quizzes Flashcards by Lynn Cu

Which of the following is a feature that distinguishes active transport from facilitated diffusion?

a. carrier molecules have specificity
b. presence of a transport maximum
c. requirement for a carrier molecule
d. requirement for metabolic energy
e. saturation of transport rate

d. requirement for metabolic energy

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Ion channels in cell membranes:

a. are nonspecific.
b. only allow ions to move from the intracellular fluid out of the cell.
c. only allow ions to move from the extracellular fluid into the cell.
d. are not affected by differences in electrical potential across the membrane.
e. may open in response to binding a ligand.

e. may open in response to binding a ligand.

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Pinocytosis is a method by which molecules can leave cells whose membranes are impermeable to the molecules.

a. True
b. False

b. false

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What will happen if a normal cell is placed in a hypotonic solution?

a. It will swell in size.
b. It will shrink in size.
c. The result can’t be predicted.
d. It will stay the same size.

a. It will swell in size.

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Which of the following would decrease the net flux of a penetrating solute into a cell?

a. increasing the permeability constant for that solute
b. increasing the area of the cell membrane
c. increasing the concentration of the solute in the extracellular fluid
d. decreasing the thickness of the membrane
e. decreasing the temperature

e. decreasing the temperature

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Which is TRUE regarding diffusion?

a. It is the principle mechanism by which molecules are moved over large distances in the body.
b. It results in net movement of molecules from regions of low concentration to regions of high concentration.
c. It requires energy in the form of ATP.
d. It requires integral membrane proteins to occur.
e. It depends upon the random motion of molecules.

e. It depends upon the random motion of molecules.

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The concentration of calcium in the cytosol of most resting cells is very much lower than the concentration of extracellular calcium.

a. True
b. False

a. true

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Which is true about mediated transport across cell membranes?

a. It is nonspecific; any transporter can transport any molecule across the cell membrane.
b. As the concentration gradient across a membrane increases, the transport rate always increases.
c. It refers to the movement of ions through protein channels.
d. It refers both to simple diffusion and to the active transport of molecules.
e. It is characterized by saturable carriers and a maximum velocity of transport.

e. It is characterized by saturable carriers and a maximum velocity of transport.

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Molecules increase their rate of diffusion as temperature increases.

a. True
b. False

a. true

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The final equilibrium state reached by a molecule that enters a cell by facilitated diffusion is the same as that for a molecule that enters the cell by diffusion.

a. True
b. False

a. true

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Which is true about mediated transport of substances across cell membranes?

a. There is no limit to how fast it can occur as the concentration gradient becomes larger.
b. It is always directly coupled to the splitting of ATP molecules.
c. It is the main mechanism for transporting hydrophobic molecules across membranes.
d. It always involves the movement of substances against a concentration gradient.
e. It involves a specific membrane protein that functions as a carrier molecule.

e. It involves a specific membrane protein that functions as a carrier molecule.

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The Na/K ATPase pump is an enzyme that phosphorylates itself.

a. True
b. False

a. True

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What will happen if a normal cell is placed in a hyperosmotic solution?

a. It will shrink in size.
b. It will stay the same size.
c. It will swell in size.
d. It may swell, shrink, or stay the same size, depending upon the concentration of penetrating and nonpenetrating solutes in the solution

d. It may swell, shrink, or stay the same size, depending upon the concentration of penetrating and nonpenetrating solutes in the solution.

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The component of the plasma membrane that acts as a selective barrier to diffusion of polar molecules is the integral proteins.

a. True
b. False

b. false

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Which is most directly responsible for the falling (repolarizing) phase of the action potential?

a. Voltage-gated Na+ channels are opened.
b. The Na+, K+ pump restores the ions to their original locations inside and outside of the cell.
c. The permeability to Na+ increases greatly.
d. ATPase destroys the energy supply that was maintaining the action potential at its peak.
e. The permeability to K+ increases greatly while that to Na+ decreases.

e. The permeability to K+ increases greatly while that to Na+ decreases.

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Which of these would occur if the concentration of ATP were depleted in a typical nerve cell?

a. Resting membrane potential would become more negative.
b. Resting membrane potential would become less negative.
c. The concentration gradient for Na+ would remain the same.
d. The resting membrane potential would eventually become positive inside with respect to outside.
e. There would be no change in the resting membrane potential.

b. Resting membrane potential would become less negative.

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Compartments A and B are separated by a membrane that is permeable to K+ but not to Na+ or Cl-. At time zero, a solution of KCl is poured into compartment A and an equally concentrated solution of NaCl is poured into compartment B. Which would be true once equilibrium is reached?

a. The concentration of Na+ in A will be higher than it was at time zero.
b. Diffusion of K+ from A to B will be greater than the diffusion of K+ from B to A.
c. There will be a potential difference across the membrane, with side B negative relative to side A.
d. The electrical and diffusion potentials for K+ will be equal in magnitude and opposite in direction.
e. The concentration of Cl- will be higher in B than it was at time zero.

d. The electrical and diffusion potentials for K+ will be equal in magnitude and opposite in direction.

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Acetylcholine is the main neurotransmitter released by:

a. preganglionic sympathetic neurons and cells of the adrenal medulla.
b. cells of the adrenal medulla and postganglionic parasympathetic neurons.
c. motor neurons and postganglionic sympathetic neurons.
d. preganglionic sympathetic neurons and postganglionic sympathetic neurons.
e. preganglionic sympathetic neurons and motor neurons.

e. preganglionic sympathetic neurons and motor neurons.

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An action potential in a neuronal membrane differs from a graded potential in that:

a. an action potential requires the opening of Ca2+ channels, whereas a graded potential does not.
b. an action potential is propagated without decrement, whereas a graded potential decrements with distance.
c. an action potential has a threshold, whereas a graded potential is an all-or-none phenomenon.
d. movement of Na+ and K+ across cell membranes mediate action potentials, while graded potentials do not involve movement of Na+ and K+.
e. action potentials vary in size with the size of a stimulus, while graded potentials do not.

b. an action potential is propagated without decrement, whereas a graded potential decrements with distance.

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Which of the following statements regarding neurotransmitters is TRUE?

a. Acetylcholine is broken down by enzymes present on postsynaptic cell membranes.
b. Acetylcholine that is released at synapses binds to adrenergic receptors in the postsynaptic cell membrane.
c. Catecholamines are the most abundant neurotransmitters in the central nervous system.
d. Opiate drugs, such as morphine, are antagonists of a class of neurotransmitters called endorphins.
e. Gamma-aminobutyric acid (GABA) is a major excitatory transmitter in the central nervous system.

a. Acetylcholine is broken down by enzymes present on postsynaptic cell membranes.

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A threshold stimulus applied to an excitable membrane is one that is just sufficient to:

a. trigger an excitatory postsynaptic potential.
b. cause a change in membrane potential.
c. trigger an action potential.
d. be conducted to the axon hillock.
e. depolarize a dendrite.

c. trigger an action potential.

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A presynaptic synapse:

a. is a synapse between an axon terminal and a dendrite that can be either excitatory or inhibitory.
b. is a synapse between an axon terminal and another axon’s terminal that can be either excitatory or inhibitory.
c. is any synapse onto a cell body, and they can be either stimulatory or inhibitory.
d. is a synapse between an axon terminal and a dendrite of the same cell, which is always inhibitory.
e. is a synapse between an axon terminal and another axon terminal that is always inhibitory

b. is a synapse between an axon terminal and another axon’s terminal that can be either excitatory or inhibitory.

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Drug X interferes with the action of norepinephrine at synapses. Which of the following mechanisms would not explain the effects of X?

a. X inhibits synthesis of norepinephrine at the axon terminal.
b. X inhibits norepinephrine release from the terminal.
c. X blocks reuptake of norepinephrine by the terminal.
d. X is an adrenergic receptor antagonist.
e. X stimulates the catabolism of norepinephrine.

c. X blocks reuptake of norepinephrine by the terminal.

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Which is TRUE about the initial segment of an axon?

a. Its threshold potential is more positive than that of the cell body and dendrites.
b. Its threshold potential is more negative than that of the cell body and dendrites.
c. Synapses far from the initial segment are more effective in influencing whether an action potential will be generated in the axon than are synapses close to the initial segment.
d. It is the region where neurotransmitter vesicles are docked and ready to be released by exocytosis.
e. It can only conduct graded potentials because it lacks voltage-gated Na+ channels.

b. Its threshold potential is more negative than that of the cell body and dendrites.

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Which of the following statements concerning the properties of action potentials is true? a. The rate of propagation of an action potential down an axon is independent of stimulus strength. b. Action potentials can undergo summation. c. A supra-threshold stimulus can stimulate an action potential during the absolute refractory period. d. Action potentials generally propagate from the axon terminal toward the initial segment. e. Increasing the size of a stimulus will increase the amplitude of an action potential.

a. The rate of propagation of an action potential down an axon is independent of stimulus strength.

Which of the following statements concerning the rate of action potential propagation is true? a. It is faster in small-diameter axons than in large-diameter axons. b. It is faster for a strong stimulus than for a weak one. c. It is faster in myelinated axons than in nonmyelinated axons. d. It is faster in the dendrites than in the axon. e. It occurs at the same rate in all axons, regardless of their diameter.

c. It is faster in myelinated axons than in nonmyelinated axons.

Which is one of the major inhibitory neurotransmittors in the CNS? a. Glutamate b. Dopamine c. Norepinephrine d. Gamma-aminobutyric acid (GABA) e. Beta-endorphin

d. Gamma-aminobutyric acid (GABA)

Spinal nerves are composed of the axons of both afferent and efferent neurons. a. True b. False

a. True

Although nerve cells in each cerebral hemisphere make connections with other cells in the same hemisphere, there is no crossover of information between the two hemispheres. a. True b. False

b. False

Alzheimer's disease is thought to involve primarily: a. loss of neurons that secrete or respond to catecholamines. b. loss of adrenergic neurons. c. loss of cholinergic neurons. d. loss of neurons that secrete or respond to dopamine. e. tumors that produce excess serotonin.

c. loss of cholinergic neurons.

The absolute refractory period of an excitable membrane roughly corresponds to the period when sodium channels are opening and inactivated. a. True b. False

a. True

The diffusion potential due to the concentration gradient for Na+ across a nerve cell membrane: a. favors its movement into the cell at the resting membrane potential. b. favors its movement out of the cell at the resting membrane potential. c. is equal and opposite to the electrical potential acting on Na+ at the resting membrane potential. d. Is in the same direction as the diffusion potential due to the concentration gradient for K+. e. favors movement of Na+ in the opposite direction as the electrical potential acting on Na+ at the resting membrane potential.

a. favors its movement into the cell at the resting membrane potential.

The Na+ and K+ channels that open during an action potential are voltage regulated, both opening in response to depolarization of the membrane. a. True b. False

a. True

Which is TRUE about receptor potentials? a. They are action potentials. b. They always trigger action potentials. c. They vary in magnitude with stimulus strength. d. They propagate without decrement. e. They generally occur at the axon hillock of afferent neurons.

c. They vary in magnitude with stimulus strength.

Which of the following statements regarding sensory systems is correct? a. All sensory information that reaches the brain can be experienced as a conscious sensation. b. Sensory information that leads to conscious awareness of the stimulus is called transduction. c. The term, "sensory unit," refers to a group of receptors that receive a particular stimulus and the afferent neuron associated with those receptors. d. The term "adequate stimulus" means that a stimulus is strong enough to be detected. e. Some sensory receptors are modifications of the peripheral endings of efferent neurons.

c. The term, "sensory unit," refers to a group of receptors that receive a particular stimulus and the afferent neuron associated with those receptors.

c. They vary in magnitude with stimulus strength.

A sensory unit is defined as a. all of the sensory receptors in a given area of the body that respond to the same stimulus. b. a single receptor ending and its afferent nerve fiber. c. a single afferent neuron and all its receptor endings. d. an afferent neuron and its postsynaptic interneurons. e. a reflex composed of an afferent neuron, an interneuron, and an efferent neuron.

c. a single afferent neuron and all its receptor endings.

What is the best definition of the "receptive field" of an afferent neuron? a. The number of interneurons with which the central process of the afferent neuron makes synaptic contact via divergence. b. The type of stimulus energy to which the afferent neuron is most sensitive. c. All of the interneuron cell bodies and dendrites onto which the afferent neuron synapses. d. The area of the cerebral cortex in which information from that afferent neuron is initially received. e. The area of the body that, when stimulated, leads to activity in that particular afferent neuron.

e. The area of the body that, when stimulated, leads to activity in that particular afferent neuron.

Which best describes the process of "adaptation" in sensory receptors? a. Information from sensory receptors reaches the cerebral cortex and the person becomes aware of it. b. Conversion of the energy of a stimulus into a pattern of electrical activity. c. Persistence of the sensation of a limb even after it has been severed from the body. d. A decrease in receptor sensitivity despite continuation of a stimulus. e. A depolarization of receptive membrane that increase in magnitude as the stimulus intensity increases.

d. A decrease in receptor sensitivity despite continuation of a stimulus.

Polymodal neurons are: a. afferent neurons. b. interneurons that receive synaptic input from different kinds of sensory units. c. part of specific ascending sensory pathways. d. interneurons that receive synaptic input from only one type of sensory unit. e. efferent neurons.

b. interneurons that receive synaptic input from different kinds of sensory units.

Which is an accurate description of the cortical association areas? a. They are all found in the parietal lobe of the cerebral cortex. b. They integrate multiple types of sensory information and are responsible for complex processing of sensory information. c. They are the cortical locations where primary sensory information first arrives from specific ascending pathways. d. They are found deep in the cerebrum, surrounding the thalamus. e. Their main input is sensory information arriving along neurons that project directly from the thalamus.

b. They integrate multiple types of sensory information and are responsible for complex processing of sensory information.

Which of the following is most important for the determination of stimulus type? a. the relative sensitivity of different receptors to different stimulus energies b. the presence of polymodal neurons in the sensory pathway c. the intensity of a stimulus d. the location on the body where a stimulus is applied e. propagation of a signal along a nonspecific ascending pathway

a. the relative sensitivity of different receptors to different stimulus energies

Which of these is one reason you can distinguish between a needle prick on the foot and an ice cube on the wrist? a. The ice cube stimulates a different class of receptors than the needle prick, even though both signals go to exactly the same location in the brain. b. The action potentials from the needle prick are inherently different from the impulse generated by the ice cube. c. The region of the brain to which one receptor pathway leads is different from the region to which the other pathway leads. d. The needle prick generates a stronger action potential in any one neuron than an ice cube does. e. The needle prick generates a higher frequency of action potentials than the ice cube does.

c. The region of the brain to which one receptor pathway leads is different from the region to which the other pathway leads.

Which of the following statements regarding the determination of stimulus intensity is true? a. Stronger intensity stimuli cause rapid adaptation, while weaker stimuli cause slower adaptation. b. The amplitude of action potentials increases with increasing stimulus intensity. c. The duration of receptor potentials decreases with increasing stimulus intensity. d. The frequency of action potentials increases with increasing stimulus intensity. e. The only means of detecting intensity changes is through recruitment of greater numbers of sensory units.

d. The frequency of action potentials increases with increasing stimulus intensity.

Which best describes lateral inhibition in the somatic sensory system? a. The frequency of action potentials along pathways from the site of a stimulus is increased by lateral inhibition. b. The precision of locating a stimulus is increased by inhibiting signaling along nearby, parallel pathways. c. The precision of locating a stimulus is enhanced by increasing the frequency of action potentials in nearby, parallel pathways. d. Stimuli of one particular modality in a region of the body block transmission of action potentials coding for other modalities generated in the same region of the body. e. Lateral inhibition reduces the contrast between the frequency of action potentials generated at the center of a stimulus and the frequency of action potentials in surrounding pathways.

b. The precision of locating a stimulus is increased by inhibiting signaling along nearby, parallel pathways.

A stimulus to which afferent neurons X, Y and Z are sensitive is applied in the middle of Y's receptive field. The same stimulus simultaneously activates receptors on the periphery of the receptive fields of X and Z. Which of the following is likely to be true? a. The receptor potential in neurons X and Z will be more depolarized than in neuron Y. b. It won't be possible to discriminate which neuron's receptive field was stimulated at its center. c. The frequency of action potentials in the afferent pathway from neuron Y will be increased by excitatory interneurons projecting from the afferent pathways from neurons X and Z. d. The frequency of action potentials in neuron Y will be greater than that in neurons X and Z. e. The receptor potentials in all three neurons will achieve the same, average value.

d. The frequency of action potentials in neuron Y will be greater than that in neurons X and Z.

Which of the following would NOT be categorized as a "somatic" sensation? a. pressure b. cold and warmth c. sound d. proprioception e. kinesthesia

c. sound

Which of the following statements regarding sensory pathways is correct? a. All somatic sensory information that reaches the cerebral cortex is first processed in the thalamus. b. Somatic sensory information from the left side of the body projects to the left side of the somatosensory cortex. c. All somatic sensory information travels together in a single tract in the spinal cord. d. Ascending pathways in the anterolateral column of the spinal cord carry information about fine touch discrimination. e. Ascending pathways in the dorsal column of the spinal cord carry information about pain from the back muscles.

a. All somatic sensory information that reaches the cerebral cortex is first processed in the thalamus.

Which of the following statements regarding pain pathways is FALSE? a. Substance P is an important neurotransmitter in specific pain pathways. b. Transmission of information in pain pathways may be inhibited by activation of neurons that synthesize opiate neurotransmitters. c. Synaptic activity in afferent neurons associated with pain receptors can be inhibited by axon-axon synapses with neurons from descending pathways. d. Afferents neurons that detect painful stimuli in the skin can converge onto common ascending pathways with neurons that detect painful stimuli in internal organs. e. Substance P is released by neurons descending from the brain, and it inhibits activation of ascending pain pathways.

e. Substance P is released by neurons descending from the brain, and it inhibits activation of ascending pain pathways.

Which of the following symptoms would a patient with a lesion (injury) that destroyed the right side of the spinal cord in the region of the neck be most likely to experience? a. loss of both pressure sense and pain in the right foot b. loss of both pressure sense and pain in the left foot c. loss of pressure sense in the right foot and pain in the left foot d. loss of pressure sense in the left foot and pain in the right foot

c. loss of pressure sense in the right foot and pain in the left foot

Accommodation for near vision requires: a. flattening of the lens. b. contraction of the ciliary muscles. c. activation of the sympathetic nervous system. d. increased rounding of the cornea. e. dilation of the pupil.

b. contraction of the ciliary muscles.

A person struggling with a stressful exam question might experience difficulty focusing her eyes because: a. she suddenly develops presbyopia. b. activation of her parasympathetic nerves causes sudden contraction of her ciliary muscles. c. activation of her sympathetic nerves causes sudden contraction of her ciliary muscles. d. activation of her parasympathetic nerves inhibits contraction of her ciliary muscles. e. activation of her sympathetic nerves inhibits contraction of her ciliary muscles.

e. activation of her sympathetic nerves inhibits contraction of her ciliary muscles

Which of the following statements with regard to vision is FALSE? a. Photoreceptors are neurons. b. There are two basic types of photoreceptors in the retina, rods and cones. c. There are normally four different photopigments in the retina. d. There are four different chromophore molecules in the retina. e. There are four different opsins in the retina.

d. There are four different chromophore molecules in the retina.

Which of the following statements about rods and cones in the retina is TRUE? a. Cones enable us to see in dim light; rods provide color vision. b. Rods and cones all have the same kind of opsin. c. Cones are found in highest density in the fovea; rods are more prevalent near the edges of the retina. d. Rods require brighter light to activate them than do cones. e. Rods provide higher visual acuity than do cones.

c. Cones are found in highest density in the fovea; rods are more prevalent near the edges of the retina.

Which of these occurs when light strikes photoreceptors? a. The chromophore retinal undergoes a change of shape. b. There is an increase in neurotransmitter release from photoreceptor cells. c. The photoreceptor cell membrane becomes depolarized. d. The concentration of cyclic GMP inside cells increases. e. The photoreceptor cells are stimulated and fire action potentials.

a. The chromophore retinal undergoes a change of shape.

The plasma membranes of rod and cone cells are: a. at their resting potential in the dark and depolarized in the light. b. at their resting potential in the dark and hyperpolarized in the light. c. depolarized in the dark and hyperpolarized in the light. d. hyperpolarized in the dark and at their resting potential in the light. e. hyperpolarized in the dark and depolarized in the light.

c. depolarized in the dark and hyperpolarized in the light.

Each of the following statements regarding vision is true. Which statement best explains why we cannot see colors in dim light? a. The human eye has three kinds of cone photoreceptors. b. There are six types of opponent color cells in the lateral geniculate nucleus. c. The human eye has only one kind of rod photoreceptor. d. All photoreceptors contain the same chromophore. e. Cone photoreceptors are concentrated in the fovea.

c. The human eye has only one kind of rod photoreceptor.

Vitamin A plays a critical role in night vision because: a. it is required for the synthesis of the retinal portion of rhodopsin. b. it is transformed into the opsins found in cone cells. c. it acts as the coenzyme required to degrade scotopsin in brightly lit circumstances. d. it catalyzes the mitotic generation of light-reflecting epithelial cells which support widely dispersed rod receptors. e. it deactivates the photopigment-transducing chemical pathways within cone cells.

a. it is required for the synthesis of the retinal portion of rhodopsin.

Which of these is most responsible for "light adaptation"--the process by which we only gradually become able to see objects in a brightly lit place after being in the dark? a. Cone receptors are very hyperpolarized in the dark, and they must be exposed to bright light for awhile before they will depolarize. b. Rhodopsin is quickly inactivated so rods become unresponsive, and the higher-acuity cones then become the main detectors of vision. c. Because rods are more sensitive to light than cones, they gradually become extremely activated in bright light. d. Cones and rods are stimulated equally, leading to difficulties in interpreting the sensory inputs to the brain e. Rhodopsin is not activated by colored light, and the lack of stimulation causes rods to gradually depolarize when we are exposed to bright light.

b. Rhodopsin is quickly inactivated so rods become unresponsive, and the higher-acuity cones then become the main detectors of vision.

In the visual pathway providing sensory action potentials to the brain, the first cells which are capable of initiating action potentials are: a. cone cells. b. rod cells. c. lateral geniculate cells. d. ganglion cells. e. bipolar cells.

d. ganglion cells.

Which of the following statements related to the "ON pathway" of the visual system is correct? a. Bipolar cells fire action potentials only when bright light strikes the photoreceptors linked to them b. Bipolar cells spontaneously depolarize in the absence of input from photoreceptor cells. c. Bipolar cells hyperpolarize in the absence of input from photoreceptor cells. d. Glutamate receptors on bipolar cells are excitatory. e. Only cones are associated with bipolar cells of the ON pathway, rods are not.

b. Bipolar cells spontaneously depolarize in the absence of input from photoreceptor cells.

Which of the following statements regarding hearing is TRUE? a. The pitch of sounds is conveyed by the intensity of the vibration of the oval window. b. Low-pitched tones selectively cause vibration of the basilar membrane at a point closer to the oval window than high-pitched tones do. c. Sound is amplified as it is conducted from the oval window to the tympanic membrane. d. Conduction deafness is a result of damage to the hair cells of the inner ear. e. The loudness of a sound is conveyed by the frequency of action potentials generated in the cochlear nerve.

e. The loudness of a sound is conveyed by the frequency of action potentials generated in the cochlear nerve.

The incus, malleus, and stapes of the middle ear a. serve to keep the pressure on the two sides of the tympanic membrane equal. b. are part of the vestibular apparatus. c. are in direct contact with both the tympanic membrane and the round window. d. serve to amplify the pressure of sound vibrations from the air in the outer ear to the fluid in the inner ear. e. are found inside the cochlear duct.

d. serve to amplify the pressure of sound vibrations from the air in the outer ear to the fluid in the inner ear.

The actual receptors for hearing are called: a. baroreceptors. b. nociceptors. c. hair cells. d. pacinian corpuscles. e. somatic receptors

c. hair cells.

The receptors for hearing are found on the: a. tympanic membrane. b. basilar membrane. c. stapes. d. oval window. e. scala vestibuli.

b. basilar membrane.

Distinguishing the pitch of sounds is possible because: a. different frequencies of sounds make the eardrum vibrate with different amplitudes. b. different frequencies of sounds stimulate different regions of the basilar membrane in the cochlear duct. c. different frequencies of sounds cause different kinds of action potentials in neurons in the auditory nerve. d. different frequencies of sounds cause different frequencies of action potentials in neurons in the auditory nerve. e. there are many different types of receptors for sound, each of which responds to a single frequency.

b. different frequencies of sounds stimulate different regions of the basilar membrane in the cochlear duct.

As the pitch of a sound gets higher, displacements of the basilar membrane: a. occur closer to the oval window. b. occur closer to the helicotrema. c. occur uniformly throughout the membrane. d. become greater in amplitude. e. become smaller in amplitude.

a. occur closer to the oval window.

Which of the following is not a function of the tensor tympani and stapedius muscles? a. maintaining the proper amount of "stretch" or tension in the membranes of the middle and inner ear associated with proper auditory acuity b. protection of the delicate inner ear from sudden intermittent loud sounds c. reflexive contraction when vocalizing to reduce the loudness of your own voice d. optimization of the state of the inner ear for hearing over certain frequency ranges

b. protection of the delicate inner ear from sudden intermittent loud sounds

Which of the following are classified as "mechanoreceptors?" a. cone cells in the eye b. taste buds on the tongue c. hair cells in the olfactory mucosa d. hair cells in the cochlea

d. hair cells in the cochlea

Where are receptors for the chemical senses located? a. in the organ of Corti and saccule b. in the cochlea and lateral geniculate nucleus c. in the skin and tendons d. in the tongue and nose e. in the fovea and semicircular canals

d. in the tongue and nose

Which is TRUE about olfactory receptors? a. They can discriminate only four primary chemicals - sweet, sour, salty, and bitter. b. When stimulated, their signaling pathway sends action potentials directly to the limbic system. c. They are unable to detect odorants without activation of taste buds. d. Only four different types of odorant receptor proteins are found in the plasma membrane of olfactory receptors. e. They are found in the floor of the nasal cavity and on the upper surface of the hard palate, which separates the mouth from the nose.

b. When stimulated, their signaling pathway sends action potentials directly to the limbic system

Which of the following correctly pairs a chemical with its associated taste modality? a. poisonous alkaloids, sour b. acids, bitter c. sugars, salty d. glutamate, umami e. lipids, sweet

d. glutamate, umami

Perceptions are derived from higher-order processing of sensory information. a. True b. False

a. True

c. The region of the brain to which one receptor pathway leads is different from the region to which the other pathway leads.

Which of the following statements regarding the precision of locating a somatic stimulus is FALSE? a. The precision is greater in areas of the body that have small, overlapping receptive fields than in areas with large, nonoverlapping receptive fields. b. The precision is greater in the lips and fingers than on the back. c. The precision is greater for the skin than for the internal organs. d. Lateral inhibition of parallel afferent pathways increases the precision of locating a stimulus. e. Convergence of afferent neurons onto common ascending pathways increases acuity.

e. Convergence of afferent neurons onto common ascending pathways increases acuity.

b. The precision of locating a stimulus is increased by inhibiting signaling along nearby, parallel pathways.

c. loss of pressure sense in the right foot and pain in the left foot

e. activation of her sympathetic nerves inhibits contraction of her ciliary muscles.

c. The human eye has only one kind of rod photoreceptor.

a. it is required for the synthesis of the retinal portion of rhodopsin.

b. Rhodopsin is quickly inactivated so rods become unresponsive, and the higher-acuity cones then become the main detectors of vision.

Recruitment of different types of motor units in a muscle is one means of varying the amount of tension generated in that muscle. a. True b. False

a. true

Skeletal muscles are made up of bundles of muscle fibers attached to bone by connective-tissue called tendons. a. True b. False

a. True

Which of the following statements regarding contraction of a skeletal-muscle fiber is TRUE? a. Thick filaments shorten when muscle cells contract. b. Some contractions occur without cross-bridge activation. c. Contracting muscle fibers do not always shorten. d. Contraction does not always require the occurrence of an action potential. e. Contraction only occurs following summation of action potentials from many motor neurons

c. Contracting muscle fibers do not always shorten.

What is the function of the transverse tubules in a skeletal-muscle fiber? a. They store the calcium ions that are the main source of activation for the cross-bridge cycle. b. They form the Z lines that mark the end of each sarcomere. c. They allow action potentials to propagate deep into the center of skeletal muscle cells. d. They manufacture and store ATP. e. They run in parallel with the myofibrils, and have abundant Ca2+-ATPase proteins for pumping Ca2+ back into the sarcoplasmic reticulum.

c. They allow action potentials to propagate deep into the center of skeletal muscle cells.

When the load on a skeletal muscle is less than the tension the muscle generates, a concentric isotonic contraction results. a. True b. False

a. True

The step of the cross-bridge cycle that immediately follows the attachment of ATP to the myosin head is referred to as the "powerstroke." a. True b. False

b False

Which is a TRUE statement about smooth muscle? a. Smooth muscle is striated. b. Smooth muscle does not have thick and thin filaments. c. Smooth muscle does not use troponin-tropomyosin to regulate cross-bridge activity. d. Changes in cytosolic calcium do not regulate cross-bridge activity in smooth muscle. e. The myosin in smooth muscle requires phosphorylation before it can bind to ATP.

c. Smooth muscle does not use troponin-tropomyosin to regulate cross-bridge activity.

Which of the following statements regarding the motor end plate of a skeletal-muscle fiber is TRUE? a. Muscarinic receptors in the end plate are activated by binding to acetylcholine. b. Temporal summation of multiple end plate potentials is required in order to trigger an action potential in the muscle-fiber membrane. c. Acetylcholinesterase in the end plate membrane catalyzes the breakdown of acetylcholine. d. Sympathetic nerve fibers terminate on skeletal muscle fibers at the motor end plate. e. The motor end-plate under the axon terminal contains a large number of voltage-gated Na+ channels.

c. Acetylcholinesterase in the end plate membrane catalyzes the breakdown of acetylcholine.

Which best describes a "myofibril?" a. It is a single skeletal-muscle cell. b. It is a cylindrical cellular organelle composed of myofilaments. c. It is a hollow membranous structure that stores calcium. d. It is composed of a single type of protein and forms cross-bridges. e. It is a fibrous junction between a muscle cell and a tendon

b. It is a cylindrical cellular organelle composed of myofilaments.

Neuronal stimulation of skeletal muscle is always excitatory, whereas neuronal stimulation of smooth muscle may be excitatory or inhibitory. a. True b. False

a. True

Which of the following statements regarding myosin in skeletal muscle is TRUE? a. Myosin cross-bridge heads contain two binding sites, one for actin and one for tropomyosin. b. Myosin is an ATPase. c. The rate of ATP hydrolysis by myosin is the same in all types of skeletal muscle. d. All of the myosin cross-bridge heads in a thick filament are oriented and rotate in the same direction. e. Troponin covers the binding site on myosin molecules until Ca2+ binds to troponin to remove it from its blocking position.

b. Myosin is an ATPase.

During isometric contraction of a skeletal-muscle fiber, tension increases but the fiber length stays the same. a. True b. False

a. True

Which dietary supplement is most likely to contribute to greater skeletal muscle ATP availability in the first few seconds of skeletal muscle contraction? a. fatty acids b. sports drinks with electrolytes and mineral spirits c. sugar d. protein e. creatine

e. creatine

The phenomenon of rigor mortis demonstrates that myosin can remain bound to actin in the absence of additional ATP, but the bond cannot then be broken. a. True b. False

a. True

Which of these occurs during an isometric contraction of a skeletal muscle? a. The I bands shorten and the A bands stay the same length. b. The thick and thin filaments slide past each other. c. Sarcomere length does not change. d. The A bands shorten and the I bands stay the same length. e. Cross-bridges lock onto actin, similar to what occurs in rigor mortis.

c. Sarcomere length does not change.

Which occurs FIRST as a result of ATP binding to myosin? a. cross-bridge heads are cocked into an "energized" state b. actin dissociates from from myosin c. Ca2+ is released from the sarcoplasmic reticulum d. actin binds to myosin e. cross-bridges rotate, sliding past the thin filament

b. actin dissociates from from myosin

In skeletal muscle cells, cross-bridge cycling will continue as long as the calcium concentration of the cytosol remains elevated. a. True b. False

a. True

In contracting skeletal muscle cells, thick and thin filaments always continuously slide past each other. a. True b. False

b. False

In isometric contractions, cross-bridges repeatedly bind to and detach from the same region of the thin filament, so the filaments do NOT slide past each other. When tropomyosin is removed from binding sites on actin, energized cross-bridges automatically bind to those sites. a. True b. False

a. True

How is the role of Ca2+ different in the activation of smooth and skeletal muscle cells? a. It activates contraction in smooth muscle by binding to calmodulin, while in skeletal muscle it activates by binding primarily to troponin. b. It activates contraction in smooth muscle by binding to troponin, while in skeletal muscle it activates by binding primarily to calmodulin. c. It activates contraction in smooth muscle by binding to calmodulin, while in skeletal muscle it activates by binding primarily to myosin. d. It activates contraction in smooth muscle by binding to myosin light-chain kinase, while in skeletal muscle it activates primarily by binding to a protein on the thin filament. e. It activates contraction in smooth muscle by binding to myosin, while in skeletal muscle it activates by binding primarily to calmodulin.

a. It activates contraction in smooth muscle by binding to calmodulin, while in skeletal muscle it activates by binding primarily to troponin.

Which correctly compares the state of cross-bridges in resting smooth and skeletal muscle fibers? a. Cross-bridge heads in both types have ADP and Pi attached and are energized in preparation for a power stroke. b. Cross-bridge heads in skeletal muscle have ADP and Pi attached and are energized in preparation for a power stroke, while in smooth muscle the cross-bridge heads must be phosphorylated by myosin light-chain kinase before they can become energized. c. Cross-bridge heads in both types of muscle are free to diffuse and contact the thin filament, but thin filament binding sites are not available in either type of muscle at rest. d. Cross-bridge heads in both types of muscles are energized in preparation for a power stroke, but in skeletal muscle the cross-bridges are not free to diffuse and contact the thin filament unless myosin light-chains are phosphorylated. e. Cross-bridge heads in smooth muscle have ADP and Pi attached and are energized in preparation for a power stroke, while in skeletal muscle the cross-bridge heads must be phosphorylated by myosin light-chain kinase before they can become energized.

a. Cross-bridge heads in both types have ADP and Pi attached and are energized in preparation for a power stroke.

Which correctly compares the role of ATP in smooth and skeletal muscle fiber contraction? a. The role of ATP is exactly the same in both the activation of cross-bridges and in cross-bridge cycling in both kinds of muscle. b. An extra ATP must be hydrolyzed to phosphorylate myosin light-chains and activate contraction in smooth muscle, but otherwise ATP plays the same role in the cross-bridge cycling in the two types of muscle. c. The termination of cross-bridge cycling in both smooth and skeletal muscle requires the removal of ATP from the cross-bridge binding site by the enzyme myosin light-chain phosphatase. d. ATP causes detachment of cross-bridges when it binds to the hydrolysis site of skeletal muscle cross-bridges, but it causes attachment of cross-bridges when it binds to the same site in smooth muscle. e. ATP hydrolysis causes a conformational change that energizes the cross-bridge heads in skeletal muscle, while that same conformational change is caused by the myosin light-chain kinase in smooth muscle.

b. An extra ATP must be hydrolyzed to phosphorylate myosin light-chains and activate contraction in smooth muscle, but otherwise ATP plays the same role in the cross-bridge cycling in the two types of muscle.

Contraction is initiated in both smooth muscle and skeletal muscle fibers when there is an increase in Ca2+ in the cytosol. a. True b. False

a. True

When both smooth and skeletal muscles undergo shortening contractions, thin (actin) filaments slide past the thick (myosin) filaments. a. True b. False

a. True

Which statement(s) are true about the parasympathetic system? a. Post-ganglionic neurons are longer than pre-ganglionic neurons. b. Acetylcholine is released at both the pre-ganglionic and the post-ganglionic neuron. c. Contains both nicotinic and muscarinic receptors. d. Contains receptors stimulated by isoproterenol. e. Pre-ganglionic fibers originate in the thoracic and lumbar portions of the spine

b. Acetylcholine is released at both the pre-ganglionic and the post-ganglionic neuron. c. Contains both nicotinic and muscarinic receptors.

The ANS has effects on the heart and other tissues in body with fight/flight or rest/digest responses from the Sympathetic and Parasympathetic divisions, respectively, and is under voluntary control. a. True b. False

b. False "and is under voluntary control" makes the statement false, whereas the removal of that phrase makes the statement true.

Which of the following mechanism(s) is/are involved with parasympathetic signaling in the heart? a. G-Protein is activated, converting GDP to GTP which then influences the opening of Potassium channels b. G-Protein is activated, converting GDP to GTP, and closing the Calcium channels, preventing a depolarization c. G-Protein is activated, then an Adenylyl Cyclase causes an increase of intracellular cAMP leading to a phosphorylation cascade to open the Potassium channels d. G-Protein is activated, then Adenylyl Cyclase causes an increase of intracellular cAMP leading to a phosphorylation cascade to open Chlorine channels which then cause a hyperpolarization

a. G-Protein is activated, converting GDP to GTP which then influences the opening of Potassium channels

Which of the following is NOT characteristic of the sympathetic division of the ANS? a. Preganglionic neurons release acetylcholine at synapses with postganglionic neurons. b. Postganglionic neuron cell bodies are located in the collateral chain ganglia (sympathetic trunk). c. Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissue(s). d. Postganglionic neurons release norepinephrine at their neuroeffector junctions.

c. Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissue(s).

Drug X inhibits the action of norepinephrine at synapses. Which of the following mechanisms would not explain the effects of X? a. X inhibits norepinephrine release from the terminal. b. X stimulates the catabolism of norepinephrine. c. X is an adrenergic receptor antagonist. d. X inhibits synthesis of norepinephrine at the axon terminal. e. X blocks reuptake of norepinephrine by the terminal.

e. X blocks reuptake of norepinephrine by the terminal.

The portion of the peripheral nervous system that is composed of nerve fibers that innervate skeletal muscle is called the: a. parasympathetic nervous system. b. sympathetic nervous system. c. somatic motor nervous system. d. autonomic nervous system. e. afferent nervous system.

c. somatic motor nervous system.

Which of the following statements about acetylcholine is correct? a. Acetylcholine binds to nicotinic and muscarinic receptors. b. Acetylcholine binds to adrenergic receptors. c. Acetylcholine synthesis is catalyzed by acetylcholinesterase d. Acetylcholine is the neurotransmitter released by most sympathetic postganglionic neurons.

a. Acetylcholine binds to nicotinic and muscarinic receptors.

Which of the following substances would be contained in plasma but not serum? a. Plasminogen b. Fibrin c. Thrombin d. Fibrinogen e. Plasmin

d. Fibrinogen

Which of the following are true of Plasma a. Contains Electrolytes: Na, Cl, Mg, K, etc b. Contains proteins such as albumin, globulin, and fibrinogen c. Is considered the "Hematocrit" portion of blood d. Contains gases such as O2, CO2, and N2 e. Contains White Blood Cells (WBC's)

a. Contains Electrolytes: Na, Cl, Mg, K, etc b. Contains proteins such as albumin, globulin, and fibrinogen d. Contains gases such as O2, CO2, and N2

Unlike veins in systemic circulation, pulmonary veins return __________ to the heart. a. None of the above b. Deoxygenated blood c. Oxygenated blood d. CO2 rich blood

c. Oxygenated blood

Which of the following describes the Extrinsic Pathway of clot formation a. Blood makes contact with foreign surface such as collagen, glass, plastic, etc. (anything that is not the interior of blood vessels) b. Tissue damage and release of thromboplastin c. Drugs such as Heparin, Ca Chelators, and Warfarin can amplify the process of clotting d. Release of Tissue Plasminogen Activator, or TPA

b. Tissue damage and release of thromboplastin

Which of the following is an accurate statement a. Vitamin K is essential for synthesis of clotting factors b. Plasminogen is converted to Plasmin during a process called Fibrinolysis by TPA c. Plasma is the fluid part of blood after clotting has occured d. Drugs such as Heparin, Ca Chelators, Warfarin, and Cummadin are antagonists of clotting and are otherwise known as anticoagulants e. Serum is the fluid part of blood after clotting has occurred

a. Vitamin K is essential for synthesis of clotting factors b. Plasminogen is converted to Plasmin during a process called Fibrinolysis by TPA d. Drugs such as Heparin, Ca Chelators, Warfarin, and Cummadin are antagonists of clotting and are otherwise known as anticoagulants e. Serum is the fluid part of blood after clotting has occurred

Which of the following allows electrical activity to propogate or spread through heart cells simultaneously by directly connecting neighboring cells? a. AV Node b. Gap Junctions c. If channels d. SA Node e. Bundle of His

b. Gap Junctions

Which of the following accurately describes the SA Node a. Is the origin of the Cardiac Impulse b. Requires innervation from both Parasympathetic and Sympathetic divisions as described by the Principle of Dual Innervation c. Is located in the wall of the Right Atrium d. Is located at the junction of the Atrium and ventricle e. Relays its signals directly to the AV node f. Involves spontaneous depolarization g. Has ion channels that open at -60mV and cause depolarization h. Is considered the ectopic pacemaker

a. Is the origin of the Cardiac Impulse c. Is located in the wall of the Right Atrium f. Involves spontaneous depolarization

Which of the following choices are accurate of the Cardiac Cycle during Isometric contraction? a. Atrial Depolarization b. Start of ventricular systole c. Start of atrial systole d. Isovolumetric Contraction e. Atrial diastole begins f. Ventricular Repolarization g. Closure of SL Valves h. Closure of AV Valves i. Opening of AV Valves j. Blood volume inside ventricles increases k. Blood volume inside ventricles decreases l. Blood Pressure in ventricles elevates

b. Start of ventricular systole d. Isovolumetric Contraction e. Atrial diastole begins h. Closure of AV Valves l. Blood Pressure in ventricles elevates

An increase in End Diastolic Volume is defined as a. an increase in preload to the heart b. a decrease in preload to the heart c. an increase in afterload to the heart d. a decrease in afterload to the heart

a. an increase in preload to the heart

Indicate which of the following events would have the largest effect on increasing vascular resistance a. increasing the length of the vessel by 4X b. increasing the diameter of the blood vessel by 2X c. a two-fold increase in the viscosity of the blood d. reducing the radius of the vessel by 2X

d. reducing the radius of the vessel by 2X

Which of the following class of drugs would best mimic the effects of the vagus on the heart? a. Nicotinic receptor antagonist b. Muscarinic receptor antagonist c. Muscarinic receptor agonist d. Nicotinic receptor agonist e. adrenergic receptor antagonist

c. Muscarinic receptor agonist

During exercise, cardiac output increases but pulmonary arterial pressure remains near resting of baseline values. In order for this to occur, total pulmonary vascular resistance must a. not change b. increase c. decrease d. not enough information if provided to predict the change of total pulmonary vascular resistance

c. decrease

Which structure is NOT part of the "anatomical dead space?" a. respiratory bronchiole b. bronchiole c. bronchus d. terminal bronchiole e. trachea

a. respiratory bronchiole

What is one function of the type II alveolar cells? a. phagocytizing bacteria and other foreign particles b. production of surfactant c. make up the majority of the epithelial wall of the alveoli d. lining the pleural space e. secretion of mucus

b. production of surfactant

Physiological dead space a. is equal to tidal volume minus anatomical dead space b. includes alveolar units with abnormally high V/Q ratios c. includes alveolar units with abnormally low V/Q ratios d. is the volume of air in the lung after a maximal inspiration e. is always less than anatomical dead space

b. includes alveolar units with abnormally high V/Q ratios

After expiration and before the next inspiration begins, which is TRUE about the pressures involved in respiration? a. Alveolar pressure is greater than atmospheric pressure. b. Intrapleural pressure is equal to atmospheric pressure. c. Alveolar pressure is equal to atmospheric pressure. d. Alveolar pressure is equal to intrapleural pressure. e. Alveolar pressure is less than atmospheric pressure.

c. Alveolar pressure is equal to atmospheric pressure.

Which of these occurs during inspiration? a. A decrease in alveolar volume causes an increase in alveolar pressure. b. An increase in alveolar volume causes a decrease in alveolar pressure. c. An increase in alveolar volume causes an increase in alveolar pressure. d. A decrease in alveolar volume causes a decrease in alveolar pressure. e. Alveolar pressure increases above atmospheric pressure.

b. An increase in alveolar volume causes a decrease in alveolar pressure

Which of the following occurs during expiration? a. An increase in alveolar volume causes a decrease in alveolar pressure. b. Alveolar pressure falls below atmospheric pressure. c. Alveolar pressure rises above atmospheric pressure. d. An increase in alveolar volume causes an increase in alveolar pressure. e. A decrease in alveolar volume causes a decrease in alveolar pressure.

c. Alveolar pressure rises above atmospheric pressure.

During the respiratory cycle, the alveolar pressure is never equal to the pressure in the atmosphere a outside the body. a. True b. False

b. False

During an unforced exhalation/expiration, which would NOT be true? a. alveolar pressure is greater than atmospheric pressure b. the diaphragm relaxes c. intrapleural pressure is greater than alveolar pressure d. intrapleural pressure becomes less negative e. lung volume decreases

c. intrapleural pressure is greater than alveolar pressure

Which of the following does NOT contribute to the interface or barrier between alveolar air and pulmonary capillary blood? a. Type I alveolar epithelial cell b. Type II alveolar epithelial cell c. pulmonary capillary endothelial cell d. layer of surfactant on the alveolar wall e. interstitial layer or fluid between alveolar epithelial cell and pulmonary capillary endothelium

b. Type II alveolar epithelial cell

A poison has led to the paralysis of both inspiratory and expiratory muscles. Which of the following class of drugs could include this poison? a. muscarinic receptor antagonist b. beta adrenergic receptor antagonist c. nicotinic receptor antagonist d. alpha adrenergic receptor antagonist

c. nicotinic receptor antagonist

Which of the following drugs, administered as an aerosol spray, would be most likely to help an infant with respiratory distress syndrome of the newborn? a. pulmonary surfactant b. a beta-adrenergic agonist c. a beta-adrenergic antagonist d. a muscarinic agonist e. histamine

a. pulmonary surfactant

Which of the following statements regarding pulmonary surfactant is TRUE? a. It increases the compliance of the lungs. b. It can only interact with other lipid molecules. c. It increases airway resistance. d. It is secreted by type I alveolar cells. e. It is secreted into the intrapleural space.

a. It increases the compliance of the lungs.

Which of these causes inhalation/inspiration? a. flattening (downward movement) of the diaphragm b. contraction of the abdominal muscles c. alveolar pressure increasing above atmospheric pressure d. increase in the curvature (upward movement) of the diaphragm e. movement of the ribs closer together due to contraction of the internal intercostal muscles

a. flattening (downward movement) of the diaphragm

Which is normally TRUE about the intrapleural pressure? a. It is always the same as atmospheric pressure during a passive exhale. b. It is between +5 and +10 mm Hg above atmospheric pressure at functional residual capacity. c. It alternates between being less than, and greater than, atmospheric pressure. d. It is lower than alveolar pressure. e. During a passive exhale, it increases to a value above atmospheric pressure.

d. It is lower than alveolar pressure.

Which of the following drugs, administered as an aerosol spray, would be most likely to help a victim of an asthmatic attack? a. pulmonary surfactant b. a muscarinic agonist c. histamine d. a beta-2 adrenergic antagonist e. a beta-2 adrenergic agonist

e. a beta-2 adrenergic agonist

Regarding the partial pressures of O2 and CO2, which of the following statements is NOT true in a normal person at rest? a. The PCO2 in air is less than alveolar PCO2. b. Atmospheric PO2 is greater than alveolar PO2. c. The PO2 in systemic arteries is typically greater than the alveolar PO2. d. PCO2 in the pulmonary arteries is greater than pulmonary venous PCO2. e. PCO2 in the systemic veins is greater than systemic arterial PCO2.

c. The PO2 in systemic arteries is typically greater than the alveolar PO2.

What second messenger most directly causes calcium ions to be released from intracellular stores? a. Phospholipase C b. Phospholipase A c. Inositol Triphosphate d. Diacylglycerol e. Adenylyl Cyclase

c. Inositol Triphosphate

The process whereby repeated exposure to a hormone can cause a decrease in the number of receptors for that hormone is called a. Antagonism b. Inhibition c. Competition d. Saturation e. Down Regulation

e. Down Regulation

Cells can increase their responsiveness to an external chemical regulator by a. Mutating their extracellular receptors so that the affinity for the chemical regulator is reduced. b. Decreasing the number of their transmembrane receptor by endocytosis c. Increase the number of their transmembrane receptor by endocytosis d. Increasing the number of their transmembrane receptor by exocytosis e. Uncoupling their receptors from the second message generator.

d. Increasing the number of their transmembrane receptor by exocytosis

Epinephrine activates the cyclic AMP pathways in the liver cells. In this example, epinephrine is a ____ and cAMP is a ________. a. Enzyme, second messenger b. Ligand, receptor c. First messenger, hydrophobic hormone d. Second messenger, Ion channel e. First messenger, second messenger

e. First messenger, second messenger

With regard to the action of hormones and neurotransmitters on cellular receptors, which of these describe “amplification?” a. When the extracellular concentration of a chemical messenger reaches a very high level, it overwhelms transporter molecules and the chemical floods into the cell. b. Only hydrophilic first messenger molecules can activate second messenger molecules within the cell cytosol c. Some cellular receptors have such low affinity for chemical ligands that it can require a million or more molecule to activate them. d. A single first messenger molecules activates multiple second messenger molecules, each of which activates thousands of enzymes.

d. A single first messenger molecules activates multiple second messenger molecules, each of which activates thousands of enzymes.

Which of these is a lipid soluble messenger? a. Thyroid hormone b. Protein kinase c. Sodium d. Glucose e. cAMP

a. Thyroid hormone

Lipid-soluble hormones: - diffuse through the cell membrane - Within the nucleus, the receptor-hormone complex binds with a DNA molecule to produce a mRNA molecule.

The activated G protein stimulates ____ to produce large amounts of cAMP a. Phosphorylase b. ATPase c. cAMP phosphodiesterase d. Adenylyl cyclase e. Ligase

d. Adenylyl cyclase

Amplification of a second messenger cascade can take place at which level of a signal cascade? a. One activated receptor can activate numerous G-proteins. b. One activated G-protein can activate numerous effector enzymes. c. One active effector enzyme can catalyze numerous reactions. d. One activated protein kinase can allosterically modulate numerous proteins. e. All of the choices are correct. e. All of the choices are correct.

e. All of the choices are correct.

Methadone is a drug given to treat heroin addicts. It works by binding to the same receptors as heroin but with greater affinity, thereby preventing heroin from binding. This is an example of a. Down regulation. b. Signal transduction. c. Agonistic behavior. d. Up regulation. e. Competition.

e. Competition.

What is the definition of a prohormone? a. Hormones that bind to endocrine glands and stimulate the secretion of a second hormone. b. Hormones that bind to endocrine glands and inhibit the secretion of a second hormones. c. A longer protein or peptide that is cleaved into shorter ones, at least one of which is a protein hormone. d. Hormones that stimulate the expression of receptors for a second hormone, promoting their action. e. Steroid hormones that are inactivated by having hydroxyl-groups removed from their structure.

c. A longer protein or peptide that is cleaved into shorter ones, at least one of which is a protein hormone.

Which is a function of the gonadotropic hormones? a. Stimulating the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) b. Inhibiting the release of growth hormone c. Inhibiting the release of prolactin d. Inducing the secretion of steroid hormones by the gonads in both males and females e. Stimulating the release of gonadotropin-releasing hormone (GnRH)

d. Inducing the secretion of steroid hormones by the gonads in both males and females

Which is a characteristic of hydrophobic hormones? a. They mostly bind to receptor proteins in the surface membrane of target cells. b. They are generally polar molecules. c. They usually have very rapid effects on target cells. d. Their mechanism of action generally involves altering protein synthesis. e. They are highly soluble in blood plasma.

d. Their mechanism of action generally involves altering protein synthesis.

Which statement best describes the manner in which growth hormone stimulates cell proliferation? a. It directly stimulates cell division in most tissues. b. It stimulates the release of insulin-like growth factor I (IGF-1) from the liver. c. It stimulates metabolism. d. It stimulates the release of eicosanoids from lymphoid tissues. e. It stimulates sleep.

b. It stimulates the release of insulin-like growth factor I (IGF-1) from the liver.

A deficiency in dietary iodine can cause: a. Congenital hypothyroidism (cretinism). b. A slowing of mental functions. c. A low metabolic rate. d. A goiter. e. All of the choices are correct.

e. All of the choices are correct.

Which of the hormones listed below has the most profound direct effect to stimulate the increased resorption of bone when plasma Ca2+ levels decrease? a. Thyroxine b. Parathyroid hormone c. Calcitonin d. Cortisol e. Insulin

b. Parathyroid hormone

Peptide hormones are: a. Synthesized by the ribosomes of endocrine cells. b. Synthesized in the nucleus of endocrine cells. c. Synthesized out of the amino acid tryptophan. d. The least prevalent type of hormone in the body. e. Manufactured cooperatively by the mitochondria and smooth endoplasmic reticulum.

a. Synthesized by the ribosomes of endocrine cells.

Short-loop negative feedback occurs when hormones from the ______________ inhibit hormone secretion by the ______________. a. Hypothalamus; anterior pituitary b. Adrenal cortex; hypothalamus c. Anterior pituitary; hypothalamus d. Adrenal cortex; anterior pituitary e. Anterior pituitary; adrenal cortex

c. Anterior pituitary; hypothalamus

Which of the following acts to decrease blood glucose levels? a. Glucagon b. Insulin c. Growth hormone d. Epinephrine e. Cortisol

b. Insulin

When plasma glucose concentration increases, the secretion of insulin is ________ and the secretion of glucagon is ________. However, an increase in sympathetic activity will cause ________ secretion of insulin and ________ secretion of glucagon. a. Decreased; increased; increased; decreased b. increased; decreased; decreased; increased c. increased; decreased; increased; decreased d. increased; increased; decreased; increased e. decreased; decreased; increased; unchanged

b. increased; decreased; decreased; increased

Excess absorbed glucose is initially converted to triacylglycerides and very low density lipoprotein by: a. adipose cells. b. liver cells. c. intestinal mucosa cells. d. muscle cells. e. lymphoid cells.

b. liver cells.

Which of the following is NOT a symptom that is associated with untreated type 1 diabetes mellitus (insulin-dependent diabetes mellitus)? a. hypoglycemia b. metabolic acidosis c. dehydration d. glucosuria (glucose in urine) e. increased lipolysis

a. hypoglycemia

With regard to fat metabolism, insulin increases: a. the activity of lipoprotein lipase, which catabolizes triglycerides. b. the activity of hormone-sensitive lipase, which synthesizes triglycerides. c. the activity of hormone-sensitive lipase, which catabolizes triglycerides. d. the activity of lipoprotein lipase, which increases triglyceride synthesis. e. the export of fatty acids and mononglyceride from adipocytes.

d. the activity of lipoprotein lipase, which increases triglyceride synthesis.

If more calories are ingested in food than are expended by metabolism: a. a person will gain weight. b. a person will lose weight. c. a person will stay the same weight because the excess energy is destroyed. d. whether weight is gained or lost depends upon whether the calories are in the form of proteins, carbohydrates, or fat.

a. a person will gain weight.

Which is NOT stimulated by the hormone insulin? a. an increase in the number of glucose transporters in cell membranes b. an increase in amino acid uptake by cells c. an increase in glycogen synthesis d. an increase in triglyceride synthesis e. an increase in ketone synthesis

e. an increase in ketone synthesis

Which factor, when increased, increases metabolic rate to the greatest extent? a. skeletal muscle activity b. mental activity c. dietary caloric intake d. environmental temperature e. blood glucose levels

a. skeletal muscle activity

Which of the following statements regarding digestion and absorption of carbohydrates is true? a. Carbohydrate digestion begins in the stomach. b. Lactose intolerance results from an insufficiency of the enzyme, amylase. c. Digestible polysaccharides are broken down into the monosaccharides glucose, galactose and fructose, which can be absorbed. d. Sucrose is the main form of carbohydrate that can be absorbed by active transport across the intestinal epithelium. e. Cellulose from plants is a polymer of glucose that can be easily digested and absorbed by the human GI tract.

c. Digestible polysaccharides are broken down into the monosaccharides glucose, galactose and fructose, which can be absorbed.

Which of the following processes is NOT associated with gastrointestinal function? a. digestion b. filtration c. secretion d. motility e. absorption

b. filtration

What structure secretes the enzyme that breaks down starch to smaller carbohydrates? a. the esophagus b. pancreatic exocrine cells c. pancreatic duct cells d. the liver e. the large intestine

b. pancreatic exocrine cells

The primary kind of motility in the stomach during digestion of a meal is: a. peristalsis. b. segmentation. c. relaxation of the pyloric sphincter. d. mass movement. e. regurgitation.

a. peristalsis.

Constipation: a. is associated with symptoms caused by accumulation of toxins present in feces. b. is caused by failure to defecate at least once a day. c. may be prevented by ingestion of foods with a high proportion of cellulose and other indigestible carbohydrates. d. results in metabolic acidosis. e. occurs in people who are lactose intolerant when they drink milk.

c. may be prevented by ingestion of foods with a high proportion of cellulose and other indigestible carbohydrates.

Which of the following statements about pancreatic enzymes is FALSE? a. Trypsinogen is secreted in an inactive form. b. Pancreatic amylase digests carbohydrates. c. Pancreatic lipase digests fats. d. Except for trypsinogen, other proteolytic enzymes are secreted in active form. e. Trypsinogen is activated by enterokinase.

d. Except for trypsinogen, other proteolytic enzymes are secreted in active form.

Which correctly describes a major function of the stomach? a. the complete digestion of protein to amino acids b. maintaining an alkaline pH for the digestion of proteins c. absorption of saliva and chyme into the bloodstream d. lubricating food so it can be formed into a bolus e. storing ingested food and partially digesting macromolecules

e. storing ingested food and partially digesting macromolecules

Which of the following is secreted by the chief cells of the gastric mucosa? a. pepsinogen b. HCl c. intrinsic factor d. gastrin e. pepsin

a. pepsinogen

Which of the following statements regarding protein digestion and absorption is TRUE? a. Only the exocrine pancreas produces enzymes that can digest proteins. b. After absorption, the products of protein digestion are carried by blood directly to the liver. c. Pepsin digests protein mainly in the small intestine. d. The enzymes that digest protein are secreted in active form. e. Free amino acids are the only product of protein digestion that can be absorbed from the lumen into intestinal epithelial cells.

b. After absorption, the products of protein digestion are carried by blood directly to the liver

The main source of enzymes that cleave disaccharides into monosaccharides is: a. the pancreas. b. the liver. c. gastric secretory cells. d. the luminal membrane of epithelial cells in the small intestine. e. the salivary glands.

d. the luminal membrane of epithelial cells in the small intestine.

Which combination of substances would cause the greatest stimulation of gastric HCL secretion when applied to parietal cells? a. somatostatin, gastrin, and histamine b. acetylcholine, histamine, and somatostatin c. somatostatin and acetylcholine d. gastrin, histamine, and acetylcholine e. histamine and gastrin

d. gastrin, histamine, and acetylcholine

Which of the following breakfasts would likely remain in the stomach longest? a. toast, orange juice, and coffee b. fried eggs, bacon, and hash browns c. a bowl of cereal with skim milk d. a boiled egg, toast, and juice e. The type of meal has no effect on the rate of gastric emptying.

b. fried eggs, bacon, and hash browns

Which of the following pathways is activated during the cephalic phase of gastrointestinal control? a. sympathetic nerves to enteric nervous system b. secretion of cholecystokinin c. secretion of secretin d. parasympathetic nerves to enteric nervous system e. short reflexes between the small intestine and stomach

d. parasympathetic nerves to enteric nervous system

Which of the following statements regarding renal handling of Na+ is correct? a. Without vasopressin, the collecting duct is impermeable to Na+. b. Atrial natriuretic factor increases Na+ reabsorption. c. In the absence of aldosterone, Na+ will be secreted by the cortical collecting ducts. d. In the proximal tubule, Na+ is actively transported across the luminal membrane of the tubular epithelial cells. e. Na+ is actively reabsorbed in the ascending limb of the loop of Henle.

e. Na+ is actively reabsorbed in the ascending limb of the loop of Henle.

Which of the following best describes the process of renal secretion? a. Substances move from peritubular capillaries into the nephron lumen at some point after Bowman's capsule. b. Substances move from the collecting duct into the renal pelvis. c. Substances move from the glomerular capillaries into the nephron lumen at some point beyond Bowman's capsule. d. Substances move from the nephron lumen into the peritubular capillaries. e. Substances move from glomerular capillaries into Bowman's capsule.

a. Substances move from peritubular capillaries into the nephron lumen at some point after Bowman's capsule.

Which of the following best describes the renal process of filtration? a. Substances move from peritubular capillaries into the nephron lumen. b. Substances move by bulk flow from glomerular capillaries into Bowman's capsule. c. Substances move from Bowman's capsule into the nephron lumen. d. Substances move from glomerular capillaries into peritubular capillaries. e. Substances move from the nephron lumen into peritubular capillaries.

b. Substances move by bulk flow from glomerular capillaries into Bowman's capsule.

Which of the following best describes renal reabsorption? a. Substances move from the nephron lumen into peritubular capillaries. b. Substances move from peritubular capillaries into glomerular capillaries. c. Substances move from glomerular capillaries into Bowman's capsule. d. Substances move from peritubular capillaries into the nephron lumen. e. Substances move from the nephron lumen into glomerular capillaries.

a. Substances move from the nephron lumen into peritubular capillaries.

In which region of the nephron does the fractional reabsorption of water vary the most in response to variation in the state of hydration? a. the loop of Henle b. the distal convoluted tubule c. the collecting duct d. the proximal convoluted tubule e. the glomerulus

c. the collecting duct

What is the rate-limiting (regulated) step for stimulating the secretion of aldosterone? a. conversion of angiotensinogen to angiotensin I in the blood b. secretion of angiotensinogen by the liver c. secretion of angiotensin II by the kidney d. conversion of angiotensin I to angiotensin II in the blood e. secretion of ACTH by the anterior pituitary

a. conversion of angiotensinogen to angiotensin I in the blood

Which one of the following substances is LEAST dependent on the kidney for regulation of its plasma concentration? a. HPO4- b. glucose c. K+ d. Na+ e. water

b. glucose

Which of the following is least likely to be filtered into Bowman's capsule in a normal, healthy person? a. sodium b. plasma protein c. glucose d. bicarbonate ion e. urea

b. plasma protein

Which of the following most accurately describes the actions of aldosterone? a. Aldosterone increases Na+ reabsorption and K+ secretion in the proximal tubule. b. Aldosterone decreases Na+ reabsorption and K+ secretion in the cortical collecting ducts. c. Aldosterone increases Na+ reabsorption and K+ secretion in the cortical collecting ducts. d. Aldosterone increases Na+ secretion and K+ reabsorption in the proximal tubule. e. Aldosterone increases Na+ secretion and K+ reabsorption in the cortical collecting ducts.

c. Aldosterone increases Na+ reabsorption and K+ secretion in the cortical collecting ducts.

After the bladder is stretched, where does the neural integration of the reflex occur? a. in the bladder wall b. in the sacral region of the spinal cord c. in the hypothalamus d. in the pituitary gland e. in the cerebral cortex

b. in the sacral region of the spinal cord

Bladder smooth muscle contracts when it receives action potentials from which of the following? a. somatic motor neurons from the sacral spinal cord b. sympathetic neurons from the sacral spinal cord c. parasympathetic neurons from the sacral spinal cord d. somatic motor neurons from the cerebral cortex e. sympathetic neurons from the hypothalamus

c. parasympathetic neurons from the sacral spinal cord

When urination is desired, decreased action potentials along which of the following causes relaxation of the external urinary sphincter? a. ascending spinal pathways to the pons and cerebrum b. the parasympathetic neurons from the spinal cord to the urinary bladder c. somatic motor neurons d. neurons from the urinary bladder to the sacral region e. sympathetic neurons in the spinal cord

c. somatic motor neurons