Can ossification occur without calcification during longitudinal growth? Explain
What will be an ideal response?
No, calcification must occur before ossification is possible during longitudinal growth. During longitudinal growth, chondrocytes die and their matrix calcifies. Chondrocytes then reach the zone of calcification. Here, chondrocytes are quite far from the blood supply, which causes them to die and their ECM to accumulate calcium salt deposits. Calcified cartilage is replaced with bone. In the final zone, the zone of ossification, osteoblasts invade the calcified cartilage and begin to lay down bone on top of it.
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The specificity of an antibody molecule depends on the structure of which of the following?
A) the constant segments of the light and heavy chains B) the constant and variable segments of the light and heavy chains C) the variable segments of the light and heavy chains D) the variable segments of the light chains only E) the constant segments of the heavy chains only
Which of the following nerves is labeled B in the diagram?
a) phrenic nerve b) axillary nerve c) intercostal nerve d) femoral nerve e) common fibular nerve
Sensory innervation of the lower teeth and gums is by the ________ nerve
A) ophthalmic branch of the trigeminal B) maxillary branch of the trigeminal C) mandibular branch of the trigeminal D) glossopharyngeal E) hypoglossal
Which of the following statements concerning the micturition reflex is false?
A. The micturition reflex is initiated by stretching the bladder wall. B. Afferent signals are conducted to the sacral segments of the spinal cord by the pelvic nerves. C. Efferent signals are sent to the bladder by sympathetic fibers in the pelvic nerve. D. The micturition reflex usually produces a series of contractions of the urinary bladder. E. The micturition reflex is modified by centers in the pons and cerebrum.