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What do action potentials travel down to cause muscle contraction?
Wiki User
∙ 10y ago
Axon of neuron, sarcolemma, and T-tubules.
Wiki User
∙ 12y ago
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How does an action potential differ from a graded potential?
Action potentials also known as spikes, differ from graded potentials in that they do not diminish in strength as they travel through the neuron.
What does communication in the nervous system depend on which are electrical impulses that travel from neuron to neuron?
action potentials
When the what reaches the end of the axon the neurotransmitter is released?
When the _____________reaches the ends of the axon the neurotransmitter is released and it diffuses to the muscle cell membrane to combine with receptors there?Sarcolemma
What type of cell signals travel throughout the body?
neuronal cell signals travel throughout the body through the nervous system. The signal is electrical, and the fastest type of cellular signal. The electrical impluse is generated by action potentials.
Where does the heart contraction start and how does it travel?
no
How do the nerve impulses get from the sarcolemma plasmalemma into the individual muscle fiber?
Nerve impulses travel down from the neuron and cause ACh to be released at the axon terminal. If enough Ach binds to the receptors on the plasmalemma the action potential is tranmitted through the whole muscle fiber because Na+ enters the cell and depolarize it. The action potential travels along the T-tubules. These transmit it to the Sarcoplasmatic Reticulum which releases Ca2+ into the muscle fiber (as do the T-tubules themselves). The Ca2+ frees the bindingsite for myosin on actin so that contraction can occur.
What does a conduction velocity of an action potential depend on?
An action potential does not have a conduction velocity. Rather, it makes sense to measure the conduction velocity of nerves or nerve cells and this is usually done in metres per second (m/s.). An action potential is characterised as "an all or none response". This means you cannot alter the characteristics of an action potential in a given nerve cell. If you get a nerve cell and manage to get it to threshold, produce and measure an action potential 1000 times or more at the exact same point on the cell, the action potential you measure will not change in timing or amplitude. Information travels down a nerve cell through action potentials. But it is not one action potential that travels the whole length of the axon. Instead what happens is that one action potential causes the next bit of the nerve cell to reach threshold and therefore creates an entirely new action potential. So you actually need multiple action potentials to happen along a nerve cell to send information down it. We call this "propagation of action potentials" since each action potential produces a new one. More properly, it is referred to as "saltatory action potential conduction". Conduction velocity is basically a measure of how quickly we can produce a series of action potentials to travel the distance of the nerve cell axon. Since action potentials only happen at each "Node of Ranvier", then the longer the distance between each node (internodal distance), the faster the conduction velocity of a nerve cell. Since the internodal distance is positively correlated with myelin thickness, more thickly myelinated nerve cells have faster conduction velocities. The thickest and fastest nerve cells are motor neurones and Ia fibres from muscle spindles with a diameter of 12-20 micrometres and a conduction velocity of 70-120 m/s. The thinnest/slowest are fibres used to convey slow pain (<1.5 micrometres and 0.5-2 m/s).
What are the basic principles of somatic motor pathways?
The basic "principal" behind somatic motor pathways is a pathway from your "brain" or regions in or near the brain where nerve impluses travel from and go to skeletal muscle to cause a muscle contraction. (It's complicated, but doesn't get any more basic than this) -Jordan Bourne
Is travel an action verb or linking verb?
It should be an action word as it makes sense here; we travel / they travel.
What characterizes the normal operation of the heart?
each part contracts in a specific order. Contraction of the muscle is triggered by an electrical impulse. These electrical impulses travel through specialized cells that form a conduction system. Following this pathway ensures that contractions will
How an action potential was initiated?
When muscle cells are stimulated, they contract and exert a force in one direction. Stimulation of muscle cells is caused by nerve impulses carried from the central nervous system to the muscles. When the nerve impulse reaches the end of the neuron, it causes a transfer of the action potential in muscles, which leads to a contraction.There are three types of muscle cells in the body, which are cardiac, smooth and skeletal. Cardiac muscle is only found within the heart and has its own intrinsic method for contracting, although nerves can stimulate it to speed up or slow down as necessary. Smooth muscle is found in layers surrounding the organs, and it is stimulated by the autonomic, or involuntary, nervous system. Skeletal muscle is made up of fibers and causes movement. The action potential in muscles of the skeleton is carried by the somatic, or voluntary, nervous system.Muscle cells will not contract on their own, but must be stimulated first by a nerve impulse. The axons of neurons meet muscle cells at the neuromuscular junction. To ensure that muscle contraction is simultaneous and fast, there are many neuromuscular junctions found across a muscle. All of these neurons send impulses at the same time to initiate an action potential in muscles. Having many neuromuscular junctions for each muscle allows the body to control the force of the contraction by varying the number of units that send the impulse to the muscle.When the action potential reaches the terminal end of the axon at a neuromuscular junction, vesicles fuse with the cell membrane to allow the release of a neurotransmitter - acetylcholine. The neurotransmitter spreads across the gap between the neuron and the muscle cell, until it reaches the sarcolemma, which is the membrane surrounding a muscle cell. Acetylcholine causes the permeability of the sarcolemma to change, so that sodium ions can enter and leave the membrane. This change in ions depolarizes the membrane and causes an action potential in muscles to be fired.When a muscle is at rest, tropomyosin blocks the myosin binding sites found on the actin filaments. During a contraction, myosin attaches to actin and performs a type of rowing action along the actin filaments. This causes the muscle to contract. For this to occur, myosin must be able to bind to actin, so the tropomyosin must be moved.The depolarization caused by the nerve impulse spreads across the sarcolemma and the T system - a system of tubes connected to the sarcoplasmic reticulum. Both the T system and the sarcoplasmic reticulum contain calcium ions, which are released when there is an action potential in muscles. The calcium ions diffuse throughout the muscle cell and attach to a protein called troponin, which is attached to the tropomyosin filaments found on the actin fibers. The troponin changes shape when calcium ions attach to it, which moves the tropomyosin filaments and frees the myosin binding sites along actin fibers. Myosin can now come in contact with actin and cause a muscle contraction.
What is the white lipid material that insulates the axon of a neuron?
The white lipid material that insulates the axon of a neuron is called myelin. In the central nervous system, myelin is created by oligodendrocytes while in the peripheral nervous system the myelin is created by Schwann cells. The purpose of myelin is to speed up action potentials. It's important to know that the myelin does not coat the axon entirely; each sheath of myelin is separated by a gap, called a node of Ranvier. These gaps are responsible for the quick transport of action potentials, due to the fact that the potentials can "jump" from node to node rather than having to travel down the entire length of the axon (this is called saltatory conduction).
