Week 5 Class Notes
Week 5 Class Notes 3244
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This 4 page Class Notes was uploaded by Alexandra Notetaker on Monday September 26, 2016. The Class Notes belongs to 3244 at University of Colorado Denver taught by Dr. Kent Nofsinger in Fall 2016. Since its upload, it has received 11 views. For similar materials see Human Anatomy in Biology at University of Colorado Denver.
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Date Created: 09/26/16
Anatomy Lecture Notes 9/19 Actin and myosin are: Myofilaments During contraction which areas of the sarcomere change in size? Zone of overlap between thick and thin filaments H zone I band Sphincters are often: Single unit tonic smooth muscle Sensory neurons are also described as: (exam 2) Afferent neurons Chapter 14 III. Neurons A. Parts of Neurons 3. Axons -since there isn’t a nucleus present, ribosomes are also absent c. Axon Hillock: this area is rich in neurofibrils so it’s very electro- sensitive and very excitable electrically. g. Myelin and myelin sheaths: increases the speed significantly. Acts as an insulator in a sense h. Nodes of Ranvier: where sodium and potassium channels are very concentrated. Greatly expedites the speed. B. Classification of Neurons 1. Structural or Morphological d. Anaxonic: “ana = without”, without axons 2. Functional or Physiological a) Afferent: afferent = sensory b) Efferent: efferent = motor IV. Neuroglial cells Glial is Greek word for glue A. Cells of CNS Function is determined geographically 1. Oligodendrocytes: Oligo = few; wrap a few dendrites; help create this blood brain barrier 2. Astrocytes: shaped as a star due to many projections from their surface. Large cell with numerous cell processes; in contact w/ neurons and capillaries; most common type of glial cell. Act as a second security system which helps minimizes the likelihood of unwanted material into the brain (bacteria). Constitute over 90% of nervous tissue in some areas of their brain Functions: help form the blood-brain barrier (BBB), regulate tissue fluid composition, help regulate synaptic transmission, form a structural network, replace damaged neurons, assist neuronal development 3. Microglia: micro = little; small cells that have slender branches extending from the main cell body. Function like macrophages –wander through the CNS and replicate in response to an infection. Perform phagocytic activities and remove debris from dead or damaged nervous tissue 4. Ependymal cells: cuboidal epithelial cells that line the internal cavities of the brain and the central canal of the spinal cord. These cells and nearby blood capillaries together form a network called the choroid plexus which produces cerebrospinal fluid B. Cells of PNS 1. Satellite: functioning much like astrocytes in CNS. Flattened cells arranged around neuronal cell bodies in ganglia. Cells physically separate cell bodies in a ganglion from their surrounding interstitial fluid and regulate the continuous exchange of nutrients and waste products between neurons and their environment 2. Neurolemmocytes: similar function to oligodendrocytes but only myelinates 1 axon. V. Coverings of Nerve Fibers (the PNS) A. Endoneurium: delicate layer of areolar CT that separates and electrically isolates each axon B. Perineurium: Layer supports blood vessels supplying the capillaries within the endoneurium. C. Epineurium: thick layer of dense irregular CT encloses the entire nerve, providing both support and protection to the fascicles within the layer Chapter 15 VI. Coverings and Spaces of CNS A. Meninges 1. Dura mater: external tough, dense irregular CT composed of 2 fibrous layers—meningeal layer and periosteal layer. Strongest of the meninges. Protects brain from trauma. Dura mater and the bones of the skull may be separated by the potential epidural space which contains the arteries and veins that nourish the meninges and bones of the cranium. 2. Arachnoid mater: resembles a web, contains collagen and elastic fibers. Lies external to the pia mater. 3. Pia mater: innermost of the meninges. Thin layer of delicate areolar CT that is highly vascularized and tightly adheres to the brain C. Spaces within the CNS 1. 4 cavities or ventricles within the brain a) Continuous with one another and with the central canal of the spinal cord b) 2 Lateral ventricles are in the cerebrum rd c) Eath lateral ventricle communicates with the 3 ventricle d) 4 ventricle—located between the pons/medulla of the cerebellum e) All ventricles contain cerebrospinal fluid (CSF) VII. Cerebrospinal Fluid (CSF) A General Functions: surround brain, spinal cord, and fill the CNS spaces (VI. C above); clear, colorless liquid that circulates in the ventricles and subarachnoid space 2. Decreases weight of brain from 1.5 kg to 50 grams - Buoyancy 3. Reduces impacts to brain by spreading force over larger area 4. Transports nutrients, chemical messengers, and waste products from the brain 5. Protects nervous tissue from chemical fluctuations that would disrupt neuron function B. Formation and Composition -fluid is produced in the ventricles Arachnoid granulations—collections of arachnoid villi which drains the CSF back into the blood. Excess CSF moves across arachnoid mater membrane at the arachnoid villi to return to the blood within the dural venous sinuses. Within the subarachnoid space, cerebral arteries and veins are supported by the arachnoid trabeculae and surrounded by CSF
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