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Exam practice 2015 questions with answers...

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Multiple-choice questions 1) Which body fluid compartment contains higher levels of Na+, Cl-, and HCO3-? A) plasma B) interstitial fluid C) intracellular fluid D) A and C E) A and B For questions 2-6, match the terms to changes presented, assuming a resting membrane potential of -70 mV. Answers may be used once, more than once, or not at all. A. electrical polarization B. hyperpolarization C. depolarization D. repolarization E. more than one of the above 2) to -50 mV from resting potential 3) to -70 mV from -50 mV 4) to -90 mV from resting potential 5) to +30 mV from resting potential 6) to -70 mV from -90 mV 7) A simple nervous system A) must include chemical senses, mechanoreception, and vision. B) includes a minimum of 12 effector neurons. C) has information flow in only one direction: toward an integrating center. D) has information flow in only one direction: away from an integrating center. E) includes sensory information, an integrating center, and effectors. 8) A graded hyperpolarization of a membrane can be induced by A) increasing its membrane's permeability to Na+. B) decreasing its membrane's permeability to H+. C) decreasing its membrane's permeability to Cl-. D) increasing its membrane's permeability to Ca++. E) increasing its membrane's permeability to K+.

9) A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to A) prevent the hyperpolarization phase of the action potential. B) prevent the depolarization phase of the action potential. C) prevent graded potentials. D) increase the release of neurotransmitter molecules. E) have most of its effects on the dendritic region of a neuron. 10) The primary means by which a neuron can communicate to a second neuron is by A) the frequency of its action potentials. B) the peak of the depolarization phase of an action potential. C) the peak of the undershoot/hyperpolarization of an action potential. D) varying how much neurotransmitter it releases for a given action potential. E) remaining in the depolarization phase of the action potential for an extended interval. 11) Neural transmission across a mammalian synaptic gap is accomplished by A) the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. B) impulses traveling as electrical currents across the gap. C) impulses causing the release of a chemical signal and its diffusion across the gap. D) impulses ricocheting back and forth across the gap. E) the movement of calcium ions from the presynaptic into the postsynaptic neuron. 12) When several IPSPs arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of A) temporal summation. B) spatial summation. C) tetanus. D) the refractory state. E) an action potential with an abnormally high peak of depolarization. 13) The major excitatory neurotransmitter of the human brain is A) acetylcholine. B) epinephrine. C) glutamate. D) nitric oxide. E) GABA.

14) Sometimes prolonged excessive exposure to high hormone concentrations causes a phenomenon known as ________. A) diabetes mellitus B) cellular inhibition C) down-regulation D) metabolism of protein kinases E) autoinhibition 15) Hormones often cause a cell to elicit multiple responses; this is because ________. A) there are thousands of receptors on the cell membrane B) the receptors bind to several hormones at the same time C) the protein kinases are rapidly metabolized D) during protein kinase activation, enzymes phosphorylate many other enzymes E) they activate some receptors and not others 16) The body's automatic tendency to maintain a constant and optimal internal environment is termed A) balanced equilibrium. B) physiological chance. C) homeostasis. D) static equilibrium. E) estivation. !

17) An example of a properly functioning homeostatic control system is seen when A) the core body temperature of a runner rises gradually from 37°C to 45°C. B) the kidneys excrete salt into the urine when dietary salt levels rise. C) a blood cell shrinks when placed in a solution of salt and water. D) the blood pressure increases in response to an increase in blood volume. E) the level of glucose in the blood is abnormally high whether or not a meal has been eaten. 18) Specific responses to changes in body temperature are regulated by the A) thermoreceptors. B) hypothalamus. C) medulla oblongata. D) skin. E) cardiac output. 19) Heat loss is promoted by A) sweating. B) dilation of cutaneous blood vessels. C) nonshivering thermogenesis. D) A and B E) A, B, and C

20) The hormone that directly controls water excretion by the kidneys is A) ADH. B) aldosterone. C) epinephrine. D) ANP. E) angiotensin. 21) Juxtaglomerular cells in the nephron secrete A) angiotensinogen. B) angiotensin I. C) aldosterone. D) renin. E) angiotensin converting enzyme. 22) Which of the following might trigger erythropoiesis? A) hypoxia of EPO-producing cells B) decreased tissue demand for oxygen C) an increased number of RBCs D) moving to a lower altitude E) low K+ levels 23) The parathyroid glands maintain adequate levels of blood calcium. This is accomplished through ________. A) blocking the action of growth hormone B) targeting the bone and activating osteoclasts so that calcium will be released C) antagonizing the synthesis of calcitonin D) slowing the activity of tissues that require calcium for activity E) reducing activation of vitamin D 24) Glucagon A) is secreted from beta cells of the liver B) is the primary catabolic hormone (correct answer) C) release is stimulated by rising glucose levels D) a lack this hormone is diabetagenic E) all of the above 25) Stimuli for the activation of the renin-angiotensin-aldosterone system include A) low blood pressure in arterioles in the nephron. B) a decrease in fluid flow into the collecting tubule. C) high blood pressure in the renal artery. D) A and B E) A, B, and C

26) At membrane potentials more –ve than the sodium equilibrium potential (+60 mV), sodium will leak A) into the cell, down its concentration gradient B) into the cell, down its electrical gradient C) out of the cell, down its electrical gradient D) out of the cell, down its concentration gradient E) none of the above

Written answer questions 1) Diuretics cause the kidneys to produce large amounts of urine. Unfortunately, they can also cause the loss of large quantities of K+ in the urine. What effect might prolonged use of diuretics have on nerve or muscle cells? (8 marks) 2) Briefly discuss target cell activation by hormone-receptor interaction. (4 Marks) 3) Imagine a neuron that has several hundred synapses forming on it. The majority of these synapses are shown to be "firing." However, the neuron in question does not generate and transmit an action potential. Give a valid explanation of why this could occur. (4 marks) 4) Homeostatic regulation involves receptors and effectors. Explain how they are involved in relation to the stimulus. (2 marks) 5) Briefly compare and contrast the two types of diabetes mellitus. (5 marks) 6) Draw a diagram of the reactions and interactions of the renin-angiotensinaldosterone pathway in response to low blood pressure. (8 marks for indicating any eight of the correct reactions and interactions)

Multiple-choice questions 1) E 2) C 3) D 4) B 5) C 6) D 7) E 8) E 9) B 10) A 11) C 12) A 13) C 14) C 15) D 16) C 17) B 18) B 19) D 20) A 21) D 22) A 23) B 24) B 25) D 26) A Written-answer questions 1) Concentration of potassium in the blood would become low (1). Therefore, the K+ concentration in the extracellular fluid would also become low (1). As the resting potential of nerve and muscle cells depends primarily on K+ concentration (1), the potential would be altered (1). Decreased extracellular K+ would increase the concentration gradient for movement of K+ out of the cells (1), which would gradually hyperpolarize the potential (1) as positive ions exit (1) and make the cells less excitable (farther from threshold) (1). 2) The first step is hormone-receptor binding to target cells (1), but interaction depends on blood levels of the hormone (1), relative number of receptors for that hormone on or in the target cells (1), and the strength of the binding between the hormone and the receptor (1). 3) Both excitatory and inhibitory synapses formed on a neuron (1) are “firing”, generating EPSPs and IPSPs, respectively (1). IPSPs generated at the inhibitory synapses significantly hyperpolarize the neuron (1), preventing it from reaching threshold for action potential generation (1). Therefore, no action potentials are generated and transmitted.

4) A receptor is sensitive to a particular stimulus (1) and an effector’s activity counters the same stimulus by negative feedback (1). 5) Type I diabetes mellitus is a condition of insulin deficiency (1) due to pancreatic beta cell destruction (0.5), is autoimmune condition (0.5), and usually arises during childhood (0.5). Type 2 diabetes mellitus is insulin-resistant (1), often due to a lack of physical activity (0.5) and a poor diet (0.5), and usually arises in adulthood (0.5). 6)...