Euglena is an elongated animalcule with anterior end slightly broad and posterior end slightly tapering The anterior end bears flagellum. The food particle is captured with the help of flagellum. It is brought near the anterior end which invaginate to form a food cup which becomes totally enclosed and finally internalized as a food vacuole.The digestion is intracellular.

When a cell needs to take in a particle larger than the membrane channels can passage, it will invaginate the cell membrane around the particle(s) and pinch off part of the membrane containing the particles inside the cell membrane. This is called phagocytosis (when the particles are primarily solid) or pinocytosis (when the particles are primarily liquid).

This suggests that the cell membrane is a dynamic structure that can bend and invaginate to form vesicles during endocytosis. It is composed of a phospholipid bilayer with hydrophilic heads facing the aqueous environments (inside and outside) and hydrophobic tails sandwiched in between. The ability of the cell membrane to undergo endocytosis implies its flexibility and capability to change shape.

See this link for nice details...http://people.eku.edu/ritchisong/301notes3.htm

In muscle contraction the transverse tubules transmit the muscle impulse into the inner cell.

Cardiac muscle doesn't go into tetanic contraction due to the effect of calcium ions which are slowly released into the cell during an action potential, prolonging the action potential. As a result, the graph for electrical activity in cardiac cells has a 'plateau' area because of the release of calcium and the decreased membrane permeability to potassium. By the time the action potential is over, the refractory period (channel inactivation period) for the ions are over, and the cardiac cell is relaxed and ready to be excited again. skeletal action potential = 5-10 msec. cardiac action potential = 250 msec.