# Cell Specialisation

In multicellular organisms, functions are typically divided between specialised cell types. Cells of similar origin working together are organised into **tissues**. Despite having the same genetic material, the cells of an organism acquire distinct structural and molecular characteristics that enable them to perform their specific role. This process is known as cellular **differentiation**. During differentiation, different genes are selectively switched on and off, leading to the development of specialised cell types.

To illustrate the structural diversity that cells can achieve through differentiation, let us take a look at several examples from hundreds of specialised cell types of the human organism. 

The respiratory epithelium is a specialised tissue which lines the lung airways preventing the entry of pathogens and dust particles into the organism. Its predominant cell type is the ciliated cells. Ciliated cells are adapted to move mucus, a viscous fluid that traps pathogens and foreign particles, towards the pharynx. These elongated cells are characterised by the presence of numerous hair-like structures called cilia, which extend from their surface. The coordinated beating of cilia propels the mucus along the airways, clearing it from the lungs.

<figure><img src="https://3514673221-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FdDE3NSiCXcu5YQDQmgdU%2Fuploads%2FCl2W1EUR5x0ZqT8smn6K%2FFig_63_lung_epithelium.jpg?alt=media&#x26;token=056b710c-b22b-49fd-85df-1451fd8e4319" alt="" width="563"><figcaption><p>Light microscopy image of lung epithelium. Goblet cells secrete mucus and ciliated cells propel the mucus by the beating of cilia<br>Image source:<br>OpenStax College - Anatomy &#x26; Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=30148359</p></figcaption></figure>

Another example of highly specialised cells is macrophages. Macrophages, a subtype of white blood cells, engulf and digest pathogens, such as bacteria, as well as dying cells. Macrophages are capable of moving towards their targets by extending long flexible processes called pseudopodia. Upon encountering a pathogen, a macrophage initiates phagocytosis, ingesting the invader into a vesicle for subsequent digestion.

<figure><img src="https://3514673221-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FdDE3NSiCXcu5YQDQmgdU%2Fuploads%2Fjm0PMVrMWEH1rOnvITTR%2FFig_64_macrophage.jpg?alt=media&#x26;token=ffbf626d-9bcd-4a07-a0cc-24d07620c791" alt="" width="375"><figcaption><p>Light microscopy image of macrophage stretching pseudopodia to engulf two particles<br>Image source:<br>Obli - Transferred from en.wikipedia to Commons., CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=635700</p></figcaption></figure>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://edu.abi.am/molecular-biology/the-cell/cell-specialisation.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.