Lecture Exam 3 Study topics PDF

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UNIT 3 Lecture Exam Study Guide Fundamentals of the Nervous system and Nervous tissue (Chapter 11) •

What are the basic functions of the nervous system? Fig. 11.1

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Know the different levels of organization of the nervous system Fig.1

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Neuroglia in the CNS and PNS – locations and functions *Astrocytes= most abundant, not found in Medulla or Hypothalamus. *Microglial= Phagocytic

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List the special characteristics of neurons Pg. 392

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Structure of the motor neuron – know all the features listed on this figure along with their functions Fig 11.5

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Where o o o

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Dendrites and Axon: functional characteristics – where are graded an action potentials generated? o Processes of cell body, dendrites receive and axons transmit o Graded potentials are generated on the postsynaptic membrane (neurolemma) can be excitatory or inhibitory.

are the receptive, conducting and secretory regions of the neuron? Receptive- Dendrites Conductive- Axon Secretory- Axon Terminal

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Axon transport – anterograde versus retrograde movement o Anterograde—away from cell body * Examples: mitochondria, cytoskeletal elements, membrane components, enzymes o Retrograde—toward cell body * Examples: organelles to be degraded, signal molecules, viruses, and bacterial toxins (polio, rabies, tetanus toxin, herpes virus)

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Which cells are responsible for myelination in the CNS and PNS o Schwann Cells- PNS o Oligodendrocytes- CNS

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What is gray and white matter? o White matter * Regions of brain and spinal cord (CNS) with dense collections of myelinated fibers – usually fiber tracts o Gray matter * Mostly neuron cell bodies and nonmyelinated fibers

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Structural classification of neurons Table 11.1

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Functional classification of neurons Table 11.1 o Grouped by direction in which nerve impulse travels relative to CNS o Three types: * Sensory (afferent) * Motor (efferent) * Interneurons

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What are the differences between interneurons, sensory and motor neurons? What are their functions and where are they most commonly seen? Sensory neurons- neurons that carry incoming information from the sensory receptors to the central nervous system (CNS), some unipolar and some bipolar, AFFERENT Motor neurons- carry out going information to the muscle and glands (effectors), multipolar, EFFERENT Inter-neurons- within the brain and spinal cord; they communicate internally and process information between sensory inputs and motor outputs (association neurons), multipolar

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Types of membrane ion channels Page 398

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Resting membrane potential Focus

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Depolarization and repolarization

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Define graded potentials. Where do they typically occur in a neuron? o Graded potentials (IPSP (Hyperpolarization) & EPSP (Depolarization)), potentials varying in strength dictated by stimulus strength. o Occur in Dendrites and Cell body plasma membrane via ligand (chemically) gated or mechanically gated channels.

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How are graded potentials generated? Fig 11.10 o Generated by neurotransmitter in the dendrites (chemically gated channels). o Neurotransmitter dictates whether the GP is Excitatory- EPSP or Inhibitory- IPSP.

Fig 11.9

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Define action potentials (AP). Where do they typically occur in a neuron? o Action Potentials are brief long distance signals generated by EPSP at the Axon Hillock. o Conducted along membrane of a cell (Neurolemma, Sarcolemma, Axolemma)

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Generation of an action potential – know the channels involved Focus Fig 11.2

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Propagation of AP– repolarization chases depolarization Fig 11.11

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Relationship

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Know the differences between absolute and relative refractory periods?

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How does the degree of myelination affect conduction velocity?

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Classification of nerve fibers – group A, B and C

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Describe the events occurring at a chemical synapse Focus fig 11.3

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Post-synaptic potentials – EPSP versus IPSP Fig 11.17

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Temporal and spatial summation Fig 11.18

between stimulus strength and AP frequency Fig 11.12

Fig 11.14

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Comparison ofgraded and action potentials Table 11.2

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What is synaptic potentiation? Page 416 o The continuous use of a synapse resulting in enhancement of presynaptic neuron’s ability to excite the postsynaptic neuron, producing larger-then-expected EPSPs. (presynaptic= high Ca+ concentration)

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Structural classification of neurotransmitters (for simplified details refer to lecture ppt) I. Acetylcholine (ACh) * First identified and best understood * Released at neuromuscular junctions * Also used by many ANS neurons and some CNS neurons * Synthesized from acetic acid and choline by enzyme choline acetyltransferase * Degraded by enzyme acetylcholinesterase (AChE) II. Biogenic amines 1. Catecholamines * Dopamine, norepinephrine (NE), and epinephrine: made from the amino acid tyrosine 2. Indolamines * Serotonin, Histamine * All widely used in brain: play roles in emotional behaviors and biological clock III. Amino acids * Amino acids make up all proteins: therefore, it is difficult to prove which are neurotransmitters * Amino acids that are proven neurotransmitters * Glutamate * Aspartate * Glycine * GABA: gamma (g)-aminobutyric acid IV. Peptides (neuropeptides) * Strings of amino acids that have diverse functions * Substance P * Mediator of pain signals * Endorphins * Act as natural opiates; reduce pain perception * Gut-brain peptides * Play a role in regulating digestion

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Functional classification of neurotransmitters o EFFECTS AND ACTIONS

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Neuronal pools and zones Fig11.21

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Serial processing – simple reflex arc Fig 11.22

Central Nervous System (Chapter 12) • Pattern of distribution of gray and white matter in the CNS Fig 12.3

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List the brain ventricles – where are they located? Fig 12.4

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Cerebral hemispheres – gyri/sulci, longitudinal/transverse fissures, 5 lobes

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Cerebral cortex functional domains – motor, sensory and association areas (SEE FIGURE BELOW) Motor areas – where is each area located and specific functions? (SEE FIGURE BELOW) Sensory areas – where is each area located and specific functions? (SEE FIGURE BELOW)

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What is the purpose of a multimodal association area? o Receive inputs from multiple senses and outputs to multiple areas, gives meaning to the information that we receive, store it in memory, tie it to previous experience and knowledge, and decide what action to take.

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Anterior (prefrontal), posterior and limbic areas – location and functions

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Concepts of lateralization andcerebral dominance Page 440 Cerebral white matter – 3 types of fibers

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Basal nuclei of cerebrum– functions o Basal nuclei: A region located at the base of the brain composed of 4 clusters of neurons, or nerve cells. This area of the brain is responsible for body movement and coordination, motor learning, executive functions and behavior, and emotions. The basal nuclei are also called the basal ganglia. ▪ Huntington’s Disease

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Thalamus – functions o The thalamus (from Greek- "chamber") is a large mass of gray matter in the dorsal part of the diencephalon of the brain with several functions such as relaying of sensory signals, including motor signals, to the cerebral cortex, and the regulation of consciousness, sleep, and alertness. ▪ Parkinson’s

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Hypothalamus – mammillary bodies, infundibulum/pituitary, functions -Also partially encloses the third ventricle -Extends from the optic chiasma (cross-over point for the optic nerves) to the mammillary bodies --Infundibulum: stalk that connects to pituitary gland -Contains many nuclei: 1. Mammillary bodies – olfactory relay stations 2. Lateral geniculate nuclei – visual relay center 3. Medial geniculate nuclei – auditory relay center 1. Controls autonomic nervous system (e.g., blood pressure, rate and force of heartbeat, digestive tract motility, pupil size) 2. Physical responses to emotions (limbic system) • Lies at the heart of the limbic system (“emotional brain”) • Perception of pleasure, fear, and rage, and in biological rhythms and drives 3. Regulates body temperature– sweating (cooling) or shivering (heat generation) 4. Regulates sleep-wake cycles – Suprachiasmatic nucleus (biological clock) sets the timing of the sleep cycle in response to light-dark cues from visual pathways 5. Regulates hunger and satiety – in response to nutrient blood levels or hormones 6. Regulates water balance and thirst - releases ADH from posterior pituitary and kidneys retain water, activates thirst center 7. Controls endocrine system • Controls secretions of anterior pituitary gland • Produces posterior pituitary hormones – ADH and oxytocin

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Epithalamus– pineal gland o The epithalamus is a dorsal posterior segment of the diencephalon. A main function of the epithalamus is the secretion of melatonin by the pineal gland. ▪ Insomnia

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Midbrain – cerebral peduncles, corporal quadrigemina, substantia nigra • Joins spinal cord at foramen magnum • Forms part of ventral wall of fourth ventricle • Contains choroid plexus of fourth ventricle • Pyramids- two ventral longitudinal ridges formed by pyramidal tracts • Decussation of the pyramids- crossover of corticospinal tracts 1. Autonomic reflex center • Functions overlap with hypothalamus 2. Cardiovascular center • Cardiac center- adjusts force and rate of heart contraction • Vasomotor center- adjusts blood vessel diameter for blood pressure regulation 3. Respiratory centers • Generate respiratory rhythm • Control rate and depth of breathing 4. Other centers – vomiting, hiccuping, swallowing, coughing, sneezing

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Pons– fourth ventricle, functions

• Pons is a “bridge” composed of conduction tracts • Fourth ventricle separates pons and cerebellum • Fibers of ponso Connect higher brain centers and spinal cord o Relay impulses between motor cortex and cerebellum • Some nuclei involved in reticular formation • Nuclei help maintain normal rhythm of breathing •

Medulla oblongata – decussation of pyramids, nucleus gracilis and cuneatus associated with ascending medial lemniscus tract, functions

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Cerebellum – folia, arbor vitae, cerebellar peduncles

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Cerebellar processing of motor functions, other cognitive functions

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Limbic system “Emotional

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Reticular formation Pages 453-454

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Summary of functions of major brain regions Table 12.1

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Language – roles of Broca’s and Wernecke’s areas o Broca’s- production of coherent speech o Wernecke’s- comprehension and understanding speech

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Memory – hippocampus, short and long term storage of data

brain” Pages 452-453

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EEG and different types of brain waves Fig 12.20b o Alpha- (Restful) 8-13 Hz o Beta- (Awake) 14- 30 Hz o Delta- (Deep sleep, anesthesia) 4-7 Hz o Theta- (Children) 4 Hz

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Consciousness – drowsiness, syncope, coma and brain death

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Types and stages of sleep Fig 12.21

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How is sleep regulated? Page 459 o Circadian Rhythm- regulated by the Hypothalamus (timing), it’s superchiasmatic nucleus (biological clock) regulates preoptic nucleus (sleep-inducing center) By inhibiting the brain’s Reticular Activating System (RAS) the preoptic center puts the cerebral cortex to sleep. Hypothalamic neurons release peptides- orexins= wake-up chemicals. Meninges – dura, arachnoid, pia mater, spaces between meninges Fig 12.22

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Formation, location and circulation of CSF Fig 12.24

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Blood brain barrier  Helps maintain stable internal environment for brain – less chemical variation maintained inside the brain  Blood-borne substances transmitted through the capillaries must pass through three layers before they reach the neurons within the brain: -Continuous endothelium (tight junctions) of capillary walls -Thick basal lamina around capillaries -Feet of astrocytes *Provide signal to endothelium for formation of tight junctions

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Cerebrovascular accidents o Cerebrovascular accidents (CVAs or strokes) o Ischemia- Tissue deprived of blood supply; brain tissue dies, e.g., blockage of cerebral artery by blood clot o Hemiplegia (paralysis on one side), or sensory and speech deficits o Transient ischemic attacks (TIAs)- temporary episodes of reversible cerebral ischemia, lasts 550 minutes, temporary numbness, paralysis or impaired speech o The role of glutamate (excitotoxin)

o Tissue plasminogen activator (TPA) is only approved treatment for stroke •

Degenerative disorders – Alzheimer’s, Parkinson’s disease o Alzheimer's disease (AD): ▪ Progressive degenerative disease of brain that results in dementia ▪ Memory loss, short attention span, disorientation, eventual language loss, irritable, moody, confused, hallucinations ▪ Plaques of beta-amyloid peptide form in brain ▪ Toxic effects may involve prion proteins ▪ Neurofibrillary tangles inside neurons kill them ▪ Brain shrinks – vulnerable regions include hippocampus, forebrain, association areas of the cerebral cortex o Parkinson's disease ▪ Degeneration of dopamine-releasing neurons of substantia nigra ▪ Basal nuclei deprived of dopamine become overactive à persistent tremors at rest ▪ Cause unknown ▪ Mitochondrial abnormalities or protein degradation pathways? ▪ Treatment with L-dopa; deep brain stimulation; gene therapy with inhibitory neurotransmitter GABA; research into stem cell transplants promising

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Spinal cord – gross anatomy and protection Fig 12.27

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Lumbar puncture– location o L2 or below

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Spinal cord - gray matter and spinal roots Fig 12.29

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Organization of gray matter Fig 12.30

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White matter tracts– ascending, descending and transverse Fig 12.31 o Ascending- up to higher centers, CNS (Sensory inputs) o Descending- down to the cord from the brain or within the cord to lower levels (Motor outputs) o Transverse- across from one side of the cord to the other (Commissural fibers)

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Ascending pathway to the brain – 1st, 2nd and 3rd order neurons

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Trace ONLY the dorsal column-medial lemnisci pathway Fig 12.32a

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Descending pathways – general details, upper and lower motor neurons

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Trace ONLY the Pyramidal (corticospinal) pathway Fig 12.33

Peripheral Nervous System (Chapter 13) • Classification of sensory receptors based on stimulus type – what type of stimulus is detected by each of these receptors? o Mechanoreceptors—respond to touch, pressure, vibration, and stretch o Thermoreceptors—sensitive to changes in temperature o Photoreceptors—respond to light energy (e.g., retina) o Chemoreceptors—respond to chemicals (e.g., smell, taste, changes in blood chemistry) o Nociceptors—sensitive to pain-causing stimuli (e.g. extreme heat or cold, excessive pressure, inflammatory chemicals) • Classification of sensory receptors based on location o Exteroceptors -Respond to stimuli arising outside body

-Receptors in skin for touch, pressure, pain, and temperature Most special sense organs o Interoceptors -Respond to stimuli arising in internal viscera and blood vessels -Sensitive to chemical changes, tissue stretch, and temperature o Proprioceptors -Respond to stretch in skeletal muscles, tendons, joints, ligaments, tissue coverings of bones and muscles -Inform brain of one's movements • Non-encapsulated nerve ending receptors of the general senses – thermoreceptors, nociceptors, tactile discs, hair follicle receptors • Encapsulated receptors Table 13.1 – location and type of stimulus sensed

• Processing at the receptor level – concepts of receptive field, transduction • What is generator versus receptor potential? • Processing at the circuit level – first, second and third order neurons • What are sensory, motor and mixed nerves?

• Differences between somatic and visceral fibers? • Hierarchy of motor control Fig. 13.14

• Reflex activity – intrinsic and acquired reflexes o Inborn (intrinsic) reflex: a rapid, involuntary, predictable motor response to a stimulus -EX: Patellar Reflex o Learned (acquired) reflexes result from practice or repetition -EX: Boxing

• Five components of a reflex arc Fig. 13.15

v • Stretch and tendon reflexes – receptors, reflex arcs, effectors • Stretch reflex – Patellar (knee jerk) reflex Focus Figure 13.1 • What is reciprocal activation versus reciprocal inhibition? • Tendon reflex Fig. 13.18...