which type of cell gets shorter as it does its job?

Answer 1

A muscle fiber, also spelled muscle fibre , also technically known as a myocyte, is a single cell of a muscle. Muscle fibers contain many myofibrils, the contractile unit of muscles. Muscle fibers are very long; a single fiber can reach a length of 30cm.

Muscle fibres can be grouped according to what kind of tissue they are found in -- skeletal muscle, smooth muscle, and cardiac muscle. The muscle cells of heart muscle tissue are called cardiomyocytes.

Skeletal muscles are used to facilitate movement, by applying force to bones and joints; via contraction. They generally contract voluntarily (via nerve stimulation), although they can contract involuntarily.

The strength of skeletal muscle is directly proportional to its length and cross-sectional area. The strength of a joint, however, is determined by a number of biomechanical principles, including the distance between muscle insertions and pivot points and muscle size. Muscles are normally arranged in opposition so that as one group of muscles contract, another group 'relaxes' (in fact simply stretched) or lengthens. Antagonism in the transmission of nerve impulses (epsp and ipsp balance) to the muscles means that it is impossible to stimulate the contraction of two antagonistic muscles at any one time. During ballistic motions such as throwing, the antagonist muscles act to 'brake' the agonist muscles throughout the contraction, particularly at the end of the motion. In the example of throwing, the chest and front of the shoulder (anterior Deltoid) contract to pull the arm forward, while the muscles in the back and rear of the shoulder (posterior Deltoid) also contract and undergo eccentric contraction to slow the motion down to avoid injury. Part of the training process is learning to relax the antagonist muscles to increase the force output of the chest and anterior shoulder.

Skeletal muscle cells are stimulated by acetylcholine, which is released at neuromuscular junctions by motor neurons. Once the cells are "excited", their sarcoplasmic reticulums will release ionic calcium (Ca2+), this interacts with the myofibrils and induces muscular contraction (via the sliding filament mechanism). Besides calcium, this process requires adenosine triphosphate (ATP). The ATP is produced by metabolizing creatine phosphate and glycogen within the muscle cells by mitochondria, as well by metabolizing glucose and fatty acids, obtained from blood and within the cell. Each motor neuron activates a group of muscle cells, and collectively the neurons and muscle cells are known as motor units. When more strength is required than can be obtained from a single motor unit, more units will be stimulated; this is known as motor unit recruitment. If more strength is required than can be obtained from the current degree of unit contraction, the motor neurons continue to recruit more motor units, and increase the frequency of neuronal firing. This results in tetanic contraction, which causes maximal muscular contraction.
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Answer 2

Muscle cells contract when stimulated, therefore getting shorter (skeletal muscle cells are usually found in antagonistic pairs which enables one muscle to contract and straighten out the other muscle in the pair e.g. biceps and triceps muscles of the arm).

Answer 3

Muscle cells contract (get shorter) when they do their job.

Answer 4

A muscles cells contracts when you flex the muscle. This is why the muscles in your joints are in pairs, example the bicep and tricep, the bicep contracts to bend the arm and the tricep contracts to straighten the arm.

Answer 5

Brain cells

Answer 6

A muscle cell. Unless, of course, you are pushing against a wall or similar object.

Answer 7

muscle cells contract allowing movement. (Also cardiac myocytes, heart cells, contract as the heart beats)

Answer 8

Um..body ones? Like cell division?

Answer 9

telomeres in the nucleus get shorter everytime the cell divides

Answer 10

Red blood cells...as they do their job (which is to carry oxygen) they get worn out and 'shrink' which your body then discards. More are made from your red bone marrow.