Question

2ⁿᵈ line of defense: infection control by phagocytes
the 2ⁿᵈ line of defense of the innate immune system acts as soon as pathogens have broken barriers of the 1ˢᵗ line of defense. the human immune system has several specialized cells in order to fight infections. each of these cells plays a significant role in the defense against invading pathogens.
leukocytes (white blood cells)
phagocytes
macrophages
basophiles
eosinophil
neutrophils
monocytes
mast cells
dendritic cells
phagocytes work together with lymphocytes
act as \vacuum cleaners\ - take in pathogens by phagocytosis
lymphocytes
t- cells b - cells nk- cells
action of phagocytic white blood cells:
phagocytes are large, irregularly shaped leukocyte cells that remove bacteria, viruses, cellular debris, and dust particles.
different phagocyte cells work in various locations: neutrophils circulate in the blood, while macrophages are found in lymph, tissue fluid, lungs and other spaces, where they kill microbes before they enter the blood.
using the diagram and the video https://1drv.ms/v/s!au8zke_edcrqhjdri8yvocteo2hr4w, describe the steps in phagocytosis:

Explanation:

1. The phagocyte first identifies and moves toward the invading microbe, extending pseudopods to surround it.
2. The pseudopods fuse, trapping the microbe inside a membrane-bound sac called a phagosome.
3. The phagosome fuses with a lysosome (a vesicle containing digestive enzymes) to form a phagolysosome.
4. Digestive enzymes from the lysosome break down the microbe inside the phagolysosome.
5. Indigestible waste material from the breakdown is packaged into a residual body.
6. The residual body fuses with the phagocyte's plasma membrane, and the waste is expelled from the cell via exocytosis.

Answer:

1. Phagocyte extends pseudopods to surround the microbe.
2. Pseudopods fuse, forming a phagosome enclosing the microbe.
3. Phagosome fuses with a lysosome to create a phagolysosome.
4. Lysosomal enzymes digest the trapped microbe.
5. Indigestible material forms a residual body.
6. Waste is expelled from the cell through exocytosis.