Notes On Animal Tissues - CBSE Class 9 Science
A group of cells that have similar structure and function constitute a tissue.  Tissues aggregate to form an organ.  Many organs together constitute organ system.  Organ systems aggregate to form an organism. Tissues can be plant tissues or animal tissues. Animal tissues:  These are the tissues present only in animals.  Different types of animal tissues are epithelial tissue, connective tissue, muscle tissue and nervous tissue. Epithelial tissue forms a lining all over the body of the organism.  It protects the inner lying parts.  It is also secretory in function to secrete sebum and excrete wastes along with sweat.  Sometimes it is absorptive in nature.  Epithelial tissues act like a barrier to keep the different body systems separate.     •  Squamous epithelium has flat and thin cells with no intercellular spaces.  Squamous epithelium provides mechanical support and is found in the outer layer of the skin, lining the cavities of ducts, blood vessels and the chambers of the heart.     •  Columnar epithelium consists of cylindrical cells.  It is found in the lining of the stomach and intestines, and facilitates the movement of nutrients across the epithelial barrier.     •  Glandular epithelium consists of modified columnar cells, and is found in the sweat glands and tear glands to produce secretions.     •  Ciliated epithelium consists of columnar cells with cilia.  These cilia push the mucus forward into the nasal tract to clear it.     •  Cuboidal epithelium consists of cubical cells.   It is found in the lining of the kidney tubules, salivary glands and thyroid glands, where it provides mechanical support.     •  Stratified epithelium has epithelial cells lined up one over another.  It is found in the epidermis of the skin, the lining of the mouth cavity, and oesophagus. Connective tissues are fibrous in nature.  They include blood, bone, ligament, cartilage, areolar and adipose tissues.  These help in binding other tissues together.  They also provide support to other tissues.     •  Blood has plasma and blood cells.  The blood cells suspended in the plasma include RBC’s, WBC’s and platelets. Blood flows within blood vessels, and transports gases, digested food and hormones to different parts of the body.     •  Bone cells are embedded in a hard matrix composed of calcium and phosphorus compounds.  Bones anchor the muscles.     •  Ligaments are tough and elastic.  They provide strength and flexibility.  Tendons are tough and non-elastic, and provide great strength and limited flexibility.     •  Cartilage has widely spaced cells suspended in a matrix of proteins and sugars.  It is found in the nose, ears, and the rings of the trachea to give flexibility.     •  Areolar connective tissue has irregular shaped cells and is found between the skin and muscles, around blood vessels and nerves.     •  Adipose tissue contains cells filled with fat globules.  It is found below the skin and acts as an insulator. Muscle tissues are made up of muscle cells.  These are elastic in nature they have tensile strength. They bring about movement in the organism.  These muscles can be voluntary or involuntary in function.  Muscle tissue is categorized into visceral muscles, skeletal muscles and cardiac muscles. Muscular tissues are of three kinds namely striated muscles, unstriated muscles and cardiac muscles. Nervous tissue is the tissue which works in coordinating the organs of the body by generating impulses.  It is made up of special cells called as neurons.   Each neuron consists of a cell body, which contains a nucleus, cytoplasm, called cyton, and elongated hair-like extensions, called dendrites.  One of the dendrites, called the axon, is very long.  Nervous tissues are found in the brain, spinal cord and nerves.

#### Summary

A group of cells that have similar structure and function constitute a tissue.  Tissues aggregate to form an organ.  Many organs together constitute organ system.  Organ systems aggregate to form an organism. Tissues can be plant tissues or animal tissues. Animal tissues:  These are the tissues present only in animals.  Different types of animal tissues are epithelial tissue, connective tissue, muscle tissue and nervous tissue. Epithelial tissue forms a lining all over the body of the organism.  It protects the inner lying parts.  It is also secretory in function to secrete sebum and excrete wastes along with sweat.  Sometimes it is absorptive in nature.  Epithelial tissues act like a barrier to keep the different body systems separate.     •  Squamous epithelium has flat and thin cells with no intercellular spaces.  Squamous epithelium provides mechanical support and is found in the outer layer of the skin, lining the cavities of ducts, blood vessels and the chambers of the heart.     •  Columnar epithelium consists of cylindrical cells.  It is found in the lining of the stomach and intestines, and facilitates the movement of nutrients across the epithelial barrier.     •  Glandular epithelium consists of modified columnar cells, and is found in the sweat glands and tear glands to produce secretions.     •  Ciliated epithelium consists of columnar cells with cilia.  These cilia push the mucus forward into the nasal tract to clear it.     •  Cuboidal epithelium consists of cubical cells.   It is found in the lining of the kidney tubules, salivary glands and thyroid glands, where it provides mechanical support.     •  Stratified epithelium has epithelial cells lined up one over another.  It is found in the epidermis of the skin, the lining of the mouth cavity, and oesophagus. Connective tissues are fibrous in nature.  They include blood, bone, ligament, cartilage, areolar and adipose tissues.  These help in binding other tissues together.  They also provide support to other tissues.     •  Blood has plasma and blood cells.  The blood cells suspended in the plasma include RBC’s, WBC’s and platelets. Blood flows within blood vessels, and transports gases, digested food and hormones to different parts of the body.     •  Bone cells are embedded in a hard matrix composed of calcium and phosphorus compounds.  Bones anchor the muscles.     •  Ligaments are tough and elastic.  They provide strength and flexibility.  Tendons are tough and non-elastic, and provide great strength and limited flexibility.     •  Cartilage has widely spaced cells suspended in a matrix of proteins and sugars.  It is found in the nose, ears, and the rings of the trachea to give flexibility.     •  Areolar connective tissue has irregular shaped cells and is found between the skin and muscles, around blood vessels and nerves.     •  Adipose tissue contains cells filled with fat globules.  It is found below the skin and acts as an insulator. Muscle tissues are made up of muscle cells.  These are elastic in nature they have tensile strength. They bring about movement in the organism.  These muscles can be voluntary or involuntary in function.  Muscle tissue is categorized into visceral muscles, skeletal muscles and cardiac muscles. Muscular tissues are of three kinds namely striated muscles, unstriated muscles and cardiac muscles. Nervous tissue is the tissue which works in coordinating the organs of the body by generating impulses.  It is made up of special cells called as neurons.   Each neuron consists of a cell body, which contains a nucleus, cytoplasm, called cyton, and elongated hair-like extensions, called dendrites.  One of the dendrites, called the axon, is very long.  Nervous tissues are found in the brain, spinal cord and nerves.

#### Activities

Activity 1 Proprofs.com  has composed an user interface to know about different types of tissues. The template displays a crossword puzzle. Instructions are given to solve the puzzle. User can know different of cells involved in forming the tissue.User is allowed to type in using the keyboard. He is assessed at the end of the game by clicking on the submit button. Go to Activity Activity 2 Mbdalchemie.com has created a virtual lab to make the activity of 'Blood' understandable. Click on the 'Teacher's Desk' button. Under that 'Simulation' option has to be selected. It gives the student a clear-cut idea about the blood, blood groups, blood clotting etc. It explains different tests done by using blood as blood test, sedimentation test, blood call count, chemical analysis and haemoglobin test. Information is clearly explained in words and different types of cells flowing in the blood are shown.  Go to Activity Activity 3 Howstuffworks.com has devised a small game to provide clear information about 'Blood'. The information is split into questions and the student has to answer these questions. Right answer will be highlighted in green colour and the reason or explanation for the answer is also provided. Student is scored then and there after providing the answer. Wrong answers are marked red and right answers in green. Go to Activity

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