Tissues: - A group of cells similar in structure and performing a particular function forms a tissue.

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Kellie Lucas
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1 Plant Tissues Class- IX Tissues: - A group of cells similar in structure and performing a particular function forms a tissue. PLANT TISSUES ANIMAL TISSUES 1. Most of the plant tissues are Most of the tissues are living. supportive and hence dead. 2. Growth is localized like root and Growth is uniform in the body. shoot tip. 3. They contain such tissues that divide throughout their life. There are no specific dividing and non dividing regions. 4. They do not consume much energy. They use more energy. MERISTEMATIC TISSUES PERMANENT TISSUES 1. Capable of cell division Lost the power of cell division 2. Undifferentiated cells Differentiated cells 3. Living cells May be living or dead 4. Few or no vacuoles Large vacuoles CHARACTER PARENCHYMA COLLENCHYMA SCLERENCHYMA Nature of cell living living Dead Intercellular space large Very little No Occurrence Nature of cell wall FUNCTIONS Epidermis, cortex, endodermis, pith etc. Made up of cellulose Provides support, stores food and waste products, chlorenchyma performs photosynthesis, parenchyma provides buoyancy Below epidermis in the petiole, leaves and young stems Angular thickening due to deposition of cellulose Provides mechanical support, provides elasticity to plant tissues Husk of coconut, around vascular bundles, leaves veins, hard covering of seeds and nuts Thick walls due to deposition of lignin Main mechanical tissue, provides rigidity to leaves and strength to seed coverings

2 XYLEM PHLOEM 1. It consists of mainly dead elements It consists of mainly living elements except except xylem parenchyma phloem fibres. 2. FUNCTION- It conducts water and It translocate prepared food from the leaves dissolved minerals from roots to to storage organs and growing parts of the other parts of the plant, provides plant. mechanical strength 3. Water moves in single direction. Materials move in both the directions. FORMATION OF CORK: - As plants grow, the epidermis undergoes certain changes. A layer of meristem called cork cambium replaces epidermis of stem. Cork cambium gives off new cells on both the sides. The cells on outer side forms CORK or PHELLEM. Characteristic features of cork: - Cells of cork are dead and compactly arranged without intercellular spaces. Walls are thick due to deposition of SUBERIN. Function/ Significance:- 1. Protective 2. Prevents loss of water 3. Prevents against infection 4. Has insulating properties

3 ANIMAL TISSUES They are of four types depending on the function. I EPITHELIAL TISSUE Structure:- 1. The cells are closely packed and lack intercellular space. 2. The cells are held together by a cementing substance (carbohydrate derivative). 3. The lowermost layer rests on non-cellular fibrous basement membrane (collagen fibres). 4. They obtain nutrients through diffusion( not supplied with blood vessels) Location / Occurrence:- Skin, the lining of the mouth, the lining of blood vessels, lining of lung alveoli and kidney tubules Functions:- 1. They protect the underlying tissues from mechanical injury, entry of germs, harmful chemicals and drying up. 2. It forms a barrier to keep different body systems separate. 3. They regulate the exchange of materials between the body and the external environment and also between different parts of the body. Types of epithelial tissue:- 1. SQUAMOUS EPITHELIUM:- They are of two typesa) Simple squamous epithelium:- Structure- Cells are extremely thin and flat. Location- Lining of blood vessels and lung alveoli Function- Exchange of gas b) Stratified squamous epithelium:- Structure- Cells are multilayered Location- Lining of buccal cavity and esophagus, external skin surface Function- Protection of the underlying tissues 2. COLUMNAR EPITHELIUM:- They are of two typesa) Simple columnar epithelium:- Structure- Tall column like cells with nucleus at the basal end. Location- inner lining of the stomach and intestine Function- absorption/ secretion b) Ciliated columnar epithelium:- Structure- Tall column like cells with nucleus at the basal end and cilia at the free end. Location- respiratory passage Function- flow the fluids in particular direction

4 3. CUBOIDAL EPITHELIUM Structure- Cube like cells with a central nucleus Location- Lining of ducts e.g. salivary duct, pancreatic duct etc. Function- Mechanical support 4. GLANDULAR EPITHELIUM:- Structure- A portion of the epithelial tissue folds inward and a multicellular gland Is formed. Location- Salivary gland, Gastric gland Function- Secretion of substances at the epithelial surface II CONNECTIVE TISSUE It has three basic components. i) Cells ii) Fibres iii) Matrix Types of connective tissue- 1. AREOLAR TISSUE- Structure- Cells are widely spaced, contains collagen and elastic fibres Location- Between skin and muscles, around blood vessels and nerves Function- a) fills space inside the organs b) Supports internal organs c) Helps in repair of the tissues 2. ADIPOSE TISSUE- Structure-Cells are known as adipocyte. The cytoplasm along with the nucleus and organelles is shifted to the periphery. Location-Below the skin, around kidney, heart, eye balls. Function-a) energy reserve b) Shock absorber c) Insulator 3. FLUID CONNECTIVE TISSUE- Structure-Cells- RBC, WBC, Platelets No fibres Matrix- Fluid called plasma containing proteins and hormones. Location-In blood vessels Function-a) Transportation of useful and waste products b) RBC transports oxygen and carbon di oxide. c) WBC forms antibodies to fight against diseases d) Platelets help in blood clotting

5 4. SKELETAL TISSUE- They are of two types. 1) BONE Structure-Cells are known as osteocytes. Collagen fibres Matrix is hard composed of calcium and phosphorus compounds Function- forms structural framework of the body 2) CARTILAGE- Structure- Cells are known as chondrocytes. Collagen fibres/ Elastic fibres Matrix is solid composed of proteins and sugars. 5. DENSE CONNECTIVE TISSUE- They are of two types. 1) LIGAMENTS-They join two bones. They have considerable strength and good flexibility. 2) TENDONS- They connect muscles to the bones and muscles to muscles. They have good strength and limited flexibility. III.MUSCULAR TISSUE- SMOOTH STRIATED/SKELETAL CARDIAC Unstriated Striated Striated Spindle shaped Cylindrical Cylindrical Single nucleus Many nuclei Single nucleus Involuntary Voluntary Involuntary No fatigue Fast fatigue No fatigue IV. NERVOUS TISSUE- Brain, Spinal cord and nerves are made of nervous tissue. Nerve cell/ Neuron- It consists of cell body or cyton with a nucleus and cytoplasm. Usually each neuron has a single long part called the AXON, and many short branched parts called DENDRITES. Axon of a nerve cell is called nerve fibre.many nerve fibres bound together is called a nerve. Function- It receives the stimulus and transmits it to the brain or spinal cord. It also transmits back the response to the effector organ.

Chapter 6: Tissues. KEY CONCEPTS : [ *rating as per the significance of concept]

Chapter 6: Tissues. KEY CONCEPTS : [ *rating as per the significance of concept] Chapter 6: Tissues KEY CONCEPTS : [ *rating as per the significance of concept] CONCEPTS RATING Meristems in plants ** Permanent tissues in plants **** Animal tissues ***** 1. Tissue is a group of cells