Unit 1 Case Study and Homework
Unit 1 Case Study and Homework PSL 310
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Date Created: 10/11/15
Fall 2015 PSL 310 Study Guide for the Case Studies for Unit 1 Anything on this Study Guide is fair game for the Unit 1 Exam VERY IMPORTANT NOTE YOU SHOULD USE THE RESOURCES LISTED AFTER THE QUESTIONS TO HELP YOU THEY SHOULD SAVE YOU LOTS OF TIME AND PREVENT CONFUSION If you don t use the Resources listed you will struggle with the questions These case studies deal with the effect of abnormal blood K levels demyelinating disease addition of nonisotonic uids to the body and diseases that affect water loss in the urine and more These cases are all important clinically and help you learn to apply what you have learned in physiology to clinical settings and the real world Some of the cases are similar to help reinforce your learning For this first Unit since we have not covered any organ systems yet these are more mini cases First Case Before the following occurred Brendon seemed a normal healthy 25 year old man Brendon started to have symptoms of weakness and later had difficulty walking Eventually an ambulance was called for Brendon because of his symptoms of weakness He was taken to a hospital where blood tests revealed he had hypokalemia lower than normal blood potassium ion concentration 21 Could Brendon not being able to walk be related to the hypokalemia Can hypokalemia decrease excitability the ability to produce electrical signals can hypokalemia decrease the ability to produce action potentials A yes B no 22 During the hypokalemia were Brendon s cells closer or further from threshold compared to a normal person or compared to Brendon s cells before the hypokalemia A closer B further Resources Challenge Questions and Reading Questions 12 and 14 on A15A16 and the ANSWERS to those questions on page A20 Course Pack pages 4142 Here is what you should do draw a diagram Below is normal that is before hypokalemia YOU NEED TO MAKE THE DRAWING OF WHAT OCCURS WITH HYPOKALEMIA see page 41 of the Course Pack Normal With Hypokalemia or 1 K 0 46 l Jr ma 54m 101 Your I wing shows that less K leaves the cell than normal with hypokalemia which makes the cell less negative ins1 e compared to normal Circle the right answers this does not go on the scan ron but helps you think about what is happening Now draw another diagram Draw resting membrane potential and threshold potential before and with hypokalemia see page 42 of the Course Pack 55 mmJ Omvg Nafwmj KW 3s mgtlt xxxyxxx l0 Your drawing shows that with hypokalemia cell membrane potential is closer to threshold than normal which would make the cell more excitable than normal Circle the right answers this does not go on the scantron but helps you think aout what is happening in the answer to question above Hypokalemia means more K leaves the cell than normal this means the cell is hyperpolarized compared to normal and further from threshold see pages 4142 of the Course Pack Because neurons are further from threshold with hypokalemia neurons are less excitable than normal see page 42 and question 14 on page A16 of the Course Pack and the answer to question 14 on page A20 As the answer to question 14 describes this situation of inability to walk due to hypokalemia actually occurred in a close relative brother of Dr Denison about 30 years ago Weakness fatigue and paralysis of muscles including respiratory muscles and inability to breathe can occur Hypokalemia can cause serious problems in heart function including a decrease in heart rate Interesting note in Dr Denison s brother the cause of the hypokalemia was never identi ed however the physicians suspected too much aldosterone secretion at the time which reinforces a question below 2 l A 22B Imagine you are working in the hospital as a health care professional when Brendon comes into the emergency department for example imagine you are a medical resident You are asked by your superior about causes of hypokalemia You want to look smart Note we have not covered hormones yet but you should be able to find the answer and make hypokalemia make more sense Here s a hint aldosterone is a hormone that increases K loss in the urine 23 You correctly tell your superior that hypokalemia can be caused by A Addison s disease with below normal aldosterone secretion B Hyperaldosteronism or Conn s syndrome with above normal aldosterone secretion Resources Course Pack page 42 which explains the causes of decreased concentration of K in the ECF Readings Appendix at the very end of the Course Pack pages 697 and 698 or you can use ebook pages 697 and 698 and the information above that aldosterone is a hormone that increases K loss in the urine On page 42 of the Course Pack it describes that hypokalemia can be due to too much aldosterone On page 697 of the ebook or Readings Appendix it describes Conn s syndrome as caused by a tumor that secretes excess aldosterone The reading also notes that the symptoms are related to the exaggerated effects of aldosterone which includes K depletion hypokalemia As noted in an answer above physicians suspected hyperaldosteronism or Conn s syndrome as the cause of the hypokalemia in Dr Denison s brother 24 Your supervisor begins quizzing you more She asks whether certain diuretics can cause hypokalemia You correctly respond with A of course B no that s ridiculous Resources Diuretics cause diuresis or increased urine output Diuretics are commonly called water pills because they increase water loss in the urine they increase urine volume The Course Pack on page 42 which eXplains the causes of decreased concentration of K in the ECF will also help You will learn more later in the course about certain diuretics ie those water pills that increase loss of water in the urine which can cause hypokalemia Diuretics are actually the most common cause of hypokalemia 23 B 24 A Second Case Jerome was found on the oor nearly unconscious 911 was called and he was rushed to the hospital Blood tests revealed Jerome had hyperkalemia higher than normal blood potassium ion concentration An electrocardiogram EKG revealed that Jerome s heart was not functioning normally and he had a lower than normal heart rate 25 During the hyperkalemia were Jerome s cells closer or further from threshold compared to a normal person or compared to Jerome s cells before the hyperkalemia A closer B further Resources Course Pack pages 4142 Challenge Questions and Reading Questions 12 and 13 on pages A15A16 and the ANSWERS to those questions on page A20 You should do the same thing you did with the first case Students have problems with the effect of ECF K concentration on membrane potential that s why you are walking through it step by step in these case studies Here is what you should do draw a diagram again Below is normal that is before hyperkalemia YOU NEED TO MAKE THE DRAWING OF WHAT OCCURS WITH HYPERKALEMIA see page 41 of the Course Pack Z g5 Normal V With Hyperkalemia or T K 0 gVM m 4 Q MaiaKT k agaia Your drawi shows that more leaves the cell than normal with hyperkalemia which makes the cell more egative inside compared to normal Circle the right answers this does not go on the scantron but helps you think about what is happening Now draw another diagram Draw resting membrane potential and threshold potential before and with hyperkalemia see page 42 of the Course Pack m z JWA l o mfoo 00000000 Your drawing shows that with hyperkalemia cell membrane potential isurther from threshold than normal circle the right answer this does not go on the scantron but helps you think about what is happening to answer the question above 26 This may be a tough question Could severe hyperkalemia cause a lack of excitability of cells and decrease the ability of the cell to produce action potentials A yes B no Resources Same as the previous question but see especially the answer to Challenge Questions and Reading Question 13 on page A20 Hint if you have persistent depolarization of cells with severe hyperkalemia what would happen to the voltage gated Na channels of excitable tissues See the action potential on page 49 of the Course Pack How do the voltage gated Na channels reset look at the Figure s step 6 could continual depolarization prevent resetting and new action potentials Hyperkalemia means less K leaves the cell than normal this means the cell is depolarized compared to normal and closer to threshold see pages 4142 of the Course Pack Because neurons are closer to threshold with hyperkalemia neurons are more excitable than normal initially see answer to 13 on page A20 With severe hyperkalemia however Na channels remain inactivated since the membrane stays depolarized and the membrane Na channels cannot reset to allow new action potentials to occur and there is a DECREASE in excitability and a decrease in the ability to produce action potentials Of particular importance clinically is the effect of abnormal ECF K concentration on cardiac muscle the heart Above it is noted that hypokalemia affects heart function hyperkalemia also affects heart function In the description of the second case Jerome had a decrease in heart rate which can also occur in hypokalemia as stated above As described above Jerome s hyperkalemia caused changes from normal in his electrocardiogram EKG Hypokalemia can also causes changes in the EKG 25 A 26A Case 1 and 2 show that opposite changes in ECF K concentration from normal can have similar effects on excitability and on heart rate Both hypokalemia and hyperkalemia can decrease the excitability of cells Thus these cases illustrate it can be difficult to tell these ion imbalances ie too little too much K in the ECF apart just based on external signs and symptoms Interesting note Jerome is also based on a person Dr Denison knows This person was taking a drug that decreased aldosterone secretion which therefore decreased K excretion by the kidneys but his physician did not take Jerome off his K supplements that had been previously prescribed The drug and the K supplements caused Jerome s K to increase in the ECF 27 Now you are asked by your superior about causes of hyperkalemia You now desperately want to look smart You correctly tell your superior that hyperkalemia can be caused by A Addison s disease with below normal aldosterone secretion B Hyperaldosteronism or Conn s syndrome with above normal aldosterone secretion Resources Course Pack page 42 explains the causes of increased concentration of K in the ECF Readings Appendix or ebook pages 697 and 698 and the information above that aldosterone is a hormone that increases K loss in the urine On page 42 of the Course Pack it describes that hyperkalemia can be due to not enough aldosterone Addison s disease is described on page 698 of the Readings Appendix and symptoms of Addison s disease are caused by a deficiency not enough aldosterone As it states on page 698 patients with aldosterone deficiency display K retention hyperkalemia caused by reduced K loss in the urine Interesting note It s a very rare disease but John F Kennedy a president of the United States had Addison s disease He needed to take medication hormone replacement therapy We will learn later that without aldosterone being secreted and without hormone replacement therapy death will occur since aldosterone is needed for life 27A Third case A patient with a demyelinating disease comes to the emergency department with symptoms of loss of sensation in extremities and muscle weakness 28 Could the symptoms of loss of sensation and muscle weakness be caused by the patient s disease that is destroying the myelin of neurons A yes B no 29 Could loss of myelin slow action potential propagation A yes B no 30 Could loss of myelin prevent transmission of signals A yes B no Resources Course Pack page 56 Hopefully these were easy questions As the Course Pack describes on page 56 In demyelinating diseases several neural diseases including MS or multiple sclerosis conduction is slowed or blocked in areas of neurons that are now without myelin Decreased myelin means less current arrives at the node and arrives slower If myelin is gone there s no jumping from node to node and there is current leak through pores in the membrane that used to be covered with myelin It s now possible that not enough charge gets to the node and conduction is blocked These case study questions get you to think about why myelin is so important 28 A 29 A 30 A STATEMENTS THAT WILL HELP STUDENTS before the next cases K and Na act as nonpenetrating solutes due to the NaK pump that is the K that leaks out of the cell is pumped back in and the Na that leaks into the cell is pumped back out This has application to medicine It means that a solution of sodium chloride can be isotonic at a certain concentration and can be used to increase the volume of the extracellular uid Since Na acts as a nonpenetrating solute it stays outside the cell and it holds water with it which would increase the volume of the extracellular uid You could infuse a solution of isotonic saline into a patient to increase the volume of the extracellular uid if the patient lost extracellular uid for example if the patient lost blood This may help look on page 24 of the Course Pack at the bottom The isotonic solution used in the hospital could be a certain concentration of sodium chloride Fourth case A mistake has been made on your oor of the hospital Somehow instead of infusing 1 liter of isotonic saline solution into a patient 1 liter of pure water was infused instead yikes Isotonic solution should have been infused in this particular patient because the patient lost isotonic uid due to loss of plasma with a hemorrhage and pure water will change the osmolarity of the ECF of this patient 31 Assuming that before the infusion described above the patient s ECF and ICF osmolarity were normal this patient who received the pure water infusion will have A hyponatremia B hypernatremia 32 Assuming that before the infusion described above the patient s ECF and ICF osmolarity were normal this patient s cells will be more than normal after the infusion of pure water A swollen B shrunken Resources Course Pack page 24 and the following hyponatremia refers to a lower than normal concentration of Na in the blood hypematremia refers to a higher than normal concentration of Na in the blood Hint the case is similar to what happened with the marathon runner who drank water after the marathon in question 9 on page Al4 of the Course Pack It s a Challenge Question and Reading Question This patient lost isotonic uid and that is why the patient should have been given an infusion of isotonic uid The isotonic uid infusion would replace uid they lost The patient lost blood Blood plasma is isotonic and a clinician could choose to or may be forced to eg on the battlefield replace the lost plasma with isotonic uid instead of whole blood which replaces the lost cells too Interesting note there are instances in which nonisotonic uids ARE used for example to correct hyponatremia or hypernatremia However it states in the question that this particular patient before the infusion had normal ECF and ICF osmolarity and should have had an isotonic solution infused In the answer to 9 about the marathon runner who drank pure water which this question is similar to on page A19 it states If you replace the uid you lost with pure water then you have a decrease in the concentration of Na in the extracellular uid It would be like putting a cell that was in an isotonic solution into a hypotonic solution The cell would swell The consequences of swelling of cells can be severe including coma and death Brain cells especially don t like swelling 3 l A 32 A Fifth case You have a patient with the disease diabetes insipidus We will cover this disease later but for now you need to know that the patient is not secreting enough antidiuretic hormone or ADH ADH is a hormone that saves water from the forming urine This means the patient with diabetes insipidus will lose large volumes of water in the urine This is an elderly patient with mobility problems and is unable to replace all the water lost in the urine by drinking water it s hard for the patient to get glasses of water Interesting note in some ways this patient s problem is similar to the effects of drinking alcohol since alcohol inhibits decreases the release of ADH 33 The patient with diabetes insipidus will have and the patient s cells will likely be more than normal A hyponatremia swollen B hypernatremia shrunken C hypernatremia swollen D hyponatremia shrunken Resources Course Pack page 24 and the following hyponatremia refers to a lower than normal concentration of Na in the blood hypernatremia refers to a higher than normal concentration of Na in the blood In diabetes insipidus ADH de ciency patients can lose 201itersday of water in the urine Obviously they are thirsty a lot In this patient it states in the question that they can t replace all the water they lost due to mobility problems This means ECF water would decrease which increases the Na concentration in the ECF and would cause hypernatremia Patients with diabetes insipidus can be treated with hormone replacement therapy with synthetic preparations of the hormone ADH Actually the treatment depends on the severity of the disease sometimes the patient can keep up with the water loss in the urine by drinking water if some ADH is secreted and they are not losing huge volumes of water in the urine Page 24 of the Course Pack is given as a resource because the Figure on page 24 shows that if you increase the concentration in the ECF the uid around the cell water will move out of the cell so the cells are more shrunken than normal The consequences of shrinking of cells can be severe including coma and death Brain cells especially don t like shrinking either Notice hyponatremia and hypernatremia both affect brain cells but in opposite ways that is swelling with hyponatremia and shrinking with hypernatremia but both can cause coma and death in a patient 33 B Sixth case You recently diagnosed one of your patients with syndrome of inappropriate antidiuretic hormone secretion In syndrome of inappropriate antidiuretic hormone secretion there is excessive release of the hormone antidiuretic hormone ADH This patient complains of headache 34 As an exceptionally excellent physician which of the following should you expect is occurring in this patient A hypernatremia B decreased ICF osmolarity read this carefully and think about it C both A and B D neither A nor B Resources Course Pack page 24 and the following High ADH means less water is lost in the urine and more water would then go into the blood compared to normal Hyponatremia refers to a lower than normal concentration of Na in the blood hypernatremia refers to a higher than normal concentration of Na in the blood Also think about what happens to ICF osmolarity when you have an increase or decrease of osmolarity in the ECF This one was for students to answer Syndrome of inappropriate ADH ADH excess could be caused by tumors that produce ADH injury surgery pain or stress which cause ADH release It can be shortlived or chronic It s the opposite of what s occurring in diabetes insipidus Too much ADH is secreted which causes too much water to be saved from the forming urine which causes hyponatremia Decreased osmolarity of the ECF with hyponatremia means decreased osmolarity of the ICF since water freely moves through cell membranes ECF and ICF osmolarity will be lower than normal and equal Interesting note HIV infection can cause syndrome of inappropriate ADH Diuretics to increase urine loss and drugs that inhibit the action of ADH can be used as treatment 34 B Several cases There are several patients in your hospital with different uid and electrolyte imbalances Listed below are descriptions of the patients and questions about them The questions are based on the questions above and our discussions during the Case Study sessions 35 A patient has lost plasma volume due to a hemorrhage The patient lost a substantial amount of blood 1 L but the hemorrhage is not lifethreatening Assuming the patient has NOT ingested anything and has NOT had any medical treatment since the hemorrhage occurred What would most likely be the state of the patient s cells after this loss of plasma Hint assume no tissue or cell damage due to the hemorrhage A very swollen B very shrunken C normal sized This one was for students to answer An increase or decrease in isotonic uid will not change the volume of cells This idea will help you later when we study the Cardiovascular System This patient lost isotonic uid which will not cause uid movement it will not cause water to enter or leave cells If a lot of plasma is lost blood pressure could crash to low values the cells and their membranes could become damaged which could affect cell volume However it s stated there was no cell damage due to the hemorrhage 35 C Though choice A or choice B was also accepted for this question since we haven t covered blood pressure yet but at least it got you thinking 36 A psychiatric patient has psychogenic polydipsia He is constantly drinking large amounts of water to ush monsters out of his body He has What is called water intoxication a term used in medicine to describe his neurological effects Because he is drinking water faster than he can excrete the water he has A hyponatremia B hypernatremia C hyperkalemia This one was for students to answer Part of the reason for this question was for students to see another way hyponatremia can occur Normally a person will stop drinking before hyponatremia occurs but not so in this patient with psychogenic polydipsia Severe water intoxication symptoms can include seizures and coma and can be lethal Remember the brain cells don t like swelling 36 A 37 A patient has a traumatic crushing injury in which many cells and their membranes have been damaged and many cells were killed Due to the cell and cell membrane damage andor cell death this patient likely has AThfprenatremia deletechoiceA Brhynpernatremia deletechoiceB C hyperkalemia D hypokalemia If cell membranes are damaged then K will move out of the cells into the ECF and cause hyperkalemia Also if the cell has died then the NaK pump is no longer working since ATP is not being made by the cell Loss of the NaK pump will allow the K that leaks out of the cell to remain in the ECF causing hyperkalemia What can happen with what s called crush syndrome is an abnormal heart beat due to hyperkalemia Hyperkalemia was the more obvious answer Then Dr Denison got thinkingmaybe it s not just the obvious answer We deleted choices A and B because my intention was to have you focus on K It actually gets complicated because hyponatremia can occur an interesting cause of hyponatremia is that there could be increased release of antidiuretic hormone ADH due to injury pain and stress This shows you that it s not always the obvious answer and the body is very complicated 37 C 38 In a patient with an infusion of saline could be therapeutic or helpful A hypematremia hypertonic B hyponatremia hypertonic C hyponatremia hypotonic Of the choices only B makes sense an infusion of a hypertonic solution could correct the hyponatremia The question uses the word could because it is actually much more complicated than it seems and clinicians need to be very careful with how fast the Na concentration in the ECF is increased in chronic hyponatremia What s in these brackets is not required to know but is very interesting Over time cells protect themselves from changes in volume due to hyponatremia by altering the concentration of solutes that stay inside the cell A rapid infusion of a nonisotonic solution as therapy in an instance of chronic hyponatremia when brain cells have reduced their intracellular solute concentration could cause a big change in cell volume One of the effects of treatment can be osmotic demyelination syndrome which occurs when the hypertonic therapy causes water to move out of cells and damages them Severe damage of the myelin sheath of nerve cells in the pons of the brain can occur Again this syndrome is caused by the treatment which makes you think about the fact that sometimes a treatment can harm a patient 38 B 39 Hypokalemia and hyperkalemia can both cause decreased excitability of excitable cells A True B False This one was for students to answer Hypokalemia and hyperkalemia can both cause decreased excitability but by different mechanisms In hypokalemia the cell is further from threshold which makes it less excitable because it takes more ow of positive charge to get it to threshold In hyperkalemia because neurons are closer to threshold neurons at rst or initially are more excitable than normal But with severe hyperkalemia Na channels remain inactivated the membrane Na channels cannot reset to allow new action potentials to occur and there is a DECREASE in excitability and a decrease in the ability to produce action potentials 39 A 40 The way hypokalemia and hyperkalemia affect excitability is both cause Na channels to remain inactivated for a prolonged or a long time A True B False This one was for students to answer As explained in the previous answer hypokalemia and hyperkalemia both cause decreased excitability but by different mechanisms Severe hyperkalemia causes Na channels to remain inactivated which decreases excitability but hyperkalemia causes decreased excitability because the cell is further from threshold 40 B both answers were accepted for this question because we did not discuss the state of the Na channels with hyperpolarization but at least it got you thinking Important physiology learned from this case study 0 You learned how changes in ECF K concentration can affect membrane potential and excitability of cells and the ability to produce action potentials 0 You learned hyperkalemia and hypokalemia can both cause decreased excitability of cells 0 You learned that severe hyperkalemia with persistent depolarization of the membrane can cause inactivation of Na channels and that the membrane Na channels cannot reset to allow new action potentials to occur 0 You learned hyperkalemia and hypokalemia can both cause decreased heart rate 0 You learned why studying membrane potentials and having a sound foundation in understanding what affects membrane potentials is very important clinically 0 You learned about the important hormone aldosterone and that aldosterone increases K loss in the urine 0 You learned hypokalemia can be caused by too much aldosterone secretion in hyperaldosteronism or Conn s syndrome 0 You learned that certain diuretics can cause hypokalemia because they cause K loss in the urine and that diuretics are the most common cause of hypokalemia 0 You learned hyperkalemia can be caused by too little aldosterone secretion in Addison s disease 0 You learned aldosterone is needed for life so John F Kennedy with Addison s disease needed hormone replacement therapy 0 You learned that in demyelinating disease loss of myelin can slow action potential propagation 0 You learned that loss of myelin can cause a loss of sensation and muscle weakness and can prevent transmission of signals it can block conduction of signals that is it can block action potential propagation 0 You learned that Na acts as a nonpenetrating solute since the Na that leaks into the cell is pumped back out and that Na holds water with it so isotonic saline can be used to increase the volume of the ECF in medicine 0 You learned that infusion of pure water can cause hyponatremia 0 You learned that hyponatremia causes swelling of cells and brain cells are especially sensitive to swelling 0 You learned about the important hormone called antidiuretic hormone or ADH which saves water from the forming urine and decreases urine volume 0 You learned about the disease diabetes insipidus in which there is a deficiency of ADH and excessive loss of water in the urine which causes hypernatremia and shrunken cells 0 You learned that brain cells are especially sensitive to shrinking in addition to swelling lO You learned hyponatremia and hypernatremia both affect brain cells but in opposite ways that is swelling with hyponatremia and shrinking with hypernatremia but both can cause coma and death in a patient You learned that alcohol inhibits ADH secretion which would increase urine volume You learned about syndrome of inappropriate ADH in which there is an excess of too much ADH secreted You learned syndrome of inappropriate ADH causes hyponatremia since water is saved from the forming urine and stays in the body You learned that decreased osmolarity of the ECF with hyponatremia causes decreased osmolarity of the ICF since water freely moves through the cell membranes of tissue cells and therefore ECF and ICF osmolarity will be lower than normal You learned there are several causes of inappropriate ADH You learned that decreased osmolarity of the ECF with hyponatremia means decreased osmolarity of the ICF since water freely moves through the cell membranes of tissue cells and that in hyponatremia ECF and ICF osmolarity will be lower than normal You learned or were reminded that an increase or decrease in isotonic uid in the body will not change the volume of cells You learned that psychogenic polydipsia can cause hyponatremia and that severe water intoxication can cause seizures coma and death You learned that infusion of a hypertonic solution can correct for hyponatremia but clinicians need to be very careful with how fast the Na concentration in the ECF is increased with chronic hyponatremia You learned that hypokalemia and hyperkalemia can both cause decreased excitability but by different mechanisms You learned or were reminded that in hypokalemia the cell is further from threshold which makes it less excitable because it takes more ow of positive charge to get it to threshold You learned or were reminded that in hyperkalemia because neurons are closer to threshold neurons initially are more excitable than normal But with severe hyperkalemia Na channels remain inactivated the membrane Na channels cannot reset to allow new action potentials to occur and there is a decrease in excitability and a decrease in the ability to produce action potentials You learned that severe hyperkalemia what causes decreased excitability is the Na channels remain inactivated but in hyperkalemia what causes decreased excitability is the cell is further from threshold 11 Fall 2015 PSL 310 Homework for Unit 1 HOMEWORK ANSWERS ARE NOT ACCEPTED UNLESS THE STUDENT ATTENDS THEIR CASE STUDY SESSION You should print this and record your answers on this document since the correct answers will be posted by Thursday night before the exam and that will be the only way you know whether you got questions right or not before the exam the Homework will not be graded until after the exam Note the answers to this Homework will be turned in at the end of your Case Study meeting using a scantron We will continue using the Homework scantron for the Case Study answers To get a scantron students can do either 1 or 2 below 1 Pick up a scantron outside the Physiology main office 2201 Biomedical and Physical Sciences Building If you face Room 2201 and look on the right wall you will see a sign PSL 310 SCANTRONS with the scantrons in a slot below the sign You only need one scantron we will give you during class another kind of scantron for later HomeworkCase Studies 2 Bring their answers clearly listed on this Homework document and transfer their answers to a scantron available in the classroom before the Case Study session begins Students who chose this option must carefully fill out the scantron before the Case Study session starts Preparation for doing this Homework You should finish all the Lecture Recordings from Homeostasis through and including Membrane Potentials all Learning Objectives and all the Practice Questions for those Lecture topics The main function of this Homework is 1 encouraging you to keep up with the class and to give you credit for working through and understanding the Lecture Objective and the Practice Questions and 2 to get you prepared to learn the most you can during the Case Study session Remember the Practice Questions include the Comprehension Checks answered in videos posted on D2L the Study Questions in the Course Pack the Extra Study Questions in the Appendix of the Course Pack and the Challenge Questions and Text Reading Questions and the Answers to those questions in the Appendix of the Course Pack If you do that work ahead of this Homework you should a learn a lot b get credit for going through all the Practice Questions and c will be prepared to understand the Case Studies well This means you will be learning the right way If you do not prepare in the way I am encouraging you you will not understand the material well because you will be rushing at the end of the unit to get done and you will struggle through the Case Study session Don t forget to do the Learning Objectives which allow you to understand the practice questions These Homework Questions are based on the Objectives too For all questions select the single BEST answer based on the Learning Objectives and the Practice Questions First set of questions the function is to help you keep up with the material 1 This question should be easy but the idea is VERY important Homeostasis is the maintenance of a relatively constant intracellular not extracellular uid Hint the Study Questions A True B False Answer is B See Homeostasis Study Question 2 2 Hint The Challenge Question and Reading Question 3 on page Al3 in the Appendix of the Course Pack will help you with this question one function of this question is to remind you that there is reading you must do for the Challenge Questions and Reading Questions and you are responsible for that reading on the Unit 1 Exam This question also reminds you to 1e4arn from the Answers to the Challenge Questions and Reading Questions You can use the ebook to do the readings or the reading pages are also in the Appendix that is in the Readings Appendix at the very end of the Course Pack Based on Challenge Question and Reading Question 3 and the Answer to that question which the following is NOT or is LEAST correctly matched A desmosomes found in tissues that stretch B tight junction can prevent substances from moving between cells C gap junctions allow ions to move from one cell into another cell D collagen fiber type best able to stretch and recoil E gap junctions in cardiac muscle and smooth muscle Answer is D See Challenge Questions and Reading Question 3 and the Answer to that question 3 Hint Challenge Question and Reading Question 1 on page Al3 in the Appendix of the Course Pack will help you with this question one function of this question is to remind you that there is reading you must do for the Challenge Questions and Reading Questions and you are responsible for that reading on the Unit 1 Exam This question also reminds you to m from the Answers to the Challenge Questions and Text Reading Questions After reading about quotFick39s Law of Diffusionquot on page 6667 of your ebook or the Readings Appendix in your Course Pack and studying Table 31 quotFactors In uencing the Rate of Net Diffusion of a Substance across a Membranequot on page 66 select the choices below that would INCREASE the rate of diffusion through a membrane A increased lipid solubility of the substance B increased surface area of the membrane C decreased molecular weight of the substance D decreased distance or thickness of the membrane E all of the choices are correct and would increase the rate of diffusion through a membrane Answer is E See Challenge Question and Text Reading Question 1 and the Answer to that question 4 During labor increased stretch of the cervix causes more oxytocin release which causes stronger uterine contractions which causes more oxytocin release This is an example of negative feedback A True B False Answer is B See Comprehension Check for Homeostasis 4 all is true except it is an example of positive feedback 5 Hint the Challenge Questions This question is similar to but NOT the same as a Challenge Question Blood plasma glucose concentration is maintained within the range of normal in healthy people A certain hormone that we will call Hormone Z causes a decrease in the glucose concentration of blood plasma Hormone Z secretion is controlled by a negative feedback control system which involves the concentration of glucose in blood plasma and the Hormone Z secreting cells that is changes in the glucose concentration of blood plasma changes Hormone Z secretion Therefore given what you know about negative feedback control systems which of the following would be correct A decreased blood glucose decreases Hormone Z secretion B increased blood glucose increases Hormone Z secretion C decreased blood glucose increases Hormone Z secretion D A and B Answer is D See Challenge Question and Reading Question 2 and the Answer to that question Hormone Z is insulin 10 11 12 Consider a small ion that can move through a channel or pore in the cell membrane This ion could be moved against a concentration gradient by Hint page 18 of the Course Pack will help Another Hint 12 of the Extra Study Questions for Membrane Transport will also help A facilitated diffusion or active transport B moving through channels C by moving through channels or by active transport D facilitated diffusion using carriers E active transport Answer is E This Question was Challenge Question and Reading Question 5 slightly changed See the Answer to that question if you need an explanation This question taken from the Extra Study Questions for Membrane Transport It is 7 of those questions It is here because it seems students miss this idea Do the question first and THEN check your answer This question is to give you credit for doing this Extra Study Question Glucose is a large charged molecule is too big for pores If glucose is in lower concentration inside the cell than outside the cell glucose will enter the cell by A simple diffusion B active transport C facilitated diffusion D B or C E A or C Answer is C glucose goes down a concentration gradient into the cell facilitated by a carrier which is facilitated diffusion This was Extra Study Question 7 for Membrane Transport A solution with an osmolarity of 200 mOsmL has a water concentration than a solution with an osmolarity of 800 mOsmL A lower B higher Answer is B This question was Challenge Question 8 changed Hint the Study Questions for Membrane Transport Electrical potentials do not affect the movement of ions electrolytes through cell membranes only concentration gradients affect the movement of ions electrolytes through cell membranes A True B False Answer is B This question was Study Question for Membrane Transport 41 changed It s important for you to realize both an electrical and a chemical gradient or an electrochemical gradient can affect the movement of ions through cell membranes Which of the following is NOT or is LEAST correctly matched concerning Resting Membrane Potential RMP A electrogenic effect of the NaK pump direct effect of the NaK pump on RMP B electrogenic effect of the NaK pump pumps more positive ions out of the cell than into the cell C indirect effect of NaK pump creates ion concentration gradients down which ions diffuse which causes about 20 of RMP D indirect effect of NaK pump creates ion concentration gradients down which ions diffuse which causes most of RMP Answer is C See Extra Study Questions for Membrane Potentials 4 The function of this question was to have you think about how important the indirect effect of the NaK pump is on the creation of RMP The function of this question is to have you clearly think about where the concentrations of Na and K are higher It s really important to get this straight The NaJ39K pump pumps into the cell and out of the cell A K Na B Na K Answer is A This is Comprehension Check 1 for Membrane Potentials changed Imagine you could suddenly decrease Na permeability in a resting nerve cell Due to the decrease in Na permeability the nerve cell would Hint page 40 of the Course Pack should help A depolarize B hyperpolarize C have an action potential Answer is B This is Challenge Question 11 changed Read the Answer to that question if you need help with this Second set of questions the function is to get the wheels greasedquot in your head so you understand and get the most out of the Case Studies for Unit 1 13 Thinking about this question will help you with the Case Studies A cell placed an uid will NOT change size but a cell placed in an will swell A isotonic hypertonic B isotonic hypotonic C hypertonic hypotonic D hypotonic hypertonic Answer is B This question was Study Questions for Membrane Transport 17 and 23 merged 14 There is only one answer to this question but you have to fill the answer in on your scantron for credit I am giving you this question so you think about the important idea that Na acts as a nonpenetrating solute This means solutions containing a certain concentration of NaCl can be used to increase the volume of the extracellular uid ECF in a patient How does Na act as a nonpenetrating solute Hint this is covered on the bottom of page 17 of the Course Pack A the Na that leaks into the cell is moved out of the cell by active transport Answer the only answer is A 15 Study page 45 of the Course Pack so that you understand the terms depolarization repolarization and hyperpolarization Notice at 0 mV zero millivolts there are NO CHARGES SEPARATED across the membrane When the nerve cell is the most charges are separated A depolarized B at resting membrane potential C hyperpolarized Answer is C This question is important because you will be constantly confused if you don t understand these terms pi ON Hint Extra Study Questions for Membrane Potentials Which of the following lists the numbered events that occur during the action potential in the correct order Hint start with depolarization l depolarization 2 opening of activation gates of voltage gated Na channels 3 closing of inactivation gates of voltage gated Na channels 4 closing of voltage gated K channels K permeability back to permeability at RMP 5 after hyperpolarization 6 threshold reached 7 opening of voltage gated K channels 8 repolarization A l2367 854 B l 2 6 3 7 84 5 C l 7 6 3 245 8 D l 26 37 854 ANSWE IS D see Extra Study Questions for Membrane Potentials ll 17 There is only one answer to this question but you have to fill the answer in on your scantron for credit I am giving you this question to have you think about this idea which will help you understand the Case Studies Look at the events that occur during the action potential on page 49 of the Course Pack At what point does the Na channel reset Hint when the Na channel resets it is now capable of opening again with depolarization A at 6 when the membrane returns to resting membrane potential Answer the only answer is A 18 19 This question is Challenge Question 12 not changed much so DON T LOOK Do the question first and THEN check your answer This Homework question is to give you credit for working through this Challenge Question Students tend to have difficulty understanding what happens to resting membrane potential when K concentration in the extracellular uid increases above normal in quothyperkalemiaquot or decreases below normal in quothypokalemiaquot This question should help you understand the effects of increased and decreased extracellular K concentration on resting membrane potential Please note one of the reasons quotMembrane Potentialsquot is such an important topic for prehealth professionals is because you will have patients with hyperkalemia and hypokalemia Understanding what happens at the cell membranes of these patients is important because it will help you understand the symptoms involved Hyperkalemia above normal concentration of K in the blood causes resting cell membrane because K leaves the cell compared to normal because the concentration gradient for K is compared to normal Hypokalemia below normal concentration of K in the blood causes resting cell membrane because K leaves the cell compared to normal because the concentration gradient for K is compared to normal HERE39S WHAT YOU SHOULD DO draw a picture similar to the one we drew in Lecture on page 41 of the Course Pack before and after changes in extracellular K concentration This tends to be the most challenging part of Membrane Potentials and Membrane Potentials is the most challenging part of Unit 1 YOU NEED PRACTICE WITH THIS YOU SHOULD BE ABLE TO DRAW THE PICTURE WITHOUT LOOKING A depolarization more increased hyperpolarization less decreased B hyperpolarization less increased depolarization more decreased C depolarization more decreased hyperpolarization less increased D depolarization less decreased hyperpolarization more increased E hyperpolarization less decreased depolarization more increased Answer is D See Challenge Question 12 if you need help with this question of the of the This question is a Challenge Question Do the question first and THEN check your answer This Homework question is to give you credit for working through this Challenge Question As a health care professional you are treating a person who just completed a marathon 26 mile running race on a very hot day Although the person was encouraged by others to drink uid with Na a sports drink your patient did not like the taste and instead drank pure water about 15 liters This patient lost a lot of Na and water in their sweat but replaced the uid they lost with pure water Which below would accurately predict the state of the patient39s cells compared to normal Note This change in the patient39s cells is responsible for symptoms patients like this one will have that you will learn about later in your health professions career Hint page 24 of the Course Pack may help think of what is replacing normal ECF when the patient drinks pure water A impossible to tell B the cells would be more swollen have a larger amount of water inside the cell compared to normal C the cells would be more shrunken have a smaller amount of water inside the cell compared to normal Answer is B See Challenge Question 9 if you need help with this question 20 This question can keep you from becoming confused during the Case Studies Will an increase e g by infusion or a decrease e g by loss of plasma of isotonic uid cause a change in cell size in a patient OK I will give you the answer because I want everyone to have this clear before the Case Studies There is only one answer to this question but you have to fill the answer in on your scantron for credit A NO Answer the only answer is A The rest of the scantron to Question 40 will be used for answers filled in during your Case Study Session
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