FINAL EXAMINATION OF PHYSIOLOGY Date:January 22,2005Time:8:00 a.m.-10:00 a.m. ANSWERS FOR REFERENCE I.MULTIPLE CHOICE QUESTIONS (20%) 1.B 2.C 3.E4.E5.B6.E7.A8.D9.C10.B II.TERMS (30%) 1.Negative feedback Negative feedback is a type of feedback,during which a system responds so as to reverse the direction of change.Since this process tends to keep things constant, it is stabilizing and attempts to maintain homeostasis. 2.Baroreceptor reflex The baroreceptor reflex is the body's rapid response system for dealing with changes in blood pressure.This reflex is initiated by stretch receptors,called either baroreceptors or pressoreceptors,which are located in the walls of several of the large systemic arteries.If a rise in arterial pressure stretches the baroreceptors and causes them to transmit signals into the central nervous system. "Feedback"signals are then sent back through the autonomic nervous system to the circulation to reduce arterial pressure downward toward the normal level. 3.Surfactant Surfactant is secreted by type II alveoli epithelial cells.It is a complex mixture of several phospholipids,proteins,and ions.The most important components are the phospholipids dipalmitoylphosphatidylcholine,surfactant apoproteins,and calcium ions.The dipalmitoylphosphatidylcholine,along with several less important phospholipids,is responsible for reducing the surface tension
FINAL EXAMINATION OF PHYSIOLOGY Date: January 22, 2005Time: 8:00 a.m.-10:00 a.m. ANSWERS FOR REFERENCE I. MULTIPLE CHOICE QUESTIONS (20%) 1.B 2.C 3.E 4.E 5.B 6.E 7.A 8.D 9.C 10.B II. TERMS (30%) 1. Negative feedback Negative feedback is a type of feedback, during which a system responds so as to reverse the direction of change. Since this process tends to keep things constant, it is stabilizing and attempts to maintain homeostasis. 2. Baroreceptor reflex The baroreceptor reflex is the body's rapid response system for dealing with changes in blood pressure. This reflex is initiated by stretch receptors, called either baroreceptors or pressoreceptors, which are located in the walls of several of the large systemic arteries. If a rise in arterial pressure stretches the baroreceptors and causes them to transmit signals into the central nervous system. “Feedback” signals are then sent back through the autonomic nervous system to the circulation to reduce arterial pressure downward toward the normal level. 3. Surfactant Surfactant is secreted by type II alveoli epithelial cells. It is a complex mixture of several phospholipids, proteins, and ions. The most important components are the phospholipids dipalmitoylphosphatidylcholine, surfactant apoproteins, and calcium ions. The dipalmitoylphosphatidylcholine, along with several less important phospholipids, is responsible for reducing the surface tension
4.Specific dynamic action of food After a meal is ingected,the metabolic rate increases as a result of the different chemical reactions associated with digestion,absorption,and storage of food in the body.This is called the thermogenic effect of food or specific dynamic action of food. 5.Renal threshold for glucose The critical value of the plasma glucose concentration when the kidney begins to excrete glucose.Normal value:160-180 mg/dL. 6.Paradoxical sleep Rapid eye movement sleep (REM sleep),a recurring sleep state during which dreaming occurs:a state of Rapid Eye Movements during sleep. III.QUESTIONS (40%) 1.Briefly describe the integrated,multifaceted system for arterial pressure regulation. (1)Rapidly acting pressure control mechanisms acting within seconds or minutes: (2)Pressure control mechanisms that act after many minutes; (3)Long-term mechanism for arterial pressure regulation. 2.Describe the composition and physiological function of the pancreatic juice. (1)Bicarbonate ions:Neutralizing acid entering the duodenum from the stomach. (2)Pancreatic digestive enzymes: i.Carbohydrates:Pancreatic amylase; ii.Fat:Pancreatic lipase,Cholesterol esterase,Phospholipase; iii.Proteins:Trypsinogen,Chymotrypsinogen,Procarboxypolypeptidase, Proelastase; (3)Trypsin inhibitor:Inhibits the activity of trypsin and thus guards against the possible activation of trypsin and the subsequent autodigestion of the pancreas
4. Specific dynamic action of food After a meal is ingected, the metabolic rate increases as a result of the different chemical reactions associated with digestion, absorption, and storage of food in the body. This is called the thermogenic effect of food or specific dynamic action of food. 5. Renal threshold for glucose The critical value of the plasma glucose concentration when the kidney begins to excrete glucose. Normal value: 160-180 mg/dL. 6. Paradoxical sleep Rapid eye movement sleep (REM sleep), a recurring sleep state during which dreaming occurs; a state of Rapid Eye Movements during sleep. III. QUESTIONS (40%) 1. Briefly describe the integrated, multifaceted system for arterial pressure regulation. (1) Rapidly acting pressure control mechanisms acting within seconds or minutes; (2) Pressure control mechanisms that act after many minutes; (3) Long-term mechanism for arterial pressure regulation. 2. Describe the composition and physiological function of the pancreatic juice. (1) Bicarbonate ions: Neutralizing acid entering the duodenum from the stomach. (2) Pancreatic digestive enzymes: i. Carbohydrates: Pancreatic amylase; ii. Fat: Pancreatic lipase, Cholesterol esterase, Phospholipase; iii. Proteins: Trypsinogen, Chymotrypsinogen, Procarboxypolypeptidase, Proelastase; (3) Trypsin inhibitor: Inhibits the activity of trypsin and thus guards against the possible activation of trypsin and the subsequent autodigestion of the pancreas
3.What is the effect of intravenous administration of 50%glucose 100 milliliter on urine formation in rabbit?Describe the underlying mechanism. The amount of the urine would increase. After one is injected intravenously 50%glucose 100 milliliter,the amount of glucose filtered from glomerulus exceeds tubular transport maximum for glucose.The osmotic effect of the extra glucose remained in the renal tubules greatly decreases tubular reabsorption of water and solute,and causes much loss of fluid into the urine. 4.List the main physiological actions of thyroid hormones. (1)Effects of thyroid hormone on general metabolism Thyroid hormone exerts numerous effects on metabolic processes in a wide variety of different tissues and cells. Calorigenesis or the heat production and BMR in the body Glucose absorption from the intestine and increase the uptake of glucose from the blood into adipose tissue and muscle All aspects of lipids.In general,however,the degradation is affected more than synthesis. Protein synthesis when present in physiological concentrations.However,when the thyroid hormone is present in excess,it tends to cause a decrease in protein synthesis and an increase in protein breakdown. (2)Cardiac output by increasing both the rate and the strength of cardiac contraction.Systolic blood pressure is augmented and diastolic blood pressure is decreased,so that the net result is a widened pulse pressure. (3)Effects of The Thyroid Hormone on Growth and Development The thyroid hormone is required for normal skeletal growth.Development and maturation of the central nervous system are markedly affected by thyroid hormones. IV.CASE (10%)
3. What is the effect of intravenous administration of 50% glucose 100 milliliter on urine formation in rabbit? Describe the underlying mechanism. The amount of the urine would increase. After one is injected intravenously 50% glucose 100 milliliter, the amount of glucose filtered from glomerulus exceeds tubular transport maximum for glucose. The osmotic effect of the extra glucose remained in the renal tubules greatly decreases tubular reabsorption of water and solute, and causes much loss of fluid into the urine. 4. List the main physiological actions of thyroid hormones. (1) Effects of thyroid hormone on general metabolism Thyroid hormone exerts numerous effects on metabolic processes in a wide variety of different tissues and cells. Calorigenesis or the heat production and BMR in the body Glucose absorption from the intestine and increase the uptake of glucose from the blood into adipose tissue and muscle All aspects of lipids. In general, however, the degradation is affected more than synthesis. Protein synthesis when present in physiological concentrations. However, when the thyroid hormone is present in excess, it tends to cause a decrease in protein synthesis and an increase in protein breakdown. (2) Cardiac output by increasing both the rate and the strength of cardiac contraction. Systolic blood pressure is augmented and diastolic blood pressure is decreased , so that the net result is a widened pulse pressure. (3) Effects of The Thyroid Hormone on Growth and Development The thyroid hormone is required for normal skeletal growth. Development and maturation of the central nervous system are markedly affected by thyroid hormones. IV. CASE (10%)
1.The weakness of the muscles in the distribution of the sciatic nerve was caused by the interruption of this nerve.The pattern of motor loss (weakness of the hamstring muscles,as well as of more distal muscles)indicates a proximal location of the interruption.A proximal location is consistent with the location of the gunshot wound in the thigh.The transection of the sciatic nerve interrupted sciatic nerve motor axons that originated from motoneurons in the ventral horn of the lumbosacral spinal cord.Therefore,motor commands could no longer reach the muscles supplied by the sciatic nerve,and hence the muscles could not longer be activated. 2.The sensory loss was caused by interruption of sensory axons in the sciatic nerve.The cutaneous sensory loss was in the distribution of the sciatic nerve. Sensory function in muscles and joints would also be lost.The cell bodies of the sensory neurons of the sciatic nerve are in dorsal root ganglia of the lumbosacral enlargement. 3.Autonomic function in the distal part of the left leg would also be lost because the sciatic nerve contains sympathetic postganglionic axons,as well as somatic motor and sensory axons. 4.Skeletal muscle fibers depend on innervation for their maintenance.Motor axons may release a trophic factor that provides signals to the muscle.Denervation deprives the muscle cells of this trophic factor,and it leads to their atrophy and eventual disappearance if the muscle is not reinnervated.Muscle that is not used will also atrophy to some extent ("disuse atrophy"),and this type of atrophy is not nearly as profound as denervation atrophy. 5.After complete denervation of a skeletal muscle,motor unit potentials can no longer be observed because these potentials depend on the synchronous activation of a collection of muscle fibers by an individual motor axon.The motor unit,which
l. The weakness of the muscles in the distribution of the sciatic nerve was caused by the interruption of this nerve. The pattern of motor loss (weakness of the hamstring muscles, as well as of more distal muscles) indicates a proximal location of the interruption. A proximal location is consistent with the location of the gunshot wound in the thigh. The transection of the sciatic nerve interrupted sciatic nerve motor axons that originated from motoneurons in the ventral horn of the lumbosacral spinal cord. Therefore, motor commands could no longer reach the muscles supplied by the sciatic nerve, and hence the muscles could not longer be activated. 2. The sensory loss was caused by interruption of sensory axons in the sciatic nerve. The cutaneous sensory loss was in the distribution of the sciatic nerve. Sensory function in muscles and joints would also be lost. The cell bodies of the sensory neurons of the sciatic nerve are in dorsal root ganglia of the lumbosacral enlargement. 3. Autonomic function in the distal part of the left leg would also be lost because the sciatic nerve contains sympathetic postganglionic axons, as well as somatic motor and sensory axons. 4. Skeletal muscle fibers depend on innervation for their maintenance. Motor axons may release a trophic factor that provides signals to the muscle. Denervation deprives the muscle cells of this trophic factor, and it leads to their atrophy and eventual disappearance if the muscle is not reinnervated. Muscle that is not used will also atrophy to some extent (“disuse atrophy”), and this type of atrophy is not nearly as profound as denervation atrophy. 5. After complete denervation of a skeletal muscle, motor unit potentials can no longer be observed because these potentials depend on the synchronous activation of a collection of muscle fibers by an individual motor axon. The motor unit, which
consists of a motoneuron and all of the muscle fibers that it innervates,is disrupted when the axons that connect the motoneuron cell body with the muscle fibers are severed.Fibrillations are spontaneous contractions of denervated individual muscle fibers.They are recognized in electromyography by their narrow and relatively small action potentials.Furthermore,they do not respond to attempts at voluntary contractions.Motor unit potentials are broader and larger because they represent the compound action potentials of many muscle fibers.Some asynchrony in the action potentials of different muscle fibers also occurs
consists of a motoneuron and all of the muscle fibers that it innervates, is disrupted when the axons that connect the motoneuron cell body with the muscle fibers are severed. Fibrillations are spontaneous contractions of denervated individual muscle fibers. They are recognized in electromyography by their narrow and relatively small action potentials. Furthermore, they do not respond to attempts at voluntary contractions. Motor unit potentials are broader and larger because they represent the compound action potentials of many muscle fibers. Some asynchrony in the action potentials of different muscle fibers also occurs