Central Nervous System: Movement of Muscles in the Body

Topics: Action potential, Muscle, Nervous system Pages: 6 (2146 words) Published: April 21, 2011
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 system is like a network that relays messages back and forth from the brain to different parts of the body. It does this through the spinal cord, which runs from the brain down through the back and contains nerves that branch out to every organ and body part. In the inner part of the forebrain sits the thalamus. The thalamus carries messages from the sensory organs like the eyes, ears, nose, and fingers to the cortex. The midbrain, located underneath the middle of the forebrain, acts as a master coordinator for all the messages going in and out of the brain to the spinal cord The hindbrain sits underneath the back end of the cerebrum, and it consists of the cerebellum, pons, and medulla. The cerebellum is responsible for balance, movement, and coordination. The pons and the medulla, along with the midbrain, are often called the brainstem. The brainstem takes in, sends out, and coordinates all of the brain's messages. The skeletal system is moved by the constriction of the skeletal muscle. The skeletal muscle constricts because of the signal sent by neurotransmitter, acetylcholine. This signal is sent by the nervous system which wants the muscle to constrict so the bone can bend. The nervous system controls everything. Muscle contraction is initiated when calcium is made available within the muscle fiber. This calcium is then used to initiate contraction, given the affinity of troponin to calcium.  As troponin attaches to calcium, it produces a movement of the tropomyosin molecule that frees up the actin site so that the charged cross-bridge can contact the site resulting in the liberation of energy from the adenosine triphosphate (ATP) molecule. Nerve impulses are sent from the motor cortex of the brain through the spinal cord. The musculocutaneous nerve continues the wave of axon depolarization to individual muscle fibers via motor units.  Each motor unit has so many number of motor nerves that extend to individual muscle fibers by way of a neuromuscular junction called the synapse. When the motor nerve is depolarized, acetylcholine is released from the axon terminals at the neuromuscular junction. .  The acetylcholine binds to the receptor sites on the motor end plate membrane.  The neurotransmitter, acetylcholine, increases the motor end plate’s permeability to sodium and potassium ions, which produces an end-plate potential.  This potential depolarizes the sarcolemma that creates a muscle action potential that is propagated throughout the muscle membrane causing depolarization of the transverse tubules. All the muscles that are included in this action are: biceps, pectoral, quadriceps,shoulder, abs, gastrocnemius, erector spinae, lastissimus dorsi, gluteus maximus, medius, and minimus.

1.  Label structures from the following parts of the nervous system that are involved in the movement: a.  At least five structures of the afferent division of the peripheral nervous system (i.e., sense organs and afferent nerves) b.  At least two structures of the central nervous system

c.  At least seven structures of the efferent division of the peripheral nervous system 2.  Label structures from the following parts of the skeletal system that are involved in the movement: a.  At least thirteen bones

b.  At least five joints
3.  Label at least thirteen muscles from the muscular system that are involved in the movement.  
B.  Analyze (suggested length of 1–2 pages) the functions and interactions of the structures of the...
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