary – can’t be moved according to will
b. Do not have striations
i. Hence called unstriated muscles.
(iii)
Cardiac Muscles
1. Location
a. In and around the heart
2. Structure
a. Involuntary
b. Cells are cylindrical
c. Cells are branched and uninucleate.
iv) Nervous Tissue
(1) Location
(a) In and around the brain
(b) In the spinal cord
(c) In the nerves
(2) Structure
(a) Highly specialized for stimulus and its rapid transportation
(b) Parts
(i) The brain
(ii) The spinal cord
(iii)
The nerves
1. Each nerve cell is called a neuron.
a. Structure
i. Cell body
ii. Nucleus and cytoplasm are present
iii. Long thin hair like parts rise
iv. Has a single long part called the axon
v. Has short branched parts called dendrites
vi. May be upto a metre long
vii.