A&P Multiple Choice Exam #5

Summarize how the 31 pairs of spinal nerves attach to the spinal cord.

- 8 pairs of cervical nerves - 12 pairs of thoracic nerves - 5 pairs of lumbar nerves - 5 pairs of sacral nerves - 1 pair of tiny coccygeal nerves

What is a nerve? Describe the three connective tissues associated with nerves.

- A nerve is a cord-like organ consisting of parallel bundles of peripheral axons enclosed by connective tissue wrappings. 1. Each axon within a nerve is surrounded by a thin layer of loose connective tissue, the endoneurium. 2. A perineurium is a connective tissue wrapping that bundles groups of fibers into fascicles. 3. An epineurium bundles all fascicles into a nerve.

What is a synapse?

- A synapse is a junction that mediates information transfer from one neuron to the next or from a neuron to an effector cell- its where the action is.

How can consciousness be described clinically?

- Consciousness is defined on a continuum that grades behavior in response to stimuli as (1) alertness, (2) drowsiness or lethargy (which proceeds to sleep), (3) stupor, and (4) coma.

What are the key characteristics of neuronal pathways?

- Decussation - Relay - Somatotopy - Symmetry

What is an EEG? Distinguish between alpha, beta, theta, and delta brain waves.

- EEGs are used for diagnosing epilepsy and sleep disorders, in research on brain function, and to determine brain death. -Alpha waves (8-13 Hz) are relatively regular and rhythmic, low-amplitude, synchronous waves. In most cases, they indicate a brain that is "idling"—a calm, relaxed state of wakefulness. -Beta waves (14-30 Hz) are also rhythmic, but less regular than alpha waves and with a higher frequency. Beta waves occur when we are mentally alert, as when concentrating on some problem or visual stimulus. -Theta waves (4-7 Hz) are still more irregular. Though common in children, theta waves are uncommon in awake adults but may appear when concentrating. -Delta waves (4 Hz or less) are high-amplitude waves seen during deep sleep and when the reticular activating system is suppressed, such as during anesthesia. In awake adults, they indicate brain damage.

What are ganglia? Ganglia of sensory and motor neurons are associated with which types of nerve fibers?

- Ganglia are collections of neuron cell bodies associated with nerves in the PNS. -Ganglia associated with afferent nerve fibers are cell bodies of sensory neurons; ganglia associated with efferent nerve fibers are mostly cell bodies of autonomic motor neurons.

What causes synaptic delay, and how does this affect the rate of neural transmission?

- It reflects the time required for neurotransmitter to be released, diffuse across the synaptic cleft, and bind to receptors. - Typically, this synaptic delay lasts 0.3-5.0 ms, making transmission across the chemical synapse the rate-limiting (slowest) step of neural transmission.

Describe the difference between presynaptic neurons, postsynaptic neurons, axodendritic synapses, and axosomatic synapses.

- Presynaptic neuron- neuron conducting impulses toward the synapse - Postsynaptic neuron- neuron transmitting the electrical signal away from the synapse - Axodendritic synapses- between the axon endings of one neuron and the dendrites of other neurons - Axosomatic synapses- between axon endings of one neuron and the cell body of another neuron

What are rami? Compare and contrast dorsal rami and ventral rami.

- Rami lie distal to and are lateral branches of the spinal nerves that carry both motor and sensory fibers. - The back is innervated by the dorsal rami with each ramus innervating the muscle in line with the point of origin from the spinal column. - Only in the thorax are the ventral rami arranged in a simple segmental pattern corresponding to that of the dorsal rami.

Distinguish between flaccid and spastic paralysis, and between paralysis and paresthesia.

- Severe damage to the ventral root or ventral horn results in flaccid paralysis, since nerve impulses are not transmitted to the skeletal muscles. When upper motor neurons of the primary motor cortex are damaged, spastic paralysis occurs, in which voluntary control over skeletal muscle is lost. -Any localized damage to the spinal cord or its roots leads to paralysis (loss of motor function) or paresthesia (loss of sensory function).

Where are the limbic system and reticular formation located? Explain the role of each of these functional systems.

- The limbic system is involved with emotions and is extensively connected throughout the brain, allowing it to integrate and respond to a wide variety of environmental stimuli. - The reticular formation extends through the brain stem, keeping the cortex alert via the reticular activating system and dampening familiar, repetitive, or weak sensory inputs.

What causes presynaptic inhibition, and what is the end result of it?

-Presynaptic inhibition results when another neuron inhibits the release of an excitatory neurotransmitter from a presynaptic cell.

Summarize the three levels of motor control and the nervous system structures associated with them.

-Segmental is the lowest level and consists of the spinal cord circuits. -Projection has direct control of the spinal cord and acts on direct and indirect motor pathways. - Precommand is made up of the cerebellum and the basal nuclei and is the highest level.

Describe the difference between neurotransmitter receptors (channel-linked receptors vs. G-protein-linked receptors).

1. Channel- linked receptors are ligand-gated ion channels that cause changes in the membrane potential of the target cell. 2. G protein-coupled receptors act through second messengers, resulting in slow, prolonged responses, such as closing or opening of channels, changes in enzyme activity, or modification of other proteins.

Describe the difference between serial processing and parallel processing in neurons. Which are reflexes?

1. Serial processing is exemplified by spinal reflexes and involves sequential stimulation of the neurons in a circuit. 2. Parallel processing results in inputs stimulating many pathways simultaneously and is vital to higher-level mental functioning.

Describe the gross and microscopic structure of the spinal cord.

1.The spinal cord extends from the foramen magnum of the skull to the level of the first or second lumbar vertebra and provides a wo-way conduction pathway to and from the brain and serves as a major reflex center. 2. Fibrous extensions of the pia mater anchor the spinal cord to the vertebral column and coccyx, preventing excessive movement of the cord. 3. The spinal cord has 31 pairs of spinal nerves along its length that define the segments of the cord. 4. There are cervical and lumbar enlargements for the nerves that serve the limbs and a collection of nerve roots (cauda equina) that travel through the vertebral column to their intervertebral foramina.

Identify the brain areas associated with language and memory.

A.The ability to both speak and understand language is produced through coordination of several brain areas, notably Broca's area and Wernicke's area B. Memory is the storage and retrieval of information, and there are different kinds of memory: declarative (fact-based), procedural (skills), motor, and emotional. - Memory consolidation involves communication between brain areas, allowing memories to become permanent. 28. Compare and contrast the events and importance of slow-wave and REM sleep.

What are the major lobes, fissures, and functional areas of the cerebral cortex?

Gyri (Gyrus) - Ridges or folds in the brain Sulci (sulcus) - grooves in the brain Longitudinal Fissure - Midline that separates the cerebral hemispheres Transverse cerebral fissure - Separates the cerebellum with the cerebral hemispheres Central Sulcus - extends across the lateral surface of the cerebrum from superior to inferior (about midway along the length of the brain) Precentral gyrus - Primary motor cortex, anterior of the central sulcus Postcentral gyrus - Primary somatosensory cortex Frontal Lobe - Voluntary motor function, concentration verbal communication, decision making, motivation, aggression, sense of smell, planning, personality and mood Parietal Lobe - Major center for receiving and evaluating most sensory information (except olfaction, hearing and vision) Occipital lobe - receiving and integrating visual input and storing visual memories Temporal lobe - Receives and evaluates input for smell and hearing. Abstract thought and judgementInsula - Social emotions (lust, disgust, pride, humiliation, guilt & atonement) Lights up when people crave drugs, feel pain and processes taste (gustatory)

Summarize the three basic levels of neural integration in sensory systems. (Figure 13.2)

STEP 1 Receptor level: sensory receptors STEP 2 Circuit level: processing in ascending pathways STEP 3 Perceptual level: processing in cortical sensory areas

Compare and contrast the somatic and autonomic peripheral motor nerve endings in terms of their structure and their neurotransmitters.

- The terminals of the somatic motor fibers that innervate voluntary muscles form elaborate neuromuscular junctions with their effector cells and they release the neurotransmitter acetylcholine. - The junctions between autonomic motor endings and the visceral effectors involve varicosities and release either acetylcholine or epinephrine as their neurotransmitter.

Describe how electrical synapses are different from chemical synapses structurally and in the way they transmit information.

- They consist of gap junctions like those found between certain other body cells. Their channel proteins (connexons) connect the cytoplasm of adjacent neurons and allow ions and small molecules to flow directly from one neuron to the next. These neurons are electrically coupled, and transmission across these synapses is very rapid. - They are specialized to allow the release and reception of chemical messengers known as neurotransmitters. A typical chemical synapse is made up of two parts: A knoblike axon terminal of the presynaptic neuron, which contains many tiny, membrane-bound sacs called synaptic vesicles, each containing thousands of neurotransmitter molecules -A neurotransmitter receptor region on the postsynaptic neuron's membrane, usually located on a dendrite or the cell body

What is the difference between excitatory and inhibitory postsynaptic potentials?

-An excitatory postsynaptic potential creates a local depolarization in the membrane of the postsynaptic neuron that brings it closer to threshold. An inhibitor postsynaptic potential does the opposite; it hyperpolarizes the membrane and brings it farther away from threshold.

Describe the general function of the basal nuclei (basal ganglia).

-Basal Nuclei consist of a group of subcortical nuclei that have overlapping motor control with the cerebellum that regulate cognition and emotion.

How is cerebrospinal fluid formed? Describe its circulatory pathway.

-CSF is a watery "broth" similar in composition to blood plasma, from which it is formed. However, it contains less protein than plasma and its ion concentrations are different. For example, CSF contains more -Once produced, CSF moves freely through the ventricles. CSF enters the subarachnoid space via the lateral and median apertures in the walls of the fourth ventricle. The long cilia of the ependymal cells lining the ventricles help keep the CSF in constant motion. In the subarachnoid space, CSF bathes the outer surfaces of the brain and spinal cord and then returns to the blood in the dural sinuses via the arachnoid granulations.

Compare and contrast regeneration of nerve fibers in the CNS and the PNS.

-Damaged CNS nerve fibers almost never regenerate, but if a PNS nerve fiber is cut or compressed, and the cell body remains intact, axons can regenerate.

What factors affect the formation of long-term memories?

-Emotional state. We learn best when we are alert, motivated, surprised, or aroused. For example, when we witness shocking events, transferral is almost immediate. Norepinephrine, a neurotransmitter involved in memory processing of emotionally charged events, is released when we are excited or "stressed out," which helps to explain this phenomenon. -Rehearsal. Rehearsing or repeating the material enhances memory. -Association. Tying "new" information to "old" information already stored in LTM appears to be important in remembering facts. -Automatic memory. Not all impressions that become part of LTM are consciously formed. A student concentrating on a lecturer's speech may record an automatic memory of the pattern of the lecturer's tie.

Explain the function of these reflexes: flexor, crossed-extensor, plantar, abdominal.

-Flexor causes automatic withdrawal of the threatened body part from the stimulus - Crossed- extensor accompanies the flexor reflex in weight-bearing limbs and is particularly important in maintaining balance - Plantar tests the integrity of the spinal cord from L4 to S2 and indirectly determines if the corticospinal tracts are functioning properly - Abdominal check the integrity of the spinal cord and ventral rami from T8 to T12

Describe the location of the diencephalon and name its subdivisions and functions.

-Forming the central core of the forebrain and surrounded by the cerebral hemispheres -Thalamus plays a key role in mediating sensation, motor activities, cortical arousal, learning, and memory. -Hypothalamus is the control center of the body, regulating ANS activity, initiating physical responses to emotions, and regulating body temperature, food intake, water balance, thirst, sleep-wake cycles, and endocrine function. -Epithalamus includes the pineal gland, which secretes melatonin, and regulates the sleep-wake cycle.

How are neurotransmitters classified according to their effects and their actions?

-Neurotransmitters fall into several chemical classes: acetylcholine, the biogenic amines, amino acid derived, peptides, purines, and gases and lipids - Functional classifications of neurotransmitters consider whether the effects are excitatory or inhibitory and whether the effects are direct or indirect, including neuromodulators that affect the strength of synaptic transmission.

What is a neurotransmitter, and what are examples of daily activities affected by them?

-Neurotransmitters, along with electrical signals, are the "language" of the nervous system—the means by which neurons communicate, integrate, and send messages to the rest of the body. -Sleep, thought, rage, hunger, memory, movement, and even your smile reflect the actions of these versatile molecules.

How are peripheral nerves classified?

-Peripheral nerves, either cranial or spinal, are classified according to the direction in which they transmit impulses.

Classify general sensory receptors by stimulus detected, body location, and structure.

-Stimulus detected 1. Mechanoreceptors: stimulated by mechanical force, such as touch, pressure, vibration, stretch. 2. Thermoreceptors respond to changes in temperature. 3. Photoreceptors detect light. 4. Chemoreceptors are stimulated by chemicals, such as odorants, taste stimuli, or chemical components of body fluids. 5. Nociceptors respond to painful stimuli and can stimulate some types of thermoreceptors, mechanoreceptors, or chemoreceptors. -Location 1. Exteroceptors located at or near the body surface and detect stimuli arising from outside the body, such as touch, pressure, pain, skin temperature receptors, & most special senses. 2. Interceptors, associated with internal organs & vessels, monitor chemical changes, stretch, or temperature. 3. Proprioceptors are found within skeletal muscles, tendons, joints, ligaments, and connective tissue coverings of bones and muscles and relay information concerning body movements. - Structure 1. Simple receptors are general senses and may be nonencapsulated or encapsulated dendritic endings. a. Nonencapsulated dendritic endings are free nerve endings and detect temperature, pain, itch, light touch, or are located at the base of hair follicles. b. Encapsulated dendritic endings consist of a dendrite enclosed in a connective tissue capsule and detect discriminatory touch, initial, continuous, and deep pressure, and stretch of muscles, tendons, and joint capsules.

Describe the difference between the stretch reflex and the tendon reflex.

-Stretch reflexes cause muscle contraction in response to increased muscle length (stretch). The polysynaptic tendon reflexes, on the other hand, produce exactly the opposite effect: Muscles relax and lengthen in response to tension.

Compare and contrast temporal and spatial summation at the postsynaptic neuron.

-Summation by the postsynaptic neuron is accomplished in two ways: temporal summation, which occurs in response to several successive releases of neurotransmitter, and spatial summation, which occurs when the postsynaptic cell is stimulated at the same time by multiple terminals.

Describe the structure and function of the cerebellum.

-The cauliflower-like cerebellum -By processing inputs received from the cerebral motor cortex, various brain stem nuclei, and sensory receptors, the cerebellum provides the precise timing and appropriate patterns of skeletal muscle contraction for smooth, coordinated movements and agility needed for our daily living—driving, typing, and for some of us, playing the tuba.

What are the three major regions of the brain stem, what is the function of each area?

-The midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing. -Pons contains fiber tracts that complete conduction pathways between the brain and spinal cord, as well as giving rise to some cranial nerves, and contains some important nuclei, including one that helps control breathing. -Medulla oblongata act as crossover points for corticospinal motor tracts, resulting in the contralateral control of voluntary movements, as well as housing some ascending sensory tracts, and several visceral motor nuclei controlling vital functions such as cardiac and respiratory rate.

What is the function of the perception of pain? Distinguish among these concepts: pain threshold, visceral pain, referred pain.

-The perception of pain protects the body from damage and is stimulated by extremes of pressure and temperature, as well as chemicals released from damaged tissues. -The pain threshold: the stimulus intensity at which we begin to perceive pain & is the same for most people, although pain tolerance is a genetically determined trait that varies among people. -Visceral pain results from stimulation of receptors within internal organs from stimuli such as extreme stretch, ischemia, chemical irritation, and muscle spasms. a. Visceral pain travels along the same fiber tracts as somatic pain impulses, giving rise to referred pain that is located in an area different from the affected area.

What are the names and locations of the ventricles of the brain?

-There are four ventricles in the brain: paired lateral ventricles deep within each cerebral hemisphere, a third ventricle within the diencephalons, and a fourth ventricle within the hindbrain.

Explain lateralization of cortical function.

-There is lateralization of cortical functioning, in which each cerebral hemisphere has unique control over abilities not shared by the other half. a. Often, the left hemisphere dominates language abilities, math, and logic, and the right hemisphere dominates visual-spatial skills, intuition, emotion, and artistic and musical skills; however, both sides of the brain are involved in all skills.

How do neuronal pools organize neurons?

-These functional groups of neurons integrate incoming information from receptors or different neuronal pools and then forward the processed information to other destinations.(MotororSensory)

How does information transfer occur across chemical synapses (6 steps)?

1. Action potential arrives at axon terminal. 2. Voltage-gated Ca2+ channels open and Ca2+ enters the axon terminal. 3. Ca2+ entry causes synaptic vesicles to release neurotransmitter by exocytosis. 4. Neurotransmitter diffuses across the synaptic cleft and binds to specific receptors on the postsynaptic membrane. 5. Binding of neurotransmitter opens ion channels, creating graded potential. 6. Neurotransmitter effects are terminated.

Compare and contrast the events and importance of slow-wave and REM sleep.

Sleep is a state of partial unconsciousness from which a person can be aroused, and has two major types that alternate through the sleep cycle. Non-rapid eye movement (NREM): sleep has four stages. Rapid eye movement (REM): sleep is when most dreaming occurs. Sleep patterns change throughout life, and are regulated by the hypothalamus. NREM sleep is considered restorative, and REM sleep allows the brain to analyze events or eliminate meaningless information.

At the receptor level of neural integration, summarize the following: generator potentials, receptor potentials, and adaptation.

a. If the receptor is part of a sensory neuron, the graded potentials produced are generator potentials that can cause the generation of action potentials on the sensory neuron. b. If the receptor is a separate structure from the sensory neuron, the graded potentials produced are receptor potentials that may cause generator potentials on the sensory neuron. c. Many receptors exhibit adaptation, in which a constant stimulus results in a gradual decrease in receptor sensitivity.

Describe the six aspects of processing at the perceptual level.

a. Perceptual detection sums input from several receptors and is the simplest level of perception. b. Magnitude estimation: ability to detect stimulus intensity through frequency coding. c. Spatial discrimination allows identification of the site or pattern of stimulation through spatial discrimination. d. Feature abstraction mechanism through which we identify complex features of a sensation. e. Quality discrimination: involves the ability to differentiate specific qualities of a particular sensation. f. Pattern recognition:ability to recognize a pattern in a complete scene.

How do space constraints affect brain development?

because the brain grows faster than the skull, it folds to fit in the available space