Class 7: Nervous System

Which of the following senses relies on chemoreceptors? I. Touch II. Taste III. Olfaction

- II and III only - both taste and smell rely on chemoreceptors. - the sense of touch relies primarily on mechanoreceptors, and somewhat on nociceptors (pain) and thermoreceptors (temperature), but not chemoreceptors.

Which of the following processes always result(s) in a negative membrane potential? I. Repolarization II. Depolarization III. Hyperpolarization

- I and III only - Item II is false: depolarization is defined as "the movement of membrane potential away from resting potential in the positive (less negative) direction". For example, a change in membrane potential from -70 mV to -60 mV is a depolarization. However, if the change to a less negative potential is enough to cause the voltage-gated sodium channels to open, then membrane potential can spike to positive values. Keep in mind that the question uses the word "always"; sometimes depolarization can lead to a negative potential, and sometimes to a positive potential

Hair cells used to detect motion are found in which of the following structures? I. the organ of Corti II. the skin III. the semicircular canals

- I and III only Items I and III are true: Both the organ of Corti and the semicircular canals contain hair cells with small "hairs" that project from the apical surface of the cell into the surrounding fluid. Movement of the fluid around the hair cells detects sound in the organ of Corti and a change in body orientation in the semicircular canals. Item II is incorrect: Hair in the skin is different; it is not made up of "hair cells" but is made up of dead epithelial cells.

Myelination facilitates in which of the following? I. Increasing action potential rate of travel II. Increasing action potential strength III. Restricting ion flow across the membrane

- I and III only - Item I is true: myelination results in significantly increased rates of action potential conductance along an axon - Item II is false: action potential "strength" (or size) does not change as it is an all-or-none process - Item III is true: myelination prevents ion flow across the membrane, effectively allowing the action potential to "jump" from one Node of Ranvier to the next (nodes are breaks in the myelin sheath

Blood pressure is affected by many factors. Which of the following would increase blood pressure? I. An increase in peripheral blood vessel diameter II. An increase in heart rate due to physical exertion III. An increase in blood volume due to aldosterone

- II and III only I. is false: an increase in vessel diameter would reduce peripheral resistant. Since peripheral resistant and blood pressure are directly proportional this would decrease the blood pressure. II. is true because cardiac output and blood pressure are directly proportional III. is true because if the volume of blood increases without increasing the container then the pressure inside the container must increase

Both the sympathetic and parasympathetic divisions of the ANS can affect the cardiovascular system. Which of the following statements regarding sympathetic activation is/are true? I. Activation causes the heart to contract II. Activation relaxes smooth muscle in blood vessels serving skeletal muscle III. Activation relaxes smooth muscle in blood vessels serving skin and digestive organs

- II only - Item I is false: The heart is autorhythmic and can generate its own contraction without input from the nervous system. However, activation of the sympathetic division can make the heart contract more frequently (i.e., increase the heart rate). - Item II is true: It is helpful to have increased blood flow to skeletal muscles during times of stress to provide adequate oxygen and nutrients to the working muscles. Relaxing the smooth muscle in the blood vessels serving the skeletal muscle would cause dilation of the vessels and increased blood flow. - Item III is false: during stress situations, blood is diverted from skin and digestive organs by constricting those vessels (i.e., contracting the smooth muscle).

Which of the following is/are a function of the lymphatic system? I. Recover excess tissue fluid and return it to the circulatory system II. Absorb and transport fats from the intestines III. Filter fluid to remove antigens and other potentially harmful substances

- all of them

ADH (antidiuretic hormone, also called vasopressin) causes increased water retention by the kidneys, allowing a more concentrated urine to be produced. Which of the following is/are true about ADH? I. It is released when blood pressure is low. II. It is made in the posterior pituitary gland. III. Its release is controlled by ADH-RH from the hypothalamus.

- only I - Item I is true: the release of ADH when blood pressure is low allows more water to be retained and urine to be concentrated (i.e., less water is eliminated in the urine). This water is returned to the bloodstream, increasing blood volume and subsequently, blood pressure - Item II is false: ADH is actually made in the hypothalamus, then transported to the posterior pituitary, where it is stored until release - Item III is false: the release of ADH is triggered by an action potential, not a releasing hormone (RH). Only the anterior pituitary hormones are controlled by releasing hormones

All of the following statements about oxygen transport and hemoglobin are true EXCEPT: A. 2,3-BPG, made by red blood cells in low-oxygen environments, increases hemoglobin's affinity for oxygen so that more O2 can be delivered to the tissues. B. Hemoglobin is almost fully saturated in the lungs and is less saturated in the tissues. C. The Bohr shift is triggered by exercise conditions (increased CO2, decreased pH, and increased temperature), and reduces hemoglobin's affinity for oxygen, facilitating oxygen delivery to the tissues. D. Fetal hemoglobin has an increased affinity for oxygen compared to adult hemoglobin so that it can "steal" oxygen from maternal hemoglobin.

A. 2,3-BPG, made by red blood cells in low-oxygen environments, increases hemoglobin's affinity for oxygen so that more O2 can be delivered to the tissues. - while it is true that 2.3-BPG is made in low O2environments, it decreases hemoglobin's affinity so that more oxygen can be delivered to the tissues. Hemoglobin with an increased O2 affinity would tend to hang on to its oxygen, which is the exact opposite of what is needed in low-oxygen environments

Which of the following neurotransmitters is most commonly used to conduct autonomic nervous system responses? A. Acetylcholine B. Serotonin C. GABA D. Norepinephrine

A. Acetylcholine

What impact do the hormones aldosterone and ADH have on the nephron? A. Aldosterone increases plasma osmolarity by increasing sodium reabsorption, and ADH increases water permeability in the distal tubule and collecting duct, allowing water reabsorption. B. Aldosterone increases plasma osmolarity by increasing potassium reabsorption, and ADH increases water permeability in the distal tubule and collecting duct, allowing water reabsorption. C. Aldosterone increases plasma osmolarity by increasing sodium reabsorption, and ADH increases water permeability in the distal tubule and collecting duct, allowing water to dilute the filtrate. D. Aldosterone decreases plasma osmolarity by increasing potassium reabsorption, and ADH increases water permeability in the distal tubule and collecting duct, allowing water to dilute the filtrate.

A. Aldosterone increases plasma osmolarity by increasing sodium reabsorption, and ADH increases water permeability in the distal tubule and collecting duct, allowing water reabsorption. - Antidiuretic hormone (ADH, or vasopressin) induces expression of water channels (aquaporins) on the cells that make up distal tubule and collecting duct. This makes these typically water-impermeable tubes now permeable to water.

Which of the following is NOT a function of antibodies? A. Destroy antigen directly B. Crosslink antigen C. Activate complement system D. Stimulate macrophages to destroy antigen

A. Destroy antigen directly - antibodies only bind to antigen and crosslink it to other antigen molecules to inactivate it, activate the complement system to destroy the pathogen that the antigen is a part of, or stimulate macrophages to ingest and destroy the antigen

A patient suffering from menopause experiences decreased levels of estrogen due to decreased ovarian production. Which of the following lab results would be expected? A. Increased FSH, increased GnRH B. Increased FSH, decreased GnRH C. Decreased LH, increased GnRH D. Decreased LH, decreased GnRH

A. Increased FSH, increased GnRH - with menopause, the ovaries begin to degenerate and fail to produce appropriate levels of estrogen. This decrease in estrogen impacts the hormone feedback loop to GnRH and FSH/LH; the lack of negative feedback by estrogen triggers an increase in GnRH (and subsequently FSH and LH) in an attempt to generate more estrogen

Which of the following would have the greatest impact on the resting membrane potential? A. Increasing membrane permeability to sodium B. Increasing membrane permeability to potassium C. Increasing extracellular calcium concentration D. Decreasing extracellular calcium concentration

A. Increasing membrane permeability to sodium - the resting membrane potential of a typical neuron is -70 mV - there is relatively little sodium permeability across the membrane under resting conditions and an increase would significantly depolarize the membrane (bringing it closer to sodium's equilibrium potential of +40 mV, choice A is correct). - an increase in potassium permeability may hyperpolarize the membrane, but this would have a less significant effect than an increase in sodium permeability

What type of receptor is represented by the hair cells of the ear? A. Mechanoreceptor B. Baroreceptor C. Nociceptor D. Chemoreceptor

A. Mechanoreceptor

Auditory transduction occurs inside the cochlea. How is the pitch of a sound determined? A. Pitch is determined by the location of maximal vibration along the basilar membrane. High pitched (high frequency) sounds vibrate the stiffer region of the basilar membrane near the oval window, while low pitched (low frequency) sounds vibrate the more flexible apex of the basilar membrane. B. Pitch is determined by the location of maximal vibration along the basilar membrane. High pitched (high frequency) sounds vibrate the more flexible apex of the basilar membrane, while low pitched (low frequency) sounds vibrate the stiffer region of the basilar membrane near the oval window. C. Pitch is determined by the amplitude of vibration; high pitched (high frequency) sounds produce large amplitude vibrations, which low pitched (low frequency) sounds produce smaller amplitude vibrations. D. Pitch is determined by the amplitude of vibration; high pitched (high frequency) sounds produce smaller amplitude vibrations, which low pitched (low frequency) sounds produce large amplitude vibrations.

A. Pitch is determined by the location of maximal vibration along the basilar membrane. High pitched (high frequency) sounds vibrate the stiffer region of the basilar membrane near the oval window, while low pitched (low frequency) sounds vibrate the more flexible apex of the basilar membrane. - pitch is determined by location, and loudness is determined by amplitude

Tetrodotoxin (TTX) is a potent neurotoxin that binds to and inhibits the action of voltage-gated sodium channels in neurons. Poisoning can be rapidly fatal, within 4-6 hours of ingestion. Which of the following is the most likely cause of death from TTX poisoning? A. Respiratory failure B. Cardiac arrest C. Dehydration from excessive vomiting D. Increased blood pH due to hypoventilation

A. Respiratory failure - vomiting may occur, but death due to dehydration would take a few days, not a few hours ("dehydration from excessive vomiting" is wrong), and while hypoventilation probably occurs (remember diaphragm contraction depends on neural stimulation), hypoventilation would lead to decreased blood pH, not increased

The cardiac muscle cell action potential is approximately 100 times longer than the neural action potential due to a long plateau phase. Which channel is responsible for the plateau in the cardiac action potential? A. Voltage-gated Ca2+ B. Fast voltage-gated Na+ C. Voltage-gated K+ D. Slow voltage-gated Na+

A. Voltage-gated Ca2+ - the plateau phase in the cardiac muscle cell action potential is due to the influx of calcium through voltage-gated Ca2+ channels. - fast Na+ channels are responsible for the initial depolarization - voltage-gated K+ channels are responsible for the repolarization - slow Na+ channels are not found in cardiac muscle cells

When the bladder is full, neurons in the sacral spinal cord notify the brainstem of the need to urinate. Inhibitory signals from the brain prevent urination until the time is judged appropriate; then the inhibition is removed and urination is allowed to proceed under the control of neurons in the sacral spinal cord. Cutting the thoracic spinal cord would most likely cause: A. automatic bladder, in which the entire bladder empties when it becomes full, whether the time is appropriate or not. B. inability to urinate. C. return of normal bladder function. D. stress incontinence, in which urine leaks from the bladder upon physical stress, as in climbing stairs.

A. automatic bladder, in which the entire bladder empties when it becomes full, whether the time is appropriate or not. - the brain is required for the inhibition of urination, not the actual urination itself, which is controlled by the sacral neurons. If the brain is removed from the picture by severing the spinal cord between the sacral neurons and the brain (the thoracic region), then urination would simply become automatic

Which of the following do peptide and steroid hormones have in common? A. They function on a similar timescale. B. Both bind to protein effectors. C. They are both synthesized at the rough endoplasmic reticulum. D. Both travel through the blood bound to a protein.

B. Both bind to protein effectors. - peptide hormones function on a much shorter time scale than steroid hormones and only peptide hormones are synthesized at the RER - Steroid hormones, because they are hydrophobic, travel through the blood bound to protein (generally albumin) while peptides generally do not require a carrier

Damage to which one of the following would be most likely to hinder the detection of high-frequency, but not mid-frequency sound by the ear? A. Outer ear B. Cochlea C. Auditory nerve D. Malleus, incus, or stapes

B. Cochlea Damage to the auditory nerve or to the auditory ossicles (malleus, incus, and stapes) would hinder the detection of all frequencies since the nerve would be unable to send impulses to the brain and the ossicles would be unable to transmit sound waves to the inner ear, and neither of these functions is pitch-specific. Damage to the outer ear would not hinder pitch-specificity at all. The cochlea is a large, curled structure in the inner ear, along which the basilar membrane is stretched. The basilar membrane supports the hair cells of the ear (the sound receptors), and vibrates in sound waves. However, since one end of the basilar membrane is considerably thicker than the other, maximum vibration of a particular area depends of the frequency of the wave stimulating the membrane. Damage to the cochlea is the most likely injury to hinder the detection of particular frequencies.

Depletion of extracellular calcium would have which of the following effects on synaptic transmission? A. Increased neurotransmitter release B. Decreased neurotransmitter release C. Increased EPSPs D. Increased IPSPs

B. Decreased neurotransmitter release - this decrease in neurotransmitter release would result in a decrease in either EPSPs (excitatory postsynaptic potentials) or IPSPs (inhibitory postsynaptic potentials), depending on the synapse in question

Nerve cells that control thermoregulation are concentrated in which portion of the brain? A. Cerebrum B. Hypothalamus C. Medulla D. Cerebellum

B. Hypothalamus - hypothalamus is a key regulator in many different processes, including food intake, blood pressure, and neuroendocrine control, as well as temperature regulation.

How do the photoreceptors of the eye respond to stimulation by light? A. Light closes Na+ channels, the cells become depolarized and the optic nerve is stimulated. B. Light closes Na+ channels, the cells become hyperpolarized and the optic nerve is stimulated. C. Light opens Na+ channels, the cells become hyperpolarized and the stimulation of the optic nerve stops. D. Light opens Na+ channels, the cells become depolarized and the stimulation of the optic nerve stops.

B. Light closes Na+ channels, the cells become hyperpolarized and the optic nerve is stimulated. - Stimulation by light causes Na+ channels in the photoreceptors to close. This causes the cells to hyperpolarize and to stop releasing an inhibitory neurotransmitter onto the bipolar cells. Removal of the inhibition causes the bipolar cells to fire action potentials, ultimately transmitted to the optic nerve.

Which of the following neurotransmitters is released by sympathetic neurons onto the heart? A. Acetylcholine B. Norepinephrine C. Epinephrine D. Serotonin

B. Norepinephrine - ACh is the primary neurotransmitter of the parasympathetic division - epinephrine is a hormone; its release into the blood is triggered by the sympathetic nervous system and it can stimulate similar receptors as norepinephrine - serotonin is a neurotransmitter used in the brain; it is not secreted by autonomic neurons

Which of the following would be an appropriate example of difference threshold? A. Recognizing a family member based on his/her pattern of walking without being able to see his/her face B. Picking up two cantaloupes one after the other to determine which is heavier since each costs the same C. No longer perceiving the sound of a television after being in a room with it for an extended period of time D. Creating a list of pros and cons to aid in decision making processes

B. Picking up two cantaloupes one after the other to determine which is heavier since each costs the same Difference threshold is the minimum difference needed between two stimuli to be able to detect that there is in fact a difference at least 50% of the time. The "weighing" of the cantaloupes best describes this, as perceiving a difference in their size would require them to be proportionally distinct in their mass. Adaptation stops us from perceiving a constant sound if exposed to it long enough and top-down processing allows us to make a specific connection or recognition based on prior experience. Decision making strategies are not part of the difference threshold.

The myelin sheath of many axons is produced by the: A. nerve cell body. B. Schwann cells. C. nodes of Ranvier. D. axon hillock.

B. Schwann cells. - the myelin sheath is not produced by the neuron it is associated with. Instead, it is produced by a different type of cell, the Schwann cell, that wraps around the axon to create layers of insulating myelin. (Note that this is only the case in the PNS. A different cell, an oligodendrocyte, is responsible for myelination in the CNS.)

Which of the following neurons could directly stimulate the relaxation of bronchial smooth muscle? A. Parasympathetic postganglionic neurons B. Sympathetic postganglionic neurons C. Sympathetic preganglionic neurons D. Somatic motor neurons

B. Sympathetic postganglionic neurons Relaxation of bronchial smooth muscle is an involuntary process that is triggered by activation of the sympathetic nervous system. Postganglionic neurons directly stimulate target tissues; preganglionic neurons stimulate postganglionic neurons.

Temporal summation relies upon which of the following? A. The rate of recovery must be more rapid than the excitation rate. B. The rate of excitation must be more rapid than the recovery rate. C. The synaptic inputs must be in close proximity to one another. D. The synaptic inputs may be distant, but must still be additive.

B. The rate of excitation must be more rapid than the recovery rate.

Shapes, patterns, and movement are perceived by the retina and a complex network of pattern-recognition circuits in the brain. Colors, however, are identified: A. by selective filtering of light in the retina. B. by the relative stimulation of cones in the retina, of which there are only three types with regard to color perception. C. by the activation of all cones, which is different for every different wavelength of light. D. by the relative stimulation of rods in the retina, of which there are only three types with regard to color perception.

B. by the relative stimulation of cones in the retina, of which there are only three types with regard to color perception. Cones transduce color for the brain, while rods respond to black and white images. There are only three types of cones, and they are specific for different wavelengths of light. There is no selective filtering of light in the retina.

The cell bodies of a somatic sensory nerve are located in the: A. ventral horn. B. dorsal root ganglion. C. brain. D. spinal cord.

B. dorsal root ganglion. - the cell bodies of somatic sensory neurons are not located in the CNS. They are located in dorsal root ganglia just behind and along the length of the spinal cord.

In the condition myopia the inverted image formed by the lens falls: A. on the retina. B. in front of the retina. C. behind the retina. D. on the optic nerve.

B. in front of the retina. In myopia, the image is formed in front of the retina, generally due to the shape of the eye being too long.

A red blood cell leaving the heart on its way to the lungs would travel through the: A. aorta. B. pulmonary artery. C. pulmonary vein. D. superior vena cava.

B. pulmonary artery. - arteries always carry blood away from the heart, and veins carry blood toward the heart - aorta carries blood to the body and the pulmonary artery carries blood to the lungs

An individual with blood type B- has: A. type B antigen, anti-B antibodies, and will make anti-Rh antibodies if exposed to Rh positive blood. B. type B antigen, anti-A antibodies, and will make anti-Rh antibodies if exposed to Rh positive blood. C. type B antigen, anti-B antibodies, and anti-Rh antibodies. D. type B antigen, anti-A antibodies, and anti-Rh antibodies.

B. type B antigen, anti-A antibodies, and will make anti-Rh antibodies if exposed to Rh positive blood. - the individual automatically makes antibodies to the opposite antigen - the Rh factor works a little bit differently; anti-Rh antibodies are only made if the individual gets exposed to Rh+ blood

Damage to which component of the ear would be most likely to alter a person's perception of pitch? A. Cochlea B. Tympanic membrane C. Basilar membrane D. Semicircular canals

C. Basilar membrane Sound waves are transmitted to the basilar membrane, causing it to vibrate. The location along the basilar membrane that experiences maximal vibration determines a person's perception of pitch. The cochlea does contain the basilar membrane, but it is this membrane specifically that is involved in pitch transduction. The tympanic membrane and semicircular canals are not part of this process.

Brain damage due to head trauma can be seen as lesions in different areas of the brain. A patient recently involved in a car accident presents with severely unsteady gait (difficulty walking), uncoordinated eye movements, and poor motor control in general . Which of the following regions of the brain is the likely location of the lesion afflicting this patient? A. Cerebrum B. Hypothalamus C. Cerebellum D. Corpus callosum

C. Cerebellum - cerebellum plays an important role in motor control and coordination - cerebrum is involved in many functions, typically associated with a particular lobe - hypothalamus is involved in many processes to maintain body homeostasis, including body temperature, hunger/thirst, and sleep - corpus callosum is the bridge between the two hemispheres of the brain

Which description below correctly identifies the role of the myelin sheath in action potential transmission? A. Protein fibers assemble along the axon of neurons, preventing leakage of current across the membrane. B. Convolutions in the axons of neurons dissipate current through specialized leakage channels. C. Schwann cells insulate the axons of neurons, causing membrane depolarization to jump from node to node. D. Glial cells cover the nodes of Ranvier to prevent backflow of current along the axon of neurons.

C. Schwann cells insulate the axons of neurons, causing membrane depolarization to jump from node to node. The myelin sheath insulates the neuronal axon except for small gaps (nodes of Ranvier) through which ions can traverse the membrane, causing the action potential to leap from node to node (saltatory conduction).

Which of the following is NOT true of the sympathetic nervous system? A. Epinephrine prolongs and enhances its effects. B. It increase heart rate, dilates bronchial tubes, and increases blood flow to skeletal muscle. C. It increases pupil diameter to enhance near-object vision. D. ACh stimulates the adrenal medulla.

C. It increases pupil diameter to enhance near-object vision. One of the first effects of the sympathetic system is to release ACh onto the adrenal medulla; this triggers the release of epinephrine into the blood to enhance and prolong the overall effects of the system. Among those effects are increased rate and force of cardiac contraction, dilation of bronchial tubes to increase the volume of air that can enter the lungs, and increased blood flow to skeletal muscles to ensure adequate delivery of glucose and oxygen during stress situations. However, while it is true that the sympathetic system increases pupil dilation, this increases distance vision, not near-object vision. Distance vision is an advantage in a stress situation.

Which of the following represents the correct order of events? A. Light stimulates rod cells, rod cells depolarize and stimulate biopolar cells, which stimulate ganglion cells, a signal is sent along the optic nerve. B. Light stimulates rod cells, rod cells depolarize and stimulate ganglion cells, which stimulate bipolar cells, a signal is sent along the optic nerve. C. Light stimulates rod cells, rod cells hyperpolarize and release the inhibition on biopolar cells, which stimulate ganglion cells, a signal is sent along the optic nerve. D. Light stimulates rod cells, rod cells hyperpolarize and release the inhibition on ganglion cells, which stimulate bipolar cells, a signal is sent along the optic nerve.

C. Light stimulates rod cells, rod cells hyperpolarize and release the inhibition on biopolar cells, which stimulate ganglion cells, a signal is sent along the optic nerve.

Which of the following valves prevents backflow of blood into the right ventricle? A. Tricuspid AV valve B. Bicuspid AV (mitral) valve C. Pulmonary semilunar valve D. Aortic semilunar valve

C. Pulmonary semilunar valve - pulmonary semilunar valve separates the right ventricle from the pulmonary artery and closes at the beginning of diastole to prevent backflow of blood into the right ventricle - tricuspid AV valve separates the right atrium from the right ventricle and prevents backflow into the atrium during systole - the bicuspid AV valve does the same thing but on the left side of the heart - aortic semilunar valve separates the left ventricle from the aorta and prevents backflow into the left ventricle during diastole

Sodium plays the principle role in rapid depolarization during action potentials due to which of the following? A. The rapid inactivation of voltage-gated sodium channels B. The rapid efflux of sodium from the neuron C. Sodium conductance results in a positive membrane potential D. Sodium conductance results in a negative membrane potential

C. Sodium conductance results in a positive membrane potential - sodium conductance is responsible for the rapid depolarization observed during the action potential. This is due to the fast opening of voltage-gated sodium channels which allow the flow of sodium across the membrane. Sodium flows into the cell down its electrochemical gradient resulting in depolarization of the cell - while inactivation of the voltage-gated sodium channels does occur, this occurs after the rapid depolarization observed and thus cannot be the cause of the depolarization (choice A is wrong).

Which of the following is not a component of the Organ of Corti? A. Hair cells B. Tectorial membrane C. Tympanic membrane D. Basilar membrane

C. Tympanic membrane

Olfactory receptors would be classified as: A. nociceptors. B. mechanoreceptors. C. chemoreceptors. D. thermoreceptors.

C. chemoreceptors. - nociceptors respond to pain - mechanoreceptors to physical movement - thermoreceptors to temperature

The first heart sound is produced by the: A. closure of the semilunar valves at the beginning of systole. B. closure of the semilunar valves at the beginning of diastole. C. closure of the AV valves at the beginning of systole. D. closure of the AV valves at the beginning of diastole.

C. closure of the AV valves at the beginning of systole. When the ventricles begin to contract (the beginning of systole), pressure inside those chambers rises dramatically. Blood would like to flow backwards, into the lower pressure atria, but pushes up against the AV valves, closing them to prevent backflow and producing the first heart sound (choice C is correct and choice A is wrong). Pressure continues to rise in the ventricles and eventually exceeds arterial pressure, at which point blood is ejected from the heart. When the ventricles begin to relax (at the beginning of diastole), pressure inside immediately drops below arterial pressure; blood would like to backflow into the ventricles but pushes up against the semilunar valves and closes them, producing the second heart sound (choices B and D are wrong).

B cells participate in: A. cell-mediated immunity. B. innate immunity. C. humoral immunity. D. non-specific immunity.

C. humoral immunity. B cells - secrete antibodies into the blood. Antibodies are highly specific markers for antigen

How does absolute threshold function as a measure of sensory perception? A. As the minimum stimulus needed to activate sensory receptors at least 50% of the time, this measure of perception has a well-established profile that differs between men and women. B. As the maximum stimulus which can be tolerated by sensory receptors before incurring damage, this measure of perception varies with age and by person. C. As the maximum stimulus which can be tolerated by sensory receptors before incurring damage, this measure of perception has a well-established profile that differs between men and women. D. As the minimum stimulus needed to activate sensory receptors at least 50% of the time, this measure of perception varies with age and by person.

D. As the minimum stimulus needed to activate sensory receptors at least 50% of the time, this measure of perception varies with age and by person.

Which of the following is the correct pathway of light entering the anterior surface of the eye leading to stimulation of the optic nerve? A. Choroid -> cornea -> vitreous chamber -> anterior chamber -> retina B. Cornea -> vitreous chamber -> anterior chamber -> choroid C. Cornea -> pupil -> sclera -> anterior chamber -> optic disk -> fovea D. Cornea -> anterior chamber -> lens -> retina

D. Cornea -> anterior chamber -> lens -> retina The cornea is the first structure that light must pass through ("choroid cornea vitreous chamber anterior chamber retina" is wrong). The anterior chamber is before the vitreous chamber ("cornea vitreous chamber anterior chamber choroid" is wrong). The sclera is the tough, outer, white covering of the eyeball; light cannot pass through this layer. This is why the cornea exists in the first place—to have a transparent outer layer for light to pass through. In any case, once light has passed through the cornea and the pupil, it can't reach the sclera until it passes through the lens, the vitreous humor, and the retina ("cornea pupil sclera anterior chamber optic disk fovea" is wrong).

Which of the following best characterizes the difference between the soma and axon hillock? A. Increased ribosomal activity in the axon hillock B. Axon hillocks are denoted by demyelinated areas between myelin sheets along the axon C. Decreased myelination surrounding the soma D. Decreased voltage-gated sodium channel density in the soma

D. Decreased voltage-gated sodium channel density in the soma The axon hillock, the area linking the soma to the axon, possesses an increased voltage-gated sodium channel density, allowing it to fire action potentials. In the soma, the decreased density allows for local depolarization which degrades exponentially over the distance of the soma. Neither the soma nor axon hillock are myelinated, and biosynthetic activity takes place in the soma, not the axon hillock. Nodes of Ranvier are the demyelinated areas between myelin sheets along the axon; the hillock is only at the area connecting the axon and soma.

All of the following are examples of non-specific body defense mechanisms EXCEPT: A. the complement system. B. lysozyme. C. the skin. D. lymphocytes.

D. lymphocytes. * Lymphocytes are B cells and T cells and participate in the adaptive immune response, a highly specific defense response * choices A, B, and C are all examples of non-specific defense and can be eliminated: the complement system destroys bacteria non-specifically, lysozyme is an enzyme found in saliva and tears that kills bacteria, and the skin is a great non-specific barrier.

The relative refractory period of an action potential could be extended by which of the following? A. Increasing the rate of voltage-gated Na+channel inactivation B. Increasing the rate of voltage-gated K+channel deactivation C. Decreasing the rate of voltage-gated Na+channel inactivation D. Decreasing the rate of voltage-gated K+channel deactivation

D. Decreasing the rate of voltage-gated K+channel deactivation - the relative refractory period results from the hyperpolarization of the membrane due to the slow deactivation of voltage-gated potassium channels. To extend the relative refractory period, we would need to decrease the rate of deactivation of these channels (i.e., make them deactivate even more slowly).

How does myelin increase the efficiency with which an action potential is conducted in a neuron? A. Decreasing the amount of Na+ allowed into the cell B. Increasing the amount of neurotransmitter released C. Increasing the number of K+ channels D. Decreasing the surface area to be depolarized

D. Decreasing the surface area to be depolarized

When is a neuron in its relative refractory period? A. During depolarization B. During the transmission of an action potential C. During repolarization D. During hyperpolarization

D. During hyperpolarization

On what part of the retina does the image focus on when you stare directly at something? A. Optic disk B. Pupil C. Lens D. Fovea centralis

D. Fovea centralis - fovea centralis, also known as the focal point, is responsible for extreme visual acuity. When you stare directly at something, the image is focused on the fovea centralis part of the retina to maximize the visual acuity. - the lens is not part of the retina, but rather it is in front of the retina. Its role is to focus incoming light beams onto the retina. - the pupil is also not part of the retina. Its role is to control the amount of light that enters the eye. - while the optic disk is part of the retina, it has no photoreceptors. For this reason, it is also called the blind spot.

How does the auditory cortex in the temporal lobe receive stimulation from the ear? A. Sound waves flex the tectorial membrane to trigger release of neurotransmitter B. Hair cells directly trigger bipolar auditory neurons via mechanical stimulation C. Sound waves stimulate baroreceptors to open ion channels in hair cells D. Hair cells contacting the tectorial membrane open ion channels to trigger release of neurotransmitter

D. Hair cells contacting the tectorial membrane open ion channels to trigger release of neurotransmitter - hair cells are mechanoreceptors - perception of sound begins with sound waves vibrating the basilar membrane. This causes hair cells (mechanoreceptors) to come in contact with the tectorial membrane, and this contact opens ion channels in the hair cells. The cells depolarize and release neurotransmitter to stimulate the bipolar auditory neurons that run to the auditory cortex in the temporal lobe. Baroreceptors are not involved in this process.

What area of the brain is responsible for primary regulation of the endocrine system? A. Thalamus B. Pons C. Epithalamus D. Hypothalamus

D. Hypothalamus

Which of the following statements is true about cortisol? A. It is released from the adrenal medulla in a stress situation and helps mobilize fats for energy. B. It is released from the adrenal cortex in a stress situation and binds to an extracellular receptor to mediate its effect. C. It is released from the adrenal medulla in a stress situation and reduces inflammation. D. It is released from the adrenal cortex in a stress situation and modifies transcription to exert its effect.

D. It is released from the adrenal cortex in a stress situation and modifies transcription to exert its effect. - cortisol is released from the adrenal cortex and because it is a steroid hormone, enter cells, binds to an intracellular receptor and modifies transcription. Mobilizing fats for energy and reducing inflammation are among cortisol's effects, but it is not released from the adrenal medulla

A resident is asked to assist on his first surgery and starts to panic. Which of the following would be the LEAST likely response? A. Increased heart rate B. Bronchial dilation C. Increased blood flow to skeletal muscle D. Pupillary constriction

D. Pupillary constriction - this example triggers a fight-or-flight response, i.e., activates the sympathetic division of the autonomic nervous system. Increased heart rate, bronchial dilation, and increased blood flow to skeletal muscle are all typical responses of sympathetic activity - pupillary constriction is typical of a parasympathetic response

A researcher treats cultured neurons with an RNA polymerase II inhibitor. Which of the following areas of the neuron will be most directly impacted? A. Axon terminal B. Axon hillock C. Dendrites D. Soma

D. Soma - RNA polymerase II is responsible for the production of mRNA in the nucleus of eukaryotic cells. In neurons, the cell body (or soma) houses the nucleus and the majority of metabolic activity - axon terminal is the end of an axon which frequently forms a synapse with another neuron or effector organ - axon hillock is the region where the axon and soma meet and is important in action potential initiation - dendrites are offshoots from the soma which receive input from other neurons

A man on a hunting trip sustains an accidental gunshot wound. The bullet penetrates the skull and travels a short way into the cerebral cortex. Shortly after the accident, the man finds that his sense of smell has been impaired. Which of the following brain regions was most likely damaged? A. Parietal lobe B. Occipital lobe C. Frontal lobe D. Temporal lobe

D. Temporal lobe

A researcher isolates a squid giant axon and places it into an electrolyte bath that mimics its normal conditions. She stimulates the axon and normal action potentials occur. She then introduces a drug into the electrolyte bath that blocks voltage-gated potassium channels, and again attempts to elicit action potentials. Which of the following is most likely to occur? A. Since the voltage-gated channels are blocked, the action potential will not occur. B. The resting potential will become more positive since potassium is unable to exit the cell normally through leak channels. C. Since the cell remains depolarized for a longer period of time, subsequent action potentials will be easier to elicit and the frequency of action potentials will increase. D. The axon will depolarize normally when stimulated but the time to return to rest potential will be exceedingly long.

D. The axon will depolarize normally when stimulated but the time to return to rest potential will be exceedingly long.

Which of the following statements is true about arteries but not about veins? A. They have valves to maintain flow in a single direction. B. They carry only oxygen-rich blood. C. They are a low-pressure system of vessels. D. They have a muscle layer to regulate blood flow.

D. They have a muscle layer to regulate blood flow. - veins have valves, but arteries do not (choice A is true about veins, not arteries) - most arteries carry oxygen-rich blood, but the pulmonary arteries carry oxygen-poor blood; likewise, most veins carry oxygen-poor blood, but the pulmonary veins carry oxygen rich blood (choice B is true of neither arteries nor veins) - arteries are a high-pressure system and veins are a low pressure system (choice C is true about veins)

Testosterone is a steroid hormone that does each of the following EXCEPT: A. create negative feedback to the anterior pituitary and hypothalamus in the brain. B. induce male sex characteristics such as a deep voice, broad shoulders and body hair. C. stimulate sustentacular cells, thereby indirectly stimulating spermatogenesis. D. create negative feedback to the interstitial cells, keeping systemic hormone levels low during certain developmental stages.

D. create negative feedback to the interstitial cells, keeping systemic hormone levels low during certain developmental stages - testosterone is made by interstitial cells, but does not feedback significantly to these cells.

the region of the brain that processes voluntary movement and problem solving?

frontal lobe

the region of the brain that processes visual sensation?

occipital lobe

the region of the brain that processes general sensations of pain, pressure, and touch?

parietal lobe

postsynaptic

referring to the region of a synapse that receives and responds to neurotransmitter

humoral immunity

specific immunity produced by B cells that produce antibodies that circulate in body fluids

the region of the brain that processes olfactory sensation (smell)?

temporal lobe