1. The peripheral nervous system (PNS) consists of nerves that connect the spinal cord and the brain to the different organs of the body. PNS is involved with a physical sensation. The PNS has two components: the motor system and the sensory system. The sensory system performs voluntary actions, while the motor system performs involuntary control.
The sensory system is associated with a physical sensation as it consists of the neurons that run through the head, spine and the limbs. Its sensory neurons convey information about the external surroundings inward from the receptors in the tendons, skeletal muscles and skin.
The receptors in the skin stimulate sensory impulse. The sensory impulse then moves to the sensory neurons that move through the afferent fibers, then to the spinal cord, and, lastly, to the brain for interpretation.
2. The motor system is involved in the movement of skeletal muscle. The impulse from the central nervous system is then transmitted to the motor system. The motor system then conveys the information in order to contract the muscles and secretes glands.
The motor impulses move through the body via the efferent nerve fibers to the brain for interpretation. Once the right response is processed, the brain sends an impulse via the efferent fibers.
3. A motor unit refers to the motor neurons together with all muscle fibers associated with it. It comprises of a fiber that consists of a sarcomere and the large muscles like gastrocnemius. The sarcomere comprises of approximately 1000 myofibrils. Lastly, there is a myofibril that comprises of myosin and myofilaments.
4. The contractions of quadriceps, plantaris, tibialis anterior, gastrocnemius, soleus, the gluteal muscles, and the hamstrings muscles are involved in the action of standing up. Quadriceps contracts the legs, while the hamstrings contract the hip while standing up. The gluteal muscles contract the thigh. The gastrocnemius, soleus, plantaris and the tibialis anterior stabilize the lower leg in the action of standing up.
5. They include muscle, fascicle, muscle fiber, myofibril, and myofilaments.
A sarcomere refers to the nominal contractile of a muscle. It has two crucial proteins: myosin and actin. Myosin forms a thick filament that links ATP and actin, which is essential in movement of the muscles. The actin forms a thin filament that is formed by the double intertwined actin filaments.
6. The distal end of a motor neuron is stimulated to produce acetylcholine. Acetylcholine then diffuses across the neuromuscular junction. The muscle fiber membrane is activated to transmit muscle impulse to the sarcoplasmic reticulum. Calcium ions diffuse into sarcoplasmic from the sarcoplasm reticulum. Tropomyosin and troponin associate to form a binding site on actin. Actin and myosin filaments produce associations. Myosin contracts filaments inward as the muscle fiber shortens in the process of contraction.
Acetylcholinesterase breaks down the acetylcholine at the neuromuscular junction, ending the streams of action potentials along the muscle fiber. Production of calcium ions is stopped, and the sarcoplasmic reticulum is induced to requester all calcium ions that have been produced.
7. Yes, it is related to both motor and sensory neurons. Kathy had visual disturbances when she lost her hearing. She also did not feel pain from the wound she sustained, when she fell on the floor.
8. Myelin is a fatty material that insulates the axons and the dendrites of nerves in the spinal cord and brain tissue. It accelerates the movement of impulses through the NS by insulating axonal membrane from the absorbing nerve impulses.
9. Myelin is formed by myelinating Schwann cells in the PNS and oligodendrocyte cells in the CNS.
10. Sclerosis is a hard area referred to as “plaque” that arises along a neuron’s axon due to the damage of myelin. MS occurs mainly in the CNS, especially in the myelinated sheath that surrounds axons in the brain and other parts of the NS.
11. MS disorders, the way messages, are conveyed through the NS. It is an autoimmune disease whereby ones’ immune system harasses its own tissue, i.e. immune system assaults myelin.
12. MRI uses powerful magnetic fields to form a clear image of the spinal cord and brain. Therefore, the parts of the destroyed tissues can be easily seen. Spinal tap displays numerous immunoglobulins as well as oligoclonal bands that are the breakdown products of myelin, which indicate the presence of MS.
13. Asteroids are related to hormones released by adrenal glands. They stem the body’s immune system and function as an anti-inflammatory agent.
14. Copaxone is a compound that looks like myelin. Once Copaxone is in the body, the body attacks it instead of the natural myelin. The Copaxone can be digested by the digestive system if it is ingested in the mouth. Hence, the drug is injected in order to avoid digestion. The drug reduces lesions along the axons.
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14. Interferon drugs repress the immune response and are also used as anti-viral agents. Beta interferon drugs are used in treating relapse-remitting type of MS.
16. The burning sensation was a result of breakdown of the work of sensory neurons, which convey information from the sense organ to the brain. Kathy had muscle spasms, which reduced immobility and dexterity, as well as difficulty in achieving a comfortable position.
17. Yes, hearing loss is always associated with the presence of inflammations around the cranial nerve (the auditory nerve) as it moves into the brainstem.