Neuro Study guide-Exam 1.pdf

WEEK 1: INTRODUCTION TO NEUROSCIENCE New terminology Different brain cuts/planes ○ Sagittal: right/left ○ Coronal(frontal): anterior/posterior ○ Horizontal: transverse; cuts at right angle to long axis of structure Locations, functions and illustrations of brain str...

WEEK 1: INTRODUCTION TO NEUROSCIENCE New terminology Different brain cuts/planes ○ Sagittal: right/left ○ Coronal(frontal): anterior/posterior ○ Horizontal: transverse; cuts at right angle to long axis of structure Locations, functions and illustrations of brain structures ○ Lobes Frontal Parietal Temporal Occipital ○ Sulci, gyri ○ Brainstem: Medulla, Pons, Midbrain - Medulla: life support center; located in caudal end - Pons: regulates respiration; bridge to cerebellum/ located rostral to medulla - Midbrain: visionary and auditory reflexes ; most rostral section of brainstem ○ Cerebellum - Coordination of movement, controls range and force of movement, balance, motor learning/memory ○ Diencephalon ○ Telencephalon (cerebral cortex) ○ What will happen if you have a lesion in any of these brain structures? Function and location of the neuron and all its parts ○ Neuron ○ Soma ○ Axon hillock ○ Axon ○ Dendrites ○ Synaptic terminals ○ Synapse Site of communication between neurons OR between neuron and a muscle or gland Glial cells  NS Cells Neurons Glial Macroglia Micro ○ Functions: Astrocytes Schwann (P ○ Types: Microglia: phagocytes that act as the immune system of the CNS and clean neuronal environment Oligodendrocytes (CNS) Macroglia Astrocytes: part of blood brain barrier; plays critical role in nutritive, signaling, and cleaning functions Oligodendrocytes (CNS) and Schwann cells (PNS): form myelin sheaths around neuron’ axons In broad terms, what are stem cells? ○ Undifferentiated cells that can turn into neurons or glial cells Clinical correlates related to neural tube formation: ○ Anencephaly Superior neuropore does not close —> skull does not form over incomplete brain, which leaves brainstem and meninges exposed; many fetuses die before birth and hardly any survive ○ Spina Bifida Inferior neuropore does not close Cerebrospinal fluid system ○ Broadly understand what the purpose of CSF Helps maintain homeostasis Shock absorber Fluid transport system ○ Meninges Connective tissue surrounding the brain and spinal cord Protective circulatory system ○ Clinical correlates:  Hydrocephalus (E:congenital or acquired,P:build up of CSF in the ventricles causes enlargement of ventricles, compressing brain tissue,S: enlarged head (fetus/infant) main thing is the enlarged head) Meningitis (E:usually Viral, P:inflammation of the meninges, S: headache,fever, confusion, vomiting, neck stiffness,prognosis: viral meningitis rarely life threatening, bacterial meningitis is rare but potentially fatal). Neuroplasticity ○ Critical periods of development ○ Changes with aging ○ Involved in habituation, learning and memory, recovery after injury, maladaptation after injury WEEK 2: SYNAPTIC TRANSMISSION, AUTONOMIC NERVOUS SYSTEM, AND CRANIAL NERVES  Classification Systems of neurons ○ By number of processes ○ By function ○ Signaling in the Nervous System ○ Resting Membrane Potential -70mv ○ Action potentials fires at -55mv 6 Phases of an AP ○ 1.Resting Potential ○ 2.Threshold ○ 3.Depolarization ○ 4.Repolarization ○ 5.Hyperpolarization ○ 6. Return to Resting membrane potential Propagation of the AP-Once AP generated it will spread passively along the axon. ○ Spreading of AP along axon dependant on passive properties Diameter of Axon Myelin Saltatory conduction  Saltatory Latin Salta (jump) Conduction-AP appears to “jump” from node to node Synaptic Transmission-AP reaches presynaptic terminal,calcium enters Presynaptic terminal,vesicles move forward, presynaptic releases neurotransmitter, neurotransmitter binds to postsynaptic membrane receptor, membrane channel changes shape and ions enter postsynaptic cell Neuromuscular junction- where motor neurons synapse with muscle fibers Clinical Correlates: Multiple Sclerosis-E:Autoimmune, P: demyelination of CNS, (Sclerosis-scar tissue), demyelination can occur in a variety of locations. Sensory-impaired,Motor-Weakness, Cranial Nerve- impaired vision, Cognition-infrequent Guillain Barre-E:Autoimmune, P: Demyelination of the PNS, Motor:weakness, paresis/paralysis, sensory: atypical sensations, pain, Cranial nerves, motor CNs most affected. Myasthenia Gravis-E- E:Autoimmune, P:decreased number of functional muscle membrane ACh receptors, M: weakness increases with muscle use Autonomic Nervous System: ○ Sympathetic Nervous System: functions Fight or flight Activated during exercise, excitement, emergencies ○ Parasympathetic Nervous System: functions Rest and digest Energy conservation & storage ○ Clinical correlates: Autonomic dysreflexia SC injury to T6 Sympathetic neurons below the level of the lesion are activated due to some noxious stimuli. Excessive sympathetic response Sudden spike in blood pressure may be life-threatening Peripheral Nervous System ○ Cranial nerves Know which are pure motor, pure sensory, mixed(some say marry money, but my brother says bad blood marries money) S=sensory M=motor B=Both Basic functions of all 12 nerves: ○ I. Olfactory-smell(sensory) ○ II. Optic-vision (Sensory) ○ III. Oculomotor-eye movement, eyelids,pupils (motor) ○ IV. Trochlear-up and down eye movement (motor) ○ V. Trigeminal-taste,masticate (both) ○ VI. Abducens- left and right (motor) ○ VII. Facial-face expressions,close eyes, produce salive and tears (both) ○ VIII. Vestibulocochlear-balance and hearing (Sensory) ○ IX.Glossopharyngeal-swallow and taste (both) ○ X. Vagus -autonomic processes(both) ○ XI. Accessory- shoulder and neck movement(motor)  ○ XII. Hypoglossal - move tongue,eat, speak(motor) Clinical correlates: ○ Bell’s Palsy E:Viral infection or immune disorder, P:lesion to the facial nerve, S: unimpared,motor-unilateral paresis/paralysis of the muscles supplied by facial nerve. Prognosis: majority of people muscles recover within 2 months, depending on the severity of damage. ○ Trigeminal neuralgia P:comression of trigeminal nerve (CN 5), S: sensory-no loss, but severe, sharp,stabbing pain, triggered abruptly by (eating, talking, touch), and end abruptly. Prognosis: variable WEEK 3 – PERIPHERAL NERVOUS SYSTEM Brachial Plexus (you do not need to memorize the diagram of the BP) ○ Motor, Sensory, and Functional Roles of nerves: Musculocutaneous nerve- -Elbow flexion, sensory-lateral forearm Median Nerve - muscles of forearm - “musician hand” -finger reduction, fingers -motor tasks affected: can’t sow, play instrument, writing -claw hand/ median & ulnar nerve injury Ulnar nerve -Music piano finger abduction and adduction -Motor: innervates medial half of muscles of the forearm and intrinsic muscles of the palm -wrist and finger flexion -if affected there is ulnar claw Radial nerve - formed from posterior cord (all 3 dorsal cords) - back muscles of arms and forearm - elbow, wrist, hand extension and supination - sensory: medial half of dorsal surface of hand - inability to lift wrist or fingers extensor weakness aka Wrist Drop - motor tasks affected: extend hand, unable to release things ○ Types of brachial plexus injuries - formed from ventral rami c5-T1  ○ Clinical Correlates: Erb’s Palsy: birth injury *most common cause (hyperextension of neck), motorcycle accident, contact sports -starts from C5-C6 -shoulder and elbow -waiter’s tip position -nerve regeneration IS POSSIBLE (increased by Shoulder (internal rotation)- difficulty/loss of shoulder abduction -Elbow flexion -Forearm (pronation) -Fingers (slight flex) Klumpke’s palsy: birth injury, violent traction injury -damage to lower part of brachial plexus (C8-T1) -claw hand Carpal Tunnel Syndrome: gripping vibrating tools, repetitive use of flexor/extensor muscles -damage to medial nerve -forearm flexor, thenar muscles -CLASS 1 neuropraxia Is recovery possible when a neuron is damaged? In the CNS? In the PNS? ○ Nerve degeneration Retrograde: degeneration of proximal axon Orthograde: degeneration of distal axon ○ Nerve regeneration -injury to cell body or axon hillock means death -CNS- CAN NOT REGENERATE -PNS- CAN REGENERATE Neuropathies: Disease or dysfunction of one or more peripheral nerves o Signs & symptoms of peripheral nerve injuries o Mononeuropathies- Single Nerve Neuropraxia (CLASS 1) -aka traumatic myelinopathy -anything you do repeatedly can cause neuropraxia -axon is intact -recovery tends to be complete but very slow Axonotmesis (CLASS 2) -axons are affected, myelin sheath is compressed, connective tissue intact -usually occurs bc of crashing of nerves; after dislocation/ closed fracture) -surrounding tissue is intact? -regeneration is possible after injury -prognosis is good Neurotmesis (CLASS 3) -entire nerve cuts(severance) -prognosis is variable -excessive stretch or laceration Clinical Correlates: Radial nerve palsy Polyneuropathies- many nerves -presents distally (away from trunk) and symmetrically -usually not traumatic Hallmark symptoms: progresses from distal to proximal Clinical correlates: Guillain Barre, Diabetic Polyneuropathy Guillain Barre: demyelination of _peripheral nerves(SHWAN CELLS) -more severe motor than sensory effects Diabetic Polyneuropathy: *symptoms: sensations mainly affected -sensory: glove/stocking distribution -proper diabetic foot care is important -distal is most affected -motor: balance & coordination problems