scenario based questions
A 16-year-old patient with cystic fibrosis visits the clinic for a routine check-up. The patient has been experiencing thicker-than-normal mucus and has noticed that their sweat is saltier than usual. They ask you, "Why is my saline production and mucus so different from other people?"
Which of the following best explains the underlying cause of the patient’s altered saline production in cystic fibrosis?
A) Mutations to the sodium-potassium pumps in epithelial cells
B) Overproduction of aquaporins creating a saline layer nonfunctional
C) Mutations in the CTFR gene that make chloride pumps, but fail to install the pumps in the plasma membrane
D) Absence of gap junctions, preventing chloride to pump into the ECF and producing the saline layer
C) Mutations in the CTFR gene that make chloride pumps, but fail to install the pumps in the plasma membrane
A patient presents with weakness and spasticity in the right side of the body following a stroke. Imaging reveals a lesion located above the medullary pyramids in the left corticospinal tract. Which of the following is the most likely effect of this lesion?
A) Flaccid paralysis on the left side of the body, affecting both upper and lower limbs.
B) Spastic paralysis on the left side of the body, with hyperreflexia and increased muscle tone.
C) Spastic paralysis on the right side of the body, with hyperreflexia and increased muscle tone.
Loss of fine motor control in the right hand, with no other significant motor deficits.
C) Spastic paralysis on the right side of the body, with hyperreflexia and increased muscle tone.
Which of the following is a hydrophilic second messenger?
A) CO
B) Diacylglycerol (DAG)
C) cGMP
D) Phosphatidylinositol’s (PIP3)
C) cGMP
A pharmaceutical company is developing a new drug designed to target G-protein coupled receptors (GPCRs) on cell surfaces. The drug is expected to activate the GPCR upon binding. What is the immediate consequence of the drug binding to the GPCR?
A) Activation of adenylate cyclase, resulting in increased cAMP production.
B) The G-protein's alpha subunit exchanges GDP for GTP, leading to the activation of downstream effectors.
C) The receptor directly phosphorylates intracellular proteins.
D) Opening of ion channels, allowing the influx of calcium into the cell
B) The G-protein's alpha subunit exchanges GDP for GTP, leading to the activation of downstream effectors.
what are the 3 inputs to alpha motor neurons that determine which muscle fibers will contract?
A) Basal ganglia, cerebellum, muscle spindles
B) Spinal interneurons, upper motor neurons, sensory neurons
C) type 1a afferent neurons, extrafusal fibers, intrafusal fibers
D) Type 1b afferent neurons, gamma motor neurons, GTO’s
B) Spinal interneurons, upper motor neurons, sensory neurons
You are an PA student that is on their ER clinical rotation. You are introduced to a patient that has lost 2 liters of plasma volume due to Postpartum hemorrhage (PPH). Your preceptor asks you to approximate how many liters of intravascular isotonic saline must be infused to stabilize this patient.
A) 1 Liters
B) 5 Liters
C) 10 Liters
D) 8 Liters
C) 10 Liters
A patient is admitted to the hospital with severe motor dysfunction following a traumatic brain injury. The PA needs to determine whether the patient's condition is due to a lower motor neuron lesion or decerebrate posturing. Which of the following correctly differentiates between these two conditions?
A) A lower motor neuron lesion causes spastic paralysis and hyperreflexia, while decerebrate posturing causes flaccid paralysis with absent reflexes.
B) A lower motor neuron lesion results in flaccid paralysis with muscle atrophy and decreased reflexes, while decerebrate posturing is characterized by rigid extension of both upper and lower limbs due to brainstem damage.
C) A lower motor neuron lesion leads to increased muscle tone and exaggerated reflexes, whereas decerebrate posturing leads to muscle flaccidity and hyporeflexia.
D) A lower motor neuron lesion causes flexion of the upper limbs with extension of the lower limbs, while decerebrate posturing results in extension of the upper limbs with flexion of the lower limbs.
B) A lower motor neuron lesion results in flaccid paralysis with muscle atrophy and decreased reflexes, while decerebrate posturing is characterized by rigid extension of both upper and lower limbs due to brainstem damage.
What neurotransmitter is involved in reward, motivation, executive function (in the frontal lobes) and control of movement?
A) Serotonin
B) Dopamine
C) Glutamate
D) GABA
B) Dopamine
If a drug targeted the function of the sodium potassium pump, which of the following processes would cease?
A) SGLT
B) Ca+ channels
C) Osmotic entry of water
D) Exit of K+ from the cell
A) SGLT
During regulatory volume increase, cells will increase which of the following?
A) Efflux of K+
B) Efflux of Cl-
C) Influx of Na+
D) Hydrolysis of sorbitol
C) Influx of Na+
A researcher is studying the transport of ions across epithelial cells in the kidney. She notices that a specific ion channel is present on the apical side of the plasma membrane but not on the basolateral side. What is the primary functional difference between the apical and basolateral sides of the plasma membrane in epithelial cells?
A) The apical side faces the extracellular fluid, while the basolateral side faces the lumen.
B) The apical side faces the lumen, while the basolateral side faces the extracellular fluid and blood vessels.
C) The apical side is responsible for active transport, while the basolateral side is responsible for passive transport.
D) The apical side contains only symporters, while the basolateral side contains only antiporters.
B) The apical side faces the lumen, while the basolateral side faces the extracellular fluid and blood vessels.
A neurologist is examining a patient who has suffered a lesion to the alpha motor neurons that control the muscles involved in reciprocal inhibition. What would most likely occur in the affected muscles because of this lesion?
A) The agonist muscle would become hyperactive, leading to excessive contraction, while the antagonist muscle remains unaffected.
B) Both the agonist and antagonist muscles would become flaccid and unable to contract, resulting in complete paralysis of the affected limb.
C) The antagonist muscle would no longer be inhibited, leading to simultaneous contraction of both the agonist and antagonist muscles, causing spasticity or rigidity.
D) The agonist muscle would be unable to contract, while the antagonist muscle would become hyperactive and resist any attempted movement.
C) The antagonist muscle would no longer be inhibited, leading to simultaneous contraction of both the agonist and antagonist muscles, causing spasticity or rigidity.
What can an inhibitory neurotransmitter do indirectly to achieve its effect?
A) Close K+ channels & open Ca 2+ channels for influx
B) Open Cl- channels for influx
C) Open Na+ and Ca2+ channels for influx
D) Open K+ channels for efflux and close Ca2+ channels
D) Open K+ channels for efflux and close Ca2+ channels
A new drug has been developed that specifically inhibits the function of calcium pumps (Ca²⁺-ATPase) on the plasma membrane and the sarcoplasmic reticulum of muscle cells. What would be the most likely effect of this drug on muscle function?
A) Enhanced muscle contraction due to increased intracellular calcium levels
B) Muscle relaxation due to decreased calcium availability
C) Prolonged muscle contraction due to delayed calcium reuptake
D) Decreased neurotransmitter release at the neuromuscular junction
C) Prolonged muscle contraction due to delayed calcium reuptake
What is an example of a symport carrier-mediated transport?
A) Calcium pump
B) Sodium-glucose transporters
C) Sodium-potassium pump
D) Calcium-sodium pump
B) Sodium-glucose transporters
A PA student is studying the forces that drive fluid movement across capillary walls and encounters the concepts of hydrostatic and osmotic pressures. Which of the following statements correctly distinguishes between hydrostatic pressure and osmotic pressure?
A) Hydrostatic pressure is the force exerted by plasma proteins that draws water into the capillaries, while osmotic pressure is the force exerted by blood pressure that pushes fluid out of capillaries.
B) Hydrostatic pressure is generated by the pressure of fluid within the capillaries that drives fluid out, while osmotic pressure is created by the concentration of solutes that pull water into the capillaries.
C) Hydrostatic pressure results from the concentration of electrolytes in the interstitial fluid, promoting fluid movement out of capillaries, whereas osmotic pressure is caused by the filtration of fluid into the capillaries.
D) Hydrostatic pressure facilitates the reabsorption of nutrients into the capillaries, while osmotic pressure is responsible for the filtration of waste products into the interstitial space.
B) Hydrostatic pressure is generated by the pressure of fluid within the capillaries that drives fluid out, while osmotic pressure is created by the concentration of solutes that pull water into the capillaries.
A patient is brought to the emergency room after sustaining a severe head injury. Upon examination, the patient exhibits decorticate posturing, characterized by flexion of the upper limbs and extension of the lower limbs. Which of the following is the most likely location of the lesion causing this posturing?
A) Midbrain at the level of the red nucleus
B) Pons, below the level of the red nucleus
C) Cerebral cortex or internal capsule above the red nucleus
D) Medulla, affecting the corticospinal tract
C) Cerebral cortex or internal capsule above the red nucleus
Which muscle fiber would you expect lightly myelinated, a diameter less than <3 uM, and serve preganglionic and autonomic functions?
A) Aα
B) Aβ
C) Β
D) C (dorsal root)
C) B
A new experimental drug has been developed that specifically inhibits the S2 region of the myosin head. Which of the following would most likely occur because of this inhibition?
A) The myosin head would be unable to hydrolyze ATP, preventing the initiation of the power stroke.
B) The myosin head would lose its ability to bind to actin, disrupting cross-bridge formation.
C) The myosin head would be unable to undergo the conformational change necessary for the power stroke, leading to impaired muscle contraction.
D) The myosin head would remain permanently attached to actin, causing continuous muscle contraction.
C) The myosin head would be unable to undergo the conformational change necessary for the power stroke, leading to impaired muscle contraction.
A PA student is learning about the roles of Na+ in the body and how its distribution across cell membranes influences cellular function. The student is asked to explain the difference between steady state and equilibrium in the context of Na+ ion distribution.
Which of the following statements best describes the difference between steady state and equilibrium with respect to the importance of Na+ ions?
A) In steady state, Na+ ions are continuously pumped out of the cell, maintaining a concentration gradient, whereas in equilibrium, Na+ ions would be equally distributed across the membrane, requiring no energy expenditure.
B) In steady state, Na+ ions are equally distributed inside and outside the cell, while in equilibrium, Na+ ions are pumped out to maintain a higher concentration outside the cell.
C) Steady state refers to the equal distribution of Na+ ions across the membrane without energy use, while equilibrium requires energy to maintain different concentrations of Na+ inside and outside the cell.
D) In steady state, the movement of Na+ ions across the membrane is balanced by their passive diffusion, whereas in equilibrium, the concentration of Na+ ions is kept constant only by active transport.
A) In steady state, Na+ ions are continuously pumped out of the cell, maintaining a concentration gradient, whereas in equilibrium, Na+ ions would be equally distributed across the membrane, requiring no energy expenditure.
A cell biologist is studying the transport of ions across a cell membrane and considers a scenario where the electrochemical driving force = -100 mV and the chemical driving force = -94 mV. What would be the expected effect on ion movement across the membrane?
A) The ion will move against its concentration gradient, driven primarily by the electrical potential difference across the membrane.
B) The ion will move down its concentration gradient, driven by the chemical driving force overpowering the electrical driving force.
C) The ion will remain stationary, as the electrochemical and chemical driving forces will cancel each other out.
D) The ion will move randomly across the membrane, with its direction determined equally by both electrical and chemical force
A) The ion will move against its concentration gradient, driven primarily by the electrical potential difference across the membrane.
A 58-year-old man is brought to the emergency department after suddenly losing movement and sensation in his right arm and the right side of his face. Where would imaging reveal an occlusion?
A) Left middle cerebral artery
B) Right middle cerebral artery
C) Left anterior cerebral artery
D) Right anterior cerebral artery
A) Left middle cerebral artery
A patient presents with weakness and spasticity in the right side of the body following a stroke. Imaging reveals a lesion located above the medullary pyramids in the left corticospinal tract. Which of the following is the most likely effect of this lesion?
A) Flaccid paralysis on the left side of the body, affecting both upper and lower limbs.
B) Spastic paralysis on the left side of the body, with hyperreflexia and increased muscle tone.
C) Spastic paralysis on the right side of the body, with hyperreflexia and increased muscle tone.
D) Loss of fine motor control in the right hand, with no other significant motor deficits.
C) Spastic paralysis on the right side of the body, with hyperreflexia and increased muscle tone.
A neuroscientist is investigating the mechanisms by which neurotransmitters are cleared from the synaptic cleft to terminate synaptic transmission. The study focuses on the role of transporter proteins in this process. Which of the following best describes the process by which neurotransmitter reuptake is achieved, and its significance in synaptic transmission?
A) Neurotransmitters are passively diffused across the presynaptic membrane following a concentration gradient, leading to their accumulation in the cytoplasm of the presynaptic neuron.
B) Neurotransmitters are enzymatically degraded within the synaptic cleft, and the resulting metabolites are selectively reabsorbed by the presynaptic neuron via endocytosis.
C) Neurotransmitters are actively transported against their concentration gradient into the presynaptic neuron by specialized transporter proteins, allowing the neuron to rapidly recycle or degrade the neurotransmitter.
D) Neurotransmitters bind to auto-receptors on the presynaptic membrane, triggering endocytosis of the neurotransmitter-receptor complex, which is then transported back into the neuron.
C) Neurotransmitters are actively transported against their concentration gradient into the presynaptic neuron by specialized transporter proteins, allowing the neuron to rapidly recycle or degrade the neurotransmitter.
Which of the following correctly distinguishes between the functions of intrafusal and extrafusal muscle fibers?
A) Intrafusal fibers are responsible for generating the force of muscle contraction, while extrafusal fibers detect changes in muscle length and tension.
B) Intrafusal fibers are found within the muscle spindles and detect changes in muscle length, while extrafusal fibers are responsible for generating the force of muscle contraction.
C) Both intrafusal and extrafusal fibers generate force during muscle contraction, but intrafusal fibers are more involved in fine motor control.
D) Extrafusal fibers are located within muscle spindles and detect stretch, while intrafusal fibers are responsible for force generation.
B) Intrafusal fibers are found within the muscle spindles and detect changes in muscle length, while extrafusal fibers are responsible for generating the force of muscle contraction.