Phagocytosis is the process by which phagocytes, such as neutrophils, macrophages, and monocytes, ingest and destroy pathogens and damaged cells. It occurs in five stages: chemotaxis, where phagocytes are chemically attracted to sites of damage or infection; adherence, where they attach to the target; ingestion, where pseudopods surround and engulf the target into a phagosome; digestion, where the phagosome fuses with lysosomes to form a phagolysosome to digest the contents; and killing, where digestive enzymes and toxic molecules in the phagolysosome destroy the ingested material. Phagocytosis is a key part of the immune response.

1. Phagocytosis
• Phagocytes
• Immune response

2. • Neutrophils
• Macrophages
• Monocytes
Image 1.1: Original source of image: http://pixgood.com/neutrophil-organelles.html
Images 1.2: Original source of image:
http://mcdb-webarchive.mcdb.ucsb.edu/sears/immunology/Cells-Organs/monocyte.htm

3. Stage 1. Chemotaxis
• Chemically stimulated
towards sight of
damage
Image 1.3: Original source of image: http://upload.wikimedia.org/wikipedia/commons/8/8a/Chemokine_concentration_chemotaxis.svg

4. Stage 2. Adherence
Image 1.4: Original source of image: Muniz-Junqueira et al.,2009, p.103

5. Stage 3. Ingestion
• Pseudopods meet and fuse, surrounding the
microorganism with a sac called a PHAGOSOME
Stage 4. Digestion
• Phagosome and lysosomes fuse to become a
PHAGOLYSOSOME
Image 1.5: Original source of image:
http://philschatz.com/biology-concepts-book/contents/m45432.html

6. Stage 3. Ingestion
Stage 4. Digestion
Stage 5. Killing
Image 1.6: Original source of image: https://epiehonorsbiology.wikispaces.com/Phagocytosis+2

7. References
Muniz-Junqueira, Maria Imaculada, & Tosta, Carlos Eduardo. (2009). Stages of in vitro phagocytosis of Plasmodium falciparum-infected erythrocytes by hum
Neutrophils are produced. Retrieved from: http://pixgood.com/neutrophil-organelles.html
Openstax Concepts of Biology. Eukaryotic cells. Retrieved from: http://philschatz.com/biology-concepts-book/contents/m45432.html
Phagocytosis 2. Retrieved from: http://epiehonorsbiology.wikispaces.com/Phagocytosis+2
Sears, D.W. (2009). Monocyte and macrophage morphology. Retrieved from: http://mcdb-webarchive.mcdb.ucsb.edu/sears/immunology/Cells-Organs/monoc
Wikimedia Commons. Chemokine concentration chemotaxis. Retrieved from: http://upload.wikimedia.org/wikipedia/commons/8/8a/Chemokine_concentration