5759666
Descripción
Test por Lawrence Kwan, actualizado hace más de 1 año
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Creado por Lawrence Kwan
hace más de 8 años
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Pregunta 1
Pregunta
Golgi tendon organs:
Respuesta
-
respond primarily to muscle length.
-
cause monosynaptic excitation of alpha motoneurons.
-
are rapidly adapting receptors.
-
are in series with extrafusal muscle fibres.
-
are in parallel with intrafusal muscle fibres.
Pregunta 2
Pregunta
Reflexes
Respuesta
-
must take less than 10ms otherwise they are not involuntary
-
require only an integrator and an effector.
-
can be used to keep a limb in position.
-
must involve a proprioceptive afferent such as a Golgi tendon afferent.
-
are not signalled to the cortex.
Pregunta 3
Pregunta
The traces below show action potential recordings from nine different peripheral afferent fibres. Which ONE of the following physical stimuli is most likely to have caused the observed pattern of activity?
Respuesta
-
The blunt end of a pencil pressed firmly against the skin.
-
The sharp edge of a knife pressed firmly against the skin.
-
An ice cube pressed gently against the skin.
-
A flat piece of plastic pressed gently against the skin.
-
A candle flame held near the skin.
Pregunta 4
Pregunta
Choose the CORRECT statement. The vestibular system:
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-
provides reflex information that does not go to the cortex.
-
uses hair cells to convert an electrical potential to mechanical energy.
-
uses the semicircular canals to detect linear acceleration.
-
would not generate any useful signals in a zero-gravity environment.
-
uses the utricle and saccule to provide information about static head position.
Pregunta 5
Pregunta
Which ONE of the following statements is CORRECT with regard to the
organisation of the spinal cord and peripheral nervous system?
Respuesta
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Dorsal root ganglia contain the soma of sensory neurons.
-
A dermatome is innervated from multiple levels of spinal nerves.
-
Ventral roots contain mainly afferent fibres.
-
The spinal cord has a core of white matter surrounded by grey matter.
-
Efferent fibres take information from the periphery to the central nervous system.
Pregunta 6
Pregunta
Shown in A and B are the action potentials generated in a single tactile afferent over 1s, under two different conditions. The alteration in response from A to B is due to a change in the applied stimulus. The stimulus change that best accounts for the response change from A to B is:
Respuesta
-
making the stimulus surface contact the skin with less force.
-
increasing the temperature of the stimulus surface that contacts the skin.
-
making the stimulus surface contact the skin for less time.
-
moving the stimulus surface more quickly across the skin.
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making the stimulus surface contact the skin over a larger area.
Pregunta 7
Pregunta
Inhibitory synapses from a GABA-ergic neuron:
Respuesta
-
play an important role in synaptic transmission at the vertebrate neuromuscular junction.
-
can prevent the postsynaptic neuron from reaching threshold.
-
depolarise the post-synaptic neuron membrane potential towards 0 mV.
-
cause IPSPs that do not interact with EPSPs in the same post-synaptic neuron.
-
are not found on neurons that also receive excitatory input.
Pregunta 8
Pregunta
Which ONE of the following statements about optical defects is CORRECT?
Respuesta
-
The prevalence of myopia is higher in the over 40 population.
-
Presbyopia is also called shortsightedness.
-
Myopia is corrected with a convex lens.
-
Hyperopia is usually not corrected in adolescent patients.
-
Presbyopia is corrected with a concave lens.
Pregunta 9
Pregunta
Choose the best option from the following table about spindle and Golgi tendon
organ afferents.
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 10
Pregunta
Which ONE of the following statements about motor pathways is CORRECT?
Respuesta
-
The extrapyramidal tracts synapse onto spinal motor neurons.
-
The extrapyramidal tracts are predominantly involved in control of limb muscles.
-
The corticospinal tract originates mainly in the basal ganglia.
-
The corticospinal tract carries afferent information.
-
The corticospinal tract crosses the midline.
Pregunta 11
Pregunta
Three neurons (designated N1, N2 and N3) synapse onto a common post-synaptic neuron. Simultaneous synaptic activity in these neurons has the following effects:
N1 and N2: post-synaptic action potential
N2: postsynaptic
action potential
N2 and N3: no post-synaptic action potential
Which of the following is the most likely conclusion?
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N1 is inhibitory, N2 is subthreshold excitatory, N3 is subthreshold excitatory.
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N1 is suprathreshold excitatory, N2 is subthreshold excitatory, N3 is inhibitory.
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N1 is subthreshold excitatory, N2 is suprathreshold excitatory, N3 is inhibitory.
-
N1 is subthreshold excitatory, N2 is subthreshold excitatory, N3 is inhibitory.
-
N1 is inhibitory, N2 is suprathreshold excitatory, N3 is subthreshold excitatory.
Pregunta 12
Pregunta
Which ONE of the following statements about cerebrospinal fluid is INCORRECT?
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It fills axons and the central canal of the spinal cord.
-
It freely exchanges with the brain interstitial fluid.
-
It is produced from blood at the choroid plexus.
-
It provides an appropriate chemical environment for the brain.
-
It enables the brain to float inside the skull.
Pregunta 13
Pregunta
Which ONE of the following statements is CORRECT with regard to sensory receptors and afferents? Sensory receptors and afferents characterised as “rapidly adapting” or “phasic”:
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-
can encode only the intensity of a stimulus.
-
only generate action potentials when the stimulus changes location.
-
generate action potentials continuously during a steady stimulus.
-
generate more action potentials during changes in stimulus intensity than during steady stimulation.
-
include the type of receptor used to encode joint angle.
Pregunta 14
Pregunta
A person with normal vision except for anomalous trichromacy (red-green colourblindness):
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-
sees yellow as blue.
-
has blurry vision.
-
sees blue as grey.
-
sees red and green as grey.
-
sees purple as grey.
Pregunta 15
Pregunta
In transducing mechanical energy into a neural signal, the cochlear hair cells:
Respuesta
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utilise ligand-gated channels near the apical border of the cell.
-
receive a chemical signal from the tectorial membrane.
-
utilise an influx of cations to depolarise the hair cell.
-
have the same response to a forwards deflection of the stereocilia as to a backwards deflection.
-
employ stereocilia that allow a single hair cell to combine the sound signals from the two ears.
Pregunta 16
Pregunta
During normal voluntary muscle contraction (alpha and gamma co-activation):
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extrafusal fibres provide most of the contractile force.
-
intrafusal muscle fibres shorten while extrafusal fibres do not.
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gamma motor neurons activate the alpha motor neurons.
-
extrafusal muscle fibres shorten while intrafusal fibres do not.
-
contraction of the intrafusal muscle fibres weakens the stretch reflex.
Pregunta 17
Pregunta
Which ONE of the following statements about cerebrospinal fluid (CSF) is CORRECT?
Respuesta
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CSF is made at the choroid plexus.
-
CSF contains the same white blood cell count as blood, but no red blood cells.
-
CSF is found both inside and outside the meninges.
-
CSF has a higher K+ concentration than Na+ concentration.
-
The volume of CSF in a normal individual is approximately the same as the volume of plasma.
Pregunta 18
Pregunta
With regard to the organisation of somatosensory cortex:
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The cortical representation of temperature sense in the right hand is located in the opposite hemisphere to the cortical representation of touch in the right hand.
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The cortical representation of the hand is found near that of the face.
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The cortical representation of the hip lies between the representations of the foot and knee.
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The cortical area allocated to touch for the wrist is larger than that allocated to touch for the thumb.
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The cortical representation of touch for the right hand is found in the right somatosensory cortex.
Pregunta 19
Pregunta
Which ONE of the following statements about the photoreceptors of the retina is CORRECT?
Respuesta
-
Both rods and cones are found in the centre of the visual field.
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There are three types of rod photoreceptors and one type of cone photoreceptor.
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There are more cones than rods in the retina.
-
In the peripheral retina, rods are more common than cones.
-
The highest density of photoreceptors in the eye is at the optic disc.
Pregunta 20
Pregunta
With regard to spinal motor neurons:
Respuesta
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A motor unit may be composed of more than one alpha motor neuron.
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A motor unit is composed of an alpha motor neuron and a single muscle fibre.
-
A single action potential in a single alpha motor neuron does not cause muscle contraction.
-
The activity of an alpha motor neuron can be influenced by descending cortical input.
-
Alpha motor neurons synapse onto spindle afferent neurons.
Pregunta 21
Pregunta
The traces below show action potential recordings from nine different peripheral afferent fibres. What was the likely movement of the stimulus relative to the finger?
Respuesta
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The stimulus was moved across the tip of the finger.
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The stimulus was moved along the finger from tip to base.
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No movement.
-
The stimulus was moved along the finger from base to tip.
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The stimulus was touched on the finger three times, first at the base, then at the middle and finally at the tip of the finger.
Pregunta 22
Pregunta
The blood-brain barrier:
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is produced by astrocytes and endothelial cells of the capillary wall.
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prevents all drugs from reaching the brain.
-
is permeable to both red blood cells and white blood cells.
-
is a semipermeable membrane that encases the brain and cerebrospinal fluid.
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is permeable to most small polar molecules.
Pregunta 23
Pregunta
Tactile sensory fibres with large receptive fields:
Respuesta
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do not have topographically-organised projections.
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innervate body regions with low receptor densities.
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have a large area of cortex dedicated to processing their input.
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permit precise localization of the site of a tactile stimulus.
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are found in body regions with small two- point discrimination thresholds.
Pregunta 24
Pregunta
With regard to image formation by the eye:
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the focal point of the eye lies between the cornea and the lens.
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myopia is a condition in which the image of a distant object is formed behind the retina.
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the retinal image is an upright image of the object.
-
the cornea has greater optical power than the lens.
-
the cornea and lens are concave lenses.
Pregunta 25
Pregunta
Choose the CORRECT statement about the retina.
Respuesta
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Increased light intensity causes increased transmitter release from photoreceptors.
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Stimulus colour is coded by the activity of rod photoreceptors.
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Rod photoreceptor
-
Rod photoreceptors outnumber cone photoreceptors throughout the retina except at the fovea.
-
Stimulus location is coded by the type of photoreceptor activated.
Pregunta 26
Pregunta
Which ONE of the following statements about the structure of the brain is CORRECT?
Respuesta
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The ventricles are formed by axons
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The corpus callosum is a grey matter structure.
-
Connections between cortical areas are made by white matter tracts.
-
The grey matter of spinal cord is organised as a thin sheet of neurons.
-
The layers of cortex run perpendicular to the cortical surface.
Pregunta 27
Pregunta
Choose the option that correctly assigns the roles of the outer, middle and inner ear.
Respuesta
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outer ear: sound transduction, iddle ear: impedance matching, inner ear: modify sound based on location of source transduction.
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outer ear: impedance matching, middle ear: sound transduction, inner ear: modify sound based on location of source.
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outer ear: modify sound based on location of source, middle ear: impedance matching, inner ear: sound transduction.
-
outer ear: modify sound based on location of source, middle ear: sound transduction, inner ear: impedance matching.
-
outer ear: impedance matching, middle ear: modify sound based on location of source, inner ear: sound transduction.
Pregunta 28
Pregunta
Which of the following sensory parameters are topographically organised in their primary sensory cortex?
Respuesta
-
A
-
B
-
C
-
D
-
E
Pregunta 29
Pregunta
In the myotatic reflex:
Respuesta
-
the 1A afferents increase their firing rate in response to increased muscle tension.
-
the extrafusal muscle fibres relax due to 1A activity.
-
the 1B afferents increase their firing rate in response to increased muscle length.
-
the intrafusal muscle fibres contract due to 1B activity.
-
the extrafusal muscle fibres contract due to 1A activity.
Pregunta 30
Pregunta
Which ONE of the following statements about the spinal cord is INCORRECT?
Respuesta
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A dermatome refers to the region of skin innervated by a single spinal nerve.
-
The spinal nerves have an organization where the sacral nerves tend to innervate the face, and the cervical nerves innervate the legs.
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The ventral horn of the spinal cord contains motor neurons.
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The spinal nerves may fuse and join on their way to innervate their target zone.
-
The spinal nerves are formed from the fusion of the dorsal and ventral root.
Pregunta 31
Pregunta
A person who is unable to see things to the left side of where their gaze is directed has probably suffered damage to:
Respuesta
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their left visual thalamus (lateral geniculate nucleus).
-
their right visual cortex (occipital lobe).
-
their left optic nerve after the optic chiasm.
-
their left eye.
-
their right optic nerve before the optic chiasm.
Pregunta 32
Pregunta
With regard to the vestibular senses:
Respuesta
-
The semicircular canals use small rocks to help detect inertia.
-
The semicircular canals can signal linear acceleration without significant adaptation.
-
The otolith organs can signal linear acceleration without significant adaptation.
-
The semicircular canals can signal the direction of gravitational acceleration.
-
The otolith organs can signal the direction of a steady velocity.
Pregunta 33
Pregunta
When preparing to reach down and pick up a bag, which brain area would be the final motor area to be activated before the movement begins?
Respuesta
-
cerebellum
-
supplementary motor area
-
primary motor cortex
-
pre-motor area
-
basal ganglia
Pregunta 34
Pregunta
The pitch of a pure tone:
Respuesta
-
is determined by the amplitude of the sound wave
-
is not one of the properties coded for in auditory cortex.
-
determines where the travelling wave in the basilar membrane has its peak.
-
is coded by the rate of firing of cochlear afferent fibres.
-
would be dramatically affected by a blockage in the middle ear due to infection.
Pregunta 35
Pregunta
When a neuron adapts to a stimulus, this means that it:
Respuesta
-
becomes more selective for the properties of that stimulus.
-
generates stronger action potentials.
-
becomes sensitised to the stimulus.
-
changes its morphology to accommodate the stimulus.
-
generates action potentials at a lower rate.
Pregunta 36
Pregunta
Which ONE of the following statements about the functional organization of the brain is CORRECT?
Respuesta
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The limbic system is a group of brain areas primarily related to motor control.
-
There is a specialised region of cortex for vision at the front of the brain.
-
The left cortical hemisphere generally controls the right side of the body.
-
Sensory systems are usually restricted to one level of the brain e.g. brain stem
-
The thalamus is a single nucleus with inputs from sensory and motor areas.
Pregunta 37
Pregunta
Which ONE of the following statements is CORRECT with regard to the skin pain system?
Respuesta
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Strong activation of tactile afferents will cause a sensation of pain.
-
The ipsilateral (same side) cortical hemisphere processes nociceptive inputs.
-
Nociceptive afferent fibres are slower to relay a signal to the spinal cord than the afferents for light touch on the fingers.
-
A person with their spinal cord severed at chest level would have paralysed legs but would still feel painful stimuli applied to their feet.
-
Nociceptive afferents synapse directly on alpha motor neurons to mediate the withdrawal reflex.
Pregunta 38
Pregunta
The volume reflex, in which heart rate and renal blood flow are increased following an increase in blood volume, is mediated primarily by:
Respuesta
-
atrial and vena cava baroreceptors
-
aortic baroreceptors
-
a combination of atrial and vena cava baroreceptors, aortic baroreceptors and carotid sinus baroreceptors
-
carotid sinus baroreceptors
-
peripheral chemoreceptors
Pregunta 39
Pregunta
The function of the papillary muscles and chordae tendinae is to:
Respuesta
-
Keep the AV valves from bulging into the atria during ventricular contraction.
-
Keep the AV valves from bulging into the aorta and pulmonary arteries during systole.
-
Hold the AV valves open during diastole.
-
Increase backflow into the ventricles during diastole.
-
Hold open the semilunar valves during systole.
Pregunta 40
Pregunta
During which phase of the cardiac cycle are all four heart valves open?
Respuesta
-
isovolumetric ventricular contraction
-
atrial systole
-
rapid and reduced filling
-
ventricular ejection
-
all four heart valves are normally never open simultaneously
Pregunta 41
Pregunta
If systemic blood pressure falls, the carotid baroreceptors would cause heart rate to ______ and peripheral ________.
Respuesta
-
Decrease, vasoconstriction
-
Decrease, vasodilation
-
Stay the same, vasoconstriction
-
Increase, vasodilation
-
Increase, vasoconstriction
Pregunta 42
Pregunta
The firing rate of aortic baroreceptors is increased by
Respuesta
-
increased blood oxygen concentration.
-
activation of receptors in the right atrium.
-
increased blood pressure.
-
decreased blood pressure.
-
decreased blood oxygen concentration.
Pregunta 43
Pregunta
The major mechanism controlling the diameter of arteries in the skin is:
Respuesta
-
accumulation of metabolic waste products
-
sympathetic nerve activity
-
extracellular K+ concentration
-
myogenic
-
extracellular CO concentration
Pregunta 44
Pregunta
Which ONE of the following would NOT result in an increase in the movement of fluid out of capillaries?
Respuesta
-
An increase in blood pressure within the capillary.
-
A decrease in colloid osmotic pressure of the plasma.
-
None of the above.
-
A decrease in interstitial fluid pressure.
-
A decrease in the osmotic pressure of the interstitial fluid.
Pregunta 45
Pregunta
According to the Starling Equation, which ONE of the following would NOT be a factor in the net filtration pressure controlling the movement of water across the capillary wall?
Respuesta
-
Hydrostatic (blood) pressure in the capillary.
-
The interstitial fluid pressure.
-
The number and size of the pores in the capillary wall.
-
The plasma protein concentration.
-
The concentration of Na in the interstitial fluid.
Pregunta 46
Pregunta
Which ONE of the following parameters, when increased, will cause an increase
in cardiac stroke volume?
Respuesta
-
afterload
-
end-diastolic volume (EDV)
-
end-systolic volume (ESV)
-
peripheral resistance
-
blood pressure
Pregunta 47
Pregunta
Unlike blood vessels, the lymphatic system:
Respuesta
-
reabsorbs protein and foreign particles from the interstitial fluid.
-
removes damaged erythrocytes from the circulation.
-
has a role in controlling blood pressure.
-
forms a filtrate which eventually becomes urine.
-
can generate local vasoactive substances.
Pregunta 48
Pregunta
The major mechanism controlling coronary artery diameter is:
Respuesta
-
accumulation of metabolic waste products.
-
sympathetic nerve activity.
-
extracellular CO concentration.
-
extracellular K concentration.
-
venular constriction.
Pregunta 49
Pregunta
Blood that leaves the right ventricle and later enters the left ventricle must have passed through which of the following valves?
Respuesta
-
Pulmonary and bicuspid/mitral valves.
-
Pulmonary valve only.
-
Bicuspid/Mitral and aortic valve
-
Aortic and Tricuspid valves.
-
Bicuspid/mitral valve only.
Pregunta 50
Pregunta
Which ONE of the following statements regarding blood vessels is INCORRECT?
Respuesta
-
Capillaries are the vessel type that have the greatest total surface area.
-
The pressure in venules would be less than the pressure in large veins.
-
The elastic nature of the walls of arteries allows them to act as a pressure reservoir.
-
Veins function as volume reservoirs due to their high compliance
-
The contractile activity of smooth muscle cells within arterioles is primarily involved in the control of organ blood flow.
Pregunta 51
Pregunta
According to Fick’s law, which ONE of the following would NOT be a factor in diffusion of a substance across the capillary wall?
Respuesta
-
The molecular weight of the substance
-
The concentration of the substance in the interstitial fluid
-
The total surface area of the capillary wall
-
Hydrostatic (blood) pressure in the capillary
-
The plasma concentration of the substance
Pregunta 52
Pregunta
The decrease in blood pressure is greatest across ______ because this is where ______ is highest.
Respuesta
-
capillaries, resistance
-
arterioles, resistance
-
capillaries, cross-sectional area
-
veins, cross-sectional area
-
aorta, cross-sectional area
Pregunta 53
Pregunta
A reflex increase in heart rate may be caused by:
Respuesta
-
an increase in right atrial pressure.
-
an increase in venous return.
-
a decrease in arterial blood pressure.
-
a decrease in peripheral resistance.
-
all of the above.
Pregunta 54
Pregunta
Which ONE of the following statements about an action potential generated from a non-pacemaker cardiac cell is INCORRECT?
Respuesta
-
The plateau phase of the action potential is associated with a prolonged increase in Ca2+ permeability.
-
The resting membrane potential depends to a great extent on the permeability of the cell membrane to K+.
-
Repolarisation occurs as a result of inactivation of K+ channels.
-
The refractory period in ventricular muscle corresponds approximately to the plateau phase of the action potential.
-
Depolarisation is initiated by rapid entry of Na+.
Pregunta 55
Pregunta
Cardiac stroke volume may be defined as
Respuesta
-
pre-load minus afterload
-
afterload minus pre-load
-
end-diastolic volume (EDV) minus end-systolic volume (ESV)
-
end-systolic volume (ESV) minus end-diastolic volume (EDV)
-
peak ejection pressure minus diastolic pressure
Pregunta 56
Pregunta
Which ONE choice indicates three events that occur at about the same time
during the cardiac cycle?
Respuesta
-
AV valve closure, second heart sound, ventricular diastole.
-
semilunar valve closure, first heart sound, ventricular diastole.
-
semilunar valve closure, second heart sound, ventricular systole.
-
AV valve closure, first heart sound, ventricular systole.
-
AV valve closure, first heart sound, ventricular diastole.
Pregunta 57
Pregunta
According to Poiseuille’s equation, reducing a blood vessel’s diameter by 20% would reduce blood flow in the vessel by (approximately):
Respuesta
-
40%
-
80%
-
60%
-
20%
-
50%
Pregunta 58
Pregunta
What is occurring during ventricular ejection?
Respuesta
-
The AV and semilunar valves are closed as ventricular pressure is increasing.
-
The AV valves are open and the semilunar valves are closed as ventricular pressure is increasing.
-
The AV valves are open and the semilunar valves are closed as blood is leaving the ventricles.
-
The AV valves are closed and the semilunar valves are open as blood is leaving the ventricles.
-
The AV and semilunar valves are open as blood is leaving the ventricles.
Pregunta 59
Pregunta
A patient absorbs 300ml/min of oxygen. The oxygen content of blood taken from the femoral artery = 18ml/100ml and blood taken from the pulmonary artery has an oxygen content of 13ml/100ml. If the patient has a heart rate of 60 beats/min, the patient’s stroke volume is:
Respuesta
-
100ml.
-
120ml.
-
80ml.
-
10ml.
-
12ml.
Pregunta 60
Pregunta
Which ONE of the following statements is INCORRECT? Increased sympathetic nervous system activity to the sinoatrial node:
Respuesta
-
decreases the slope of the spontaneous depolarisation of these action potentials.
-
results in a less negative membrane potential at the end of repolarisation.
-
allows threshold to be reached more quickly.
-
causes an increase in heart rate.
-
increases the frequency of action potentials generated.
Pregunta 61
Pregunta
Closure of the aortic valve is associated with all of the following except:
Respuesta
-
rapid filling of the left ventricle.
-
the second heart sound.
-
relaxation of the ventricle.
-
T-wave of the ECG.
-
dicrotic notch on the aortic pressure wave.
Pregunta 62
Pregunta
Myocardial contractility
Respuesta
-
is increased by adrenaline
-
is increased by parasympathetic stimulation
-
is decreased by sympathetic nerve stimulation
-
cannot be altered under any circumstance
-
cannot be altered by changes in heart rate
Pregunta 63
Pregunta
According to Poiseuille’s equation, blood flow in a vessel would be reduced by half when:
Respuesta
-
the pressure gradient along the length of vessel is doubled.
-
blood flow velocity is doubled.
-
blood viscosity is halved.
-
vessel diameter is halved.
-
vessel length is doubled.
Pregunta 64
Pregunta
An increase in myocardial contractility will result in:
Respuesta
-
decreased end-systolic volume and increased stroke volume.
-
increased end-systolic volume and increased stroke volume.
-
increased end-diastolic volume and increased stroke volume.
-
no change in end-systolic volume or stroke volume.
-
decreased end-diastolic volume and decreased stroke volume.
Pregunta 65
Pregunta
Key mechanisms in combating orthostatic or postural hypotension include:
Respuesta
-
reduced distensibility of leg veins compared to thoracic veins.
-
the baroreceptor reflex.
-
muscle pumps.
-
all of the above.
-
none of the above.
Pregunta 66
Pregunta
Blood flow velocity is slowest in ______ because this is where ______ is greatest.
Respuesta
-
veins, cross-sectional area
-
aorta, cross-sectional area
-
capillaries, resistance
-
arterioles, resistance
-
capillaries, cross-sectional area
Pregunta 67
Pregunta
Pre-load is equivalent to
Respuesta
-
Ventricular end-systolic volume (ESV)
-
Peak ejection pressure
-
Ventricular end-diastolic volume (EDV)
-
Stroke volume
-
Right atrial pressure
Pregunta 68
Pregunta
Which ONE of the following organs/tissues receives the greatest increase in systemic blood flow during exercise?
Respuesta
-
Muscle.
-
Heart.
-
Brain.
-
Kidneys.
-
Skin.
Pregunta 69
Pregunta
Which ONE of the following statements regarding blood vessels is INCORRECT?
Respuesta
-
Arterioles contain smooth muscle in their walls.
-
Capillaries contain smooth muscle in their walls.
-
Arteries contain large amounts of elastic tissue in their walls.
-
Arterioles are sometimes called resistance vessels.
-
Veins are sometimes called capacitance vessels.
Pregunta 70
Pregunta
Myogenic mechanisms involved in autoregulation of blood flow are activated by:
Respuesta
-
generation of local vasoactive substances.
-
the [K+] in surrounding tissue.
-
endothelium-derived vasoactive factors.
-
the [O2] in surrounding tissue.
-
altered intra-luminal blood pressure.
Pregunta 71
Pregunta
Stimulation of the heart by sympathetic nerves
Respuesta
-
results in inhibition the baroreceptor reflex
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results in activation of the baroreceptor reflex
-
causes tachycardia
-
causes bradycardia
-
has no effect on cardiac function
Pregunta 72
Pregunta
Compared to sinoatrial cells, ventricular contractile cells will have:
Respuesta
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A more negative resting membrane potential
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A smaller amplitude action potential
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A slower conduction velocity
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An action potential with a shorter duration
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A slower depolarisation during the action potential
Pregunta 73
Pregunta
Which ONE of the following statements about an action potential generated from a sinus nodal fibre is INCORRECT?
Respuesta
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The unstable baseline can be partly attributable to a progressive decrease in Ca2+ permeability.
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The sudden upstroke (depolarisation) is due to the opening of Ca2+ channels causing a rapid influx of Ca2+ into the cell.
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Repolarisation is in part due to activation of K+ channels.
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The unstable baseline can be partly attributable to a progressive spontaneous reduction in membrane permeability to K+.
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The resting membrane potential is about -60 mV.
Pregunta 74
Pregunta
Which ONE of the following is INCORRECT regarding the mechanism by which the substance moves across the wall of a capillary?
Respuesta
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Respiratory gases permeate rapidly, because they are lipid soluble.
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Net water transport depends upon net (hydraulic) filtration pressure.
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Oxygen permeation is more than 1000 times faster than glucose permeation.
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Glucose is carried across the wall by plasma filtration.
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Urea diffuses across the wall down its concentration gradient.
Pregunta 75
Pregunta
Which ONE of the following statements about the conduction system of the heart is INCORRECT?
Respuesta
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Purkinje fibres have the fastest rate of conduction of all parts of the conducting system.
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Electrical events can spread directly between atria and ventricles through gap junctions.
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The atrioventricular node has a slower inherent rate of discharge than the sinoatrial node.
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The Bundle of His receives impulses from the atrioventricular node.
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The sinoatrial node is the normal pacemaker of the heart.
Pregunta 76
Pregunta
Which ONE of the following is responsible for the rapid depolarization phase of an action potential within the pacemaker cells?
Respuesta
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An increase in PK+
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A decrease in PK+
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An increase in PCa2+
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An increase in PNa+
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A decrease in PNa+
Pregunta 77
Pregunta
In cardiac muscle, the action potential in the ventricles:
Respuesta
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is due to an increase in chloride permeability.
-
has an unstable resting membrane potential.
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is shorter than the action potential of a pacemaker cell.
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has a resting membrane potential of about -60mV.
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relies on an increase in calcium permeability.
Pregunta 78
Pregunta
Starling’s Law of the Heart means that when ventricular pre-load is increased, stroke volume will
Respuesta
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decrease momentarily, then increase over time
-
increase
-
stay the same
-
decrease
-
increase momentarily, then decrease over time
Pregunta 79
Pregunta
During the rapid ejection phase of the cardiac cycle, which ONE of the following statements is INCORRECT?
Respuesta
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The aortic pressure is rising.
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The mitral valve is closed.
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The ventricular pressure approaches its maximum
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The aortic valve is open.
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The ventricular volume is at its lowest.
Pregunta 80
Pregunta
The greatest proportion of blood volume is present within which ONE of the following vessel types?
Respuesta
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Pulmonary blood vessels
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Heart
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Systemic capillaries
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Systemic arteries and arterioles
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Systemic veins and venules
Pregunta 81
Pregunta
Stimulation of the heart by parasympathetic nerves
Respuesta
-
results in activation of the baroreceptor reflex
-
results in inhibition the baroreceptor reflex
-
causes tachycardia
-
causes bradycardia
-
has no effect on cardiac function
Pregunta 82
Pregunta
The repolarisation of pacemaker cells is due in part to:
Respuesta
-
a decrease in the permeability of sodium.
-
an increase in the permeability of calcium.
-
a decrease in the permeability of potassium.
-
an increase in the permeability of sodium.
-
an increase in the permeability of potassium.
Pregunta 83
Pregunta
Which ONE of the following is true of the ventricular filling phase of the cardiac cycle?
Respuesta
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Ventricular pressure is increasing.
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Ventricular pressure is greater than atrial pressure.
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Ventricular pressure is less than aortic pressure.
-
All valves in the heart are open.
-
Ventricular filling occurs during systole.
Pregunta 84
Pregunta
The major mechanism(s) controlling the diameter of arteries in the skeletal muscle is
Respuesta
-
myogenic mechanisms
-
extracellular K+ concentration
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accumulation of metabolic waste products
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extracellular CO2 concentration
-
all of the above
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