BIO 256 EXAM 2 | 2025/2026 Update | Questions and Verified Answers | 100% Guaranteed Pass.

BIO 256 EXAM 2 (Latest Update) Questions and Verified Answers (100% Guaranteed Pass). The neuroglia forming the myelin sheath around neuron fibers in the peripheral nervous system are Schwann cells (neurilemma). The threshold membrane potential value for a neuron to initiate an action potential is ________ mV. -55 What is the importance of the axon hillock, the first stretch of membrane on the neuron's axon? it contains a high concentration of voltage gated channels Which of the following would result in membrane depolarization influx of sodium ions In a resting neuron, the membrane potential is approximately -70 mV. Cell A and cell B are located side by side within the same tissue but are not in direct contact with each other. Cell A releases a chemical messenger. In order for cell B to respond to this chemical messenger cell B must have receptors specific for the paracrine regulator. Why is synaptic transmission the rate limiting (slowest) step of neural conduction? All of these options are correct. In general, do unmyelinated small diameter neuron fibers transmit information faster than larger myelinated fibers? No. Large diameter myelinated neurons are faster than small diameter unmyelinated neurons. In a synapse, synaptic vesicles are released from the presynaptic axon. Indirect-acting neurotransmitters act through second messengers to promote long-lasting effects. The role of acetylcholinesterase is to destroy acetylcholine shortly after its release by the axonal endings. A neural circuit with input traveling along several pathways for integration by several CNS systems and providing several response is a parallel processing circuit. Brain wave amplitude on an EEG reflects the number of neurons firing synchronously. When most dreaming takes place, your sleep is characterized by temporary skeletal muscle paralysis, except for the extrinsic eye muscles. Which of the following structures is probably NOT directly involved in memory? medulla oblongata Inhibition of the reticular activating system results in sleep. Which is true about PET scans? They detect increased or decreased metabolic activity by measuring the uptake of radioactive deoxyglucose Which stimulates inspiration? pons apneustic center Which is innervated by the somatic nervous system? skeletal muscle Autonomic ganglia contain cell bodies of postganglionic neurons In the autonomic nervous system, nicotinic cholinergic receptors respond to ____ and are found on ____. acetylcholine, postganglionic dendrites Which provides the ultimate control for the sympathetic nervous system? hypothalamus Which is NOT detected by a mechanoreceptor type? to taste Which type of receptor's frequency of sensory neuron action potentials increases with the generator potential and stimulus amplitude? tonic Which skin receptors detect deep pressure? Pacinian corpuscles When a skin area's two-point threshold is large, that skin has low sensory acuity. Which taste sensation detects alkaloids such as quinine and nicotine? bitter Salty tastes are converted to nerve impulses by a mechanism that includes Na+ influx into receptor cells. The second messenger used for detecting the presence of an odorant molecule is cAMP. The receptor for static equilibrium is the macula Which directly experiences both increases and decreases in pressure as the stapes presses on the oval window? scala vestibuli Auditory hair cells are embedded in which membrane? The intensity of sound is called ___ and it is measured in ___. amplitude, decibels (dB) Which structure contains muscles that control the amount of light passing to the visual receptors of the eye? iris There are three layers of neurons in the retina. The axons of which of these neuron layers form the optic nerves? ganglion cells Normal vision is called emmetropia The sum of visual input from _____ cone(s) stimulates ______ ganglion cell(s). This results in _____ vision one, one, distinct Nerve fibers from the medial aspect of each eye cross over to the opposite side at the optic chiasma. Which is not a driving force that moves molecules across cell membranes? Which is the most accurate description of how action potentials work? ligand gated ion channels open --> voltage gated sodium channels open --> voltage gated potassium channels open -->voltage gated sodium channels close --> voltage gated potassium channels close Which of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"? Cyclic AMP and IP3 are second messengers. Sometimes prolonged excessive exposure to a high hormone concentration causes a phenomenon known as down-regulation. Virtually all of the protein or amino acid-based hormones exert their effects through intracellular second messengers. We have an expert-written solution to this problem! ___ is the fasting hormone; ___ is the fed hormone. Glucagon, insulin Gonadocorticoids produced by the adrenal glands are insignificant compared with sex hormone release from the gonads during late puberty. In a strict sense, the posterior pituitary is not an endocrine gland because it does not make hormones. Neurotransmitter is released from rods and cones in the Dark. Which channels are activated in order to reach the threshold potential in a neuron (Phase 0, turquoise, to dotted line)? Immediately as an action potential reaches its peak, which cellular channels open? potassium The resting membrane potential is largely preserved by the sodium potassium ATPase pump. A motor neuron synapsed with skeletal muscle will release which neurotransmitter into the synaptic cleft? acetylcholine What is saltatory conduction in a neuron? Is it fast or slow? Saltatory conduction describes how an action potential jumps node to node in a myelinated fiber. It is fast. The point at which an impulse from one nerve cell is communicated to another nerve cell is the synapse. We have an expert-written solution to this problem! The period after an initial stimulus when a neuron is not sensitive to another stimulus is the refractory period. We have an expert-written solution to this problem! Which neurotransmitter is NOT a catecholamine? serotonin A neuronal circuit that concentrates or directs a large number of incoming impulses to a rather small number of neurons is called a(n) converging circuit. Which characterizes the fourth stage of sleep in the sleep cycle? EEG pattern is dominated by delta waves; skeletal muscles are relaxed; arousal difficult Which statement is true of short-term memory? it lasts from a few seconds to a few hours Which controls the motor aspects of speech? Broca's area of the cerebrum Which brain area controls speech comprehension? Wernicke's area In contrast to the somatic nervous system, the autonomic nervous system has two efferent neurons. Muscarinic cholinergic receptors respond to ____ and are found on ____. acetylcholine, effectors Which is regulated by only the sympathetic, not the parasympathetic branch, of the autonomic nervous system? - smooth muscles of blood vessels - arrector pili muscles Which skin receptors detect texture and vibrations? Meissner's corpuscles Bitter tastes are converted to nerve impulses by closing the potassium channel directly An essential conponent of the maculae involved in static equilibrium is (are) the otoliths. The sodium-potassium pump pumps three sodium ions out of the cell and two potassium ions into the cell. Very low pitched sounds we can barely hear bend organ of Corti hair cells in the portion of the organ of Corti near the helicotrema. The blind spot of the eye is where the optic nerve leaves the eye There are three layers of neurons in the retina. Which cells detect bright light and are used for highacuity color vision? cone cells Photoreceptors package visual pigment in membrane-bound discs, increasing the efficiency of light trapping. The first "way station" in the visual pathway from the eye, after there has been partial crossover of the fibers in the optic chiasma, is the lateral geniculate body of the thalamus. We have an expert-written solution to this problem! Ligand gated channels produce graded potentials How is the second messenger cAMP made? It is made from ATP by adenylyl cyclase. The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on the presence of the appropriate receptors on the target tissue or organ cells. We have an expert-written solution to this problem! Regulating hormones from the hypothalamus first enter into the hypophyseal portal system. The adrenal cortex is composed of three layers of cells. Which layer is responsible for production of mineralocorticoids including aldosterone? zona glomerulosa The part of the neuron that normally receives stimuli is called a dendrite. Which channels are actively responsible for the voltage change in Phase 2 of the action potential (green)? voltage gated potassium channels What pumps are highly active during Phase 3 of the action potential (purple) in order to restore ion balance and bring the membrane back to resting potential? the sodium-potassium ATPase (Na+/K+ ATPase) Membrane hyperpolarization means the inside of the cell becomes more negative than the resting potential When an excitatory stimulus affects a resting neuron, ligand-gated channels open, allowing Na+ to rush in. Inside an actively signaling cell, Na+ and Ca++ are higher in concentration than in the resting state. Which autonomic fiber releases norepinephrine as its neurotransmitter? postganglionic sympathetic fiber If one incoming impulse causes several outgoing nerve impulses, we know that there is a diverging circuit. Which regular, rhythmic low-amplitude brain waves indicate a conscious idling brain? alpha waves REM sleep is associated with temporary skeletal muscle paralysis, except for the extrinsic eye muscles. The process of linking new facts with old facts already stored in the memory bank is called association. Which part of the nervous system controls survival emotions and behavior? the limbic system Which is true about functional MRI (fMRI)? it detects oxygen use by determining the ratio of oxyhemoglobin to deoxyhemoglobin Which brain area controls the motor aspect of speech? Broca's area Which is NOT innervated by the autonomic nervous system? skeletal muscle Beta1 adrenergic receptors respond to ____ and ____ the heart rate. Which provides vasomotor tone? sympathetic nervous system Which receptors adapt most slowly? nociceptors Which skin receptors are able to detect a slight breeze blowing on your skin? Which is true about the spinothalamic tract? The three neuron chain decussates in the spinal cord. Which kind of papilla does not contain taste buds? filiform Odor signals are processed and sent to the olfactory cortex by mitral cells. You would expect ___ to be stimulated as you take an elevator up. These extend from the vestibule into the ___. saccular, cochlea Which is NOT connected by the helicotrema? scala media Otolithic movement in the same direction as the kinocilium results in depolarization of vestibular nerve fibers Loud high pitched sounds bend organ of Corti hair cells in the portion of the organ of Corti near the oval window. Which is another name for the site where the optic nerve exits the eye? optic disk What is the main function of the rods in the eye? vision in dim light Farsightedness associated with aging is called presbyopia. The sum of visual input from _____ rod(s) stimulates ______ ganglion cell(s). This results in _____ vision many, a single, indistinct Which is not true about voltage-gated sodium ion channels? Which incorrectly matches an endocrine tissue with what it controls (at least in part)? Thymus, metabolic rate ___ stimulates mammary gland milk synthesis while ___ causes milk let-down. Prolactin, oxytocin Aldosterone functions to increase kidney sodium resorption. Which is the correct order of events from resting through a neuron action potential? Polarization, depolarization, hyperpolarization The first phase of the action potential (Phase 1, blue), which leads the membrane potential to spike at +30 mV is due to the activation of ____________ channels. voltage gated sodium channels Depolarization means the inside of the cell gets more positive If you were to administer a drug that blocked the activity of the sodium/potassium pump, what effect would you expect that to have on the cell's ability to absorb glucose (which is absorbed by sodium cotransport)? decreased glucose transport into the cell After release into the synaptic cleft, a neurotransmitter like acetylcholine will _____ The rate-limiting, slowest, step of neural transmission is Which brain waves are not normal in large amounts for conscious adults but common for children? Theta Activation of the reticular activating system results in wakefulness. The parasympathetic nervous system is characterized by peripheral ganglia near the organs and by short postganglionic fibers. Alpha2 receptors respond to ____, and ______ digestive enzyme release to the small intestine. norepinephrine, inhibiting Feeling a gentle caress on your arm would likely involve all of the following EXCEPT Pacinian corpuscles. Which type of receptors fire quickly when first stimulated but then slow their firing to adapt to the stimulus? phasic Which skin receptors detect pain? nociceptors When a skin area's two-point threshold is small, that skin has high sensory acuity. Sweet tastes are converted to nerve impulses by a G protein gustducin transducing the sensation. Information from balance receptors goes directly to the brain stem reflex centers. Which can directly cause the round window to bulge when there is increased pressure? scala tympani Inside the crista ampullaris, rotational head movement both increases and decreases neural firing, depending on the direction of movement Choose the most accurate statement about sound. A ten-decibel increase represents a tenfold increase in sound intensity. Which type of receptor proteins are most commonly associated with the formation of second messenger molecules? voltage gated ion channels Mineralocorticoid is to aldosterone as glucocorticoid is to cortisol. Oxytocin release in labor and delivery is an example of a positive feedback control mechanism. The nervous system can overide normal endocrine controls. true How can you tell if a person is in an REM stage of their sleep? Their eyeballs are moving so much you can see this through their eyelids. What is the physiological significance of Nodes of Ranvier, or internodal gaps, on the axon? They contain voltage gated ion channels, allowing saltatory conduction. Cellular receptors on muscle and nerve cells control the opening and closing of ion channels. With electrical synapses, a signal is sent from a presynaptic neuron to a postsynaptic neuron via gap junctions. An inhibitory postsynaptic potential (IPSP) is specifically caused by membrane hyperpolarization. An excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle is acetylcholine. We have an expert-written solution to this problem! Which describes sleep occurring when you first fall asleep? eyes are closed and relaxation begins; the EEG shows normal alpha waves; easily aroused The oval window is connected directly to which passageway? scala vestibuli Which is not true about voltage gated ion channels? ions will diffuse to the area of higher ion concentration through the channels. Sympathetic fibers leave the spinal cord in the thoracolumbar region, and the postganglionic fibers secrete norepinephrine Light passes through the following structures in which order? cornea, aqueous humor, lens, vitreous humor Growth hormone promotes long bone growth during the formative years. Glucocorticoids enable the body to deal appropriately with stress. They accomplish this by increasing blood glucose, fatty acid, and amino acid levels and maintaining blood volume. We have an expert-written solution to this problem! A resting neuron is polarized Which period of a neuron action potential is characterized by a temporary loss of excitability? refractory period When the action potential reaches the end of the axon, one additional kind of voltage gated channel is activated at the terminus. What ion is this channel permeable to? calcium The substance released at axonal endings to propagate a excitatory postsynaptic impulse is called a(n) neurotransmitter. When a postsynaptic neuron receives stimuli from several presynaptic neurons, this is called spacial summation. The neurotransmitter utilized at neuromuscular junctions is acetylcholine. Which area largely controls the brain's ability to understand language? Wernicke's area of the cerebrum Which kind of neural imaging can also be used as a therapy to treat depression? Which type of receptors fire at a constant rate when stimulus is present and stop when stimulus is removed? tonic Which of these ions is actively transported through the plasma membrane to help establish the resting potential? Na+ The perception of different sound frequencies is called Which of the following could not be seen as one looks into an eye with an ophthalmoscope? optic chiasma Sympathetic responses generally are widespread because One hormone may cause a cell to elicit multiple responses; this is because when the hormone binds receptors, second messengers stimulate groups of enzymes. The parasympathetic NS affects organs not innervated by the sympathetic NS. false The neuroglia forming the myelin sheath around neuron fibers in the central nervous system are oligodendrocytes. In general, neurons with myelinated, large diameter fibers transmit information more quickly than unmyelinated, small diameter fibers. Yes, large diameter myelinated neurons are faster. Which irregular rhythmic brain waves are observed when you are awake and alert? Beta Fact memory is the ability to learn specific information. The bending of stereocilia during excitation of hair cells in the organ of corti The site of origin of the preganglionic fibers of the parasympathetic nervous system is the brain stem and the sacral region of the spinal cord. Which structure contains muscles that regulate the amount of light entering the eyeball? iris In circumstances where the body requires prolonged or increased levels of a hormone, the DNA of target cells will specify the synthesis of more receptors on the surface of the cells of the target organ. This is known as up-regulation. Insulin, a small (51-amino-acid) protein, is synthesized by the beta cells of the pancreas. This hormone is released when the body's glucose levels rise. Which disease is associated with hypersecretion of glucocorticoids and symptoms including a "buffalo hump" or an unusual deposit of fat on the back just below the neck? Cushing syndrome The parathyroid glands maintain adequate levels of blood calcium. Parathyroid hormone does this by activating osteoclasts so that calcium will be released from bone. We have an expert-written solution to this problem! Which neuron does NOT release acetylcholine as its neurotransmitter? Sympathetic postganglionic