Question 1 :Give the location and importance of Nissl's granules ?
Answer : Nissl's granules or chromatoid bodies, are located in the neuroplasm of cyton. They are dark staining minute particles of basophilic ribose nucleoproteins which plays an important role in protein synthesis.
Question 2 : Distinguish between elastic and collagen fibres.
Answer : Collagen fibres (white fibres) are wavy, unbranched, non elastic and are arranged in bundles. They are formed ofa protein, called
collagen. Elastin (yellow fibres) are nonelastic, solitary, branching and anastomosing. They are not arranged in bundles. They are formed ofan elastic protein called elastin.
Question 3 : Why is SA node or "Pace maker" called as the "heart of heart" ?
Answer : During systole the waves of contraction originate spontaneously in sir' loauricular node (S.A node), without any nervous stimulation. Since this centre initiates heart beat, it is described as the "heart of heart". It is also called as "Pace maker" or pace setter", since it gives the initial stimulus for every contraction.
Question 4 : What are alveoli ? What is their significance ?
Answer : Alveoli are cluster of elastic and richly vascular air chambers found in the infundibulum of lungs. They are the structural and functional units of lungs and the centres of gas exchange. It is formed of simple squamous epithelium. Alveoli are covered by a network of minute and thin - walled blood capillaries. Alveoli and blood capillaries together form the respiratory surface for gas exchange between air and blood.
Question S: Define vital capacity
Answer : Vital Capacity can be defined as the maximal volume of air that can be expired after a maximal inspiration. It is the sum total of tidal, complemental and supplemental air. The normal vital capacity for men is 3.5-41itres, sometimes exceeds 5 litres. For women it is lower (3-4 litres). The vital capacity can be measured by an apparatus, called spirometer.
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