(class 9th) chapter:- 6 tissues (full chapter notes)
Answers
Introduction
→ The contraction and relaxation of these cells result in movement.
→ Blood flows and carries various substances from one part of the body to the other.
→ Blood and muscles are both examples of tissues found in our body.
→ Different types of animal tissues, such as epithelial tissue, connective tissue, muscular tissue and nervous tissue.
→ Blood is a type of connective tissue, and muscle forms muscular tissue.
Epithelial Tissue
→ Always grows on some other types of tissue.
→ Cells of epithelium are set very close to each other and the tissue rests on a non-cellular basement membrane.
→ Consists of single layer of cells.
→ Blood vessels are absent and non-nervous in nature.
→ It covers all the organs and lines the cavities of hollow organs like stomach.
→ It is primarily protective in function.
Types of Epithelium
→ Epithelium tissues are classified as Squamous epithelium, Cubical epithelium, Columnar epithelium and Ciliated epithelium.
(i) Squamous epithelium:
→ It is also called pavement epithelium.
→ Cells arranged end to end like tiles on a floor.
→ Cells are polygonal in surface view.
→ It forms the delicate lining of cavities (mouth, oesophagus, nose, pericardium, alveoli etc.) blood vessels and covering of the tongue and skin.
→ Epithelial cells are arranged in many layers (stratum) to prevent wear and tear in skin. This pattern is stratified squalors epithelium.
(ii) Cubical epithelium
→ They are cube like cells that fit closely, cells look like squares in section, but free surface appears hexagonal.
→ It is found in kidney tubules, thyroid vesicles & in glands (salivary glands, sweat glands).
→ It forms germinal epithelium of gonads (testes & ovaries).
→ It involves in absorption, excretion & secretion. It also provides mechanical support.
(iii) Columnar epithelium
→ Columnar means ‘pillar-like’ epithelium. It forms lining of stomach.
→ Small intestine & colon, forming mucous membranes.
→ Border of micro villi is present at the free surface end of each cell which increases absorption efficiency in small intestine.
(iv) Ciliated epithelium
→ Cells may be cubical or columnar.
→ On its free surface are present protoplasmic outgrowths called cilia.
→ It helps in the movement of ova in the fallopian tube.
Connective Tissue
→ The cells of the connective tissue are widely spaced and embedded in an intercellular matrix.
→ The mature of matrix decides the function of tissue.
→ White and yellow fibres are present in the matrix.
→ Their basic function is to provide support to different organs & keeping them in place.
Fluid or vascular tissue
• Blood and lymph
→ Blood is a connective tissue, fluid matrix of blood is plasma having wandering or floating cells, called corpuscles, blood helps in the transportation of various materials such as nutritive substances, gases, excretory products, hormones etc.
• Plasma
→ It forms 55% part of blood. It constitute of 90-91% of water, 7% of protein (Albumin, fibrinogen, globulin), 0.9% of inorganic salt etc.
• Corpuscles
→ Forms 45% part of blood.
• RBCs
→ They are also called as erthyrocytes, containing red coloured respiratory pigment called haemoglobin that helps in transportation of oxygen.
• WBCs (Leucocytes)
→ They are also called as ‘Soldiers of the body’.
→ They are irregular, amoeboid, phagocyte cells that protect our body by engulfing bacterial & other foreign particles.
→ They are of five types: Monocytes, Lymphocytes, Basophiles, Neutrophiles, Eosinophils.
Blood platelets or thrombocytes
→ They are spindle shaped cells which are involved in clotting of blood.
hope it helps....☺️