A: In mammals, sarcolemma of muscle fibre invaginates into sarcoplasm at the A-I junctions and form T - tubules. Each T - tubule is flanked on either side by cisternae of the sarcoplasmic reticulum. T - tubule and the cisternae on its sides form the triad system.
Q: Distinguish between red muscle fibres and white muscle fibres.
A: a. Muscle fibres of some muscles contain large amounts of myoglobin (to store much oxygen) and thus they are red in colour. Such muscle fibres are called red muscle fibres. They have large number of mitochondria to produce more energy (ATP). Red muscles are also called aerobic muscles.
b. Muscle fibres of some muscles contain little amounts of myoglobin and thus they are pale in colour. Such muscle fibres are called white muscle fibres. They have less number of mitochondria. White muscles are also called anaerobic muscles.
Q: Name the key stone bone in cranium and where it is located?
A: a. As the sphenoid bone articulates with all bones of cranium, it is called keystone bone of cranium.
b. Sphenoid is located at the middle part of the base of skull.
Q: Name the type of joints between:
a. Atlanto- axial joint
b. Femur-acetabular joint
A: a. Pivot joint
b. Ball and socket joint.
Q: Name the meninges covering the brain of man.
A: a. Outer duramater
b. Middle arachnoid mater
c. Inner piamater
Q: What is corpus callosum?
A: Corpus callosum is a wide and flat bundle of myelenated nerve fibres beneath the cortex connecting the two cerebral hemispheres in the brain of human beings.
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