myelin sheath c) How would a signal travel through this neuron differently if c were not present? The myelin sheath is a layer of insulation. It forces the nerve impulse to leap from node to node as shown above. This allows the nerve impulse to travel much faster. If the myelin sheath were missing‚ the nerve impulse would travel at a much slower speed. d) What is d? Explain what happens when an action potential reaches d. The structures labeled d are synaptic knobs.
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metabolic fatigue. Nervous Fatigue Nervous fatigue is the decline in the ability of a nerve to sustain a signal resulting in innervation of the muscle. The muscle’s ability to generate force is most strongly limited by nerve’s ability to sustain a high-frequency signal. After a period of maximum contraction‚ the nerve’s signal reduces in frequency and the force generated by the contraction diminishes. Nerves are responsible for controlling the contraction of muscles. For extremely powerful contractions
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PhysioEx 9.0 Exercise 3 Neurophysiology of Nerve Impulses A C T I V I T Y 1 The Resting Membrane Potential 1. Explain why increasing extracellular K_ reduces the net diffusion of K_ out of the neuron through the K_ leak channels. Increasing the extracellular potassium reduces the concentration gradient‚ and less potassium diffuses out of the neuron and into the cell. 2. Explain why increasing extracellular K_ causes the membrane potential to change to a less negative value.
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The Muscular System: Contraction of Motor Units 1. Define a motor neuron:_____A single nerve cell that branches from the brain or the spinal cord to a muscle or a gland. 2. Define a motor unit: ___A motor neuron and all of the muscle fibers it stimulates. 3. The synapse between a motor neuron and the muscle it innervates is called a ____neuromuscular junction_______. 4. The stimulation of additional motor units will increase the strength of the contraction. This process is called
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connective tissue coverings of bones and muscles Inform brain of one’s movements depending on stretch of organs (3) Compare and contrast phasic and tonic adaptation. Be able to provide one example of a receptor for each. Phasic: Fast adapting Bursts of impulses at the beginning and end of stimulus Report changes in external and internal environment Examples: Receptors for pressure‚ touch‚ and smell Tonic: Sustained response that adapt slowly or not at all Examples: nociceptors and most proprioceptors
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Human skeletal muscle consists of hundreds of individual cylindrically shaped cells (called fibers or myofibers) bound together by connective tissue. In the body‚ these muscles are stimulated to contract by somatic motor nerves that carry signals in the form of nerve impulses from the brain or spinal cord
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1. Sensation: the process by which sensory receptors and nervous system receive and represent stimulus energies from our environment 2. Perception: the process of organizing and interpreting sensory information‚ enabling us to recognize meaningful objects and events 3. Bottom-up Processing: analysis that begins with the sense receptors and works up to the brain’s integration of sensory information 4. Top- Down Processing: information processing guided by higher-level mental processes
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granules or bodies. Neurofibrils take part in transmission of impulse Nissls granules or bodies are irregular masses of rough endoplasmic reticulum on which free ribosomes and polysomes are attached. Nissls granules probably synthesize protein for the cell. b) Cytoplasmic processes or neuritis – They are of two types. 1. Dendrites or dendrons - They contain neurofibrils‚ neutubules and Nissls granules. They conduct nerve impulse towards the cell body and are called afferent processes (receiving
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chemoreceptor trigger zone‚ impulses are relayed across the to the integrative vomiting centre‚ causing an initiation of the emetic reflex. Therefore it is not merely the chemoreceptor trigger zone that stimulates the vomiting itself‚ but the integrative vomiting centre that results in the act of emesis (Rang‚ H.P.‚ et al‚
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Picking up a box from the floor and placing it on a shelf Light entering the eye forms an upside-down image on the retina. The retina transforms the light into nerve signals for the brain. The brain then turns the image right-side up and tells us what we are seeing. Our brain then computes to pick up the box. When a message comes into the brain from anywhere in the body‚ the brain tells the body how to react. the brain as a central computer that controls all bodily functions‚ then the nervous
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