Biology Ch. 49 Neurons

A cluster of nerve cell bodies outside the central nervous system is referred to as a __________.

ganglion Explanation:

The blind spot in the human retina is the location that has the collected axons of _____.

ganglion cells

A drug that causes potassium to leak out of a neuron, increasing the positive charge on the outside, would __________.

inhibit transmission of nerve signals by the neuron

In a neuron, ion channels permit movement of (but don't pump) ____________.

sodium (Na+) and potassium (K+)

Sodium-potassium pumps transport ___________.

sodium ions (Na+) out of a neuron and potassium ions (K+) into a neuron Explanation: The Na+ and K+ gradients are maintained by the sodium-potassium pump. This pump uses the energy of ATP hydrolysis to actively transport Na+ out of the cell and K+ into the cell: three Na+ out of the cell for every two K+ that it transports in.

Which of the following is a typical resting potential of a neuron?

-60 to -70 mV

Which of the following is a component of the vertebrate central nercous system (CNS)?

All of the listed responses are correct. -Spinal cord -Gila -Brain -Nerves

How are neurons structurally adapted to chemically transmit impulses to neighboring neurons?

Axon terminals contain neurotransmitters within synaptic vesicles. Explanation: "They have Schwann cells that surround axons" is incorrect because only myelinated neurons of the peripheral nervous system (PNS) have Schwann cells. "They have numerous nodes of Ranvier" is incorrect because all neurons regardless of whether or not they are myelinated contain neurotransmitters within synaptic vesicles. "They have numerous dendrites" is incorrect because dendrites are branched extensions of the cell body of a neuron.

Which of the following statements is an accurate description of the evolution of the vertebrate brain?

Birds and mammals have evolved a proportionally larger forebrain that have other vertebrate groups.

Which of the following region(s) arose developmentally from the hindbrain?

Both C and E Explanation: Cerebellum is the part of the brain at the back of the skull in vertebrates. Its function is to coordinate and regulate muscular activity.

The central nervous system consists of the spinal cord and the brain, which is one of the most complex organs in animals.On the diagram below, label the parts of the human brain and identify one function of each part of the brain. Drag the labels to their appropriate locations on the diagram, following these steps.

Clockwise starting from A. A) Cerebrum: working a crossword puzzle B) Diencephalon: sending signals from the senses to the appropriate brain region g) Cerebellum: maintaining balance while walking f) Brainstem: regulating a person's resting heart rate e) Corpus Callosum: communicating between left and right cerebral hemispheres The brain, part of the central nervous system, is the most complex organ in the human body. The brain has four major regions, each with specialized functions. The cerebrum is the largest part of the brain and is responsible for thought, information processing, and memory. The diencephalon acts as an integrating center for sensory information and controls homeostasis. The cerebellum coordinates movement and balance (e.g., hand-eye coordination). The brainstem, which is continuous with the spinal cord, functions in some autonomic responses and relays information to and from higher brain centers.

If a person suffered a stroke which damaged brain region B (frontal lobe), what might be the expected outcome?

Higher-level integration of sensory inputs and motor outputs would be impaired. Explanation: The frontal lobe is responsible for emotional control center, decision making, the primary motor area, and motor speech (Brocha's area)

Which of the following statements is an accurate description of sleep

Humans cannot live without sleep. Contrary to appearances in humans, sleep is an active state, at least for the brain. Some animals have evolutionary adaptations that allow for substantial activity during sleep. Bottlenose dolphins, for example, swim while sleeping, rising to the surface to breathe air on a regular basis. In order to investigate brain activity during sleep, scientists can place electrodes at multiple sites on the scalp and record patterns of electrical activity, called brain waves, via an electroencephalogram (EEG). Sleep is a state in which external stimuli are received but not consciously perceived.

Which of the following statements is an accurate description of biological clocks?

In an unchanging environment, there is little variation in the periodicity of the human biological clock.

In a mammalian visual system, visual information is integrated at ________. I) the lens II) the retina III) the optic nerve IV) the visual cortex

II and IV (the retina, the visual cortex)

All else remaining constant, which of the following would constitute hyperpolarization of a neuron at rest?

Increasing Na+ outside of the cell

Which of the following statements about resting potential is true?

Inside the cell, the concentration of potassium is much higher than the concentration of sodium.

Which of the following is specifically a part or a function of the central nervous system?

Integration

Identify the correct statement(s) about sensory receptors. Select all that apply.

Mechanoreceptors detect sound.Foods taste spicy when they activate the same sensory receptors that high temperatures activate. Mechanoreceptors sense physical deformation caused by forms of mechanical energy such as pressure, touch, stretch, motion, and sound. Pheromones are detected by very sensitive chemoreceptors with great specificity. Electromagnetic receptors detect various forms of electromagnetic energy, such as visible light, electricity, and magnetism. The hot spicy taste of jalapeno pepper activates thermoreceptors that also respond to temperatures of 42°C and above. Menthol, a cool plant product, activates thermoreceptors that also respond to temperatures of 28°C and below. Read about mechanoreceptors, chemoreceptors, electromagnetic receptors, and thermoreceptors.

A physician friend of yours tells you about a patient with a head injury who suddenly stopped breathing during the examination. What portion of the brain was probably injured?

Medulla oblongata

What is the relationship between neurons and nerves?

Nerves are comprised of neurons.

Where would a ligand-gated ion channel typically be found on a neuron?

Postsynaptic membrane Explanation: Voltage-gated ion channels are typically found in the presynaptic membrane. Voltage-gated channels are also present on the axon. In addition to voltage-gated ion channels, ungated ion channels are found on the axon hillock and elsewhere on the neuron.

The amygdala serves what role in the brain of vertebrates?

Processing emotional memories Explanation: Emotional experiences are often stored as memories that can be recalled by similar circumstances, and the amygdala, an almond-shaped mass of nuclei (clusters of neurons) located near the base of the cerebrum, is the brain structure that is most important for this function. Broca's area of the frontal lobe is involved in the formation of speech. The motor cortex controls skeletal muscles. Arousal and sleep are controlled by the reticular formation, a diffuse network formed primarily by neurons in the midbrain and pons. The cerebellum functions in maintaining balance.

Which of the following is an action brought about by the sympathetic division of the autonomic nervous system?

Relaxtion of lung bronchi Explanation: The sympathetic and parasympathetic divisions of the autonomic nervous system have largely antagonistic (opposite) effects in regulating organ function. Activation of the sympathetic division corresponds to arousal and energy generation (the "fight-or-flight" response). For example, the heart beats faster, digestion is inhibited, the liver converts glycogen to glucose, and the adrenal medulla increases secretion of epinephrine (adrenaline). Activation of the parasympathetic division generally causes opposite responses, which promote calming and a return to self-maintenance functions ("rest and digest"). Thus, heart rate decreases, digestion is enhanced, and glycogen production increases. However, when regulating reproductive activity, a function that is not homeostatic, the parasympathetic division complements rather than antagonizes the sympathetic division. The parasympathetic division stimulates the gallbladder. The parasympathetic division increases salivation. Constriction of pupils is an action brought about by the parasympathetic division.

What is the relationship between membrane potential and resting potential?

Resting potential is the membrane potential or a neuron that is at rest.

Which of the following statements is an accurate description of animal cognition?

Some birds can understand abstract concepts such as numbers. Explanation: Experiments in recent years suggest that some birds have much greater intellectual capacity than previously thought. For example, Western scrub jays (Aphelocoma californica) can remember which food items they hid first. New Caledonian crows (Corvus moneduloides) are highly skilled at making and using tools, an ability otherwise well documented only for humans and some other apes. Furthermore, African gray parrots (Psittacus erithacus), in addition to understanding numbers, can comprehend other abstract concepts such as "same," "different," and "none."It is not only mammals that have cognitive abilities. Cognition in vertebrates is primarily a result of processes occurring in the forebrain. Different regions of the forebrain appear to be responsible for sophisticated information processing in birds and mammals. Mammals have a highly convoluted cerebral cortex, but birds do not.

Which of the following statements is an accurate description of neurotransmitters?

Some neurotransmitters can bind to multiple different types of receptors.

The peripheral nervous system (PNS) transmits information to and from the central nervous system (CNS) and plays a role in regulating an animal's movements and internal environment. Determine which of the following statements about the PNS are true.

The autonomic nervous system of the PNS regulates the body's internal environment. It consists of the parasympathetic division and the sympathetic division. The parasympathetic division controls "rest and digest" functions, whereas the sympathetic division controls "fight or flight" functions. This table lists some of the opposing actions of each division. Parasympathetic division: "rest and digest", constricts pupils, slows heart rate, stimulates activity of pancreas and gallbladder, stimulates activity of intestines, promotes emptying of bladder Sympathetic division: "fight or flight", dilates pupils, increases heart rate, inhibits activity of pancreas and gallbladder, inhibits activity of intestines, inhibits emptying of bladder

If a doctor attempts to trigger the patellar tendon reflex and a lack of response occurs, what are potential regions where pathology might exist?

The knee and the spinal cord

Sensory pathways have four basic functions: sensory reception, transduction, transmission, and perception. How do these functions differ between yourself and a star-nosed mole?

The perception of sensory input by humans and star-nosed moles differs. The number and type of sensory receptors in humans and star-nosed moles differ. Explanation: Animals use a range of sensory receptors to detect widely varying stimuli. For example, humans have excellent vision, whereas the mole lives in darkness and is virtually blind. The star-shaped nose of the mole has 25,000 mechanoreceptors, more than you have in your whole hand.Perception of sensory input is a construction formed in the brain of an animal, and perception of the world may vary greatly from species to species. Each species has a perceptual world shaped by natural selection to deliver the information necessary for that species' survival and reproductive success. Read about sensory reception and perception.

What governs the opening of the potassium channels, which establish the resting membrane potential in the plasma membrane of a neuron?

The potassium channels are always open.

Temporal lobe function

The temporal lobe processes memories, integrating them with sensations of taste, sound, sight and touch. It houses sensory speech (Wernicke's area) and primary auditory area.

Which type of transmembrane protein is directly responsible for maintaining the propagation of action potentials across an axon once it has been initiated?

Voltage-gated sodium channels Voltage-gated sodium channels are directly responsible for maintaining the propagation of action potentials across an axon once it has been initiated.

Which structure is not part of a neuron?

Which structure is not part of a neuron? Explanation: The myelin sheath is the layer of Schwann cells wrapped around a neuron.

The structure of the mammalian middle ear is adapted to convert ________.

air pressure waves to fluid pressure waves

If a patient has an injury in the brain stem, which of the following would be observed?

an inability to regulate heart function

Alzheimer's disease and Parkinson's disease are similar in that both ____________.

become more common with age Explanation: Both Alzheimer's disease and Parkinson's disease affect well over 1% of individuals in old age. In the U.S. population, approximately 1 million people are afflicted with Parkinson's disease alone. Both diseases have widespread effects in regions of the brain other than the hindbrain. Most cases of Parkinson's disease lack an identifiable cause; however, a rare form of the disease that appears in relatively young adults has a clear genetic basis. At present, neither Alzheimer's disease nor Parkinson's disease can be cured, although there are approaches that can be used to manage the symptoms of Parkinson's disease, including brain surgery, deep-brain stimulation, and a dopamine-related drug, l-dopa.

Wakefulness is regulated by the reticular formation, which is present in the _____.

brainstem

Which of the following terms and phrases describe structures or actions of the Central Nervous System?Which describe structures or actions of the Peripheral Nervous System?Which describe structures or actions of both?

central nervous system: -process information received from sense organs-brain and spinal cord -initiates signals to muscles and organs peripheral nervous system: -afferent and efferent neurons -carries sensory information toward the spinal cord -carries signals to muscles and organs-cranial nerves an spinal nerves Both: -reflexes -enables voluntary locomotion

As vertebrates evolved, the increasingly complex structure of the brain conferred increasingly complex function, especially apparent in the _____. See Concept 49.3 (Page 1094)

cerebral cortex, which is greatly expanded in humans, other primates, and cetaceans Explanation: This region supports language, a very complex function, and other higher-level thinking processes.

Blocking potassium ion channels in a mammalian cell membrane would __________.

decrease the magnitude of the membrane potential Blocking potassium would have no impact on sodium's equilibrium potential. Blocking potassium will increase the concentration outside of the cell and will lower the equilibrium potential.

The part(s) of a neuron that receive(s) signals is/are the ____________.

dendrites Explanation: A neuron also has a single axon, an extension that transmits signals to other neurons. The cone-shaped base of an axon, called the axon hillock, is typically where signals that travel down the axon are generated.

The limbic system is involved in __________.

emotion and memory Explanation: These structures border the brainstem in mammals and are therefore grouped as the limbic system (from the Latin limbus, "border"). The limbic system, however, is not dedicated solely to emotion. It also functions in motivation, olfaction (the sense of smell), behavior, and memory. Generating emotion and experiencing emotion require parts of the brain in addition to the limbic system. Structures in the forebrain also attach emotional "feelings" to basic, survival-related functions controlled by the brainstem, including aggression, feeding, and sexuality. "Speech and hearing" is incorrect because speech centers are found in Broca's area of the frontal lobe of the cerebrum, whereas hearing centers are located in the auditory cortex of the temporal lobe of the cerebrum. "Vision" is incorrect because the visual association cortex is located in the occipital lobe of the cerebrum. "Sleep and wakefulness" is incorrect because the reticular formation of the brain stem regulates these activities. "Control of heartbeat and respiration" is incorrect because these activities are regulated by the brainstem.

After eating a large meal, which branch of your nervous system is activated?

enteric

Which of the following shows a brain structure correctly paired with one of its primary functions?

frontal lobe: decision making

Gray matter of the nervous system differs from white matter in that ____________.

gray matter is primarily made up of neuron cell bodies, whereas white matter consists mainly of bundled axons

Rods exposed to light will _____.

hyperpolarize due to the closing of SODIUM channels

Food and water appetites are under the regulatory influence of the _____.

hypothalamus

The regulation of body temperature derives from the activity of the _____.

hypothalamus Explanation: The hypothalamus plays a crucial role in many important functions, including: releasing hormones, regulating body temperature, and controlling appetite. It also regulates food and water appetites.

Exercise and reactions to exciting stimuli include ________.

increased activity in the sympathetic, and decreased activity in the parasympathetic divisions

Emotion, motivation, olfaction, behavior, and memory, in humans, are mediated by the _____. See Concept 49.2 (Page 1093)

limbic system Explanation: The limbic system controls various appetites and motivations in the brain.

Which of the following structures or regions is incorrectly paired with its function?

limbic system motor control of speech

Increases and decreases of the heart rate results from changes in the activity of the _____.

medulla oblongata Explanation: Helps regulate breathing, heart and blood vessel function, digestion, sneezing, and swallowing. This part of the brain is a center for respiration and circulation.

Tastes and smells are distinct kinds of environmental information where ________.

neural projections from taste receptors reach different parts of the brain than the neural projections from olfactory receptors

Short-term and long-term memory are related but have important differences. Short term memory____.

occurs within the hippocampus and is essential for acquiring new long-term memories within the cerebral cortex

Which of the following sensory receptors is incorrectly paired with its category?

olfactory receptor: electromagnetic receptor Correctly Paired: hair cell: mechanoreceptor taste receptor: chemoreceptor snake pit organ: thermoreceptor

In a cephalized invertebrate, the system that transmits "efferent" impulses from the anterior ganglion to distal segments is the _____.

peripheral nervous system

One of the functions of the __________ is monitoring breathing centers in the medulla.

pons

Threshold is of great significance in the physiology of neurons because if threshold is not reached, __________.

positive-feedback depolarization will not occur Action potentials occur whenever a depolarization increases the membrane voltage to a particular value, called the threshold. For mammalian neurons, the threshold is a membrane potential of about -55 mV. Once initiated, the action potential has a magnitude that is independent of the strength of the triggering stimulus. Because action potentials occur fully or not at all, they represent an all-or-none response to stimuli. This all-or-none property reflects the fact that depolarization opens voltage-gated sodium channels, and the opening of sodium channels causes further depolarization. The positive-feedback loop of depolarization and channel opening triggers an action potential whenever the membrane potential reaches the threshold.

In descriptions of synapse organization, the __________ cell is the transmitting neuron and the __________ is the neuron, muscle, or gland cell that receives the signal.

presynaptic; postsynaptic In descriptions of synapse organization, the presynaptic cell is the transmitting neuron and the postsynaptic is the neuron, muscle, or gland cell that receives the signal.

The central nervous system is lacking in animals that have _____.

radial symmetry

Which would be present in an animal with a nerve net?

radial symmetry Explanation: Hydras, jellies, and other cnidarians are the simplest animals with nervous systems. These animals have radially symmetrical bodies organized around a central digestive compartment, the gastrovascular cavity. In most cnidarians, interconnected nerve cells form a diffuse nerve net, which controls the contraction and expansion of the gastrovascular cavity. Unlike the nervous systems of other animals, the nerve net of cnidarians lacks clusters of neurons that perform specialized functions. In more complex animals, the axons of multiple nerve cells are often bundled together, forming nerves. These fibrous structures channel and organize information flow along specific routes through the nervous system. For example, sea stars have a set of radial nerves connecting to a central nerve ring. Within each arm of a sea star, the radial nerve is linked to a nerve net from which it receives input and to which it sends signals controlling muscle contraction. Animals that have elongated, bilaterally symmetrical bodies have even more specialized nervous systems. Such animals exhibit cephalization, an evolutionary trend toward a clustering of sensory neurons and interneurons at the anterior (front) end of the body. These anterior neurons communicate with cells elsewhere in the body, including neurons located in one or more nerve cords extending toward the posterior (rear) end. In nonsegmented worms, such as the planarian, which has a small brain and longitudinal nerve cords constitute the simplest clearly defined central nervous system (CNS).

An increase in the size of the hindbrain of vertebrates has been associated with an increased ability in ____________.

rapid, complex movement Explanation: The hindbrain, part of which forms the cerebellum, controls involuntary activities, such as blood circulation, and coordinates motor activities, such as locomotion. Free swimming ray-finned fishes, such as the tuna, control movement in three dimensions in the open water and have a relatively large cerebellum. In comparison, the cerebellum is much smaller in species that don't swim actively, such as the lamprey. Olfaction is centered in the forebrain, so we would expect increases in this region to be associated with increased olfactory ability. The midbrain processes input from vision in vertebrates. Substantial further processing of sensory information occurs in the well-developed forebrain of humans and other mammals. The midbrain processes sensory input associated with hearing. An increase in the size of the forebrain is associated with an increased ability to reason, as seen in humans and other mammals and to lesser degrees in some other vertebrates.

Injury localized to the hypothalamus would most likely disrupt

regulation of body temperature.

The corpus callosum connects the __________.

right and left cerebral hemispheres

An injury to the temporal lobe will likely impair the function of the

sense of hearing Explanation: Sense of touch: Parietal lobe Sense of sight: Occipital lobe Sense of taste: Parietal lobe (temperature, taste, touch and movement)

The pathway that a nervous signal travels in completing a typical vertebrate reflex is ________.

sensors; sensory neurons; interneurons of the spinal cord; motor neuron In vertebrates, the spinal cord runs lengthwise inside the vertebral column known as the spine. The spinal cord conveys information to and from the brain and generates basic patterns of locomotion. It also acts independently of the brain as part of the simple nerve circuits that produce reflexes, the body's automatic responses to certain stimuli. A reflex protects the body by providing a rapid, involuntary response to a particular stimulus.

A neuron that transmits an impulse to the central nervous system after the neuron is stimulated by the environment is called a(n) __________.

sensory neuron

The divisions of the nervous system that have antagonistic, or opposing, actions are _____.

sympathetic and parasympathetic systems

The equilibrium potential for a particular ion is __________.

the magnitude of the membrane voltage at equilibrium for that ion

The period in which an axon membrane cannot act is called __________.

the refractory period Explanation: "Saltatory conduction" is incorrect because this occurs when an action potential "leaps" along the axon from one node of Ranvier to the next node. "Depolarization" is incorrect because this is the reduction in the magnitude of the membrane potential of a neuron. "A resting potential" is incorrect because is the membrane potential of a neuron typically between -60 mV and -80 mV during which time the neuron is not sending a signal. "An action potential" is incorrect because action potential results in massive changes in membrane voltage and a shift to depolarization of the membrane.

The conversion of a stimulus into an action potential by a receptor cell is called ________.

transduction

Patients with damage to Wernicke's area have difficulty

understanding language. Explanation: Wernicke's area is active when speech is heard and comprehended

The transduction of sound waves into action potentials occurs

when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neuron.