Tissue: Plant and animal tissue

Animal Tisue

 EPITHELIAL TISSUE

CHARACTERISTICS: Cells are flat,cuboidal or columnar in shape.

LOCATION: Covers the whole body surface.

FUNCTION:

• Protection
• Absorption
• Secretion
• Sensory perception

TYPES OF EPITHELIAL TISSUE

1. Simple squamous epithelium

CHARACTERISTICS: Cells are large, extremely thin and flat.

LOCATION: Situated in the lining of blood vessels, lung alveoli, oesophagus, the lining of the mouth and the inner lining of the cheek.

FUNCTION: Transportation of substances through selectively permeable membrane.

2. Stratified squamous epithelium

CHARACTERISTICS: Cells are arranged in a pattern of layers, resembling a brick wall.

LOCATION:  Located as the outer protective covering all over the body surface.

FUNCTION: Provides protection to underlying tissues which are subjected to continuous wear and tear.

3. Columnar epithelium

CHARACTERISTICS: Cells are tall, cylindrical and are arranged like pillars.

LOCATION: Found where absorption and secretion occur, as in the inner lining of the stomach, intestines and gall bladder.

FUNCTION: Secrete digestive enzymes and perform the function of absorption of nutrients from the digested food.

4. Ciliated columnar epithelium

CHARACTERISTICS: Cells possess fine hair-like cilia which are capable of rapid, rhythmic, wave-like beatings in a certain direction on their free surface.

LOCATION:  Found in the inner lining of the wind pipe or trachea, lungs, respiratory system and buccal chambers.

FUNCTION: In the respiratory tract, the cilia move and their movement pushes the mucus forward to clear it.

5. Cuboidal epithelium

CHARACTERISTICS: Cells are cube-shaped and are placed on a basement membrane.

LOCATION:  Found in the lining of the kidney tubules as well as in the ducts of the salivary glands.

FUNCTION: Helps in the absorption of useful material from the urine before it is passed out.

6. Glandular epithelium

CHARACTERISTICS: It is a portion of the epithelial tissue that folds inwards to form a multicellular gland.

LOCATION: Present in the secretory organs. such as stomach, intestine, pancreas etc.

FUNCTION: Capable of synthesising and secreting certain substances such as enzymes, hormones, milk, mucus, sweat, wax and saliva at the epithelial surface.

CONNECTIVE TISSUE

CHARACTERISTICS: Consists of a matrix and the cells are embedded in it.

LOCATION: Found in the deeper parts of the body in between the skin and muscles.

FUNCTION: Connects various organs and keeps them in proper place.

TYPES OF CONNECTIVE TISSUE

1. Connective tissue proper/loose connective tissue

CHARACTERISTICS: Made up of irregular cells scattered and embedded in a soft matrix.

LOCATION: Encompasses all the internal organs and body cavities.

FUNCTION: Acts as a binding and supporting structure within the body.

2. Supportive connective tissue/dense connective tissue

CHARACTERISTICS: Has fibres as its main matrix element.

LOCATION:  Found in bones and cartilage.

FUNCTION: Provides connection between different tissues.

3. Fluid connective tissue

CHARACTERISTICS:  Consist of fluid/liquid as the ground substance.

LOCATION: Present throughout the body.

FUNCTION: 

• Provides nutrition.
• Helps in transport of nutrients.
• Gets rid of waste matter.

1. TYPES OF CONNECTIVE TISSUE PROPER

1.a Areolar tissue

CHARACTERISTICS: Made of gelatinous matrix containing cells and irregularly arranged fibres.

LOCATION: Found between the skin and muscles, around the blood vessels, nerves and in the bone marrow.

FUNCTION: Fills the space inside the organs and supports and strengthens the internal organs.

1.b Adipose tissue

CHARACTERISTICS: Cells are filled with fat globules, situated in a large central vacuole of a cell, pushing the cytoplasm and the nucleus to the periphery.

LOCATION: Found beneath the skin, around the kidneys and other internal organs such as intestines.

FUNCTION: Acts as an insulator because of the storage of energy in the form of fats. It insulates the body and prevents the loss of heat.

1.c Fibrous tissue

CHARACTERISTICS:  Mainly formed of fibre-forming cells which form the tendons and ligaments.

LOCATION: Found in the spaces between the bones and muscles.

FUNCTION: 

• Tendons help to attach muscles to the bones.
• Ligaments serve to hold the structures together and keep them strong and stable.

2. TYPES OF SUPPORTIVE CONNECTIVE TISSUE

2.a Cartilage

CHARACTERISTICS:  Non-porous, semi-transparent and elastic tissue.

LOCATION: Present in the nose, external ear, trachea, larynx, ends of the long bones and between the vertebrae.

FUNCTION: Smoothens the bone surface at joints, allowing smooth movement of these joints.

2.b Bone

CHARACTERISTICS: Hard, strong and non-flexible porous tissue.Consists of living cells.

LOCATION: Forms the rigid part of the skeletal system.

FUNCTION: Forms the supporting framework of the body. Gives shape and rigidity to the body.

3. TYPES OF FLUID CONNECTIVE TISSUE

3.a Blood

CHARACTERISTICS: Contains a straw-coloured fluid matrix called blood. It consists of plasma (55%) and cellular part (45%) which contains cells, RBCs, WBCs and platelets.

LOCATION: Present throughout the body.

FUNCTION: Connects different body parts and establishes continuity within the body.

3.b Lymph

CHARACTERISTICS: Fluid surrounding the body cells. Contains WBCs.

LOCATION: Present throughout the body.

FUNCTION: Transportation of nutrients. Provides protection against diseases.

 

MUSCLE TISSUE

CHARACTERISTICS: Consists of elongated, narrow, muscle cells called muscle fibres.

LOCATION:  Mostly attached to the bones.

FUNCTION:  Helps in contraction and relaxation, which facilitates movement of the body.

TYPES OF MUSCLE TISSUE

1. Striated/skeletal/striped/voluntary muscles

CHARACTERISTICS: Muscle fibres are long, cylindrical, unbranched and multinucleate.

LOCATION: Found attached to the bones.

FUNCTION: Help in voluntary muscle movement and locomotion.

2. Non-striated/smooth/non-striped/involuntary muscles

CHARACTERISTICS: Muscle fibres are smooth and without striations.

LOCATION:  Found in ureters, digestive tract, urinary bladder, iris of the eye, bronchi of the lungs and other internal organs.

FUNCTION: Carry out the movements which cannot be carried out by our conscious will, such as movement of food in the alimentary canal, blinking of eyes, breathing etc.

3. Cardiac/heart muscles

CHARACTERISTICS: Muscle cells are short, cylindrical and have a single, centrally placed nucleus.

LOCATION: Found only in the walls of the heart.

FUNCTION: Rhythmic contraction and relaxation of cardiac muscles help to pump and distribute the blood to various parts of the body.

NERVOUS/NEURAL TISSUE

CHARACTERISTICS: Made up of elongated cells called neurons. Each neuron consists of three parts—a cell body, an axon and dendrites.

LOCATION: Component of the nervous system and encompasses the brain, spinal cord and nerves.

FUNCTION: Nerve cells mediate the transmission of messages from the brain to different parts of the body and vice versa.

Plant Tisue

  1. Meristematic tissue         2. Permanent Tissue

1.       Meristematic tissue

CHARACTERISTICS:  Cells are thin-walled and made up of cellulose.

LOCATION:  Located at the tips of the roots and stems, base of the node, base of the internode or at the base of the leaf.

FUNCTION: The cells of Meristematic tissue divide actively, resulting in growth (increase in thickness and length) of plants.

Types of meristematic tissue

a)      Apical meristem

b)      Intercalary meristem
c)       Lateral meristem/Cambium

a) Apical meristem:

LOCATION: Located at the growing points of the stem, roots, branches and in growing young leaves near the tips of stems and axillary buds.

FUNCTION: Enables the root and stem to grow by increasing the length of plants.

 
b) Intercalary meristem

LOCATION:  Located at the internodes or stem regions between the places at which the leaves attach, and at leaf bases, especially of certain monocotyledons

FUNCTION: The cells are active and continuously form a number of new cells.
 

c) Lateral meristem/Cambium

LOCATION: Present laterally (on the sides)  on the roots and stem and is situated parallel to the longitudinal axis below the bark.

FUNCTION: The girth and width/diameter/thickness of the stem or root increases due to the lateral meristem.
 

2.       PERMANENT TISSUE

CHARACTERISTICS: Formed by the division of the meristematic tissue cells that have lost their ability to multiply.
Types of permanent tissue

a)      Simple permanent tissue( parenchyma, collenchyma, sclerenchyma)
b)      Complex permanent tisse ( xylem and phloem)

a.i) Parenchyma

CHARACTERISTICS:  Consist of relatively non-specialised large, thin-walled living cells.

LOCATION: Mainly present in the soft parts of the plant such as the central pith-containing region and outer cortical region of roots and stems.
FUNCTION: Provides temporary support and maintains the shape of the plant body.

a.ii) Collenchyma

CHARACTERISTICS: Cells are living and elongated with cell walls irregularly thickened at the corners.

LOCATION: Located in the non-woody plants, leaf stalks, below the epidermis of the stems and veins of leaves.

FUNCTION: Provides Mechanical support and elasticity to the young dicotyledonous plants.

 
c.iii) Sclerenchyma

CHARACTERISTICS:

*Consists of elongated, narrow and fibre-like cells.

*Cells are dead, pointed at both the ends and thickened because of the deposition of lignin.

LOCATION:  Located in the stems around the vascular bundle, in the veins of leaves and in the hard covering of the seeds and nuts.

FUNCTION: Provides strength and hardness to the parts of the plant.
 

b. i) Xylem

CHARACTERISTICS:

*Complex permanent tissue with thick-walled cells.

* Most of the cells are dead.

LOCATION: Present in the stem, roots and leaves.

FUNCTION: Present in the stem, roots and leaves.

 
b.ii) Phloem

CHARACTERISTICS: Complex permanent tissue.

LOCATION: Lies just beneath the bark of the tree.

FUNCTION: Provides a passage for the downward movement of food manufactured in the leaves to various parts of the plant.
 

Types of Xylem tissue and its function

i) Tracheids: Provide a network of hollow and connected cells for the transport of water.

ii) Xylem vessels: Allow free flow of water and minerals in the vertical direction from the roots to the leaves.

iii) Xylem parenchyma: Stores food in the plant body.

iv) Xylem fibres:  Mainly support the plant.
 

Types of Phloem tissue and its function

i) Sieve tubes: Translocation of organic substances through perforated walls from one adjacent cell to another.

ii) Companion cells: Help to control the activity of sieve tube elements.

iii) Phloem fibres: Provide mechanical strength to the plant.
iv) Phloem parenchyma: Transports food i.e. sugars and amino acids from the leaves to other non-green parts of the plants, such as growing stems and roots.