Revision (MCQs with their answers) on homeostasis by Dr Khaled A Abulfadle
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عدد المساهمات : 9470 تاريخ التسجيل : 06/08/2009
موضوع: Revision (MCQs with their answers) on homeostasis by Dr Khaled A Abulfadle السبت أكتوبر 29, 2011 2:06 pm
Choose the correct answer (s): ============================
1- Extracellular fluid in adults differs from intracellular fluid in that its………. a. Volume is greater. b. Tonicity is lower. c. Anions are mainly inorganic. d. Sodium: potassium molar ratio is higher. e. PH is lower.
2- Total body water, expressed as a percentage of body weight………………… a. Can be measured with an indicator dilution technique using deuterium oxide. b. Is smaller on average in women than in men. c. Rises following injection of posterior pituitary extracts. d. Falls during starvation. e. Is less than 80 per cent in young adults.
3- Thirst can be……………. a. Produced by a rise in plasma tonicity. b. Produced by stimulation of certain areas in the hypothalamus. c. Produced by a fall in blood volume. d. Associated with decreased secretion of ADH. e. Relieved by water intake before the water has been absorbed from the gut.
4- A fall in plasma sodium concentration……………….. a. May result from excessive production of ADH. b. Decreases intracellular fluid volume. c. May occur in people engaged in hard physical work in humid tropical climates. d. Reduces plasma osmolality. e. Is likely to cause thirst.
5- Sodium retention…………. a. Occurs for several days after major surgery. b. Occurs in response to secretion of aldosterone, but not cortisol. c. Expands the extracellular fluid volume. d. Expands the blood volume. e. Increases the severity of edema.
6- Sympathetic……………… a. Ganglionic transmission is mediated by acetylcholine. b. Neuromuscular transmission at the heart is mediated by adrenaline. c. Neuromuscular transmission in hand skin arterioles is mediated by acetylcholine. d. Neuroglandular transmission at sweat glands is mediated by noradrenaline. e. Neuromuscular transmission at the iris is mediated by noradrenaline.
7- Parasympathetic nerves………… a. Have opposite effects to sympathetic nerves on intestinal smooth muscle. b. Have opposite effects to sympathetic nerves on iris smooth muscle. c. Cause vasodilatation in skeletal muscle during prolonged exercise. d. Cause sweat secretion in skin when body temperature rises. e. Have longer postganglionic than preganglionic fibres.
8- When a nerve cell membrane is depolarized by 5 mV…………………. a. Its permeability to sodium increases. b. Sodium ions move into the cell to cause further depolarization. c. Potassium ions move outwards down their electrochemical gradient. d. Chloride ions move inwards down their electrochemical gradient. e. An action potential is generated.
9- Generalized sympathetic activity is characterized by…………………… a. Contraction of the radial muscle in the iris. b. Increased urinary excretion of catecholamines. c. Lipolysis in adipose tissue. d. Decreased conduction rate in the atrio-ventricular bundle. e. Relaxation of sphincteric smooth muscle in the alimentary tract.
10- Stimulation of the vagus nerves causes………………… a. A reduction in the strength of ventricular contraction. b. Secretion and vasodilatation in the salivary glands. c. Mucous secretion from bronchial mucosal cells. d. The spleen to contract. e. The gallbladder to contract.
11- An action potential in a nerve fiber…………………. a. Occurs when its membrane potential is hyperpolarized to a critical level. b. Is associated with a transient increase in membrane permeability to sodium. c. Is associated with a transient decrease in membrane permeability to potassium. d. Induces local electrical currents in adjacent segments of the fiber. e. Has an amplitude which varies directly with the strength of stimulus.
السبت أكتوبر 29, 2011 2:06 pm
