BIOL 5600 Exam 2 | Complete Solutions (Verified Answers)

BIOL 5600 Exam 2 | Complete Solutions (Verified Answers) What are the three structural classifications of neurons? Bipolar, unipolar, and multipolar neurons. Where are bipolar neurons primarily found? In sensory organs like the retina and olfactory epithelium. What is the main function of unipolar neurons? To carry sensory information such as touch or pain from the periphery to the spinal cord. What distinguishes multipolar neurons from other types? They have multiple processes, including one axon and several dendrites, allowing extensive signal integration. What is the role of unipolar neurons in the skin sensory pathway? They transmit sensory information from peripheral receptors to the spinal cord. What is the approximate length of the adult mammalian spinal cord? About 45 cm. What is the cauda equina? A bundle of lumbar and sacral nerves that continue beyond the termination of the spinal cord. How many pairs of spinal nerves are there? 31 pairs. What are the five categories of spinal nerves? Cervical, thoracic, lumbar, sacral, and coccygeal nerves. What areas do cervical nerves innervate? The back of the head, neck, shoulders, arms, hands, and diaphragm. What is the function of the dorsal root of a spinal nerve? To transmit sensory input from the body to the spinal cord. What is the function of the ventral root of a spinal nerve? To send motor commands from the spinal cord to muscles and glands. What is a spinal reflex? A rapid, involuntary motor response to a specific sensory stimulus. What is a reflex arc? The pathway that mediates a reflex, including sensory receptors, afferent neurons, interneurons, efferent neurons, and effectors. What is the difference between monosynaptic and polysynaptic reflexes? Monosynaptic reflexes involve a single synapse, while polysynaptic reflexes involve one or more interneurons. What is the organization of gray matter in the spinal cord? Gray matter contains unmyelinated neuronal cell bodies organized into clusters called nuclei. What is the primary function of white matter in the spinal cord? To carry ascending sensory and descending motor information between different spinal segments and the brain. What are ascending tracts in the spinal cord responsible for? Carrying sensory information to the brain. What are descending tracts in the spinal cord responsible for? Conveying motor commands to the body. What is the dorsal column-medial lemniscus (DCML) pathway? A pathway that transmits signals related to fine touch, vibration, and proprioception. How does the spinothalamic tract differ from the DCML pathway? The spinothalamic tract conveys pain, temperature, and crude touch, decussating within the spinal cord. What happens to sensory perception when there is a lesion in the DCML pathway below the medulla? It causes ipsilateral sensory loss. What happens to sensory perception when there is a lesion in the spinothalamic tract? It causes contralateral loss of pain and temperature sensations below the injury level. What is the consequence of spinothalamic tract lesions? They cause contralateral loss of pain and temperature sensations below the injury level. What are the two main categories of descending tracts? Pyramidal tracts and extrapyramidal tracts. What do pyramidal tracts govern? Voluntary movement. Where do corticospinal tracts originate? From upper motor neurons in the cerebral cortex. What percentage of corticospinal fibers decussate at the medullary pyramids? Approximately 75%. What is the function of the corticobulbar tract? It controls head and neck movements by synapsing with cranial nerve nuclei in the brainstem. What do extrapyramidal tracts control? Involuntary and postural movements. What is the role of the tectospinal tract? It integrates visual and auditory cues to orient the head and neck. Which tract provides ipsilateral control over balance and respiration? The reticulospinal tract. What does the vestibulospinal tract control? Extensor muscles and posture. What is the mnemonic for remembering descending tracts? He drove a Honda CRV to Disneyland: C - corticospinal, R - rubrospinal, V - vestibulospinal, T - tectospinal, O - olivospinal. What are the three major regions of the brain? Forebrain, midbrain, and hindbrain. What does the forebrain consist of? The telencephalon and diencephalon. What functions does the cerebral cortex handle? Higher-order functions like perception, thought, language, and decision-making. What is the primary function of the thalamus? Regulating sensory processing and autonomic functions. What is the role of the midbrain? It serves as a bridge between the forebrain and hindbrain, playing key roles in sensory relay and motor coordination. What structures are included in the hindbrain? The pons, medulla oblongata, and cerebellum. What is lateralization in the brain? The functional specialization of the left and right hemispheres. What are the dominant functions of the left hemisphere according to Sperry's Split Brain Theory? Analytical and logical tasks, including language, math, science, and reasoning. What is the primary function of the right hemisphere? Creative and holistic tasks, including music, art, spatial awareness, and emotional interpretation. How do the left and right hemispheres communicate? Through the corpus callosum. What is sexual dimorphism in brain function? Measurable structural and functional differences between male and female brains. How does the corpus callosum differ between genders? Females typically have a wider corpus callosum, facilitating more cross-hemispheric communication. What is the role of Wernicke's area? It is the center for language comprehension, enabling understanding of spoken and written language. What happens when Wernicke's area is damaged? It leads to fluent aphasia, where speech is grammatically correct but lacks meaning. What are sulci and gyri in the cerebrum? Sulci are shallow grooves, while gyri are the ridges or folds of the cerebral cortex. What separates the frontal and parietal lobes? The central sulcus. What is the primary function of the frontal lobe? Governing voluntary movement, decision-making, and personality. What does the primary motor cortex do? Generates conscious movement commands through the somatic motor system. What is the function of Broca's area? It controls speech production and motor aspects of language. What is the primary function of the parietal lobe? Sensory integration and awareness. What does the primary somatosensory cortex receive input about? Touch, pressure, temperature, pain, and proprioception. What is a sensory homunculus? A mapping of sensations to specific body regions maintained by the primary somatosensory cortex. What is the role of the somatosensory association area? It interprets and contextualizes sensory input, linking it to past experiences and memories. What is the primary visual area of the occipital lobe responsible for? Interpreting basic visual features such as shape, color, and motion. What does the temporal lobe govern? Auditory processing and memory formation. What is the function of the thalamus? Acts as the brain's relay center, directing nearly all sensory information to appropriate cortical areas. What does the hypothalamus regulate? The autonomic nervous system and coordinates with the pituitary gland to influence hormone secretion. What are some functions controlled by the hypothalamus? Circadian rhythms, hunger, thirst, body temperature, aggression, sexual behavior, and maternal instincts. What is the limbic system's primary role? Integrating emotion, memory, and motivation. Which structures are core components of the limbic system? Thalamus, hypothalamus, hippocampus, and amygdala. What is the function of the hippocampus? Essential for memory formation and retrieval. What does the amygdala process? Emotional responses such as fear, anger, and anxiety. How does the limbic system influence behavior? It overlays emotional context onto sensory input, affecting behavior and autonomic responses. What is the gut-brain axis? The connection between the limbic system and visceral health, where emotional stress can trigger physical ailments. What role does the midbrain play? Acts as a relay station for auditory and visual information and coordinates reflexive responses. What is the function of the pons? Connects the cerebrum, cerebellum, and medulla, playing a role in respiratory control and circadian rhythms. What vital functions does the medulla oblongata regulate? Heart rate, blood pressure, and respiration. What is the significance of the area postrema? Acts as the vomiting center, detecting toxins in the bloodstream and triggering the emetic response. What can result from brainstem dysfunction? Symptoms such as double vision, hearing loss, facial weakness, and impaired coordination, depending on the lesion site. What neurotransmitter activity is associated with schizophrenia? Excess dopamine. What neurotransmitter deficiencies are linked to depression? Deficiencies in serotonin and norepinephrine. What treatments are commonly used for depression? SSRIs (e.g., Prozac) and SNRIs (e.g., Pristiq) that increase neurotransmitter availability. What is the role of the reticular formation? Maintains consciousness and arousal. What happens at the pyramidal decussation? Motor fibers cross over to the opposite side, forming the lateral corticospinal tract. What are the consequences of medullary damage? Difficulty swallowing, disrupted breathing, and heart rate abnormalities. What is the reticular activating system (RAS)? The ascending component of the reticular formation responsible for maintaining alertness and consciousness. How does the descending reticulospinal tract function? It regulates movement coordination, muscle tone, and autonomic functions such as blood pressure and respiration. What disorders are associated with the reticular formation and RAS? Hypersomnia, coma, schizophrenia, PTSD, Parkinson's disease, and narcolepsy. What is the cerebellum's primary function? Integrating proprioceptive information and coordinating voluntary movement. What are the two major tracts for communication between the cerebellum and cerebrum? Cerebellar-thalamo-cortical (efferent) tract and cortico-ponto-cerebellar (afferent) tract. What are cerebellar peduncles? Fiber bundles connecting the cerebellum to the brainstem, divided into inferior, middle, and superior peduncles. What is the function of the anterior and posterior spinocerebellar tracts? They convey proprioceptive information from muscles and joints to the cerebellum. What are the three protective membranes covering the brain and spinal cord? Dura mater, arachnoid mater, and pia mater. What is the role of the dura mater? It forms a dual sheet that separates at points to create dural sinuses for venous blood drainage. What is the function of cerebrospinal fluid (CSF)? It circulates through the ventricles and subarachnoid spaces, maintaining brain buoyancy and nutrient exchange. How is CSF produced? By the choroid plexus, specialized epithelial tissue in the ventricles. What is hydrocephalus? A disorder caused by impaired drainage of CSF, leading to increased intracranial pressure. What is the structure of the ventricular system? It includes lateral ventricles, interventricular foramen, third ventricle, cerebral aqueduct, and fourth ventricle. What is the total volume of CSF in the human body? 150-270 mL. What cranial nerves are purely sensory? Cranial nerves I (olfactory), II (optic), and VIII (vestibulocochlear). What is the function of cranial nerve III (oculomotor)? Controls eye movement and pupil constriction. What is the role of cranial nerve V (trigeminal)? Provides sensory input from the face, teeth, and tongue, and motor control of chewing. What is the primary function of cranial nerve VII (facial)? Motor control of facial expressions and secretion of tears and saliva; sensory for taste. What is the significance of the cerebellum in motor learning? It ensures smooth execution of muscle activity, posture maintenance, and balance. What is the effect of trauma to the medulla or upper spinal cord? It can sever communication between the RAS and spinal circuits, leading to loss of voluntary and autonomic control. What are the effects of PTSD on the reticular system? It is associated with hyperactivity, resulting in exaggerated startle reflexes, flashbacks, and anxiety. What is the role of the arachnoid mater? It contains arachnoid villi that allow cerebrospinal fluid to reenter the venous system. What is the function of the superior cerebellar peduncle? It contains both afferent and efferent tracts, primarily sending cerebellar outputs to the diencephalon and midbrain. What is the significance of the middle cerebellar peduncle? It is the largest and carries only afferent fibers from the pontine nuclei to the cerebellum. What is the function of the Vestibulocochlear nerve (VIII)? Hearing and balance What are the primary functions of the Glossopharyngeal nerve (IX)? Controls throat muscles, salivation, taste; monitors blood pressure and gas levels What is the primary role of the Vagus nerve (X)? Parasympathetic control of visceral organs; decreases heart rate and aids digestion What does the Accessory nerve (XI) control? Swallowing and head/neck movement What is the function of the Hypoglossal nerve (XII)? Controls tongue movements during speech and swallowing What types of fibers do spinal nerves contain? Mixed fibers, including both sensory and motor fibers What is a dermatome? A defined region of skin that receives sensory input from a single spinal nerve What are the major categories of CNS disorders? Infections, neoplasia, stroke, and neurodegenerative diseases What is meningitis? An infection involving the meninges What is the most common type of stroke? Ischemic stroke What causes hemorrhagic stroke? Vessel rupture leading to bleeding into or around brain tissue What is Multiple Sclerosis (MS)? A chronic autoimmune neurodegenerative disease characterized by inflammation and demyelination within the CNS What leads to the symptoms of Multiple Sclerosis? Disruption of signal conduction due to sclerotic plaques and neuronal loss What are common symptoms of Multiple Sclerosis? Visual disturbances, muscle weakness, numbness, and coordination issues What is the primary treatment goal for Multiple Sclerosis? To reduce inflammation and delay disease progression What is Alzheimer's Disease (AD)? The most common form of dementia, marked by neuritic plaques and neurofibrillary tangles What is the amyloid hypothesis in Alzheimer's Disease? Abnormal cleavage of amyloid precursor protein leads to toxic amyloid-beta-42 peptide aggregation What characterizes Parkinson's Disease (PD)? Progressive degeneration of dopaminergic neurons in the substantia nigra, leading to motor symptoms What is the hallmark pathological feature of Parkinson's Disease? Insoluble Lewy bodies formed from misfolded alpha-synuclein What is Amyotrophic Lateral Sclerosis (ALS)? The most common motor neuron disease, involving progressive degeneration of upper and lower motor neurons What is the primary risk factor for stroke? Hypertension What are the non-motor symptoms associated with Parkinson's Disease? Depression, cognitive decline, and sleep disturbances What is the typical pattern of Multiple Sclerosis progression? Relapsing-remitting pattern followed by chronic progression What is the role of corticosteroids in treating MS? To accelerate recovery during relapses What are the initial symptoms of ALS? The condition typically begins in the upper limbs, causing muscle weakness, atrophy, and spasticity. What is the typical prognosis for ALS patients? ALS is usually fatal due to respiratory failure within three to five years of onset. What percentage of ALS cases are hereditary? About 10% of ALS cases are hereditary, while 90% are sporadic. What is glutamate excitotoxicity in the context of ALS? It results from defective astrocytes failing to clear excess glutamate, leading to neuronal overactivation and cell death. What role do SOD1 mutations play in ALS? SOD1 mutations impair superoxide dismutase, allowing reactive oxygen species to accumulate and cause oxidative stress. What are Bunina bodies? Bunina bodies are small eosinophilic inclusions found specifically within lower motor neurons and are considered a disease-specific hallmark of ALS. What are the main components of the Peripheral Nervous System (PNS)? The PNS includes all neural structures outside the brain and spinal cord, serving as the communication link between the CNS and the rest of the body. What is the function of the afferent (somatosensory) system? It carries sensory information from receptors in the body to the CNS. How are sensory receptors classified?