intercalated discs

Examples of intercalated discs in the following topics:

• Microscopic Anatomy

  • Actin molecules are bound to the Z-disc, which forms the borders of the sarcomere.
  • Intercalated discs are gap junctions that link cardiomyocytes so that electrical impulses (action potentials) can travel between cells.
  • In cardiac muscle, intercalated discs connecting cardiomyocytes to the syncytium, a multinucleated muscle cell, to support the rapid spread of action potentials and the synchronized contraction of the myocardium.
  • Intercalated discs consist of three types of cell-cell junctions, most of which are found in other tissues besides cardiac muscle:
  • Under light microscopy, intercalated discs appear as thin lines dividing adjacent cardiac muscle cells and running perpendicular to the direction of muscle fibers.

• Mechanism and Contraction Events of Cardiac Muscle Fibers

  • Cardiac muscle fibers undergo coordinated contraction via calcium-induced calcium release conducted through the intercalated discs.
  • Cardiomyocytes are capable of coordinated contraction, controlled through the gap junctions of intercalated discs.

• Characteristics of Muscle Tissue

  • Cardiac muscle can be further differentiated from skeletal muscle by the presence of intercalated discs which control the synchronized contraction of cardiac tissues.

• Bilaminar Embryonic Disc Development

  • The floor of the amniotic cavity is formed by the embryonic disc.
  • The embryonic disc is derived from the epiblast layer, which lies between the hypoblast layer and the amnion.
  • The embryonic disc forms during early development.
  • The formation of the bilaminar embryonic disc precedes gastrulation.
  • As gastrulation progresses, the embryonic disc becomes trilaminar and the notochord is formed.

• Herniated (Slipped) Disc

  • A disc herniation is a common injury caused by a tear in the fibrous ring of an intervertebral disc, allowing the central portion to bulge.
  • A spinal disc herniation is a medical condition affecting the spine in which a tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion to bulge out beyond the damaged outer rings .
  • The condition is widely referred to as a slipped disc, but this term is not medically accurate as the spinal discs are fixed in position between the vertebrae and cannot in fact "slip. " A herniated disc may occur due to trauma, lifting injuries, or other factors.
  • If the herniated disc is in the lumbar region (where the majority of herniated discs occur), the patient may also experience sciatica due to irritation of one of the nerve roots of the sciatic nerve.
  • In the majority of cases, spinal disc herniation doesn't require surgery.

• Cartilaginous Joints: Symphyses

  • Intervertebral discs (or intervertebral fibrocartilage) lie between adjacent vertebrae in the spine.
  • The discs consist of an outer annulus fibrosus that surrounds the inner nucleus pulposus.
  • The annulus fibrosus and the nucleus pulposus distribute pressure evenly across the disc.
  • When one develops a prolapsed disc, the jelly (the nucleus pulposus) is forced out of the doughnut (the disc) and may put pressure on the nerve located near the disc, potentially causing symptoms of sciatica.
  • Aging causes disc degeneration, in which the nucleus pulposus begins to dehydrate and the concentration of proteoglycans in the matrix decreases, limiting the ability of the disc to absorb shock.

• Types of Muscle Tissue

  • The striations are fitted together with unique junctions called intercalated disks, specialized junctions that help in the transmission of electrical impulses so the heart can beat in a steady rhythm.
  • The involuntary contraction of cardiac muscle is coordinated by the intercalated disks, so the entire heart beats in a controlled, uniform manner, ensuring that blood is efficiently pumped from the chambers.

• Sciatic Nerve Injury

  • Sciatica is also referred to as lumbar radiculopathy, which involves compression of the sciatic nerve roots caused by a herniated (torn) or protruding disc in the lower back.
  • This can occur as a result of a spinal disk bulge or a spinal disc herniation (a herniated intervertebral disc), or from roughening, enlarging, or misalignment (spondylolisthesis) of the vertebrae, or as a result of degenerated discs that can reduce the diameter of the lateral foramen (natural hole) through which nerve roots exit the spine.
  • The intervertebral discs consist of an annulus fibrosus, which forms a ring surrounding the inner nucleus pulposus.

• Gap Junctions

  • Intercalated disks consist of three different types of cell–cell junctions: actin filaments anchoring adherens junctions, intermediate filaments anchoring desmosomes, and gap junctions.

• Paralysis

  • Their intervertebral disc material can calcify and become more brittle.
  • In such cases, the disc may rupture, with disc material ending up in the spinal canal, or rupturing more laterally to press on spinal nerves.
  • If no signs of pain can be elicited, surgery should be performed within 24 hours of the incident, to remove the disc material and relieve pressure on the spinal cord.
  • This is a microscopic piece of disc material that breaks off and becomes lodged in a spinal artery.