The Neuromuscular junction uses synapses to connect the muscular system with the muscular system. A nerve impulse is sent from the brain down to the motor neuron by way of the axon. Acetylcholine is released after the vesicles break open. Sodium channels are opened from Acetylcholine that bonds to the Acetylcholine receptors. Depolarization happens when Acetylcholine causes an area of the muscle fiber to become a little more positive when it leaves the nerve and docks on receptors in the muscle membrane. Large amounts of Na+ ions enter the muscle fiber because channels open after depolarization, and an action potential then spreads throughout the muscle fiber. The thick and thin filaments of the muscle fiber can then contract…
Smooth muscle contraction occurs when calcium is present in the smooth muscle cell and binds onto calmodulin to activate myosin light chain kinase (Wilson et al., 2002). Phosphorylation of myosin light chains result in myosin ATPase activity thus cross-bridge cycling occurs causing the muscle to contract (Horowitz et al., 1996). There are two known models of excitation and contraction in smooth muscle, electromechanical coupling (EMC) and pharmomechanical coupling (PMC) (Droogmans et al., 1997). EMC involves a change in membrane potential as a result of nerve stimulation (Sanders, 2008). Depolarisation causes voltage gated calcium channels to open and contraction occurs. High potassium (K+) concentration causes potassium leak channels to shut down thus no positive charge leaves the cell and the membrane becomes depolarised (Morgan et al., 1981). It is possible to determine if a tissue uses EMC, by depolarising the tissue and seeing if it contracts. Depolarisation of smooth muscle cells through the EMC can be achieved when a K+-depolarisation solution is used as a stimulus, causing calcium release and contraction. On the other hand, PMC does not require a change in membrane potential (Edman, 1962). Rather, drugs mediate smooth muscle contraction, for example acetylcholine (Ach) that bind onto receptors and cause the calcium into the smooth muscle cell causing it to contract (Devine et al., 1972, Sanders, 2008).…
channels to open and allow an action potential to occur in the muscle which is known as an…
For a skeletal muscle fiber to contract, a stimulus must be applied to it. The stimulus is delivered by a nerve cell, or neuron. A neuron has a threadlike process called and axon that my run 91 cm or more to a muscle. A bundle of such fibers from man different neurons composes a nerve. A neuron that stimulates muscle tissue is called a motor neuron.…
• At the end of each motor neuron there are tiny vesicles that store chemicals called neurotransmitters that stimulate the muscle to contract.…
When an impulse arrives at an axon terminal, the vesicles release the neurotransmitters into the synaptic cleft. The neurotransmitter molecules diffuse across the synaptic cleft and attach themselves to receptors on the membrane of the neighboring cell. This stimulus causes positive sodium ions to rush across the cell membrane, stimulating the second cell. If the stimulation exceeds the cell’s threshold, a new impulse begins.…
Obtain boiled, deionized water, pipets or burets, and 20-mL beakers or 150 mm test tubes in order to mix solutions for 8 kinetic trials.…
Number the statements in the proper sequence to describe excitation-contraction coupling. Step 1 has been numbered for you.…
a. Summation/tetanus – Increased frequency of action potentials within the somatic motor neuron leads to increased frequency of stimulation of muscle fiber causing increased force of contraction because another AP (stimulus) arrives in muscle cell before muscle fully relaxes resulting in increased intracellular calcium.…
Skeletal muscle is under voluntary control. Nerve impulses that originate in the central nervous system cause muscles to contract. Both neurons and muscle tissue conduct electrical current by moving ions across cellular membranes. A motor neuron ends in a synapse with a muscle fiber. The neuron releases acetylcholine and transfers the action potential to the muscle tissue. The signal will travel through the tissue and trigger the contraction of individual sarcomeres. One synapse generally controls an entire muscle fiber. One motor neuron usually controls several adjacent muscle fibers. A group of fibers under the control of a single motor neuron is known as a motor unit.…
Action potentials are propagated from the surface to the interior of a muscle fiber by way of…
During the action potential part of the neural membrane opens to let + charged ions in the cell and let – charged ions out. This causes a rapid increase in positive nerve fiber.…
The process of excitation-contraction coupling in skeletal muscle fibers is that the end plate potential triggers a series of events that results in the contraction of a muscle cell. End plate potential is caused by the events that occur at the neuromuscular junction.…
D. To generate an EPP, ACh acts as the neurotransmitter involved in skeletal muscle contraction…
This lab consisted of discovering what solutions will cause a muscle to contract. A muscle contraction is when the muscle shortens. A contraction, occurs when the brain delivers a message to a motor neuron (Cooper 18). The motor neuron, Ach attaches to a cell causing a release of Calcium (18). The Calcium ion is released from sarcoplasmic reticulum of the muscle (18). The calcium ion attaches the voltage gate Calcium channels in the transverse tubules (extensions of the muscle cell membrane) then diffusion…