Johnny fractured the lower third of his right tibia in a skiing accident. The soft tissues in the area were severely damaged and their surgical removal was necessary. After prolonged immobilization, it was found that Johnny was healing very poorly
The explanation offered by the orthopedic surgeon was that vascularization of the fracture site was still inadequate and good healing was absolutely dependent upon an adequate blood supply. Describe how a long bone receives its blood supply and trace the path of nutrient delivery to the osteocytes.
What will be an ideal response
Long bones are nourished by nutrient arteries that frequently enter the shaft. Removal of the soft tissues probably reduced the flow of blood to the affected area. The pathway requires transport of nutrients from blood vessels in the medullary cavity to perforating (Volkmann's) canals to central (Haversian) canals to canaliculi to lacunae that contain osteocytes.
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Kidney stones are primarily composed of
A) cholesterol and esters of other steroid compounds B) crystals and proteins that grow in the renal medulla C) heavy metals that precipitate in the urinary filtrate D) salts of weak acids that serve as buffers in the nephron
Matching
A) A band B) Z discs C) I band D) Myosin 22) A sarcomere is the distance between two ________. 23) The ________ contains only the actin filaments. 24) The thicker filaments are the ________ filaments. 25) Both actin and myosin are found in the ________. 26) The myosin filaments are located in the ________.
Compare olfactory receptors with receptors for the other special senses
A) Olfactory receptors are at the surface of the olfactory epithelium and can generate a fast action potential, whereas receptors for the other special senses are deep and slower to generate an action potential. B) Olfactory receptors are chemoreceptors and respond to dissolved chemicals, whereas the receptors for the other special senses are mechanoreceptors. C) Olfactory receptors have short axons because of their close proximity to the olfactory bulb, whereas the receptors for the other special senses have long axons because they are further away from the CNS. D) Olfactory receptors do not require the CNS for processing the signal, whereas the receptors for the other special senses require processing by the CNS. E) Olfactory receptors are the dendrites of specialized excitable olfactory neurons, whereas the receptors for the other special senses are receptor cells with inexcitable membranes and form synapses with the processes of sensory neurons.
The enzyme catalase acts on the substrate
A. peroxidase. B. oxygen. C. hydrogen. D. hydrogen peroxide.