motor-end plate

Examples of motor-end plate in the following topics:

• Excitation–Contraction Coupling

  • The area of the sarcolemma on the muscle fiber that interacts with the neuron is called the motor-end plate.
  • The end of the neuron's axon is called the synaptic terminal; it does not actually contact the motor-end plate.
  • A small space called the synaptic cleft separates the synaptic terminal from the motor-end plate.
  • Acetylcholine (ACh) is a neurotransmitter released by motor neurons that binds to receptors in the motor end plate.
  • As ACh binds at the motor end plate, this depolarization is called an end-plate potential.

• Growth of Bone

  • The epiphyseal plate is the area of growth in a long bone.
  • On the epiphyseal side of the epiphyseal plate, cartilage is formed.
  • The reserve zone, the region closest to the epiphyseal end of the plate, contains small chondrocytes within the matrix .
  • The more mature cells are situated closer to the diaphyseal end of the plate.
  • (a) Epiphyseal plates are visible in a growing bone.

• Sensory-Somatic Nervous System

  • Unlike the autonomic nervous system, which has two synapses between the CNS and the target organ, sensory and motor neurons have only one synapse: one ending of the neuron is at the organ and the other directly contacts a CNS neuron.
  • Other cranial nerves transmit almost solely motor information.
  • Other cranial nerves contain a mix of sensory and motor fibers.
  • Each sensory neuron has one projection with a sensory receptor ending in skin, muscle, or sensory organs, and another that synapses with a neuron in the dorsal spinal cord.
  • Spinal nerves contain both sensory and motor axons.

• Establishing Body Axes during Development

  • Primary neurulation begins after the neural plate forms.
  • The edges of the neural plate start to thicken and lift upward, forming the neural folds.
  • The ventral part of the neural tube contains the basal plate, which is primarily associated with motor (i.e., muscle) control.
  • Retinoic acid is required ventrally along with Shh to induce Pax6 and Olig2 during differentiation of motor neurons.
  • Three main ventral cell types are established during early neural tube development: the floor plate cells, which form at the ventral midline during the neural fold stage; as well as the more dorsally located motor neurons and interneurons.

• Meiosis I

  • At the end of prometaphase I, each tetrad is attached to microtubules from both poles, with one homologous chromosome facing each pole.
  • During metaphase I, the tetrads move to the metaphase plate with kinetochores facing opposite poles.
  • There are two possibilities for orientation at the metaphase plate.
  • In plants, a cell plate is formed during cell cytokinesis by Golgi vesicles fusing at the metaphase plate.
  • Two haploid cells are the end result of the first meiotic division.

• Post-Cambrian Evolution and Mass Extinctions

  • Continual changes in temperature and moisture throughout the remainder of the Paleozoic Era due to continental plate movements encouraged the development of new adaptations to terrestrial existence in animals, such as limbs in amphibians and epidermal scales in reptiles.
  • The end of the Permian period (and the Paleozoic Era) was marked by the largest mass extinction event in Earth's history, a loss of roughly 95 percent of the extant species at that time.
  • Another mass extinction event occurred at the end of the Cretaceous period, bringing the Mesozoic Era to an end.
  • Changes in animal species diversity during the late Cretaceous and early Cenozoic were also promoted by a dramatic shift in earth's geography, as continental plates slid over the crust into their current positions, leaving some animal groups isolated on islands and continents or separated by mountain ranges or inland seas from other competitors.

• Classification of Phylum Mollusca

  • Class Aplacophora ("bearing no plates") includes worm-like animals primarily found in benthic marine habitats.
  • Members of class Monoplacophora ("bearing one plate") posses a single, cap-like shell that encloses the body.
  • Animals in the class Polyplacophora ("bearing many plates") are commonly known as "chitons" and bear an armor-like, eight-plated dorsal shell.
  • These animals bear a single conical shell, which has both ends open .
  • The head is rudimentary and protrudes out of the posterior end of the shell.

• Comparing Meiosis and Mitosis

  • Chiasmata develop and crossover occurs between homologous chromosomes, which then line up along the metaphase plate in tetrads with kinetochore fibers from opposite spindle poles attached to each kinetochore of a homolog in a tetrad.
  • In this case, the duplicated chromosomes (only one set, as the homologous pairs have now been separated into two different cells) line up on the metaphase plate with divided kinetochores attached to kinetochore fibers from opposite poles.
  • Meiosis II is not a reduction division because, although there are fewer copies of the genome in the resulting cells, there is still one set of chromosomes, as there was at the end of meiosis I.

• Vascular Tissue: Xylem and Phloem

  • These cells are joined end-to-end to form long tubes.
  • Tracheids have thick secondary cell walls and are tapered at the ends.
  • The tracheids do not have end openings like the vessels do, but their ends overlap with each other, with pairs of pits present.
  • The end walls, unlike vessel members in xylem, do not have large openings.
  • These porous connections are called sieve plates.

• Chromalveolata: Alveolates

  • Many dinoflagellates are encased in interlocking plates of cellulose with two perpendicular flagella that fit into the grooves between the cellulose plates .
  • The apicomplexan protists are so named because their microtubules, fibrin, and vacuoles are asymmetrically distributed at one end of the cell in a structure called an apical complex .
  • The genus Paramecium includes protists that have organized their cilia into a plate-like primitive mouth called an oral groove, which is used to capture and digest bacteria .
  • Many are encased in cellulose armor and have two flagella that fit in grooves between the plates.