Striated muscle

The sarcomeres give • A sarcomere is defined as the segment between two neighbouring Z-lines (or Z-discs). In electron micrographs of cross-striated muscle, the Z-line (from the between) appears in between the I-bands as a dark line that anchors the • Surrounding the Z-line is the region of the I-band (for • Following the I-band is the A-band (for both thick and thin filaments. • Within the A-band is a paler region called the H-zone (from the German "heller", brighter). Named for their lighter appearance under a polarization microscope. H-band is the zone of the thick filaments that has no actin. • Within the H-zone is a thin M-line (from the German "mittel" meaning middle), appears in the middle of the sarcomere formed of cross-connecting elements of the cytoskeleton. The relationship between the proteins and the regions of the sarcomere are as follows: • Actin filaments, the thin filaments, are the major component of the I-band and extend into the A-band. • Myosin filaments, the thick filaments, are bipolar and extend throughout the A-band. They are cross-linked at the centre by the M-band. • The giant protein • Another giant protein, • Several proteins important for the stability of the sarcomeric structure are found in the Z-line as well as in the M-band of the sarcomere. • Actin filaments and titin molecules are cross-linked in the Z-disc via the Z-line protein alpha-actinin. • The M-band proteins • The M-line also binds creatine kinase, which facilitates the reaction...

Get a Britannica Premium subscription and gain access to exclusive content. Muscles are not the only means of movement in animals. Many myonemes, which are capable of shortening rapidly. Nonmuscular methods of movement are important for multicellular animals as well. Many microscopic animals swim by means of beating cilia. Some small

\( \newcommand\) • • • • • • • • • By the end of this section, you will be able to: • Describe the components involved in a muscle contraction • Explain how muscles contract and relax • Describe the sliding filament model of muscle contraction The sequence of events that result in the contraction of an individual muscle fiber begins with a signal — the neurotransmitter, acetylcholine (ACh) — from the motor neuron innervating that fiber. When an action potential traveling down the motor neuron arrives at the neuromuscular junction ACh is released from the axon terminal. These ACh molecules bind to receptors on the motor end plate (the specialized sarcolemma at the neuromuscular junction). This binding leads to the opening of sodium ion channels on the motor end plate and causes the sarcolemma to depolarize as positively charged sodium ions (Na +) enter, triggering an action potential that spreads to the rest of the membrane, including the T-tubules. This triggers the release of calcium ions (Ca ++) from storage in the sarcoplasmic reticulum (SR). The Ca ++ then initiates contraction by binding to a thin filament regulatory protein (troponin) causing a molecular interaction that moves another thin filament regulatory protein (tropomyosin) off the myosin binding sites on actin. As soon as the myosin binding sites are exposed, myosin heads bind to actin and move through a “cross-bridge cycle”, that leads to muscle contraction (Figure \(\PageIndex\)). The contraction of a stria...

Synonyms: Cardiac striated muscle, Myocardium , Muscle cells, commonly known as myocytes, are the cells that make up muscle Cardiac muscle cells, or cardiomyocytes, are the muscle fibers comprise the myocardium, the middle muscular layer, of the Skeletal muscle cells make up the muscle tissues connected to the skeleton and are important in locomotion. Smooth muscle cells are responsible for involuntary movement, like that of the Key facts about the muscle cells Cardiac muscle cell Rectangular in shape Single nucleus Contain many mitochondria Communicate via intercalated discs - Present in myocardium (cardiac muscle) Skeletal muscle cell Cylindrical Striated Multinucleated Contain many mitochondria - Present in skeletal muscles Smooth muscle cell Spindle shaped Single central nucleus Arranged in sheets - Present in muscular layers of the vessels, and within internal organs + Show all Skeletal muscle cells Characteristics Skeletal muscle cells are long, cylindrical, and multi-nucleated meaning that they have more than one nucleus. This is because they are formed from the fusion of embryonic myoblasts. Each nucleus regulates the metabolic requirements of the sarcoplasm around it. Skeletal muscle cells have high energy requirements, so they contain many mitochondria in order to generate sufficient ATP. Synonyms: Myocyte, Myofiber , The anatomy of muscle cells differs from that of other body cells and biologists have applied specific terminology to different parts of these cell...

[ Striated muscle tissue is a • • Structure [ ] Striated muscle tissue contains Skeletal muscle [ ] Skeletal muscle includes Based on their contractile and metabolic phenotypes, skeletal muscle can be classified as slow-oxidative (Type I) or fast-oxidative (Type II). Cardiac muscle [ ] Cardiac muscle lies between the Striated versus smooth muscle [ ] Unlike skeletal and cardiac muscle tissue, Function [ ] Main article: The main function of striated muscle tissue is to create force and contract. These Contractions in cardiac muscle tissue are due to a Signals from Damage repair [ ] Adult humans cannot regenerate cardiac muscle tissue after an injury, which can lead to scarring and thus heart failure. Mammals have the ability to complete small amounts of cardiac regeneration during development. Other vertebrates can regenerate cardiac muscle tissue throughout their entire life span. Skeletal muscle is able to regenerate far better than cardiac muscle due to Dysfunctions [ ] Skeletal muscle [ ] • • • • Cardiac muscle [ ] • • • See also [ ] • References [ ] • ^ a b c Shadrin, I. Y.; Khodabukus, A.; Bursac, N. (June 6, 2016). Cellular and Molecular Life Sciences. 73 (22): 4175–4202. • ^ a b Anatomy and Physiology. PressBooks. p.64 . Retrieved 11 April 2019. • ^ a b c Yin, Hang; Price, Feodor; Rudnicki, Michael A. (January 1, 2013). Physiological Reviews. 93 (1): 23–67. • ^ a b Biology Dictionary. Biology Dictionary. 2017-12-08 . Retrieved 12 April 2019. • ^ a b c Anatomy and Ph...