Physiology MCQ 1 - (Single Best Type) With answers for Undergraduates and Post graduates



1      Fick’s law of diffusion is dependent on all EXCEPT:

a)    thickness of membrane barrier
b)    the solubility of the gas
c)    the molecular weight of the gas
d)    the posture of the subject
e)    the area of the membrane


2      The Law of La Place predicts the following EXCEPT:

a)    increased myocardial work in dilated cardiomyopathy
b)    the protection of capillaries against rupture
c)    the relationship between transmural tension and wall tension
d)    the pattern of intravesical pressure / volume curve
e)    the failure of alveoli to collapse in expiration


3      In the kidney:


a)    Glucose is removed from the urine by secondary active transport
b)    100% glucose is absorbed in the distal tubule
c)    the calculated renal threshold for glucose is lower than its actual value
d)    phlorizin enhances glucose binding to the sodium-glucose symport
e)    levo isoform of glucose is more efficiently transported by the sodium-glucose symport


4      With regards to the normal alveolus:


a)    surfactant is produced by type I pneumocytes
b)    alveolar size has little effect on surface tension
c)    surfactant is composed of hydrophilic molecules
d)    large alveoli have a tendency to collapse into smaller ones
e)    surrounding tissues exert a force preventing alveolar collapse


5      Increased baroreceptor discharge acts via the medulla to:


a)    increase heart rate
b)    increase stroke volume
c)    increase vessel diameter
d)    increase blood pressure
e)    increase renin secretion


6      Amino acids are derived from:


a)    creatinine
b)    neurotransmitters
c)    deamination
d)    ammonia
e)    transamination



7      In the coronary circulation:

a)    blood flow is maximal during systole
b)    45-50% of o2 is extracted
c)    lactate is a vasodilator
d)    b-adrenergic receptors mediate vasoconstriction
e)    the ostia of coronary arteries are shut during systole



8      On climbing Everest:

a)    erythropoietin secretion rises after 2-3 days
b)    nifedipine alleviates the symptoms of mountain sickness
c)    alveolar PCO2 levels rise
d)    PCO2 levels fall because of decreased oxygen content of the air
e)    Initially the O2Hb dissociation shifts to the left



9      A b nerve fibres:


a)    conduct touch and pressure impulses
b)    are unmyelinated
c)    have the largest diameter of all nerves
d)    have a slow conduction velocity
e)    conduct preganglionic impulses



10    All of the following ascending sensory pathways are located in the dorsal       column  EXCEPT:

a)    pain
b)    touch
c)    pressure
d)    vibration
e)    proprioception


11   Erythropoietin:


a)    acts to increase erythrocytes by cell division
b)    is principally inactivated by the spleen
c)    causes increase in erythrocytes in 24 hours
d)    is produced by adrenal gland
e)    production is inhibited by theophylline



12      Concerning the visual pathway:

a)   macular sparing occurs due to the arrangement of fibres in the optic tract
b)   Brodmann’s area is located in the temporal lobe
c)   the optic tracts end in the medial geniculate body
d)      the optic disc lies 3mm medial to and slightly above the posterior pole of the  globe
e)   the pituitary tumour often causes a homonymous hemianopia



13      During exercise:


a)      regional blood flow to the skin remains unchanged
b)      diastolic pressures tend to rise more than systolic pressure
c)      O2 consumption of skeletal muscle usually triples
d)      blood flow to the brain increases
e)      cardiac output increases 50-fold



14      Regarding body fluids:


a)      blood plasma is 15% of body weight
b)      intracellular fluid is 20% of body weight
c)      extracellular fluid volume is about 7L in a 70kg man
d)      interstitial fluid volume is 10.5L in a 70 kg man
e)      extracellular fluid is 40% of body weight



15      Regarding CO2 transport in blood:

a)      50% is in the dissolved form
b)      the Haldane effect is the fact that oxygenation of the blood increases its ability to carry CO2
c)      ionic dissociation of carbonic acid requires the presence of carbonic acid requires the presence of carbonic anhydrase to be a fast process.
d)      an increase in PCO2 in blood shifts the oxygen dissociation curve to the left
e)      approximately 30% of the venous-arterial difference is attributable to carbamino compounds


16      Regarding movement across cell membranes:

a)      exocytosis requires Na+ and energy
b)      insulin reuptake is by receptor-mediated endocytosis
c)      thyroid hormones reduce Na+K+ATPase pump activity
d)      acute transport of Na+ is rarely coupled with other substances
e)      Na+K+ATPase has a 1:1 coupling ratio



17      Within the sympathetic nervous system:

a)     sweat glands are supplied by B2  adrenergic receptors
b)     activation promotes gluconeogenesis
c)     bronchial glandular secretion is inhibited by B2 adrenergic receptor stimulation
d)     at the post ganglionic neuron, dopamine is responsible for the slow excitory post synaptic potential
e)     the preganglionic neurons leave the spinal cord in the ventral roots of the thoracolumbar spine


18   In the visual pathway:

a)     axons of the ganglion cells pass in the optic nerve and optic tract and end in the medial geniculate body of the thalamus
b)     fibres of each temporal hemiretina decussate in the optic chiasm
c)     the primary visual receiving area is Brodmann’s area 17
d)     the fovea contains no cones
e)     80% of input to the geniculate nucleus comes from the retina; the other input is from brain regions involved in feedback regulation


19   Fluid movement across the capillary wall is mediated mainly by:

a)     diffusion
b)     filtration
c)     endocytosis
d)     exocytosis
e)     ion channels


20    Regarding conduction in the heart:

a)     stimulation of right vagus inhibits the AV node
b)     the rate of discharge of the SAN is independent of temperature
c)     depolarisation of ventricular muscle starts on the right
d)     the speed of conduction is fastest in ventricular muscle
e)     the SA node and AV node exhibit the same speed of conduction


21    In calcium metabolism:


a)      gastrin, glucagon and secretin inhibit calcitonin secretion
b)      human calcitonin has a half life of 30 minutes
c)      calcitonin increases bone resorption
d)      PTH increases phosphate excretion in the urine
e)      1,25 dihydroxycholecalciferol decreases calcium absorption from the intestine


22    In the cardiac action potential:


a)      the resting membrane potential is -70mV
b)      the initial depolarisation is due to Ca2+ influx
c)      the plateau is due to IKI current
d)      the initial rapid repolarisation is due to Na+ channel closure
e)      CAMP decreases the active transport of Ca2+ to the sarcoplasmic reticulum thus accelerating relaxation and shortening the systolic


23   When a skeletal muscle contracts:

a)     calcium is released and this initiates contraction by binding Troponin T
b)     there is always a decrease in the length of the muscle
c)     it does so at a mechanical efficiency of 80%
d)     if it is an isotonic contraction, work is done
e)     the initiating event is acetylcholine binding to a G-protein linked receptor



24     The resting membrane potential:

a)      is +70mV in mammalian cardiac cells
b)      is responsible for only a small part of the energy requirement of a nerve
c)     is increased with increased external Na+ concentration
d)     implies that the inside of the cell is positive relative to the outside of the cell at rest
e)     is decreased by increasing the external K+ concentration



25  The alveolar gas equation:


a)    is also known as Bohr’s equation
b)    can be used to calculate anatomical dead space
c)    is influenced by diet
d)    is independent of PiO2
e)    requires sampling of gas to determine PACO2


26  Regarding renal tubular function:

a)    the clearance is less than the GFR if there is tubular secretion
b)    the active transport of Na+  occurs in all portions of the tubule
c)    proximal tubular reabsorbate is slightly hypotonic
d)    water can leak across tight junctions back into the tubule lumen
e)    30% of the filtered water enters the distal tubule



27   Smooth muscle contractions:

a)    are dependent on an intact nerve supply
b)    are a result of Ca2+ influx into the sarcoplasmic reticulum
c)    are smooth, discrete and fine in multi-unit smooth muscle
d)    are dependent on troponin
e)    are exaggerated in vitro when bathed in acelylcholine



28    Under physiological conditions most of circulating T4 is bound to:

a)     thyroxine binding prealbumin
b)     tramothynetim
c)     thyroxine-binding-globulin
d)     a2 globulin
e)     iodothyronine



29     Deficiency of b oxidation of fatty acids causes:


a)     pulmonary hypersecretion
b)     cardiomyopathy
c)     cirrhosis
d)     glomerulonephritis
e)     asthma



30     Regarding ventilation during exercise:


a)     pulmonary blood flow is increased from 5.5l/min to 55 l/min
b)     abrupt increase in ventilation at onset of exercise is due to increased respiratory rate
c)     increases in ventilation are proportionate to increase CO2 production
d)     CO2 excretion increases from 200ml/min to up to 8000ml/min
e)     there is a fall in blood pH during moderate exercise


31   Regarding reflexes:
             

a)    the reaction time for knee jerk is 0.1sec
b)    Jendrassik’s manoeuvre enhances knee jerk reflex
c)    spindles are located in muscle tendons
d)    afferent neurons carry the impulse to the muscle
e)    muscle spindle fibres are innervated by Ib type nerve


32   Temperature regulation:

a)      is integrated by cortical pathways
b)      systems result in hypothermia when the anterior hypothalmus is stimulated
c)      is mediated by endogenous pyrogens produced by monocytes, macrophages and Kupfter cells
d)      is deranged due to a mutation in the ryanodine receptor resulting in excess sodium released in malignant hyperthermia
e)      results in maintenance of a constant body temperature over 24 hours


33   A decrease in the length of ventricular cardiac muscle fibres can be brought about by:

a)     stronger atrial contraction
b)     increase in total blood volume
c)     increase venous tone
d)     standing
e)     increase in negative intrathoracic pressure


34    Resting blood flow to: 

a)      the liver equals 10% of cardiac output
b)      the heart equals 5% of cardiac output
c)      the brain equals 30% of cardiac output
d)      the skin equals 20% of cardiac output
e)      the skeletal muscle equals 40% of cardiac output


35    Regarding the renal handling of sodium:


a)     80% of the total filtered load of sodium is reabsorbed
b)     sodium is actively transported out of all parts of the renal tubule except the thin portion of the loop of Henle
c)     only a minority of sodium is actively transported  via the lateral intercellular spaces
d)     sodium transport is coupled to the movement of hydrogen and glucose but not to amino acids and phosphates
e)     the sodium / hydrogen exchanges in the proximal tubule extrudes one sodium for every hydrogen reabsorbed


36    Oxygen transport:


a)     the oxygen dissociation curve shifts left with a fall in pH
b)     more oxygen is supplied to tissues by a fall in 2,3 DPG levels
c)     2,3, DPG levels are increased by ascent to 7,000 metres
d)     2,3 DPG levels in stored blood increase
e)     oxygen dissociation curve shifts right with a drop in temperature


37    Regarding the cardiac cycle:

a)      stroke volume is normally approximately 50ml
b)      contraction of the left atrium precedes the right atrium
c)      the c wave of the jugular venous pressure corresponds to movement of the closed tricuspid valve.
d)      Left ventricular pressure immediately falls after opening of the aortic valve
e)      At rapid heart rates, systole shortens more than diastole


38   The following a true regarding lung volumes and compliance EXCEPT:
           
a)    compliance decreases in obstructive lung disease
b)    FEVl / FVC ratio increase in obstructive lung disease
c)    Functional residual capacity is the sum of ERV and RV
d)    The change in lung volume per unit change in airway pressure is the compliance of the lung
e)    Vital capacity is the largest amount of air that can be expired after a maximal inspiratory effort


39   Regarding synaptic transmission:

a)      opening of sodium channels excites the post synaptic neuron
b)      voltage gated sodium channels on the presynaptic neuron determine the quantity of neurotransmitter released
c)      neuropeptides are responsible for acute responses of the nervous system
d)      small molecule type transmitters do not stimulate the receptor activated enzymes
e)      cholinesterase is responsible for synthesis of acetylcholine.


40  The juxtaglomacular apparatus:

a)    contains macular densa cells in afferent and efferent arterioles
b)    contain juxtaglomerular  cells in afferent and arterioles only
c)    responds to a fall in arterial pressure by increasing renin secretion
d)    responds to an increase in sodium concentration by increasing GFR
e)    releases renin which is activated by angiotensin  I


41  With regards to ventilation:


a)    the autonomic control centre is located in the midbrain
b)    brainstem respiratory neurons only discharge during inspiration
c)    arterial PAO2 must be below 80mmHg to produce increased discharge from peripheral chemoreceptor
d)    medullary chemoreceptors monitor O2 concentration in the CSF
e)    in metabolic alkalosis ventilation is depressed



42  In metabolic alkalosis:

a)    a common cause is ingestion of aspirin
b)    respiratory compensation can fully restore pH to normal
c)    base excess is positive
d)    treatment with NaHCO3 restores pH to normal
e)    there is more renal excretion of H+ ions



43  Compensatory mechanisms in metabolic acidosis includes:


a)     a fall in pH
b)     decreased CO2 formation
c)     decreased minute volume
d)     an alkaline urine
e)     reduction in the PCO2 of alveolar gas



44  With respect to blood pressure control:

a)    the stress relaxation mechanism is one of the immediate responses
b)    angiotensin acts by increasing venous tone
c)    baroreceptors are activated over the course of hours
d)    the rennin angiotensin is vital in controlling the effect of excess Na+ intake
e)    renal responses precede capillary fluid shifts


45  Gastric emptying occurs:


a)    via sympathetic mediation
b)    when pressure increases in the body of the stomach
c)    due to stomach contractions lasting up to 30 seconds
d)    with no regurgitation of contents from the duodenum
e)    with the passage of mixed solid and liquid gastric contents into the duodenum


46    All of the following increase blood sugar level EXCEPT:

a)    T4
b)    cortisol
c)    growth hormone
d)    somatostatin
e)    lutenising hormonethe rennin angiotensin is vital in controlling the effect of excess Na+ intake
e)    renal responses precede capillary fluid shifts


45  Gastric emptying occurs:


a)    via sympathetic mediation
b)    when pressure increases in the body of the stomach
c)    due to stomach contractions lasting up to 30 seconds
d)    with no regurgitation of contents from the duodenum
e)    with the passage of mixed solid and liquid gastric contents into the duodenum


46    All of the following increase blood sugar level EXCEPT:

a)    T4
b)    cortisol
c)    growth hormone
d)    somatostatin

e)    lutenising hormone


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