ST segment

Examples of ST segment in the following topics:

• Electrocardiogram and Correlation of ECG Waves with Systole

  • The ST segment refers to the gap (flat or slightly upcurved line) between the S wave and the T wave, and represents the time between ventricular depolarization and repolarization.
  • An elevated ST segment is the classic indicator for myocardial infarctions, though missing or downward sloping sloping ST segments may indicate myocardial ischemia.

• Facial (VII) Nerve

  • The path of the facial nerve can be divided into six segments.

• Development of Metabolism

  • During fetal life, the primitive gut can be divided into three segments: foregut , midgut , and hindgut .
  • These terms are regularly used to describe both segments of the primitive gut and components of the definitive gut.
  • In later development each segment of the gut gives rise to specific gut and gut-related structures.

• Bronchi and Subdivisions

  • A bronchopulmonary segment is a distinct region of the lung separated from the rest of the lung by connective tissue.
  • Each bronchopulmonary segment forms a discrete functional unit in the lung that is independent of the other segments.
  • This property allows a bronchopulmonary segment to be surgically removed without affecting other segments.
  • There are 10 segments in the right lung and 8 to 9 segments in the left lung due to anatomical differences.
  • The segmental bronchi divide into many primary bronchioles that divide into terminal bronchioles.

• Lobes, Fissures, and Lobules

  • It bears apical, anterior, and posterior bronchopulmonary segments.
  • It bears medial and lateral bronchopulmonary segments.
  • It bears medial, lateral, superior, anterior, and posterior bronchopulmonary segments.
  • The upper lobe of the left lung contains anterior and apicoposterior bronchopulmonary segments.
  • It contains superior and inferior bronchopulmonary segments.

• Digestive System Development

  • During fetal life, the primitive gut can be divided into three segments: foregut, midgut, and hindgut.
  • Although these terms are often used in reference to segments of the primitive gut, they are also used regularly to describe components of the definitive gut as well.
  • Each segment of the gut gives rise to specific gut and gut-related structures in later development.

• Muscularis

  • The muscularis is responsible for segmental contractions and peristaltic movement in the gastrointestinal (GI) tract.
  • The muscularis externa is responsible for segmental contractions and peristaltic movement in the GI tract.
  • Occasionally in the large intestine (two to three times a day), there will be mass contraction of certain segments, moving a lot of feces along.

• Regeneration of Nerve Fibers

  • When an axon is damaged, the distal segment undergoes Wallerian degeneration, losing its myelin sheath.
  • The proximal segment can either die by apoptosis or undergo the chromatolytic reaction, which is an attempt at repair.
  • When a nerve axon is severed, the end still attached to the cell body is labeled the proximal segment, while the other end is called the distal segment.
  • The distal segment, however, experiences Wallerian degeneration within hours of the injury; the axons and myelin degenerate, but the endoneurium remains.
  • Slower degeneration of the distal segment than that which occurs in the peripheral nervous system also contributes to the inhibitory environment; inhibitory myelin and axonal debris are not cleared away as quickly.

• Capacity of Different Tissues for Repair

  • When a nerve axon is severed, the end still attached to the cell body is labeled the proximal segment, while the other end is called the distal segment.
  • The distal segment, however, experiences Wallerian degeneration within hours of the injury; the axons and myelin degenerate, but the endoneurium remains.
  • Slower degeneration of the distal segment than that which occurs in the peripheral nervous system also contributes to the inhibitory environment because inhibitory myelin and axonal debris are not cleared away as quickly.
  • The proximal segment attempts to regenerate after injury, but its growth is hindered by the environment.

• Stages of Labor

  • Uterine muscles form opposing spirals from the top of the upper segment of the uterus to its junction with the lower segment.
  • During effacement, the cervix becomes incorporated into the lower segment of the uterus.
  • During a contraction, these muscles shorten the upper segment, drawing upwards the lower segment in a gradual expulsive motion.