Infants born prematurely do not make enough surfactant to prevent atelectasis. What role does surfactant play in preventing atelectasis? Explain how a lack of surfactant affects pulmonary ventilation
What will be an ideal response?
Surfactant's role is to reduce alveolar surface tension. Without adequate surfactant, alveoli collapse due to the high surface tension of fluid in the alveoli. Pulmonary ventilation then ceases in one or both lungs. It is difficult for alveoli to re-inflate during inspiration to allow for gas exchange to continue.
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Where do preganglionic fibers of the parasympathetic system originate?
A. The thoracolumbar region of the spinal cord B. The lateral horns of the spinal cord from T1 through L2 C. The cerebral cortex D. The paravertebral ganglia E. The brain stem and sacral region of the spinal cord
During periods of fasting, why is fat said to have a protein-sparing effect?
A) The body must have an adequate protein intake in order to absorb and metabolize fats. B) The body oxidizes its spare protein before it depletes its fat reserves. C) The body must have an adequate fat intake in order to absorb and metabolize proteins. D) The body metabolizes fats and proteins through the same metabolic pathways. E) The body does not oxidize its proteins unless it has consumed its fat reserves first.
Answer the following statements true (T) or false (F)
1. Like bone cells, cartilage cells are located in lacunae. 2. Canaliculi supply food and oxygen to cartilage cells. 3. Osteoblasts and osteoclasts do opposite functions in the bone. 4. The skull is formed by endochondral ossification. 5. When fontanels fuse, they form sutures.
What is the correct order for the parts of the spinal cord, from superior to inferior?
A. Thoracic - cervical - lumbar - coccygeal - sacral B. Cervical - thoracic - lumbar - sacral - coccygeal C. Cervical - thoracic - sacral - coccygeal - lumbar D. Thoracic - lumbar - sacral - coccygeal - cervical E. Thoracic - lumbar - sacral - cervical - coccygeal