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bio 106 exam 2
| Question | Answer |
|---|---|
| Which of the following events would increase filtration pressure? | constriction of the efferent arteriole |
| The movement of fluid into Bowman's capsule is opposed by | capsular hydrostatic pressure. |
| Water and NaCl reabsorbed from the loop of Henle directly re-enter what blood vessels? | vasa recta |
| At the rate of 125 ml of filtrate/minute, estimate the amount of filtrate formed in 24 hours. | 180 Liters |
| Which is TRUE about the juxtaglomerular apparatus? | It is the site of renin secretion. |
| If the following hypothetical conditions exist in the nephron, calculate the net filtration pressure. glomerular capillary pressure = 80 mmHg blood colloid osmotic pressure = 20 mmHg capsular hydrostatic pressure = 10 mmHg | 50 mmHg |
| Which if these would result in an increase in the osmolarity of urine? | increased levels of vasopressin in the plasma |
| Angiotensin II | stimulates aldosterone secretion. |
| hich would occur if a person lost the ability to synthesize vasopressin? | The urine would become hypoosmotic compared to plasma. |
| Atrial natriuretic hormone | is secreted when atrial blood pressure increases |
| Autoregulation in the kidney involves changes in the degree of | constriction of afferent arterioles. |
| Which of the following would cause a decrease in the excretion of Na + and water? | decreased atrial natriuretic peptide secretion |
| Glucose is usually completely reabsorbed from the filtrate by the time the filtrate has reached the | end of the proximal convoluted tubule. |
| Decreased blood colloid osmotic pressure affects renal function by | increasing net filtration pressure |
| Which of the following drugs is least likely to decrease blood pressure? | a drug that enhances the activity of angiotensin-converting enzyme |
| Which equation is equal to the net glomerular filtration pressure? | = hydrostatic pressure in glomerular capillaries - hydrostatic pressure in Bowman's capsule - osmotic force due to proteins in plasma |
| Water reabsorption by the renal tubules uses | osmosis. |
| Which of the following statements concerning the process of glomerular filtration is correct? | The hydrostatic pressure in Bowman's space opposes filtration. |
| In which region of the nephron does the fractional reabsorption of water vary the most in response to variation in the state of hydration? | the collecting duct |
| Tubular reabsorption and tubular secretion differ in that | tubular secretion adds materials to the filtrate; tubular reabsorption removes materials from the filtrate. |
| Which of the following would be most likely to increase GFR? | constricting efferent arterioles |
| The amount of a substance that is excreted in the urine is equal to the amount that is ________ plus the amount that is ________ minus the amount that is ________. | filtered; secreted; reabsorbed |
| What is the rate-limiting (regulated) step for stimulating the secretion of aldosterone? | conversion of angiotensinogen to angiotensin I in the blood |
| The kidneys produce renin when | the blood pressure in the afferent arteriole decreases |
| In what segment of the nephron is the greatest fraction of filtered water reabsorbed? | the proximal tubule |
| Plasma contains a much greater concentration of _____ than the glomerular filtrate. | protein |
| In the condition diabetes mellitus, why does glucose appear in the urine? | The filtered load of glucose becomes greater than the tubular maximum for its reabsorption. |
| Aldosterone exerts its effect on the kidney tubules by | increasing the synthesis of the transport proteins for sodium. |
| Which correctly describes renin? | It is secreted by juxtaglomerular cells in renal afferent arterioles. |
| The amount of filtrate produced per minute is called the | glomerular filtration rate. |
| What percent of filtrate becomes urine? | less than 1 percent |
| Which correctly describes the composition of the glomerular filtrate? | It is highly similar to plasma, except it does not contain plasma proteins. |
| Aldosterone targets cells in the | distal convoluted tubule. |
| Increased secretion of atrial natriuretic hormone results in | increased urine output. |
| Which of the following is NOT an action of angiotensin II? | decreases peripheral resistance |
| Lasix is a diuretic that blocks the reabsorption of sodium in the ascending loop of Henle. The result of giving this drug would be | increased urine output. |
| Which is TRUE about the hormone vasopressin (also known as antidiuretic hormone, ADH)? | It triggers insertion of aquaporins into the apical membranes of collecting duct cells. |
| Which of the following is least likely to be filtered into Bowman's capsule in a normal, healthy person? | plasma protein |
| Substances that are cotransported into proximal convoluted tubule cells include | glucose molecules with sodium ions. |
| Which of the following organs is the main site of aldosterone secretion? | adrenal glands |
| Decreased ADH levels results in a urine high in | water content. |
| Which is NOT a function of the kidneys in maintaining homeostasis? | regulation of blood glucose concentration |
| Renin converts | angiotensinogen to angiotensin I. |
| Which of the following substances undergo renal tubular secretion? | K+ |
| In the myogenic mechanism of autoregulation, what is the response to an increase in blood pressure in the afferent arteriole? | constriction of the afferent arteriole |
| Constriction of the ________ decreases hydrostatic pressure in _________. | afferent arterioles, glomerular capillaries |
| Passage of proteins into Bowman's capsule is prevented by | the size of the capillary pores, the size of the filtration slits in the podocytes, and the size of the proteins. |
| The collecting duct becomes more permeable to water when | ADH production increases. |
| As ADH production declines, | the urine volume increases. |
| The collecting ducts and distal convoluted tubules | vary in their permeability to water relative to the amounts of ADH present. |
| Which stimulates vasopressin secretion? | increased plasma osmolarity |
| All of the following substances are present in proximal tubular fluid in the kidney, but which one is not normally present in urine? | glucose |
| Which of the following statements is true? | reabsorption of water in the filtrate may be hormonally controlled. |
| Which of the following statements regarding renal handling of Na + is correct? | Na+ is actively reabsorbed in the ascending limb of the loop of Henle. |
| the juxtaglomerular apparatus is composed of | juxtaglomerular cells and the macula densa. |
| Actin myofilaments | contain strands of fibrous actin. |
| Depolarization of the cell membrane occurs when there is a rapid influx (inflow) of | sodium ions. |
| The sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called | neuromuscular junctions. |
| The active sites to which cross-bridges attach are found on the | actin myofilaments. |
| In which of the following situations does a resting membrane potential exist? | a relaxed muscle fiber |
| A muscle fiber will respond to a stimulus when that stimulus reaches the _____ level. | threshold |
| The sarcoplasmic reticulum | stores calcium ions. |
| Channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called | voltage-gated ion channels. |
| Muscles exhibit the property of excitability. This means that the muscle | responds to stimulation by the nervous system |
| The electrical properties of cells are the result of | ion concentration differences across the plasma membrane. |
| Which of the following is NOT a property of the myosin head? | They bind to troponin. |
| hich of the following is true about skeletal muscle? | Every muscle fiber receives a branch of an axon from the nerve. |
| Which of the following changes have the potential to dramatically affect the potential difference across the plasma membrane? | increased permeability of the membrane to sodium ions and increased intracellular concentration of potassium ions |
| An action potential | occurs when the local potential reaches threshold level. |
| The region of the sarcomere that contains both actin and myosin myofilaments is called the | A band. |
| A myofilament is the | protein strand composed of actin or myosin. |
| In excitation-contraction coupling, | myosin heads bind to exposed active sites on actin. |
| The sarcolemma is the | cell membrane of a muscle fiber. |
| Sarcoplasm is the | cytoplasm of muscle cells. |
| Which of the following is mismatched? | myosin myofilaments - thin myofilaments |
| Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in | depolarization. |
| Which of the following structures contains the other four items listed? | neuromuscular junction |
| The outside of the resting plasma membrane is __________ relative to the inside of the resting plasma membrane. | positively charged |
| Troponin | has a calcium-binding site. |
| Synaptic vesicles in the neuromuscular junction contain | acetylcholine. |
| Which of the following causes an unequal ion concentration across the resting plasma membrane? | negatively charged proteins do not readily diffuse across the plasma membrane |
| Arrange these structures as they participate in excitation-contraction | sarcolemma, T tubules, sarcoplasmic reticulum, calcium ions |
| T tubules are invaginations of the | sarcolemma |
| hich of the following situations occurs in electrically excitable cells? | Depolarization causes voltage-gated sodium ion channels to open. |
| Which of the following is part of a thin myofilament? | globular (G) actin |
| A sarcomere extends from | one Z disk to an adjacent Z disk. |
| Which of the following is true during the resting membrane potential? | Potassium is concentrated primarily inside the cell. |
| Myosin is also known as the | thick myofilament. |
| Skeletal muscle fibers | possess striations. |
| Muscle tone | s a constant tension produced by muscles for long periods of time. |
| A condition in which stimuli occur so rapidly that there are no intervening relaxations between contractions is called | complete tetanus. |
| The refractory period | is the time during which the tissue cannot respond again. |
| Which of the following helps explain the increased tension seen in multiple wave summation? | increased concentration of calcium ions around the myofibrils |
| Which of the following is true? | A threshold stimulus will cause contraction of a muscle fiber. |
| Incomplete tetanus | is the condition in which the muscle fiber only partially relaxes between contractions. |
| Which of the following will respond to a threshold stimulus with an all-or-none contraction? | a single muscle fiber and a single motor unit |
| A myogram is | a recording of the events of a twitch. |
| Tetanus of muscles is described as | action potential frequency is high enough that no relaxation of muscle fibers occurs. |
| he stretch of elastic components of a muscle adds to the increased tension during | multiple wave summation. |
| Whole muscles can respond in a graded fashion to stimuli by varying | the number of motor units recruited. |
| Which of the following would contribute to muscular fatigue in the muscle fiber? | depletion of ATP reserves |
| Complete tetanus | s the condition in which stimuli occur so rapidly that there are no intervening relaxations |
| A sustained muscle contraction is known as | tetanus |
| During the contraction phase of a muscle twitch | actin-myosin cross-bridges form. |
| Tetanus of a muscle is thought to be caused by | high calcium ion concentrations in the sarcoplasm. |
| Which of the following would occur as a result of a single muscle contraction? | twitch |
| The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase. | latent or lag |
| When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the | power stroke. |
| Which of the following statements is true regarding skeletal-muscle contraction? | Binding of myosin to actin cannot take place in the absence of calcium ion |
| __________ degrades acetylcholine, keeping it from accumulating in the synapse. | Acetylcholinesterase |
| During which phase of the crossbridge cycle is ATP split into ADP and P i? | Immediately preceding the resetting of the myosin head |
| drug that inhibited acetylcholinesterase would result in: | enhanced stimulation of the muscle due to decreased Ach breakdown. |
| One ATP molecule is required for | formation of the cross-bridge, for movement of the cross-bridge, and for release of the cross-bridge. |
| Binding of ________ to myosin permits cross-bridge _____________ between actin and myosin. | ATP; detachment |
| After contraction has occurred, the calcium is | released from troponin. |
| In order for muscle relaxation to occur, | the active sites on actin must be blocked. |
| In excitation-contraction coupling, | myosin heads bind to exposed active sites on actin. |
| In muscle contraction ATP supplies energy for | myofilament movement. |
| For relaxation to occur: | Ach receptors close and Ca ++ channels on the sarcoplasmic reticulum close. |
| A power stroke involves: | a myosin head pulling a thin filament toward the center of the sarcomere. |
| When a muscle relaxes: | crossbridges stop forming and muscle elasticity returns the muscle to rest length. |
| ATP is necessary for each of the following mechanisms or functions in skeletal muscle except | release of Ca2+ from the sarcoplasmic reticulum |
| rigor mortis occurs in a dead person because | ATP, which is necessary for the detachment of cross bridges, is not being formed |
| A drug that interferes with the active transport of calcium ions from the sarcoplasm back into the sarcoplasmic reticulum would result in | contraction with no relaxation. |
| the removal of calcium ions from the cytosol of skeletal muscle causes | The myosin binding sites on actin to be covered by tropomyosin |
| Which of the following statements is correct? | Actin filaments slide along myosin filaments. |
| hich sequence correctly lists the changes that allow the thick and thin filaments to slide past one another in skeletal muscle contraction? | Attach - pivot - detach - return |
| 1. The role of ATP in regulating glomerular filtration pressure is to trigger _____________, resulting in ___________fluid reabsorption in the nephron. |
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alexs13