ANA 109 Unit 6 SG KEY PDF

ANA 109 Unit 6: The Nervous System Week 12: Nervous Signaling Name the two major structures that make up the Central Nervous System: Brain & Spinal Cord Label the anatomy of a standard neuron below: Describe the three anatomical classifications of a neuron: Multipolar: many dendrites + one axon *...

ANA 109 Unit 6: The Nervous System Week 12: Nervous Signaling Name the two major structures that make up the Central Nervous System: Brain & Spinal Cord Label the anatomy of a standard neuron below: Describe the three anatomical classifications of a neuron: Multipolar: many dendrites + one axon **Most common type of neuron Bipolar: one central dendrite + one axon **Special senses: bipolar neurons relay information from rods/cones to retinal ganglion cells of the optic nerve to transmit visual information to the CNS Unipolar (Pseudo-unipolar): One axo-dendritic process that splits into one axon & one dendrite; Soma adjacent to axo-dendritic process **Allows signal to bypass the cell body Describe the three functional classifications of a neuron: Sensory (afferent): carries signals from the PNS into the CNS Motor (efferent): carriers signals from the CNS to effectors (muscles/glands) in the PNS **Efferent = Exit CNS Interneuron: make decision based upon incoming signals from the afferent neurons & transmit response signal to the efferent neuron Describe the following neuroglial cells of the CNS & PNS: Neuroglia of the CNS: Astrocytes: maintain blood-brain barrier & provide nutrients to the neurons of the brain Oligodendrocytes: myelinate multiple axons of neurons in the CNS Microglia: fight off infection (tiny ninjas) & clean up parts of dead cells to protect other neurons Ependymal Cells:modified epithelial cells that line fluid filled spaces (such as the ventricles) and generates CSF in the CNS Neuroglia of the PNS: Schwann Cells: myelinating cell of the PNS; can only myelinate ONE segment of ONE axon Satellite Cells: protect & take care of cell bodies in ganglia (nanny of PNS) Compare & contrast Schwann Cells vs Oligodendrocytes: Schwann Cells: Oligodendrocytes Myelinate axons in PNS Myelinate axons in CNS Myelinate ONE axon at a time Myelinate MULTIPLE axons at the same time Describe the purpose of myelin: Purpose of Myelin: increase the speed of signal transduction - Loss of myelin = slower speed of signal propagation Describe how Myelination + Axon Diameter influence the conduction speed of an action potential: Myelination & Axon Diameter Influence Conduction Speed: Diameter: larger = quick; smaller = slow Myelin: present = quick; absent = slow Small, unmyelinated axons = slowest Small, myelinated axon = medium speed Large, myelinated axon = quickest Define polarity: Polarity: separation of charge across a membrane (unequal distribution of charge) - Plasma membranes of neurons are POLAR since they have RMP of -70mV Describe the role of the Na/K ATPase Pump in establishing the RMP within the membrane of the neuron: Na/K ATPase Pump: maintains polarity of the neuron cell membrane by sending 3 Na out of the cell & bringing in 2 K ions per pump cycle; one cycle provides -1 charge inside the cell - Cycling continues until RMP is achieved (-70mV) - ATPase Pump = type of PRIMARY ACTIVE TRANSPORT (because ATP used as energy to move ions) Compare & contrast facilitated diffusion vs active transport: Facilitated Diffusion: - Requires ONLY a membrane protein through which the ion moves into or out of the cell - NO ENERGY used (ion DIFFUSES down its concentration gradient when the channel is open) - Ex: Ligand-Gated Na Channels, Voltage-Gated Na Channels, Voltage-Gated K Channels Active Transport: - Requires a membrane protein through which the ion moves into or out of the cell & Energy (ion moves up its concentration gradient when the channel is open) - Ex: Na+/K+ ATPase Pump Describe the term Graded Potential: Graded Potentials: local depolarization potential caused by opening of ligand-gated channels - Occur in the dendrites or soma of the neurons - Small deviations from the resting potential (such as -70 mV to -67 mV); not enough to trigger an AP - Ligand = neurotransmitter, binding allows for opening of the channel allowing an ion to flow into the neuron to change the membrane potential Summation of graded potentials reach AP threshold triggers the opening of Voltage-Gated Na+ Channels Describe the term Depolarization: Depolarization: positive deviation in the voltage of the cell membrane; movement of + ion into the neuron - Excitatory Postsynaptic Potential (EPSP): a small depolarization event occurs in response to ligand binding, opening a ligand gated ion channel, resulting in influx of that ion into the cells - EPSP & graded potential are interchangeable words - EPSP: depolarization less than action potential threshold value of -55mV Describe the term Hyperpolarization: Hyperpolarization: negative deviation in the voltage of the cell membrane - Inhibitory Postsynaptic Potential (IPSP): a small hyperpolarization event in response to inhibitory ligand binding & opening ligand-gated Cl channel, Cl (-) influx into the neuron = more negative charge inside the cell - Hyperpolarization makes the neuron less likely to fire an action potential Compare & contrast Depolarization vs Hyperpolarization: Inhibition of Presynaptic Potential = Hyperpolarization = membrane potential LESS than RMP (valley) Excitation of Presynaptic Potential = Depolarization = membrane potential GREATER than RMP (hill) Compare & contrast temporal vs spacial summation: Temporal Summation: lots of stimuli occurring in close time - Typically one neuron sending several EPSPs over a short amount of time Spacial Summation: lots of stimuli occurring in close area - Typically several neurons sending EPSPs over a small area Describe the three phases of an Action Potential (including the opening/closing of ion channels/movement of ions through the channels): Three Phases of the Action Potential: 1. Depolarization Phase: Na flows into the cell; inside of the cell more positive (mV closer to zero), opening voltage gated sodium channels - Opening of voltage gated Na channels causes LARGE rush of Na into the cell, depolarizing the cell 2. Repolarization Phase: movement of K+ out of the cell (removing positive from inside cell) retuning the inside of the cell closer to RMP (-70 mV) 3. Hyperpolarization Phase: K channels are slow to close; more K leaks out than what is needed to reach -70 mV (overshoot RMP of -70mV) Name the numeric values of the membrane potentials for the following: Resting Membrane Potential (RMP): -70 mV Action Potential Threshold: -55 mV One the action potential graph below, understanding the temporal manner of ion channel opening & how the movement of ions creates the three phases of the action potential: a: RMP of -70 mV b: Action Potential Threshold of -55 mV c: Na+ moving into of the cell d: K+ moving out of the cell 1: Ligand-Gated Na+ Channels Opening in response to ligand (neurotransmitter) binding **Ligand Gated Channels Opening creates Graded Potentials **Summation of Graded Potentials = Action Potential Threshold (b) 2: Voltage-Gated Na+ Channels open (in response to Action Potential Threshold value within the membrane) - Voltage-Gated K+ Channels closed 3: Voltage-Gated Na+ Channels QUICKLY Inactivate - Voltage-Gated K+ Channels open 4: Voltage-Gated Na+ Channels inactive & closing - Voltage-Gated K+ Channels Open 5: Voltage-Gated Na+ Channels Closed - Voltage-Gated K+ channels closing/closed **Na+/K+ ATPase Pump restores RMP in the membrane Label the absolute & refractory periods on the following temporal graph of an action potential: Describe the physiological purpose of a refractory period: Refractory periods ensure one-way transmission of the action potential. Compare & Contrast Absolute vs Relative Refractory periods of an action potential: Absolute Refractory Period: another Action Potential ABSOLUTELY cannot occur - Voltage-gated Na channels open or inactive & cannot be re-opened to trigger Action Potential - RED portion on the graph above Relative Refractory Period: a stronger than normal stimuli required to trigger an Action Potential - Hyperpolarization = membrane voltage less than RMP & must be overcome to trigger Action Potential - Relative Refractory Period ends once Na/K ATPase pump re-establishes RMP - YELLOW portion of the graph above Compare & contrast chemical vs electrical synapses: Chemical Synapses: transmit the signal from presynaptic to postsynaptic neuron using ligands/neurotransmitters that are released into a synapse. Electrical Synapses: used by the cells in the heart to transmit contraction signal Describe the steps of signal transmission within a chemical synapse: Seven Steps of the Chemical Synapse: 1. Action Potential comes down the presynaptic axon & arrives at the axon terminal 2. Voltage-Gated Calcium Channels open on the presynaptic membrane 3. Calcium floods into the axon terminal 4. Calcium stimulates exocytosis of vesicles containing neurotransmitters into the synaptic cleft 5. Neurotransmitters flow through the synapse 6. Neurotransmitter bind ligand-gated ion channels on the postsynaptic membrane 7. Na+ Channel opens = sodium flows down concentration gradient (+ moves into the cell) = depolarization, bringing membrane closer to Action Potential Threshold - Cl- Channel opens = Cl- flows down concentration gradient (- moves into the cell) = hyperpolarization **Na vs Cl channel opening depends on the type of neurotransmitter/ligand **If Action Potential Threshold is met, Voltage gated Na+ Channels open to transmit the signal down the postsynaptic neuron** Describe the three methods of removing neurotransmitters from the synaptic cleft: 1. Diffusion: flow of neurotransmitter from high concentration (in the synapse) to low concentration (outside of the synapse) 2. Enzymatic Degradation: enzyme chews up neurotransmitter to take away function (ex: acetylcholinesterase digests acetylcholine) 3. Uptake by Astrocytes: vacuuming the neurotransmitter up by the pre or postsynaptic cell Week 13: The CNS Describe the functions of of Cerebral Spinal Fluid: Cerebral Spinal Fluid: located in four ventricles of the brain Functions: shock absorption, maintaining control of ions, exchange nutrients & waste, cushioning of the brain Describe the functions of the following vessels & their roles in the blood circulation of the CNS: Internal Carotid Artery & Vertebral Arteries: supplies blood to the brain Dural Sinuses & Internal Jugular Vein: drains blood from the brain Anterior Vertebral & intercostal Arteries: supply blood to spinal cord Anterior vertebral Vein & Intercostal Veins: brains blood from the spinal cord Describe the function of the Blood Brain Barrier & include a few examples of what this structure allows into the brain & what it excludes from the brain: Blood Brain Barrier: tightly connected epithelial cells that tell what can & cannot enter the brain Allowed into Brain: Glucose, Oxygen/Carbon Dioxide, Anesthesia Medications, Alcohol & other Drugs Not Allowed: toxins, antibiotics, most proteins, cells Describe the regions of the spinal cord including the number of vertebrae within & spinal nerves originating from each area? Cervical Spinal Region: C1-C8 spinal nerves (8 pairs of spinal nerves) - Spinal nerve C1 exits superior to cervical vertebra 1 and C2 exits inferiorly [7 vertebrae but 8 spinal nerves] Thoracic Spinal Region: T1-T12 spinal nerves (12 pairs of spinal nerves) Lumbar Spinal Region: L1-L5 spinal nerves (5 pairs of spinal nerves) Sacral Spinal Region: S1-S5 spinal nerves (5 pairs of spinal nerves) Coccyx Spinal Region: ONE spinal nerve (Co1) Describe the reasoning behind the target location of a spinal tap & what this diagnostic test is sampling: Lumbar Puncture: (aka Spinal Tap) - Medical test involving the collection of a small sample of CSF - Target for needle insertion: within the Cauda Equina of the spinal cord located at or below vertebral levels L1/L2 Label the anatomy of the spinal cord below: Dorsal Root Ganglion: sensory cell bodies Dorsal Root: sensory only Ventral Root: motor only Describe the unique feature of the ganglion in the above diagram: Structure contains only sensory cell bodies. Label the following structures of the diencephalon: A: Corpus Callosum B: Thalamus C: Hypothalamus D: Pituitary Gland E: Cerebellum Describe the function of the thalamus: Relay center for incoming sensory information that will direct the afferent signals to their respective primary somatosensory areas of the cerebral cortex. Label the following diagram of the most inferior portion of the brain & describe the general functions of each area: Brainstem: located at the junction between the brain and spinal cord; functions as a relay center for motor and processing center (sensation) for vision, hearing & governs reflexes vital for live Reflexes Vital for Life: blood pressure, HR, breathing rate, blinking, hunger Cerebellum: functions in Motor coordination; Regulating BP, HR & other unconscious reflexes Three Principle Parts of the Brainstem: A: Midbrain: sensory relay center- takes information from the outside world and translates it so it can be better understood by the brain - Functions with thalamus to edit sensory information B: Pons: ball shaped; motor coordination center - Contains pneumotaxic & apneustic areas essential for breathing/control of the respiratory system C: Medulla Oblongata: medullary cardiac rhythmicity center; essential for heart rate/cardiac control Label the following sensory areas of the brain & understand each area’s basic function: Label the following motor areas of the brain & understand each area’s basic function: Label the following association areas of the brain & understand each area’s basic function: Compare & contrast Broca’s vs Wernicke’s areas of the brain: Broca’s Area: speech production; loss of Broca’s area = produce speech due to loss of muscle function Wernicke’s areas: production of coherent speech; loss of Wernicke’s Area = cannot understand meaning of words (word salad) Weeks 14 & 15: The PNS Describe the term plexus: Plexus: branching network of nerves that supply a region of the body - EX: Brachial Plexus: network of 5 main nerves that supply the upper limb Describe the three principal plexuses of the PNS: Three Principle Plexuses in the PNS: ONE: The Cervical Plexus: sensory plexus from scalp, face & neck TWO: The Brachial Plexus: Sensory & motor information to/from the upper limbs (C5-T1 region) Five Key Branches of the Brachial Plexus: Axillary, Radial, Musculocutaneous, Median, Ulnar THREE: The Lumbosacral Plexus: sensory & motor information to/from the lower limbs & pelvis (including pelvic organs) - L1-S5 Two Key Branches of the Lumbosacral Plexus: 1. Femoral Nerve: anterior aspect of the lower limb 2. Sciatic Nerve: posterior aspect of the lower limb - Sciatica: compression of intervertebral disc causing pain/tingling down the posterior aspect of the lower limb Complete the following chart: Cranial Nerve: Modality: Function: I: Olfactory (Oh) Sensory (Some) Smell II: Optic (Oh) Sensory (Say) Vision III: Oculomotor (Oh) Motor (Marry) Movement of the eye & Proprioception ****Exception to eye muscle motor innervation: SO4LR6 IV: Trochlear (To) Motor (Money) Intorsion of the eye [SO4- innervates Superior Oblique muscle of eye movement] V: Trigeminal (Touch) Both (But) Sensory: both upper & lower lips, mouth, face & scalp Motor: muscles of mastication VI: Abducens (And) Motor (My) Abduction of the eye [LR6- innervates Lateral Rectus muscle of eye movement] VII: Facial (Feel) Both (Brother) Sensory: taste from the anterior ⅔ of the tongue Motor: muscles of facial expression (smiling, frowning, etc) VIII: Sensory (Says) Hearing & Balance Vestibulocochlear (Very) IX: Glossopharyngeal Both (Big) Sensory: taste, BP, pH detection via chemoreceptors & baroreceptors (Good) Motor: muscle of the pharynx & smooth muscle of the parotid gland X: Vagus (Veggies) Both (Brains) Sensory: parasympathetic fibers Motor: smooth muscle of lungs, heart & GI tract **ONLY CN whose innervation extends inferior to the head/neck region of the body XI: Accessory (And) Motor (Matter) Trapezius & Sternocleidomastoid XII: Hypoglossal Motor (More) Muscles of the Tongue for speech, movement of food & swallowing (Hams) Label the key anatomical features of CN I on the diagram below: A: Olfactory Bulb B: Olfactory Tract C: Fila Olfactoria D: Olfactory Epithelium E: Cribriform Plate During a traumatic event, structure E can shear structure C. Name each structure below and understand the consequence of this cranial nerve injury: Cribriform plate (E) can shear Axons of the olfactory sensory neurons (C- Fila Olfactoria) resulting in loss of sense of smell. Describe the general steps shared by every reflex arc: General Steps for EVERY reflex arc: 1. Receptor activation in response to a stimulus 2. Sensory neuron transmits impulse to CNS 3. Interneurons Process information [Integration Center] Integrating center: interneurons in CNS synapse to process incoming information - Monosynaptic reflex arc (rare): synapse between sensory & motor neuron - Polysynaptic Reflex Arc (more common): interneuron between sensory & motor neuron 4. Motor neuron transmits impulse to the effector 5. Effector responds to the signal *** Autonomic reflexes contain two motor neurons extending from the CNS to the effector while somatic reflexes typically only have one neuron from CNS Describe the difference between monosynaptic vs polysynaptic reflex arcs: Monosynaptic: two neurons, one synapse Polysynaptic: more than two neurons, more than one synapse Describe the location of the following structures within an autonomic reflex pathway: Preganglionic neuron = before ganglion synapse; carried information - Cell bodies of preganglionic neuron is located in the lateral horn of the spinal cord- only thoracic & lumbar segments Autonomic Ganglion: gathering of cell bodies within the PNS where the synapse occurs between preganglionic & postganglionic neuron Postganglionic neuron = after ganglion synapse; carries information to the effector - Cell bodies of postganglionic neuron in ganglion of the sympathetic chain Compare & contrast the pathways of somatic vs autonomic reflexes: Somatic Reflex: One myelinated neuron carrying signal to effector under voluntary control (skeletal muscle) Autonomic Reflex: Two neurons - only preganglionic neuron has myelin - Postganglionic neuron carries signal to effectors controlled involuntarily (heart) Describe the Sympathetic Chain: A string of ganglion in which preganglionic & postganglionic neurons synapse or pass through prior to going to their effector destination. Describe the three pathways in which an autonomic innervation can travel to its destination: Common pathway of all three routes: exits lateral horn of the spinal cord, travel through the true spinal nerve & white ramus communicans, into the sympathetic chain 1: Synapse & exit occurs at the same level within the sympathetic chain via grey ramus communicans 2: Preganglionic neuron goes up or down a level within the sympathetic chain prior to synapsing & exiting via grey ramus communicans 3: Preganglionic neuron uses Splanchnic nerve to leave the sympathetic chain; enters the prevertebral ganglion where synapse occurs Compare & contrast sympathetic vs parasympathetic responses of the autonomic nervous system: **All autonomic signaling pathways (parasympathetic & sympathetic) contain 2 motor neurons - IN CONTRAST TO Somatic signaling that use only 1 motor neuron Parasympathetic Nervous System: Sympathetic Nervous System: Rest & Digest Fight or Flight or Freeze (Rapid ATP production) Controlled by craniosacral distribution Controlled by thoracolumbar distribution Long Preganglionic & Short Postganglionic neurons Short preganglionic & Long postganglionic neurons Heart Rate & Blood Pressure DECREASE Heart Rate & Blood Pressure INCREASES Digestion INCREASES Digestion DECREASES Increased urine production Decreased urine production Categorize the senses as either general or special; describe what is meant by a special sense: Special Sense: conversion of a stimulus modality (sound waves, light waves, etc) into electrical stimuli that is understood by the CNS - Examples of special senses: olfaction, gustation, audition, vision General Sense: Touch Name the type of membrane channel that is initially opened by touch: Mechanically gated ion channels Describe the term Receptive Field: The number of neurons within a receptive area correlates to the ability to distinguish between two points of touch - High density of neurons = sense two stimuli as separate = Hand - Low density of neurons = sense two stimuli as the same = Back Describe what triggers depolarization/action potentials in Olfaction: Odorant chemicals bind to specialized olfactory cells called fila olfactoria. - Olfactory epithelium provides the ability to smell; Olfactory epithelium contains the fila olfactoria sensory neurons Name the type of lingual papillae that lack taste buds: Filiform Papillae = NO TASTE BUDS Contain taste buds: Circumvallate papillae, foliate papillae, fungiform papillae Describe why children and babies are more prone to ear infections: Angle of the eustachian tube