1 $100a T-tubules: transverse tubules that extend across the sarcoplasm at right angles to the long axis of the muscle fiber. They are formed by inward extensions of the sarcolemma. The membrane of the t tubules has ion pumps that continually transport Ca++ ions inward from the sarcoplasm. They allow electrical impulses traveling along the sarcolemma to move deeper into the cell. Triad: triplet of tubules; a T tubule sandwiched between two sacs of sarcoplasmic reticulum. It allows electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the sarcoplasmic reticulum.
1 $100b What structures are unique to skeletal muscle fibers?
1 $200a Contractility: The impulse travels across the sarcolemma and through the t tubules that realease calcium ion into the sarcoplasm. The calcium ions bind to troponin molecules and initiate a chemical reaction that produces a contraction. The process of a muscle contracting is called the sliding filament theory. Excitability: When a skeletal fiber is stimulated by a signal from a motor neuron, the motor neurons connect to the sarcolemma. A neuromuscular junction is formed. Acetylcholine is released and stimulates acetylcholine receptors that initiate an electrical impulse in the sarcolemma. This is called excitation.
1 $200b Which of the structures involved primarily in contractility and which are in invloved in excitability?
1 $300a Myofilaments are made up of myosin, actin, tropomyosin, and troponin. The myosin heads on the thick myosin form cross bridges with the nearby thin actin that contain tropomyosin and troponin .
1 $300b how the structure of the myofilaments is related to their function
1 $400a 1. When you exercise and isolate a muscle group, lactic acid, produced naturally by your body, begins to build around that muscle. That lactic acid accumulates around the muscle, resulting in a burning sensation. While the burn is often associated with becoming stronger, the feeling of heat and fatigue often ends your workout. After a certain number of repetitions, the lactic acid causes muscle fatigue as it interacts in the calcium in your body. This is evidenced by the inability to complete any more repetitions
1 $400b WHAT IS LACTIC ACID
1 $500a 1. People who exercise seriously are sometimes told to work a muscle until they "feel the burn". In terms of how muscle is able to release energy, explain what is going on in the muscle early in the exercise and when the muscle is "burning."
1 $500b WHAT CAUSES THE “BURN” YOU FEEL WHEN A MUSCLE IS BEING EXERCISED?
2 $100aA single motor neuron and the muscle fibers connected to it act as a unit
2 $100b A MOTOR NEURON AND THE MUSCLE FIBERS CONNECTED TO IT IS CALLED WHAT?
2 $200a The number of muscle fibers in each motor unit varies in different parts of the body. Muscle fibers involved in fine motor skills contain a small number of muscle cells. This gives the nervous system the option of making very tiny adjustments. Those involved gross motor movements have many more fibers for each nerve axon or motor neuron. So the axon makes a larger movement because of how many cells are affected.
2 $200b WHAT IS A MOTOR UNIT?
2 $300a Cardiac muscle cells make up the myocardium portion of the heart wall.
2 $300b What is the meaning of a "unit of combined cells" as it relates to cardiac Muscle?
2 $400a Measure approximately 10-15 micrometers in diameter and 50-100 micrometers in length. They have an overlapping arrangement of light and dark striations.
2 $400b How does the structure arrangement affect its function?
BOUNS2 $500aUsing fiber types, design a muscle for a marathon runner.
BOUNS2 $500b Type I muscle fibers are classified as slow-twitch, which means they develop force slowly and relax at a similar pace with a longer “twitch” time in between. Don’t utilize much energy from ATP. More aerobic than anaerobic. Can function for longer periods of time with repetitive contractions, because of a readily supply of oxygen.
3 $100a Stiffening of the joints and muscles of a body after death
3 $100b What is Rigor Mortis
3 $200a The muscle contraction process first happens by a motor neuron being activated. This produces an action potential that passes outward in a ventral root of the spinal cord where it is conveyed to a motor end plate on each muscle fiber. The action potential causes the release of packets of acetylcholine into the synaptic clefts on the surface of the muscle fiber. The acetylcholine causes the electrical resting potential under the motor end plate to change, and this then initiates an action potential which passes in both directions along the surface of the muscle fiber. At the opening of each transverse tubule onto the muscle fiber surface, the action potential spreads inside the muscle fiber. At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to release Ca+2 ions. The calcium ions result in movement of troponin and tropomyosin on their thin filaments, and this enables the myosin molecule heads to "grab and swivel" their way along the thin filament. This is the driving force of muscle contraction
3 $200b What are the 4 factors that influence the strength of muscle contractions?
3 $300a is a single contraction of skeletal muscle. The three distinct phases are latent, contraction, and relaxation.
3 $300b What are the phases of a twitch contraction?
3 $400a Skeletal muscle moves bones by receiving acetelecholine from a motor nerve that triggers an action potential across the muscle fibers. Muscle fibers contain actin and myosin, which are the function components of muscle contraction. essentially, movement of a bone occurs when the muscle attached is being shortened
3 $400b how does the skeletal muscles provide movement, heat, and posture
BOUNS3 $500a Type II fibers are the fast-twitch, explosive muscle fibers associated with power and explosiveness in athletes. “Inefficient and fatigable” They characterize high anaerobic power but very low aerobic power which equates to shorter duration, but more powerful contractions of the muscle as a whole. The main difference between type 2a and type 2b muscle fibers comes from their “capacity for aerobic-oxidative energy supply.” Type 2a muscle fibers have a more efficient means of aerobic metabolism due to a higher number of surrounding capillaries that circulate blood throughout the muscle which results in a higher resistance to fatigue.
BOUNS3 $500b Using fiber types, design a muscle ffor a 100-yard-dash Sprinter.
4 $100a Latent Phase: Is the interval from the stimulus application until the muscle begins to contract (shorten). Note that there is no traced activity during this phase, but there are some electrical and chemical changes taking place during this phase. Contraction Phase: This phase is when the muscle fibers shorten, the tracings will show during this phase (a) peak(s). Relaxation Phase: This phase is represented by the downward curve in your tracings, this is when the muscle is going back to its original state of relaxation and the muscle will once again lengthen
4 $100b What molecular events occur during each of these phases?
4 $200a As you warm-up, you stretch your muscles and create microscopic tears in the muscle, making it easier to continue with the same exercise.
4 $200b How does the treppe effect relate to the warm-up exercises of athletes?
4 $300a is the explanation for how muscles produce force (or, usually, shorten). It explains that the thick and thin filaments within the sarcomere slide past one another, shortening the entire length of the sarcomere. In order to slide past one another, the myosin heads will interact with the actin filaments and, using ATP, bend to pull past the actin.
4 $300b What is the sliding filament theory?
4 $400a are an intracellular signaling molecule for muscle contraction. so This enables a contraction, and a return of the calcium in the sarcoplasmic reticulum allows the muscle to relax.