However, even if the vision of 68Ga becoming as immense as 99mTc will not get fulfilled, 68Ga has definitely strong contribution to make in the improvement of personalized patient management and there is a niche for 68Ga-based agents in nuclear medicine.
Types[ edit ] Types of muscle contractions Muscle contractions can be described based on two variables: Force itself can be differentiated as either tension or load. Muscle tension is the force exerted by the muscle on an object whereas a load is the force exerted by an object on the muscle.
Isometric exercise An isometric contraction of a muscle generates tension without changing length. Isotonic contraction[ edit ] In isotonic contractionthe tension in the muscle remains constant despite a change in muscle length. Concentric contraction[ edit ] In concentric contractionmuscle tension is sufficient to overcome the load, and the muscle shortens as it contracts.
During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory.
This occurs throughout the length of the muscle, generating a force at the origin and insertion, causing the muscle to shorten and changing the angle of the joint. In relation to the elbowa concentric contraction of the biceps would cause the arm to bend at the elbow as the hand moved from the leg to the shoulder a biceps curl.
A concentric contraction of the triceps would change the angle of the joint in the opposite direction, straightening the arm and moving the hand towards the leg. Eccentric training In eccentric contraction, the tension generated while isometric is insufficient to overcome the external load on the muscle and the muscle fibers lengthen as they contract.
This can occur involuntarily e.
Over the short-term, strength training involving both eccentric and concentric contractions appear to increase muscular strength more than training with concentric contractions alone. During an eccentric contraction of the triceps musclethe elbow starts the movement straight and then bends as the hand moves towards the shoulder.
Desmintitinand other z-line proteins are involved in eccentric contractions, but their mechanism is poorly understood in comparison to crossbridge cycling in concentric contractions.
For example, one expends more energy going up a flight of stairs than going down the same flight.
Muscles undergoing heavy eccentric loading suffer greater damage when overloaded such as during muscle building or strength training exercise as compared to concentric loading. When eccentric contractions are used in weight training, they are normally called negatives.
During a concentric contraction, muscle myofilaments slide past each other, pulling the Z-lines together. During an eccentric contraction, the myofilaments slide past each other the opposite way, though the actual movement of the myosin heads during an eccentric contraction is not known.
Exercise that incorporates both eccentric and concentric muscular contractions i. During virtually any routine movement, eccentric contractions assist in keeping motions smooth, but can also slow rapid movements such as a punch or throw.
Part of training for rapid movements such as pitching during baseball involves reducing eccentric braking allowing a greater power to be developed throughout the movement.
Eccentric contractions are being researched for their ability to speed rehabilitation of weak or injured tendons. Muscle tissue In vertebrate animals, there are three types of muscle tissues: Skeletal muscle constitutes the majority of muscle mass in the body and is responsible for locomotor activity.
Smooth muscle forms blood vesselsgastrointestinal tractand other areas in the body that produce sustained contractions. Cardiac muscle make up the heart, which pumps blood. Skeletal and cardiac muscles are called striated muscle because of their striped appearance under a microscope, which is due to the highly organized alternating pattern of A bands and I bands.
Skeletal muscle Organization of skeletal muscle Excluding reflexes, all skeletal muscles contractions occur as a result of conscious effort originating in the brain. The brain sends electrochemical signals through the nervous system to the motor neuron that innervates several muscle fibers.
Other actions such as locomotion, breathing, and chewing have a reflex aspect to them: Neuromuscular junction Structure of neuromuscular junction. A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.
The sequence of events that results in the depolarization of the muscle fiber at the neuromuscular junction begins when an action potential is initiated in the cell body of a motor neuron, which is then propagated by saltatory conduction along its axon toward the neuromuscular junction.
Acetylcholine diffuses across the synapse and binds to and activates nicotinic acetylcholine receptors on the neuromuscular junction.
The membrane potential then becomes hyperpolarized when potassium exits and is then adjusted back to the resting membrane potential. This rapid fluctuation is called the end-plate potential  The voltage-gated ion channels of the sarcolemma next to the end plate open in response to the end plate potential.These differences may be accounted for by 1) extra volume occupied by noncontractile material (collagen, water, and capillaries) in in vivo and in situ muscles compared with in vitro single fibers,2) the force contribution of the residual type fibers in the entire muscle, and 3) imperfect force transmission from fibers to tendons.
How is change in whole-muscle force achieved in vivo? The increase of electrical current causes a progressive increase in the amount of muscle force based on the amount of the electrical current.
At the beginning stage, the electric current must surpass the threshold voltage. Muscle hypertrophy involves an increase in size of skeletal muscle through a growth in size of its component cells. Two factors contribute to hypertrophy: sarcoplasmic hypertrophy, which focuses more on increased muscle glycogen storage; and myofibrillar hypertrophy, which focuses more on .
Summary of Creatine Primary Information, Benefits, Effects, and Important Facts. What is creatine? Creatine is a molecule produced in the body. It stores high-energy phosphate groups in the form of phosphocreatine.
Strain and elongation of the human semitendinosus muscle – Tendon unit In vivo passive change in muscle length is achieved by changing joint angular position. From an anatomical point of view, when the hip joint is maintained constant, the ST muscle lengthens as the knee extends.
as one would expect that lengthening of the whole ST. How is this change in whole-muscle force achieved in vivo (eg.
in the human body)? The increase of electrical current causes a progressive increase in the amount of muscle force based on the amount of the electrical current.