Exsc 224 Week 4 Notes
Exsc 224 Week 4 Notes Exsc 224
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This 8 page Class Notes was uploaded by Jane Warther on Friday February 5, 2016. The Class Notes belongs to Exsc 224 at University of South Carolina taught by Dr. Thompson in Spring 2016. Since its upload, it has received 15 views. For similar materials see Anatomy and Physiology 224 in Education and Teacher Studies at University of South Carolina.
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Date Created: 02/05/16
Chapter 12 and 13 Lecture 3 2/2/2016 Memory Declarative memory (factual knowledge) o Explicit information o Related to our conscious thoughts and our language ability o Stored in LTM with context in which it was learned o Helping something make it to LTM by association- linking it to something you already know o Can learn emotionally- traumatic or positive o Automatic- knowing something for no reason Ex. Remembering what color tie your teacher wore everyday o Sensory input →association area(some memory store here) →hippocampus →thalamus →prefrontal cortex(mainly stored here) To work have to be alert ACh primes region of brain to make it receptive to storing info o Thought to be permanent unless there is trauma to brain Over time, memories move to different areas of the brain o Synaptic pruning- gain and lose synapses between neurons Fidelity of memory changes over time, increase error in recall every time Nondeclarative memory o Less conscious or unconscious o Emotional memories can fall into this category o Acquired through experience and repetition o Best remembered by doing: hard to unlearn o Includes Procedural (skills) memory Motor memory (cerebellum) Don’t need hippocampus Emotional memory(amygdala) o Procedural and motor memory overlap Procedural involves motor pattern but more complex o Sensory/ motor inputs → association cortex→ basal nuclei→ thalamus→ premotor cortex Protection of the Brain Bone (skull) o May present possible damage to skull o Fluid fills brain, brain pushes against skull, creates pressure called headache o concussions Membranes (meninges) o Dura mater Outer layer Made of 2 layers of connective tissue Periosteal (bone) and meningeal – fused together Tough and fibrous o Arachnoid mater Refers to spider – projections from this layer to pia mater Loose, somewhat fibrous Goes down into fissures Arachnoid villi- one way valves o Pia mater Fine and delicate Adheres to cortex, tightly connected, dips in sulci and fissures Connected to arachnoid villi via arachnoid projections Space between arachnoid and pia mater - subarachnoid space Where CSF surrounds CNS o Meningitis- bacterial infection of meninges Causes swelling o Cover and protect the CNS o Protect blood vessels and enclose venous sinuses o Contain CSF o Form partitions in skull Watery cushion (CSF) o Produced in ventricles in brain, in 2 lateral ventricles and fourth ventricle at choroid plexuses which are capillaries surround by ependymal cells Capillaries have tight junctions, but may be leakier Ependymal cells held together by tight junctions Resembles plasma portion of blood Moves down in to subarachnoid space o Produced in lateral ventricles Flows down past third ventricle towards 4 ventricle o System to move it Ependymal cells are ciliated and help to move CSF so it doesn’t sit stagnant o Makes it to 4 ventricle, can continue to central canal to exit and surround CNS Or can exit medial and lateral aperture o Surrounds brain- is floating in CSF Lifts brain off skull so base of brain doesn’t have to bear the whole weight o Is reabsorbed in many places Sagittal sinus- arachnoid mater has projections that project into this sinus One way valves allow CSF to leave cerebrospinal space If plugged, the pressure surrounding brain would increase and could be damaging o In babies, accumulation of CSF-hydrocephalus Brain and ventricles get larger Shunt gets installed and drains the fluid o For molecules to become a part of CSF, it is a selective process because of a complicated transport system Blood-brain barrier o Capillaries connected by tight junctions that form impermeable barrier o Most of brain supplied by blood brain barrier o Helps maintain a stable environment for the brain o Separates neurons from some o Composition Continuous endothelium of capillary walls Basal lamina Feet of astrocytes(regulate tight junctions to get more nutrients) Provide signal endothelium for the formation of tight junctions Spinal Cord Location o Begins at foramen magnum o Ends as conus medullaris at L1 vertebrae Variable number Have spinal nerves below this area that project off spine but no spinal cord Functions o Provides two-way communication to and from the brain o Contains spinal reflex centers Spinal nerves o 31 pairs o C3 injury Loose ability to breathe Phrenic nerve that controls diaphragm exits at C4 o C4 injury- tetraplegia Only able to speak o C6 injury-tetraplegia Loose control from shoulders down o T6 injury- paraplegia Lose control of trunk, digestive and reproductive systems and legs o L1 injury- paraplegia Loose of control of legs Cervical and lumbar enlargements o The nerves serving the upper and lower limbs emerge here o Have to do with the number of neurons entering and exiting through spinal nerves through this region Cauda equine o The collection of nerve roots at the inferior end of the vertebral canal Spinal Cord: Protection Denticulate ligaments: extensions of pia mater that secure cord to dura mater Filum terminale: fibrous extension from conus medullaris; anchors the spinal cord to the coccyx o Extension from pia mater that puts tension on spinal cord Spinal meninges o Dura mater on outside No periosteal layer just meningeal o Arachnoid mater o Pia mater- wraps around spinal cord Cross-Sectional Anatomy White columns o Dorsal funiculus-tactile perception travels here o Ventral funiculus o Lateral funiculus Gray commissure- allows neurons to cross sides Spinal nerve composed of both sensory and motor info o Sensory- afferent(towards) o Motor- efferent(away) o Ventral(motor) and dorsal(sensory) roots- refer where neurons exit the spinal cord to help form nerve Neurons exit spinal cord, form ventral root, come together with dorsal root to form spinal nerve Dorsal root has ganlia (collection of nuclei) Cell bodies for sensory(afferent) neurons reside in ganglia Gray Matter Horns link commissures Dorsal horn associated with neurons associated with dorsal root Ventral horn associated with neurons associated with ventral root Even ventral and dorsal roots are subdivided Ventral horn is ALWAYS MOTOR Dorsal root has ganglion, ventral doesn’t Spinal Nerves Cranial nerves C1-C8 o First 7 cervical nerves exit above the vertebrae for which it is named o 1 cervical nerve exits above C1 o C8 exits below C7, above T1 Thoracic nerves T1-T12 o 1 thoracic nerve exits below T1 Lumbar nerves L1-L5 Sacral nerves S1-S5 Coccygeal nerve Co1 31 pairs After C8, exit below vertebrae for which it is named Dermatome The area of skin innervated by the cutaneous branches of a single spinal nerve Most dermatomes overlap, so destruction of a single spinal nerve will not cause complete numbness Pretty close to true for motor system Different for sensory system o For sensory, the spinal root enters at one spot, one above it and one below it o So if associated with T12, also associated with T11 and L1 o True for all sensory o Motor would just be associated with T12 Spinal Cord Trauma Functional losses o Paresthesia Abnormal/ loss of sensation o Paralysis Loss of motor function o Flaccid paralysis- injury to lower motor neuron (peripheral motor neuron) No voluntary control of muscles / muscle is relaxed No reflex activity Muscles atrophy – rapidly Sever lower motor neuron anywhere along its path you will have flaccid paralysis o Spastic paralysis- injury to upper motor neurons (motor neuron in CNS , controls lower motor neuron) No voluntary control of muscles Muscles can be stimulated by reflex activity Muscle atrophy delayed b/c muscle is being used In constant contraction Injury to spinal cord or cortex(like a stroke) may not be able to voluntary contract muscle, but reflex arc is still intact And as a consequence may experience spastic paralysis o Can have complete or incomplete/partial sever of spinal cord Complete- little chance of recovery Incomplete- better chance of recovery for certain things depending on injury 2/4/16 Ascending Pathways - Sensory Consist of three neurons First order neuron o Conducts impulses from cutaneous receptors and proprioceptors o Branches diffusely as it enters the spinal cord or medulla o Synapses wit second order neuron o Always peripheral, connected to receptor traveling to spinal cord, from spinal cord synapses to 2 order neuron in CNS and ascend to thalamus, then synapse to rd 3 order neuron and will go on to the sensory neuron cortex Second-order neuron o Interneuron o Cell body in dorsal horn of spinal cord or medullary nuclei o Axons extend to thalamus or cerebellum Third-order neuron o Interneuron o Cell body in thalamus o Axon extends to somatosensory cortex Dorsal Column-Medial Lemniscal Pathway Discriminative touch pathway o Pathway for tactile perception o 3 neurons go from site of stimulus to cortex Dorsal columns are in the medial portion of the dorsal portion of the spinal cord Medial lemniscal- region within brain stem and pons fibers are passing through Neuron can synapse onto interneuron or go longitudinal to dorsal columns and ascend o Ascends as the first order neuron o Gets to medulla oblongata it will synapse onto 2 order neuron nd o 2 order neurons are known for 2 things It will cross – can go from left side of spinal cord to right side o Ascends until it reaches the thalamus o In the thalamus will synapse to 3 neuron and will rise to appropriate region to somatosensory cortex based on the homunculus Anterolateral Pathways Lateral and ventral spinothalamic tracts Transmit pain, temperature, and coarse touch impulses within the lateral spinothalamic tract Spinocerebellar Pathway Ventral and dorsal tracts Convey information about muscle or tendon stretch Descending Pathways and Tracts Involve two neurons: o 1. Upper motor neurons Pyramidal cells in primary motor cortex o 2. Lower motor neurons Ventral horn motor neurons Innervate skeletal muscles Summary Spinal nerves enter and exit the spinal cord o Relate to specific regions of the body Pathways describe the route from sensory to cortex or cortex to effector Location of injury determines the nature of symptoms
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