Striated muscle tissue

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Striated muscle tissue
Musculoskeletal system
Identifiers
Latintextus muscularis striatus
MeSHD054792
THH2.00.05.2.00001
FMA67905
Anatomical terminology]

Striated muscle tissue is a

muscle tissue that features repeating functional units called sarcomeres
. The presence of sarcomeres manifests as a series of bands visible along the muscle fibers, which is responsible for the striated appearance observed in microscopic images of this tissue. There are two types of striated muscle:

Structure

Striated muscle tissue contains

T-tubules which enables the release of calcium ions from the sarcoplasmic reticulum.[1]

Skeletal muscle

Skeletal muscle includes

skeletal muscle fibers, blood vessels, nerve fibers, and connective tissue. Skeletal muscle is wrapped in epimysium, allowing structural integrity of the muscle despite contractions. The perimysium organizes the muscle fibers, which are encased in collagen and endomysium, into fascicles. Each muscle fiber contains sarcolemma, sarcoplasm, and sarcoplasmic reticulum. The functional unit of a muscle fiber is called a sarcomere.[2]
Each muscle cell contains myofibrils composed of actin and myosin myofilaments repeated as a sarcomere.[3] Many nuclei are present in each muscle cell placed at regular intervals beneath the sarcolemma.

Based on their contractile and metabolic phenotypes, skeletal muscle can be classified as slow-oxidative (Type I) or fast-oxidative (Type II).[1]

Cardiac muscle

Cardiac muscle lies between the

desmosomes.[5]

Striated versus smooth muscle

Unlike skeletal and cardiac muscle tissue,

mitochondria than smooth muscle. Both smooth muscle cells and cardiac muscle cells have a single nucleus, and skeletal muscle cells have many nuclei.[6]

Function

Main article: Muscle contraction

The main function of striated muscle tissue is to create force and contract. These contractions in cardiac muscle will pump blood throughout the body. In skeletal muscle the contractions enable breathing, movement, and posture maintenance.[1]

Contractions in cardiac muscle tissue are due to a

autorhythmicity. The set intervals at which they depolarize to threshold and fire action potentials is what determines the heart rate. Because of the gap junctions, the pacemaker cells transfer the depolarization to other cardiac muscle fibers, in order to contract in unison.[5]

Signals from motor neurons cause skeletal muscle fibers to depolarize and therefore release calcium ions from the sarcoplasmic reticulum. The calcium drives the movement of myosin and actin filaments. The sarcomere then shortens which causes the muscle to contract.[3] In the skeletal muscles connected to tendons that pull on bones, the mysia fuses to the periosteum that coats the bone. Contraction of the muscle will transfer to the mysia, then the tendon and the periosteum before causing the bone to move. The mysia also may bind to an aponeurosis or to fascia.[2]

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.[7]

Skeletal muscle is able to regenerate far better than cardiac muscle due to

myoblasts.[8]

Dysfunctions

Skeletal muscle

Cardiac muscle

See also

References

  1. ^
    PMID 27271751
    .
  2. ^ a b Anatomy and Physiology. PressBooks. p. 64. Retrieved 11 April 2019.
  3. ^
    PMID 23303905
    .
  4. ^ a b "Cardiac Muscle". Biology Dictionary. Biology Dictionary. 2017-12-08. Retrieved 12 April 2019.
  5. ^ a b c Anatomy and Physiology. PressBooks. p. 69. Retrieved 12 April 2019.
  6. ^ "Muscle Physiology - Introduction to Muscle". muscle.ucsd.edu. Retrieved 2015-11-24.
  7. PMID 26906733
    .
  8. ^
    PMID 25922523
    .
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