NURS242 Exam 3 Questions With Complete Solutions

NURS242 Exam 3 Questions With Complete Solutions What is ventilation? - ANSWER- the movement of air into and out of the lungs What is perfusion? - ANSWER- the circulation of blood through the lungs What are central chemoreceptors responsive to? - ANSWER- increased H+ in the brain ECF; increased PaCO2; "hypercarbic drive" What are peripheral chemoreceptors responsive to? - ANSWER- decreased pH; increased PaCO2; decreased PaO2; "hypoxic drive" What are elastic forces? - ANSWER- lungs recoil due to elastin, collagen, fibrin What are surface forces? - ANSWER- surface tension due to water-air interface What is airway resistance? - ANSWER- opposition to flow caused by the forces of friction; primarily determined by airway radius What is the distensibility of the lungs? - ANSWER- ease with which the lungs can be inflated What is lung distensibility increased in? - ANSWER- neonates and children; emphysema What is lung distensibility decreased in? - ANSWER- elderly; pneumonia, pulmonary edema, ARDS, atelectasis, fibrosis What is surfactant? - ANSWER- complex substance lining the alveoli and smallest bronchioles containing phospholipids and a number of apoproteins which reduces surface tension throughout the lungs, thereby contributing to its general compliance; stabilizes the alveoli and keeps them dry What produces surfactant? - ANSWER- produced by the Type II alveolar cells What is Ohm's law? - ANSWER- velocity = driving force/resistance What is Poiseuille law? - ANSWER- resistance = (8 x viscosity x length) / (pi x radius^4) What happens if the radius in the lungs goes down? - ANSWER- the resistance goes up How is the ventilation distributed in the lungs? - ANSWER- the top of the lungs are more distended and less compliant whereas the lower lung is small and highly compliant What factors affect lung perfusion? - ANSWER- lung capacitance; low resistance system; flow influenced by gravity; resistance primarily determined by vessel radius What does hypoxia lead to? - ANSWER- vasoconstriction of pulmonary vessels What does prolonged hypoxia lead to? - ANSWER- pulmonary hypertension