BIO 446L 1st Edition Lecture 13 Outline of Last Lecture I. Nervous Tissue—Central and Peripheral Nervous Systema. Sensory and motor neuronsb. Central and peripheral nervous systemc. Central nervous systemi. Brainii. Spinal cordiii. Neurons1. Unipolar, bipolar, multipolariv. Synapsesv. Membrane potentialOutline of Current Lecture I. Nervous Tissue contda. Peripheral nervous systemi. Organizationii. Small nerves and gangliaiii. Glial cellsiv. RegenerationII. Nerve Pathways in the CNS and PNSa. Motor pathwaysb. Indirect motor pathwaysCurrent LectureNervous Tissue contd- Peripheral Nervous Systemo Cranial and spinal nerves Afferent and efferento Nerves and gangliao OrganizationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Names of coverings have same meaning and similar names as in muscle- Epineurium—around bundle- Perineurium—surrounding fascicles- Endoneurium—around each fiber- Reticular fiber—made up of collagen type IIIo Small nerves and ganglia Small nerves have fewer axons, lots of reticular fiber surrounding, looser- Fibers are arranged longitudinally and in circular patterns Ganglia (cluster of cell bodies) are generally very large and are surrounded by satellite cells- = a glial cell, like Schwann cellso Glial cells Oligodendrocytes= CNS, secrete myalin- Processes reach out and surround several axons with myalin Neurolemmocytes= PNS, secrete myelin- One process per axon- Each lays down a segment of myelin Myelin sheath- Node of Romier—not covered in myelin, junction between Schwann cells- Microtubules—called neurofilaments Astrocytes= processes wrap around capillaries in brain- Regulate the blood brain barrier very tightly- Glial fibrilar acidic protein (GFAP)o Intermediate filament- Foot processes covering capillaries Microglia= phagocyte- Macrophage- Phenotypic change (inactive and active phenotypes)o Round, processes retracted when active Ependymal= secrete and remove cerebral spinal fluid- Lines ventricle and central canal- Secreted by filtering plasma into cerebral spinal fluido Over production or poor drainage can cause hydrocephalus—water in brain- Cilia or microvilli move cerebral spinal fluid along- Choroid plexus= fold in lining of ventricle, where cerebral spinal fluid is secreted- Nerve regeneration o When damaged, macrophage immediately cleans up debris Nucleus moves off center There’s atrophy, little ER, and no stimulationo Can re-establish protein synthesis Puts out sprouts of axons Schwann cells that are left will undergo mitosis If axon sprouts find Schwann cells, the nerve can regenerate and reinnervateo The process is slow, as said by the adage: “a millimeter a day after a month’s delay.”Nerve Pathways in CNS and PNS- See flow chart on the slide—tip: redraw this flow chart yourself!- Motor pathwayso Central sulcus= divides frontal and parietal lobeso Precentral gyrus= primary motor cortex, contains cell bodies of upper motor neurons Upper motor neurons synapse with lower motor neurons, which then extend to target Upper motor neurons extend in tracts in the white matter- May cross over at medulla or spineo See slides for alternative maps for understanding the motor pathways Fingers and tongue have lots of motor neurons controlling movement Internal capsule= tracts in white matter Cerebral peduncle= another tract Pyramidal decussation= crossing over on medulla Lower motor neurons= cell bodies in CNS, axon in PNS- From gray matter, once at spinal cord region of “interest” will extend to neuromuscular junction at targeto Motor tracts White matter Bilateral—ascending and descending nerve tracts- Indirect motor pathwayso Important in balance, smooth movements, reflex to sight and sound stimulio MA: Parkinson’s—tremors and jerky movementso MA: Polio—can attach upper and/or lower motor neurons Causes paralysis- If in upper: spastic paralysis=lower limbs can reflex but very uncontrolled- If in lower: flaccid paralysis= no movement, atrophy as a side
View Full Document
Unlocking...